Sciencemadness Discussion Board - Crystal growth and preparative details of nitrophenols (stypnic, picric acid)

Crystal growth and preparative details of nitrophenols (stypnic, picric acid)

quicksilver - 9-9-2005 at 07:00

One of the most useful (but very short) patents that I have used was US2275172 (1940), in it the author discribes both styphic salts and the ability to control crystal shape (for a pourable true cubic shape, one uses Al in the sulphonization process...amongst others... there are some good ideas there) and effects of bases on the process as a whole. The patent deals with styphic salts but does provide information on a generalized foundation that I felt useful.

This was the provess that I worked with and posted (I think to E&W or here...I don't remember) some years back. It can be scaled up or down and has been the result of a lot of work on my part find the ratios to work well w/ resorcinol. I am actually proud of it as a little lab synth because it really provides consistent bright yellow prisms (good looking crystals!) and it's really my own work. By tweaking it with some of the sulphonization process in US2275172 I have gotten some GREAT crystal shape results!

-----------------
Styphnic Acid

Needed are:
24 grams Resorcinol
30ml H2SO4 @ 95% - 55.5 gr
45ml H2SO4 @ (72%) – 75 grams
175 NHO3 @ 70%
+ H2O

Add 24 gr Resorcinol and 30 ml of H2SO4 (concentrated) to a 250ml beaker and stir at 50C (158 F) for 30 minutes (sulfonation process)*. After the solution has been sitting at this temperature, stir and watch for solidification (it should turn to a brownish pink solid, somewhat creamy). After the material has stood and started to solidify, it is broken up & diluted with 40ml H2O: clean the sulfonation vessel and all is added to the nitration beaker (this also serves to loosen the solid mass of Resorcinol / H2SO4 that occurs as part of the sulfonation process: a mix of H2O and the sulfonated Resorcinol). Here you should have a 500ml beaker with the broken sulfonated Resorcinol and poured into it, 40ml H2O. At this point it is appropriate to further stir the Resorcinol mixed solution from a solid mass to a solution again, add. 46 ml of 62% sulfuric acid (75 grams) to the product and mix /stir as thoroughly as possible then it is ready for nitration. Pour the solution from the mixing vessel into another 500-mL beaker. To review: we have a sulfonated product that is broken into chips and 40ml H2O is added to it, producing a red solution (all is dissolved) and that is readied to be nitrated by adding 62% H2SO4 (45ml /75gr). Then placing this in a water bath, using a separator funnel add 175 ml of 70% nitric acid. Add the acid very slowly, a drop at a time (see note). The addition of nitric acid will cause a vigorous reaction and release toxic gas, use a fume hood or process outdoors. When all of the acid has been added and the reaction has subsided, the mixture is heated for 2 hours on a steam bath or hot plate at 110 C (238 F) to complete the nitration (continue to stir). When this is completed the beaker is placed in another water bath (10 C) and covered. After 8 to 12 hours the Styphnic Acid crystals should have separated. These crystals will need to be filtered with glass filter paper because of the solutions high acidity. Otherwise, pour off most of the acid, dilute with water and filter with regular filter paper. Wash the crystals with several small portions of water and allow it to dry in the open air. Product will be yellow / orange high grade Styphnic Acid.
NOTE: Several elements are very important to the success of this process. First, that the sulfonation be very through. When the H2SO4 is added to the Resorcinol a complete stirring take place so as o create a pink cream solid. This is the basis for sulfonation for Resorcinol. After which H2O is added in correct proportion and the pink solid is allowed to dissolve into the H2O thus creating a red solution of sulfonated Resorcinol. This is the basis for nitration. Any thing less that total solution is bound to oxidize much of the product. Second, is imperative that after nitration takes place with the addition of HNO3 that the solution be heated; this is the element of the nitration process and must be present to achieve a reagent grade material. After that has been accomplished the product will precipitate from the nitration acids and may be filtered off (after a period of time, wherein the whole is allowed to return to room temp). Third: it is very important to the yield percentage that the heat be monitored; too hot and oxidization will occur, too cold and the Styphnic Acid product will not be nitrated to the fullest extent possible and the product will have a high hydrogen content (as would be the case if alkali impurities were introduced to the mix. A critical element in Styphnic acid production is controlling the reaction temperature. A vigorous reaction from nitration will result in loss and low yield through oxidation. Thus it very important to nitrate slowly with corresponding low levels of heat and NO fumes.
Following these steps exactly and this process will result in reagent grade material with consistency. Turning inexpensive technical grade Resorcinol in very expensive, pure, Styphnic Acid crystals!

* This proportion of H2SO4 & Resorcinol may solidify very quickly, thus creating sulfonation. Maintain observation! The pink solid must be achieved (Resorcinol Sulfate) and that broken & dissolved into 40 ml H2O. Proportions may be multiplied or divided to achieve lager or smaller lots. MAINTAIN THESE PROPORTIONS!
------1/21/01

[Edited on 19-9-2005 by chemoleo]

Rosco Bodine - 9-9-2005 at 08:55

Here is a method which I used a few times for styphnic acid which would consistently produce a 90% yield of recrystallized pure product .

10 grams of resorcinol is swirled into and dissolved in 50 ml of concentrated H2SO4 .
The dissolution is moderately exothermic due to the spontaneous sulfonation . After a few minutes a lavender colored precipitate forms and the mixture is allowed to stand for 2 hours . Then the mixture is cooled to 0 C by ice bath and
nitrated by dropwise addition of 20 ml of HNO3 d 1.4 ~68-70% to the stirred mixture kept below 35C until all is in solution except for small amount of end product which may be appearing . On recooling to 10C , 20 ml fuming HNO3 d 1.5 ~ 97% is added dropwise to the stirred mixture keeping temperature below 25C . The stirring is stopped and the mixture allowed to stand in the cold bath for a few minutes . The reaction mixture is then removed from the cooling bath and the temperature allowed to rise
from the exotherm . Some end product should be seen precipitating at about 28C and the mixture will foam and increase in volume and temperature .
The temperature rise will accellerate at an induction point of about 38C , really accelerating at 45C and from there spiking upward to 75C . Only an intermittent stirring should be done during the exotherm because the gas bubbles actually dilute the volume density and tend to regulate the reaction . Stirring the mixture causes the temperature to spike again by reconcentrating the mixture . Only stir periodically when the reaction temperature is falling and stirring down the foam will kick the reaction and temperature back up again . Generally only stir the mixture if the temperature drops below 40C from the unaided exotherm of the reaction itself . When the reaction temperature ceases to rise above 35C when stirred , allow the mixture to stand without stirring for a half hour and then dump the reaction mixture onto 250 grams of ice cubes and rinse the flask with 200 ml ice water , everything added together in one crystallizing bowl .
After 30 minutes the mixture is filtered and the crystals rinsed on the filter with about 40 ml ice water . The crude styphnic acid is redissolved in about 900 ml of boiling water , and on cooling deposits about 20 grams of hexagonal plates of pure very pale yellow styphnic acid . Yield is 90% of theoretical based on resorcinol . This method works fine for small batches but is possibly not directly scalable upwards without some provisions for temperature control . For a batch this size , a 500 ml flask is sufficent ,
a 250 ml size is marginal and will threaten to overflow at the peak of the reaction , likely would overflow without any stirring down the mixture which at times forms a solids filled curd , more than being a liquid consistency . The mixture becomes more liquid again as the reaction completes .

quicksilver - 19-9-2005 at 06:33

Quote:

Originally posted by Rosco Bodine
Here is a method which I used a few times for styphnic acid which would consistently produce a 90% yield of recrystallized pure product .

I tryed yours and (as usual) it was excellent. The resultant was a much higher final yield. Should you ever have the chance, in patent US2275172 there is a section wherein the author describes the use of additions to the sulphonation process to alter crystal shape (to allow for ease of pouring the product) he adds Al and the crystal form is a well formed cube. For long rectangular prisms he uses catechol. Which profides a shape that "flattens" when compressed.
The one area wherein I have heard mixed opinions was that temprature affected crystal SIZE. I have heard often enough that colder environments produced smaller crystals. Indeed in my lab posted above, my crystals were small and uniform, yet the batches from your lab were not smaller even though the temp was lower. Thinking that it would produce larger crystal forms (do to lower temp): it DID produce a higher yield.
However, it has not been my experience that this generalization occured in nitrated phenols....your thoughts here would be a help...

Rosco Bodine - 19-9-2005 at 15:07

The higher nitration stage using fuming HNO3 sure does put a nice finishing touch on this particular styphnic acid synthesis .

Fuming HNO3 d 1.5 , has its usefulness , and this is one of those times .

This is actually a pretty well optimized synthesis , but I deliberately avoided calling it that up front because from experience I knew that posting an unpublished synthesis under the banner of " optimized " would soon have me busy defending the proportions , temps , and every other detail , including the d 1.5 HNO3 for the nitration " kicker " . There were several experiments where I gradually worked it out what was needed to push the final stage nitration to completion , at relatively mild temperatures which would not favor oxidation byproducts and
therefore prevent contamination of the desired endproduct , so that it could be obtained pure and nearly colorless in good yield from only one recrystallization .
After a half dozen experiments and charted results compared and notes studied , that was about the best I could do ....so it probaby is " optimized "

Styphnic Acid is much less soluble than is picric acid and it is easier to crystallize in dense gritty well formed crystals from its strong solutions in boiling distilled water .
A similarity it shares with picric acid is a very very pale yellow color when pure , and dry . But even a trace of moisture or any impurity will greatly intensify and darken the color , and can also complicate obtaining the dense crystals which will form from hot solutions allowed to stand undisturbed while slowly cooling . For both materials , the largest crystals form in the very hot solution and have mostly completed forming while the solution is still slightly warm .

In near saturated solutions very near the boiling point , I have observed nascent crystals of picric acid first appearing as merely a pinpoint of reflected light grow to flat rectangular plates with pointed ends attain 10 mm length in 5 minutes . In bright light , a spiraling ribbon " mirage effect " in the liquid off the pointed ends of the crystals can be observed as the telltale sign of current in the liquid dragged along by the depositing molecules which build the crystal larger at a barely perceptible visible rate . The rate slows down drastically at lower temperatures and you cannot actually watch an individual crystal grow in length .

IIRC the purpose of the adulterants added to the sulfonation or nitration mixtures for styphnic acid was to produce a deliberately impure product where the impurities were found beneficial as modifiers of crystallization in the lead styphnate which would be the ultimate end product . Various crystal forms of the lead salt were found to have different firing properties when used in primers .

quicksilver - 19-9-2005 at 16:32

Quote:

Originally posted by Rosco Bodine

IIRC the purpose of the adulterants added to the sulfonation or nitration mixtures for styphnic acid was to produce a deliberately impure product where the impurities were found beneficial as modifiers of crystallization in the lead styphnate which would be the ultimate end product . Various crystal forms of the lead salt were found to have different firing properties when used in primers .

Indeed: I noticed that in the various crystal forms of the lead salt in the "clathrate-patent"; that appeared to be the intention. Frankly I had a damn hard time finding some of the various salts....and I have access to a fairly good lab.
I have been using a microscope to closely examine some of the crystals and those from batchs w/ impurities are quite irregular. In fact, consistently inconsistent in form. However using a fairly crude method of determining mp of the various batches of picric acid I find that it is still tri-nitrated (my varience goes no lower than 122-123 C). It had been my thought that the impurity (s) would alter the final product to a mix of di & tri nitrated product. I was wrong; according to mp temp.
Now I have a supply of PHLOROGUCANOL & had wanted to work on trinotrophloroglucanol but when I looked at a patent the sulfonation used a ridiclous amount of H2SO4 (1 LITER per 50 grams!). This would make lead salts of TNPG completely inappropriate for commercial usage. But yet, it found itself in patents for rifle primers in Europe.....(?) What gives?

Is the sulfonization of Phloroglucanol REALLY in need of such an excess?

Rosco Bodine - 19-9-2005 at 20:37

The presence of impurities in picric acid substantially increases the solubility of the mixed material beyond what would be the solubility for the amount of pure picric acid the mixture contains . But the impurities are * slightly * less soluble at the boiling point of a saturated solution of the unpurified picric acid , so boiling down a saturated solution of the crude picric acid will begin to precipitate the dark colored material and the precipitation will continue to a point , but then it will stop precipitating , even as the boiling down continues , until further along a combined precipitate will occur which appears to be a eutectic melt of the impurity but is mostly picric acid and a small percentage of the impurity . Removing what is mostly
the precipitated dark colored impurity without precipitating the bulk of the picric acid can be done by a special technique of manipulating the slightly different solubilities at and just below the boiling point of the saturated solution of crude picric acid .

Observe when boiling down the saturated solution of crude PA and note when the red colored oily impurity precipitates but seems to stop increasing in accumulation as the boiling continues
for perhaps three more minutes past the time steady accumulation ceases . Remove the flask from the hotplate and
set it on pad to cool slightly , and the solution should become milky and opaque having the appearance of rusty water .
This is an emulsion of the impurity separating from solution and it is a persistent emulsion which will be destabilized by reheating just to the boiling point , but not brought to a free boil . The flask containing the cloudy liquid
and having cooled just a few degrees is returned to the hotplate and as it warms the emulsion will break and more of the dark red oil will settle out as the liquid heats and clarifies . The flask is removed from the hotplate and returned to the pad . If the flask is tilted all of the dark red impurity will settle in a single globule ,
where it will solidify on cooling slightly ,
just before the clear solution above it begins to cloud again which should be avoided since that will be mostly picric acid . A small stirbar can be dropped into the tilted flask and the cold stirbar will help set up the globule of impurity . The supernatant still very hot solution of picric acid can be decanted away from the soldified glob of impurity or it may be removed by sliding it up the wall of the flask using a magnet against the outside .
The flask is returned to the hotplate and
the boiling down is continued and the process repeated until the solution has been stripped of the dark colored impurity
and the solution color is yellow to slightly orange . The boiling solution will only precipitate a few tiny droplets of the impurity , not even one full drop when it has been substantially stripped of the
" red goo " . The saturated boiling solution may then be diluted with an added portion of distilled water about one fourth its volume , and then to the hot solution brought just again to the boiling point is added about one fortieth the total volume of 31.45% HCl with stirring . A greatly purified product will
be precipitated on slow cooling .

A subsequent recrystallization of the product from plain distilled water will require a good bit more water for the dissolution of the highly purified picric acid , than was the original volume of the solutions of crude product from which it was obtained .

quicksilver - 23-9-2005 at 06:54

Quote:

Originally posted by Rosco Bodine
The presence of impurities in picric acid substantially increases the solubility of the mixed material beyond what would be the solubility for the amount of pure picric acid the mixture contains .

This is an extremely important concept (the whole of the post, not just the snip). Too many people don'tl continue with their synth at the precise stage where they can make a difference.
I think anyone who has been working with nitrated phenols and has had a bit of trouble should read over that pervious post.

Rosco Bodine - 23-9-2005 at 08:53

There is a solubility difference for the impurities at the boiling point of saturated solutions and I described a way to exploit the solubility difference for precipitating the impurity .

But from what I have been seeing , the solubility for the impurity is actually somewhat greater than the solubility of picric acid , for solutions of the crude picric acid which are well below saturation at whatever temperatures . So the way the
precipitation proceeds , and the way it is
more favorable for either precipitation of the impurity , or more favorable for precipitation of the picric acid , will vary depending on the relative concentration of each to the other , and the level of saturation of the combined system at
a given temperature . Trying to pin down the most efficient sequence and conditions for the purification is like trying to nail jello to a wall because the mutual solubility dynamic varies with temperature and concentration and pH . The more impure is the crude picric acid from nitration , the more difficult and tedious is the purification process . This is precisely why it is desirable that the crude product gotten directly from the nitration mixture should be as pure as possible , since that greatly simplifies everything to follow .

If a very complete nitration producing very few byproducts is accomplished as the source for the crude picric acid , then the crude picric acid can be obtained pure
directly from the first recrystallization from boiling water . But any inefficiency in the nitration causes an exponential increase in the difficulty of purifying the crude product , which will be heavily contaminated with impurities which are inclined to co-crystallize as mixed and entrapped occlusions , adversely affecting the color and density and crystal quality of the end product .

The level and nature of the impurities varies with both the nitration process and the precursor used , so what details are worked out as best for one synthesis do
not necessarily apply to another synthesis . The one priority that is completely evident is to perform the nitration as cleanly and completely as possible , which eliminates right there so much " crystallization algebra " as is otherwise going to follow if the nitration isn't everything it should be .

quicksilver - 24-9-2005 at 07:30

Quote:

Originally posted by Rosco Bodine
There is a solubility difference for the impurities at the boiling point of saturated solutions and I described a way to exploit the solubility difference for precipitating the impurity .

-=snipped for brevity=-

The level and nature of the impurities varies with both the nitration process and the precursor used , so what details are worked out as best for one synthesis do
not necessarily apply to another synthesis . The one priority that is completely evident is to perform the nitration as cleanly and completely as possible , which eliminates right there so much " crystallization algebra " as is otherwise going to follow if the nitration isn't everything it should be .

While the idea of using ammonium nitrate is a very interesting one (& a one I would like to attempt) I don't know what AN would be used but the most cost effective is, of course, prills. And with that the clay and coating there-upon. That may be at issue where we look at the impurity issue vs. cost efficiency. The extra step of purifying the AN prior to usage in nitration would eliminate this obviously but the extra step would set us back time/cost-wise.
I have wanted to emulate your experiment with AN and as I was about to proceed I realized that I had prills to work with. Crushing them and purifying them would involve some serious time usage. The larger question to me is would it be worth the time?
Sodium Nitrate is available via a hardware store (USA- ACE) purchace of a brand of lawn & garden supply product marketed by a company called:"BONIDE", they make a "Nitrate of Soda" (15-0-0) that comes in a box form of several pounds for about $1 or 2 a lb..... but here again I noticed that they are prills!
The thing is that all these methodologies involve the possablity of introducing impurites via the materials used in nitration.

After all what's the point of using very high end products to achive a high end resultant? Where is the challenge?
Extraplolating the least expensive technique for the best product I keep coming back to the added work involved in initial purification. I don't know if there is even a source for wool that has not been contaminated by something. And even though I could get raw wool from the County Fair - would that raw animal organic matter be appropriate for nitation? When I examine the various NC patents they point to highly refined sources (bleached cotton batting, etc). Could it also be that oil of wintergreen also needs an additional step prior to nitration that has been missed; something unique to a fliud?
My comment heads in that direction due to my noticing that there is an acute difference between Reagent grade resorcinol which is a hardened flake, somewhat crystaline and Technical grade product that is fiberous almost looking like fine hairs or fiberglass. Indeed, when they are nitrated using the same technique the Technical grade is a slight "peach" yellow, while the Reagent grade is a very bright yellow prism.

Rosco Bodine - 24-9-2005 at 11:19

The use of nitrates as concentrated solutions does simplify addition of the nitrate to the sulfuric acid solution of
the sulfonated organic material to be nitrated . I have mentioned that using
a solution of two or more different nitrates
can make possible an even more concentrated solution having less water content which would dilute the nitration mixture . Such solutions of mixed nitrates have been developed to provide a liquid oxidizer phase having low water content for use in manufacture of emulsion explosives . Some of these solutions are
essentially a eutectic salts mixture which
also exhibit a enhanced cosolubility in the presence of a small amount of water , similarly as they have a much lowered melting point even in the absence of water altogether . Whether this is commonly true for many or all the eutectics I do not know , but I suspect it is common for there to be a parallel .

Many such mixtures are likely , but I do not have them all listed or charted . One that I can mention is from US5454890 ,
which is an oxidizer salt solution consisting of 77% NH4NO3 , 11% NaNO3 , and 12% H2O . I do not know what is the
minimum temperature at which the mixed solution begins to crystallize but suppose that even if a few per cent more water was needed for room temperature stability , it would still have less than half the water content of a plain NH4NO3 solution .

I know I have seen other compositions mentioned and I will share any others I find .

Quince - 25-9-2005 at 00:01

I'm about to do a synthesis, so I'll try the mixture from the patent that Rosco just posted.

Is there any advantage to using HNO3 instead of nitrates? Also, has anyone tried using HNO3 extracted by the methylene chloride method, without first removing the methylene chloride (the patent mentions that a number of nitrations can be performed without that removal)?

[Edit] This far, I'm having trouble getting the nitrate mix to dissolve fully, despite using a hot water bath and fast stirrer.

[Edit] Even increasing water to 20% and heating in microwave until steam appears, the solution crystallizes into a soft, semi-liquid mass. I guess I'll just give up and use it as is.

[Edited on 25-9-2005 by Quince]

Rosco Bodine - 25-9-2005 at 06:12

Those proportions aren't working for me either . I am trying some adjustments to the ratio of nitrates with the NH4NO3 in higher percentage like 91-94% to see if the desired " salting effect " can be obtained . Sorry for the bum proportions from that patent . Evidently those are proportions used for some sort of crystallization control instead of solubility
enhancement . However I am certain that the salting effect does occur for solutions of mixed nitrates in certain proportions . It may require some experiments to determine what ratios are good if such systems can't be found published somewhere .

At worst case a heating tape can be used to warm an addition funnel above 60C , where straight solutions of NH4NO3 are
stable as 80% solutions .

From what I have observed of these strong solutions of nitrates , they will best be prepared a couple of days in advance and allowed to stand and filtered before use , since they tend to cloud and precipitate any impurities when
simply allowed to stand for awhile .

It could also be useful to dissolve NH4NO3 in HNO3 in order to provide an additional source of HNO3 without the introduction of excess water . NH4NO3 is very soluble in HNO3 , to an extent of 50%
at 15C . For example see PATR , A-329 for a chart . This could be a very useful method of
" stretching " and reenforcing the nitrating capacity of ordinary concentrated nitric acid , by in effect forming an additional amount of fuming HNO3 in situ , when the addition is being made to a sulfonate in sulfuric acid . This
may be adaptable to the styphnic acid synthesis , as a substitute for the d 1.5 fuming acid addition , simply by dissolving the equivalent amount needed of NH4NO3 in the ordinary d 1.4 acid , and
proceeding . It would not be as efficient ,
and it would have to be tested to see how well this would work .

[Edited on 25-9-2005 by Rosco Bodine]

Quince - 25-9-2005 at 14:49

Different procedures I've found have differing amounts of H2SO4 specified for a given amount of ASA. What's the minimum? At the moment, I have 82 g of ASA in 470 mL H2SO4, waiting to add the nitrate mix, but I'm wondering if I need to add any more H2SO4 (boiled drain cleaner), especially given the water content in the nitrate mix (it would be hard, though, as I'm about to overflow my largest flask...).

[Edited on 25-9-2005 by Quince]

Rosco Bodine - 25-9-2005 at 16:58

When I use solid nitrate as NaNO3 , the right amount of 92% H2SO4 is 4 ml for each 1 gram ASA , and 1.8 grams NaNO3 .

You are using somewhat more H2SO4 , which will help compensate for the extra water in the nitrate solution , and both those added liquids should give a much thinner reaction mixture . I would still recommend a reaction flask at least 3 times the total volume of the completed reaction mixture because you are going to get foaming from the decarboxylation .
Go very slowly with the additions because there is a time lag in the response of the reaction , with the foaming not immediately appearing according to real time tracking the rate of addition , but lagging two or three minutes later . It is very easy to add to much , observing no immediate reaction , and then a couple of minutes later you see the effect ....too late to slow the addition rate increase if you have overcompensated , which will cause an overflow . In general you need to push the temperature during the entire nitration , but let the appearance of red fumes be your indicator that the temp and/or addition rate needs to be decreased to avoid the loss of nitrogen .

The decarboxylation foaming may occur predominately during the first half of the nitration or it may continue through the entire nitration . Push the temperature during the second half of the nitration ,
maintaining at least 105 C , and finish at 120 C , holding the completing reaction at ~120 C for 15 to 30 minutes , and continue stirring the mixture as it cools .

Quince - 25-9-2005 at 18:14

Well, I guess I'll have to use my French coffee press, as it's the only Pyrex vessel I have that large. I guess if my coffee tastes too bitter, I'll know I didn't wash it well...

[Edit] This semi-liquid mush is not working very well. The problem is that unlike powdered nitrates, the drops here are too big and don't mix in fast enough in the acid, resulting in lots of NOx.

[Edited on 26-9-2005 by Quince]

quicksilver - 25-9-2005 at 20:46

Quote:

Originally posted by Quince
Is there any advantage to using HNO3 instead of nitrates? Also, has anyone tried using HNO3 extracted by the methylene chloride method, without first removing the methylene chloride (the patent mentions that a number of nitrations can be performed without that removal)?

[Edit] This far, I'm having trouble getting the nitrate mix to dissolve fully, despite using a hot water bath and fast stirrer.

[Edit] Even increasing water to 20% and heating in microwave until steam appears, the solution crystallizes into a soft, semi-liquid mass. I guess I'll just give up and use it as is.

Quote:

I had wondered about the methlene chloride issue for a while now. I believe that in a nitration of a phenol it may not be a good idea due to the flamability issue and heat produced by the process. MC boils at a very low temp (40C) and I have heard some horror stories with simple distilltion where that was not closely monitored... However I have heard that the use of same (with HNO3) in the preperation of nitramines (& cycllic nitramines) that had been great. - No problems ! It's been my understanding that the nitration itself would not be curtailed by MC but that it presents a significant fire hazard. At cool temps it would be a boon to a nitration involving higher strength nitric acid.
Dealing w/ the solid nitrates; I also have had a very mixed bag. The method I settled on was prior preperation using a quality magnetic stirred / hotplate and when my solution was mixed to my satisfaction I would cool it and use it at a later time. Unfortunatly this procedure & making sure of the purity of the nitrate in question lengthens & complicates the whole synth. I really like the idea of using solid nitrates but for reasons of economy. And therefore I have to work with prills. They have a wax or clay coating (or both) and that presents a problem with both the solution prep and the purity issue.

On another note I have used a process wherein picric acid is prepared by nitration of a nitrosophenol intermediate by preparing the phenol with sodium hydroxide and sodium NITRITE. The resulting nitrosophenol intermediate is then nitrated by a standard nitration process using strong HNO3 - and in this instance methlene chloride / HNO3 may not be exposed to much heat. Or a H2SO4 / solid nitrate mix may work. In any instance it is ment to be processed a much lower temp.
Unfortunatly it comes from a UK patent application (#365, 208 David Salter, 1973) so I am having trouble getting a PDF file....

quicksilver - 25-9-2005 at 21:08

Quote:

Originally posted by Rosco Bodine
The use of nitrates as concentrated solutions does simplify addition of the nitrate to the sulfuric acid solution of
the sulfonated organic material to be nitrated . I have mentioned that using
a solution of two or more different nitrates
can make possible an even more concentrated solution having less water content which would dilute the nitration mixture . Such solutions of mixed nitrates have been developed to provide a liquid oxidizer phase having low water content for use in manufacture of emulsion explosives . Some of these solutions are
essentially a eutectic salts mixture which
also exhibit a enhanced cosolubility in the presence of a small amount of water , similarly as they have a much lowered melting point even in the absence of water altogether.

I know I have seen other compositions mentioned and I will share any others I find .

I was unawair of the "mixed-nitrates" concept...and PLEASE; if you do find material related I would deeply apprieciate seeing it!

- I too use the PATR but find that patents are making much more impact in finding answers, new proceedures, & use of my time. Some of the most interesting stuff I have found have come from US patents thus far.

As I have the same trouble accessing UK patents, as you have noted yourself, that site is a real pain. But the older, valuable patents (where they were nitrating everything under the sun) and the older techniques, seem to originate in the UK.

Quince - 26-9-2005 at 01:03

Considering the amount of water needed for the purification step, I ended up using a stainless steel vessel as I don't have any Pyrex to fit 2 L. From what I've found on the Web, most stainless steel alloys are listed as resistant to picric acid, so I'm hoping that even at the higher temperature, contamination of the picric acid from the stainless steel will be minimal.

picric acid from sulfanilic acid

Rosco Bodine - 26-9-2005 at 02:06

@quicksilver

I couldn't find that patent under the number or the name you gave above ,
but while searchingI did find something similar which may give the most pure picric acid directly from nitration , of any of the processes I have ever seen described . And the sulfanilic acid precursor is a mundane , non-hazmat type of starting material which definitely fits in this discussion of alternate precursors and methods .

Attachment: GB16371 Picric Acid from Sulfanilic Acid.pdf (138kB)
This file has been downloaded 1271 times

quicksilver - 26-9-2005 at 07:27

Quote:

Originally posted by Rosco Bodine
@quicksilver

I couldn't find that patent under the number or the name you gave above ,
but while searchingI did find something similar which may give the most pure picric acid directly from nitration , of any of the processes I have ever seen described . And the sulfanilic acid precursor is a mundane , non-hazmat type of starting material which definitely fits in this discussion of alternate precursors and methods .

Thnak you for posting that one.....
I tried to find the nitroso intermediate thing also...Patent applications are even tougher than secured patents at that site. I will keep trying as it's a good one.

In the instance of the patent you posted I believe that sulphanlic acid is used in the dye industry; is there an OTC source?

Ramiel - 26-9-2005 at 08:25

This is practically off topic, however:
I would be interested to know how long it takes the crystals of SA to come out of solution. I would have thought that the crystallization of the bulk of the product would be almost immediate when the solution of nitrated product is cooled to 10*C. Am I missing something? What is the purpose of the (relitively) long sitting time at low temperatures?

With respect to the question about the effect of temperature on crystallization;
It has always been my experience that the slower a solution is cooled down - the larger and more uniform crystals are produced. I understood that as the solubility of the solution <html><i>slowly</i></html> decreaces, the product is 'forced' out of solution 'onto' a crystal seed more slowly, giving a more ordered crystal. Entropy has a part to play in there somewhere too IIRC.

Sooo, perhaps letting your solution quench very slowly (stop heating the water bath even! taking a matter of hours to cool down) by my logic yeilds bigger, more uniform crystals. For what it's worth.

- D

Quince - 26-9-2005 at 14:23

Having left a batch of picric acid (precipitated with the help of HCl) to dry in a stainless steel vessel, this morning I woke up to find the crystals touching the metal have turned black and brown...

Will a recrystallization be able to separate most of this out, or should I throw the whole batch away?

[Edit] The reaction only happened where the crystals had completely dried, around the sides, and the metal had somewhat corroded. On the bottom, where the crystals were still wet, there was no reaction with the steel at all. Can someone explain this?

[Edited on 26-9-2005 by Quince]

Joeychemist - 26-9-2005 at 19:19

Metal Picrates were most likely formed. The residual HCl in Picric Acid most likely attacked the steel and once the HCl had evaporated the Picric Acid attacked the steel forming Metal Picrates. Picrate salts cannot survive in an acid medium; they are converted back to Picric Acid.

Quince - 27-9-2005 at 03:14

Thanks, that made it all clear.

Why do people seem to prefer the long needle-like crystals? Wouldn't they be more sensitive, due to breakage when moving and packing them?

Also, during boiling down for the second batch, it seems some picric acid is evaporating along with the water, as a cool surface above the boiling liquid accumulates a yellowish condensate from just the steam, without there being any spray (even if I remove from the heat so boiling stops).

In regards to storage, is alcohol as effective a desensitizer as water? I ask as it's much faster to dry alcohol.

[Edited on 27-9-2005 by Quince]

quicksilver - 27-9-2005 at 07:05

Quote:

Originally posted by Ramiel
This is practically off topic, however:
I would be interested to know how long it takes the crystals of SA to come out of solution. I would have thought that the crystallization of the bulk of the product would be almost immediate when the solution of nitrated product is cooled to 10*C. Am I missing something? What is the purpose of the (relitively) long sitting time at low temperatures?

With respect to the question about the effect of temperature on crystallization;
It has always been my experience that the slower a solution is cooled down - the larger and more uniform crystals are produced. I understood that as the solubility of the solution <html><i>slowly</i></html> decreaces, the product is 'forced' out of solution 'onto' a crystal seed more slowly, giving a more ordered crystal. Entropy has a part to play in there somewhere too IIRC.

Sooo, perhaps letting your solution quench very slowly (stop heating the water bath even! taking a matter of hours to cool down) by my logic yeilds bigger, more uniform crystals. For what it's worth.

- D

There is a ratio of time vs yield as you pointed out regarding the PA coming out of solution. It certainly could be formed right away. I don't know if there exists a greater possibity of lower yields if the material is forced out via pouring into cold water, the nitrated mix; but it has been my personal experience that for the best yield slow is the way to go for shape and consistency.
I believe that you are correct in you second query. However PA, per se' preents little danger if moist and the larger crystals allow the individual to use certain mp apperatus more effectivly. For myself I enjoy seeing the differing structure of the crystal in various compounds I frankly attempt to grow them larger and well formed (except primares, peroxides, & things of that nature). Shape also helps determine the purity of the compound in certain instances as well. I continue to use a microscope in conjuntion w/ many synths... It really has helped & I just find it facinating.

quicksilver - 27-9-2005 at 07:32

Quote:

Originally posted by Quince
Thanks, that made it all clear.

Why do people seem to prefer the long needle-like crystals? Wouldn't they be more sensitive, due to breakage when moving and packing them?

Also, during boiling down for the second batch, it seems some picric acid is evaporating along with the water, as a cool surface above the boiling liquid accumulates a yellowish condensate from just the steam, without there being any spray (even if I remove from the heat so boiling stops).

In regards to storage, is alcohol as effective a desensitizer as water? I ask as it's much faster to dry alcohol.

[Edited on 27-9-2005 by Quince]

I don't know if you could determine if you are loosing material if the PA is still is in solution; it is a dye after all and yellow solution will be everywhere. Measuring weight when dry is the only sure method to know if you are actually loosing material in evaporation (I think it's doubtful if we are only speaking of evaperation).
Allowing PA to remain moist and off of any threads or frictional surfaces on the final container would maintain a safe environment for the most part regardless of size or shape. Some compounds [primaries and secondaries] would be problematic with crystals of size but TNP, TNR, or TNPG don't present that issue and especially when moist. But even so, the sensitivity of nitrated phenols or benzenes is not that high especially in comparison to the nitramines as a group) On that note the nitrate ester nitramines such as Dinitrooxydiethylamine Nitrate (DNAN) is famous for being detonated from impact, etc as a secondary. But it's not that pretty or useful in a variety of areas like TNP.
The use of a solution of greater solubility such as alcohol would possabily retain more of the product in solution. But for the purpose of simply drying it and using same, it's perhaps a more convienient way to go. But for myself I would be hesitant only because I may loose some of the better looking crystals when it reforms (no big deal to most folks). However, that is with nitrated phenols....there are some compounds that it has been said, could form larger crystaline structures via alcohol and it would become a danger (i.e. lead azide).

[Edited on 27-9-2005 by quicksilver]

Rosco Bodine - 11-10-2005 at 20:23

Quote:

Originally posted by Quince

Is there any advantage to using HNO3 instead of nitrates?

Using nitric acid results in a thinner mixture due to the absence of bisulfate byproduct from the reaction of the nitrate and the sulfuric acid , and a lesser amount of sulfuric acid is required since that amount which would be reacted with the nitrate to produce nitric acid in situ is not needed when the nitric acid is supplied externally . The additional amount of sulfuric acid needed as a solvent an / or liquid carrier for the solids in the nitration mixture so that the mixture remains stirrable is also reduced when the nitric acid is supplied externally .

But all things considered , it may not be as efficient to use nitric acid as to use the solid nitrate , or nitrate solution in nitric acid or water , and sulfuric acid in the increased amount required .

The usual opinion which has been expressed is that nitric acid has a higher nitrating effect than solid nitrate mixed with sulfuric acid , but for nitrations of certain materials it has been observed by experiment that higher yields are produced by the solid nitrate and sulfuric acid mixture than for similar molar strength nitrating mixtures using fuming nitric acid d. 1.5 . Urbanski supports this observation about the evident higher nitrating effect of solid nitrates mixed with sulfuric acid as a generality , but in my own experiments it tends to be somewhat reaction specific and depends on what thing is being nitrated , whether it is nitrated better by solid nitrate with sulfuric acid , or a mixed acid nitrating scheme using nitric and sulfuric acids in
whatever sequence or proportions .

Different solid nitrates have different nitration strengths or activity in combination with sulfuric acid . See the attached file for a comparison of various solid nitrates activity as nitrating agents increasing above nitric acid .

In my opinion it is evident that some amount of nitrosylsulfuric acid is formed in the nitrating mixture when solid sodium nitrate is used for the nitration of sulfonated ASA in 92% sulfuric acid .
When the completed nitration mixture is allowed to cool to about 92C and cautiously diluted with water streamed onto the inside walls of the flask , stirred into the mixture , hydrolysis of the nitrosysulfuric acid occurs and a steady evolution of NO2 and perhaps some nitric acid vapors appears . This hydrolysis is
exothermic and the products have oxidizing properties , which is likely the mechanism responsible for unexpected
" runaway reactions " which sometimes are observed in nitration mixtures which are near or at completion of the nitration .
In nitration mixtures where the water content is low , the nitrosylsulfuric acid accumulates , and the stability of the mixture depends upon the temperature and the water content , so the nitration process completion temperature and the composition of the spent acids must be deliberately controlled to enable the hydrolysis to be done by manual dilution of the finished nitration mixture , instead of occurring spontaneously at some unfavorable temperature and water content in an unfinished nitration mixture , resulting in a final nitration stage runaway . It requires some trial and error process engineering to establish the proportions of safe and efficient mixtures and determine the reaction temperatures and times which are optimum for nitrations of specific materials .

With regards to the mixed nitrates eutectics which I mentioned earlier in connection with the possible salting effect that produces anomalous increases in solubility , I found one tertiary eutectic in Urbanski 3 , page 257 .

66.5% NH4NO3
21% NaNO3
12.5% KNO3 f.p. 118.5 C

I am uncertain if this mixture exhibits the salting effect for increased water solubility in the same proportions as for the effect on lowered melting point for the eutectic . The proportions for the salting effect are posssibly different and
I have no idea where such solubility anomalies are charted for reference , but such mixtures do exist .

Attachment: Page 46 from Urbanski vol. 1.pdf (8kB)
This file has been downloaded 2649 times

Rosco Bodine - 13-10-2005 at 07:03

Quote:

Originally posted by Quince
Why do people seem to prefer the long needle-like crystals?

Purity , and identification , ease of filtration and drying , bulk density , and sensitivity to initiation are all favored by production of the picric acid in a very pure and crisply crystalline form . The crystals of picric acid first appear as rhombic plates which then lengthen into elongated flat hexagonal blades which can reach 40 mm in length by 2 mm wide in thirty minutes . The crystals are thin and brittle and fragile , and settle to a layer which forms an acicular mass of porcupine like blades growing in all directions . The open structure will occupy a third the volume of the aqueous supernatant solution after slow cooling undisturbed of a boiling saturated solution . The action of a stirbar will break up the crystals into a freely pourable form , and a tinkling sound will be made by the breakup of the crystals as if one was stirring a jar full of thin glass fragments from broken cover slips or slivers of glass from shattered Christmas tree ornaments . If the stirring is continued for too long , the broken up crystals will actually be wet milled into a fluffy and low density powder , so to obtain a good bulk density the disturbing and breakage of the crystals must be carefully watched and limited in extent , and stopped when the desired aggregate density for the material is reached .

Quote:

Wouldn't they be more sensitive, due to breakage when moving and packing them?

That's the whole idea , but there is no danger of initiation of picric acid from anything less than a hammer blow like impact . Normal handling of picric acid will not generate sufficient impact to initiate it accidentally . Like TNT , picric acid is a very safe explosive and very difficult to detonate unintentionally .

Quote:

Also, during boiling down for the second batch, it seems some picric acid is evaporating along with the water, as a cool surface above the boiling liquid accumulates a yellowish condensate from just the steam, without there being any spray (even if I remove from the heat so boiling stops).

Picric acid has a very slight volatility at elevated temperatures . More than likely
the carryover you have observed is due to microscopic particles of the solution , than from actual vapors of picric acid , but in either case it would be only a few milligrams , escaping from even boiling away several liters of solution . The intensity of the dye effect is such that even the smallest particle will cause a tint to be observable wherever it lands on a moist surface .

Quote:

In regards to storage, is alcohol as effective a desensitizer as water? I ask as it's much faster to dry alcohol.

I am not certain , but I doubt it . The water relates to reducing flammability also , which of course alcohol would do just the opposite , and for that reason would seem not to offer any advantage ,
probably being counterproductive in terms of overall safety .

In my own opinion it is unnecessary to store picric acid wet with 20% water .
This was probably something developed as a recommendation for the safer shipment of the material , since the forces generated by transportation accidents are much higher than any forces generated by dropping a bottle onto the floor . Now when it comes to
" accidentally " tossing a jar out a fourth story window , maybe 20% moisture would be a wise precaution

But for ordinary handling , picric acid is not likely to be any significant danger in any usual scenario . Nothing however is ever completely idiot proof

So this is one of those matters where it is a matter of discerning , personal discretion and situational awareness .

quicksilver - 14-10-2005 at 07:24

Quote:

Originally posted by Rosco Bodine[
Purity , and identification , ease of filtration and drying , bulk density , and sensitivity to initiation are all favored by production of the picric acid in a very pure and crisply crystalline form . The crystals of picric acid first appear as rhombic plates which then lengthen into elongated flat hexagonal blades which can reach 40 mm in length by 2 mm wide in thirty minutes . The crystals are thin and brittle and fragile , and settle to a layer which forms an acicular mass of porcupine like blades growing in all directions . The open structure will occupy a third the volume of the aqueous supernatant solution after slow cooling undisturbed of a boiling saturated solution . The action of a stirbar will break up the crystals into a freely pourable form , and a tinkling sound will be made by the breakup of the crystals as if one was stirring a jar full of thin glass fragments from broken cover slips or slivers of glass from shattered Christmas tree ornaments . If the stirring is continued for too long , the broken up crystals will actually be wet milled into a fluffy and low density powder , so to obtain a good bulk density the disturbing and breakage of the crystals must be carefully watched and limited in extent , and stopped when the desired aggregate density for the material is reached .

When I first noticed the actual vibration of crystals within the flask; it's amazing. I realized that an enourmous format of crystal forms could be developed with PA. And I think one of the major authors mentioned that there was a sensitivity element dicovered during WWI in this regard: an alteration of crystal shape and sensitivity. I posted a little picture of a asprin-PA synth in another thread wherein there is a fairly clear shot of the rhombic plates (one needs to enlarge the photograph, in a browser it doesn't look as good as it could). They almost appear as mica and reflect intensly. At first glance they do look like tiny pieces of broken glass. I have heard and read differing views on the subject of temperature's influence on crystal growth and size. Does anyone have any experience with nitrated phenols in that regard?
[Generalized concept, that of lead azide being too sensitive in a needle crystal format & thus the use of cold water during a synth and dextrine]

Rosco Bodine - 14-10-2005 at 18:27

From everything which I have observed in my own experiments with picric acid crystallizations , the two factors which are consistently critical to the formation of excellent crystals are high purity of the crude product and significant batch size or
provisions to reduce the cooling rate of
smaller batches .

The thermal mass of batches at half mole scale or larger is required for good crystal formation , due to the slowed radiational cooling of reaction vessels . If work with smaller batches is being conducted , then insulation must be wrapped around the hot solutions of picric acid , in order to slow the heat loss and enable the formation and growth of good crystals .

Recently I have performed a repetition of my own previously developed and described synthesis for picric acid which has always produced a very pure product from purified aspirin , using for each 1 gram of ASA , 4 ml of 92% H2SO4 , and 1.8 grams of NaNO3 . Typically the synthesis total yields are about 90% of the theoretical , of recrystallized picric acid , based on ASA .

My most recent synthesis was done on a slightly more than 1 mole scale , 1.04 moles of ASA used as the precursor . The crude picric acid obtained after a 5 hour nitration procedure and then a 1.5 hour dilution and cooling , was *very* light in color and the diluted reaction mixture was so pale in color and free from any dark colored impurity that upon filtration it did not even stain the filter paper yellow ! This is the first time I have ever seen this occur .

The crystals direct from the diluted nitration mixture were very uniform hard gritty fine mesh material which had the free draining easily filtering physical consistency of fine quartz beach sand found in the surf line . It is the sort of material which is semi-fluidized by a small amount of water to form a mobile slurry , which behaves as a liquid suspension for a few seconds following agitation , but then settles quickly to a dense mass from which the water rapidly drains .

The crude picric acid after filtering , required 5200 ml of boiling distilled water for its dissolution . The solution was performed in a 6000 ml Erlenmeyer flask resting upon a 12" square Cimarec hotplate stirrer . Upon cooling overnight to ambient temperature the excellent crystals were filtered and dried , 198 grams of extremely pure picric acid obtained from the first recrystallization , 83% of theoretical based on ASA . The color and crystal appearance is consistent with that of the finest reagent grade obtainable from pharmaceutical manufacturers .

The bulk density of the loosely poured untamped crystals is 0.7 .

The five liters of filtered solution from the first crystallization was boiled down to 1300 ml , and allowed to cool for a second crop of crystals . No color change was noted , not a trace of orange nor any precipitation of impurity occurred during this reduction of the original 5200 ml of solution to one fourth its volume for the second crop of crystals , which are identical in color to the first crystals . The physical form is inferior for the second crop of crystals which are fine needles , a felt like mat of fine soft crystals , which are more typical for smaller volumes of hot solution which cool too rapidly to permit the growth of the larger and more dense crystals . 16 grams obtained from the second crop of crystals .

Just for the purpose of seeing what might precipitate , the filtered 1300 ml of solution was boiled down to 300 ml for a third crop of crystals . There was still no color change nor precipitate of impurity , even at this extreme of concentration to a small residue of the original volume of the solution , and it appears there may be one or two grams at most of powder form precipitate of picric acid as the third crop ,
and the very pale yellow color is unchanged from that of the original solution which has been reduced to one seventeenth , 5.7% of its original volume ......so it was most definitely a very " clean " nitration producing a very pure product directly from nitration of the sulfonated ASA . Total yields are right on the predictable 90% based on ASA from
" Rosco's Good Old Country Recipe for Picric Acid " , and I don't ever complain because the purity is always so excellent and the reaction so predictable . But every time I wonder , where is my other 10% ?

It seems like there is just some invisible
" wall " for the reaction efficiency , where the invisible little " loss gremlins " always
get their damn 10%

Anybody else get this problem with picric acid , where it seems 10% simply vanishes into space with no explanation ?

During the course of the sulfonation and nitration , the physical observations indicated that the conversion was occurring to a high degree of completion and as I watched the reactions , it appeared to me that the process is very close to a quantitaive conversion having no observable indication of byproducts or loss . Yet no matter how clean or complete the reactions appear while in progress , and no matter how consistent the form and color of the end product , 90% yield by the numbers * always * seems to be the result . So what I am beginning to wonder seriously is if the mole weight of aspirin given in the literature as 180.16 is correct , or if aspirin is actually a hydrate having 10% greater mole weight . But the ASA which I use is recrystallized from alcohol , so it would seem likely that if there is a hydrate of aspirin , then it is molecular water , and not merely water of crystallization . The same thing could apply to resorcinol , where it seems a
similar yield limitation is observed for
conversion to the nitrated derivative .
If the mole weights being used for calculation are not on the mark for the actual precursor being used , then the discrepancy would be explained for how a reaction which looks like it is quantitative , never seems to add up that way when running the final numbers .

I really hate to question the numbers provided by authoritative sources in the literature , but when my experiments continue to point to such a possible discrepancy regarding molecular weights ,
the implication is inescapable that the numbers given in the literature just could be in error .

I suppose simple titration of a sample of ASA using a good color indicator would be a good place to start trying to see if the published mole weight of 180.16 seems correct or not .

[Edited on 15-10-2005 by Rosco Bodine]

quicksilver - 15-10-2005 at 06:51

I am making an assumption that your synthesis is not done in a sealed situation.....Perhaps it is that we are not operating in a vacume & that is a possible explanation for the "missing 10%" ?
Do not large chemical plants use most every production operation (especially nitrations) in a vacume for environmental reasons as well as reactive ones...?

Rosco Bodine - 15-10-2005 at 07:07

At one time I thought that possibly there was initial loss from volatility during sulfonation of the ASA , but have ruled that out by doing the sulfonation in a loosely glass stoppered flask . I have good ground jointed glassware and I would notice anything obvious in the way of a side reaction . I study and monitor reactions very carefully and make time and temperature notes , keep log sheets of timed observations and notes of any changes that attract attention .

For example :

I just recently in this last experiment have pegged the fact that nitrosylsulfuric acid is present in the nitration mixture and accounts for the red fumes which appear when the finished nitration mixture is diluted . Nowhere have I ever seen this reported , but I'll guarantee you that what I am observing is a fact .

quicksilver - 16-10-2005 at 12:38

Quote:

Originally posted by Rosco Bodine

I just recently in this last experiment have pegged the fact that nitrosylsulfuric acid is present in the nitration mixture and accounts for the red fumes which appear when the finished nitration mixture is diluted . Nowhere have I ever seen this reported , but I'll guarantee you that what I am observing is a fact .

This is interesting stuff......
Indeed; often I miss items that SHOULD be noted (as the above) because I believe that such a thing is not an anomly. Principally because I have nothing to compare it to. If I were to have a classic example of this or that nitration (visually, etc) , I could note a unique issue. {I don't mean to harp on the "visual" thing, it's just an example} however.... I too have had this (red fumes arise during dilution). phenominon. The finished product in that instance (it was some weeks back) lacked the purity I had gotten previously. What issues contribute to nitrosylsulfuric acids' creation at that point in the synthisis? Or is that a moot point and other factors over-ride the existence of nitrosylsulfuric acid? - As I have seen this with other nitrations as well.

Quince - 16-10-2005 at 12:43

That's interesting. The only reddish fumes I've noticed are when squirting water from the wash bottle into the foam during late nitration. I was under the impression they were just NO2 trapped by the foam being released when the water broke through it.

Rosco Bodine - 16-10-2005 at 15:33

The first mention of this was made in the earlier post where I attached the file for the page from Urbanski describing the nitration activity series for common nitrates .

My most recent nitration was one where I refined some temperatures , reaction rates and holding times by a very gradual adjustment of the conditions which I have always generally followed with good success . The nitration went more smoothly and produced a more pure product than any picric acid from ASA synthesis I have ever done , and absolutely no red fumes were produced from the beginning to the completion of the nitration , when most of the picric acid had already precipitated as fine crystals in the spent acid mixture .

Only after the nitration was completed and cooled somewhat , when the mixture was being diluted for the precipitation of any not yet precipitated product dissolved in the spent acid mixture , did red fumes suddenly appear during that stage commonly called the quenching or drowning of the spent nitration mixture .

It was very evident that water was the trigger for the evolution of the red fumes ,
the mixture boiling on contact with the stream from a wash bottle , as the dilution was cautiously performed by sheeting the water down the inner walls of the flask . There was a fair amount of the red fumes evolved when the mixture was diluted , and I have seen the same thing occur when spent nitration mixtures are dumped over ice , so it is indeed the water and not the temperature which is causing the hydrolysis . The diluted nitration mixture smells strongly of nitrous acid and I believe some of the acid is also trapped in the crude crystals , which accounts for more water being required than should be required for the dissolution of the crude picric acid . The presence of the residual acidity lowers the solubility of the crude product below what would be the solubility of the pure picric acid after being freed from the nitrous acid impurity .

I believe that nitrosylsulfuric acid is an unavoidable component of the nitration mixture when it is a low water content mixture using solid nitrate and sulfuric acid . It is accumulating in the nitration mixture over the course of the nitration ,
and it may even be essential to the nitration . Knowing it is there helps in avoiding the conditions for its decomposition in an uncontrolled fashion
which could cause a late nitration stage runaway .

There are different strategies which could be applied to exploit the usefulness of the nitrosylsulfuric acid * if * it is found to be a desirable component in the nitration process , perhaps such as using an added nitrite as well as the nitrate , in some combination of proportions or sequence . Or on the other hand if the nitrosylsulfuric acid proves to be an undesirable byproduct , then there are some combinations of temperature and water content which would tend to cause decomposition of the material and limit its formation .

Which of these findings or strategies has validity is too early for me to know , and would require further experiments . This is likely " old news " and is another aspect of the " lost art " specifics which were probably once common knowledge about picric acid , in the long lost details of manufacture done a hundred years ago .

quicksilver - 17-10-2005 at 06:22

Quote:

Originally posted by Rosco Bodine
There are different strategies which could be applied to exploit the usefulness of the nitrosylsulfuric acid * if * it is found to be a desirable component in the nitration process , perhaps such as using an added nitrite as well as the nitrate , in some combination of proportions or sequence . Or on the other hand if the nitrosylsulfuric acid proves to be an undesirable byproduct , then there are some combinations of temperature and water content which would tend to cause decomposition of the material and limit its formation .

Which of these findings or strategies has validity is too early for me to know , and would require further experiments . This is likely " old news " and is another aspect of the " lost art " specifics which were probably once common knowledge about picric acid , in the long lost details of manufacture done a hundred years ago .

The length and legibility of my notes needs to increase many fold as this question is something I am familiar with but did not have enough noted down at the time of the experiment. First off, I have seen this phenominon in the ice quencing of distilled 90+ % HNO3, however at the time I thought nothing of it. The yield was high albiet less pure than previous. But here this leads me to a speciific question of terminology. When the expression "run-a-way" is used in a nitration we assume that to mean an uncontrolable reaction. Is it possable that a run-a-way reaction may occur that simply results in oxcidation of the product to a greater or lesser extent and does not threaten a catostophic end result?
Where I am going with this is; could a run-a-way occur on a tiny scale, yielding inconsistent results, etc?

Rosco Bodine - 17-10-2005 at 06:53

Some nitrosylsulfuric acid is even produced in the mixture of nitrate and sulfuric acid from which nitric aicd is distilled , and it can be seen decomposing when water is added to rinse the residue from the flask , producing a roiling cloud of NO2 from the decomposition of the nitrosylsulfuric acid when the water contacts the material . The origin of the material is from the natural decomposition of some of the nitric acid , and this decomposition is catalyzed by direct sunlight . Sunlight by itself can cause an
autocatalytic decomposition runaway oxidation to initiate in a nitration mixture .

Direct sunlight is your friend if you are intending to get a fulminate sort of reaction going . But that is not what you want to see in a nitration mixture , so direct sunlight should be avoided .

Quince - 17-10-2005 at 15:37

Regarding red fumes appearing during distillation, I have a question. I have not observed the evolving of fumes when water is added, but when I notice orange fumes appearing during VACUUM distillation (which seems to me must mean I've heated too fast), if I momentarily let air in, the fumes disappear. At first I thought the inrush of air was simply pushing the NO2 back to the boiling flask, but on a closer look they actually become white/clear. Now, I can't think of what in air would change the NO2 to something else.

Rosco Bodine - 17-10-2005 at 18:59

2 HOH + O2 + 4 NO2 -----> 4 HNO3

Airborne water vapor and oxygen is the clarifier .

Nitric acid is found in rainwater after
thunderstorms .

Rosco Bodine - 18-10-2005 at 05:57

Quote:

Originally posted by quicksilver
On another note I have used a process wherein picric acid is prepared by nitration of a nitrosophenol intermediate by preparing the phenol with sodium hydroxide and sodium NITRITE. The resulting nitrosophenol intermediate is then nitrated by a standard nitration process using strong HNO3 - and in this instance methlene chloride / HNO3 may not be exposed to much heat. Or a H2SO4 / solid nitrate mix may work. In any instance it is ment to be processed a much lower temp.
Unfortunatly it comes from a UK patent application (#365, 208 David Salter, 1973) so I am having trouble getting a PDF file....

The patent you mentioned is GB1278576
describing the conversion of phenols to a nitrosophenol intermediate , and then nitrating to produce the normal nitro compound .

I tried to upload the file , but it is over
1 MB and the server won't allow the upload saying the file is too large .

I thought we had some bandwidth now ,
so what's up with that stuff ?

quicksilver - 18-10-2005 at 06:28

Quote:

Originally posted by Rosco Bodine
The patent you mentioned is GB1278576
describing the conversion of phenols to a nitrosophenol intermediate , and then nitrating to produce the normal nitro compound .

I tried to upload the file , but it is over
1 MB and the server won't allow the upload saying the file is too large .

I thought we had some bandwidth now ,
so what's up with that stuff ?

Thank you for hasseling that.
I want to know how you can actually get the whole thing from Espacenet......I have a terrible time with that site.
Now, the reason I was so damn off on that patent number is that it came from THE PREPRETORY MANUAL OF EXPLOSIVES, which, in another thread I continually blast for being inaccurate. Almost EVERY DAMN patent # is wrong. Some off by one number, some wildly off like this one. The synth was fine so I kept it in my notebook but the number was -=no where=- close or related. I just remembered when I read your post. --- Wow that book is so full of typos and inaccuracys, I can't tell you all of them. I'll even bet that some of the stuff is dangerously mis-directed. I always double check things from there with someone else or try to find the patent .
Thanks for trying however, I really enjoy the stuff you find and make good use of it.

Rosco Bodine - 18-10-2005 at 07:13

That " manual " is a complete fraud based on my impression of excerpts mentioned by others who reference it ....another crap book of misinformation written by some asshole who doesn't know WTF he is talking about , but pretends that he does , just to make a buck , while endangering the lives of anyone who trusts the information .... a real slimy kind of lowlife is what such authors are

I'll give away better information for free , and accurately provide references and explanations as best I can , along with some unpublished stuff of my own invention as a bonus ...all for free

You just can't beat the price folks !

Maybe I should write an e-book and call it
Rosco's Good Old Country Recipes for Pyros , with patent references and lab notes .....guaranteed penis enlargement / mind expanding formulas which even dullard dickheads can follow and see results in only thirty days ! Oh God , she blinded me with SCIENCE !

Hmmm.....about ESPACENET , the wrapper for the pdf's has to be handled in an awkward way in order to recompile a standard pdf . First you have to reset the document security setting for each saved page to " no security " , close and save changes . Reopen each page and delete the " ghost pages " which contain no images so that each page is an image that is only " page 1 of 1 " instead of
" page whatever of some other number of total pages " , by deleting any preceding or following " ghost pages " which contain no images . Close and save changes to each page . Now you should have security removed from actual single page saved files , and rename the files according to their actual page numbers ,
for example ,
GB####### ( decriptive title ) ,
GB####### ( page 2 ) ,
and so on ......

Then insert the pages one at a time to the document first page , in the correct sequence , advancing the page view to each new page just saved , and when the final page is added and viewed , close the assembled document and save changes . Simple huh ?

She Blinded Me With SCIENCE

Rosco Bodine - 18-10-2005 at 08:04

A real classic ........

Romy And Michele's High School Reunion: More Music Soundtrack Lyrics

--------------------------------------------------------------------------------

Artist: Thomas Dolby

( Lyrics ) Song :
She Blinded Me With Science .......

It's poetry in motion
She turned her tender eyes to me
As deep as any ocean
As sweet as any harmony
Mmm - but she blinded me with science
"She blinded me with science!"
And failed me in biology

When I'm dancing close to her
"Blinding me with science - science!"
I can smell the chemicals
"Blinding me with science - science!"
"Science!"
"Science!"

Mmm - but it's poetry in motion
And when she turned her eyes to me
As deep as any ocean
As sweet as any harmony
Mmm - but she blinded me with science
And failed me in geometry

When she's dancing next to me
"Blinding me with science - science!"
"Science!"
I can hear machinery
"Blinding me with science - science!"
"Science!"

It's poetry in motion
And now she's making love to me
The spheres are in commotion
The elements in harmony
She blinded me with science
"She blinded me with science!"
And hit me with technology

"Good heavens Miss Sakamoto - you're beautiful!"
I -I don't believe it!
There she goes again!
She's tidied up, and I can't find anything!
All my tubes and wires
And careful notes
And antiquated notions

But! - it's poetry in motion
And when she turned her eyes to me
As deep as any ocean
As sweet as any harmony
Mmm - but she blinded me with science
"She blinded me with - with science!"
She blinded me with

Attachment: blinded.mid (27kB)
This file has been downloaded 1457 times

Sickman - 18-10-2005 at 22:07

Right on with Quicksilver; Rosco Bodine's posts are priceless. Also dido with the Preperatory Manual of Explosives. If I'm not mistaken Rosco warned me about that book years ago.

He is right, it's a crap book. When I read through the pages I feel like the author is victimizing all of his customers by not telling them upfront where he got the info and that it's not been tested by him and how dangerous it may be based on that fact.

As far as ESpnet is concerned I use it along with other search engines, but when I find a US patent I want, I go to Patent Fetcher cause it's just a quick and free PDF download.

[Edited on 19-10-2005 by Sickman]

quicksilver - 19-10-2005 at 06:45

Quote:

Originally posted by Sickman

As far as ESpnet is concerned I use it along with other search engines, but when I find a US patent I want, I go to Patent Fetcher cause it's just a quick and free PDF download.

[Edited on 19-10-2005 by Sickman]

Good call...seems like a winner.

quicksilver - 19-10-2005 at 07:35

Quote:

Originally posted by Rosco Bodine
That " manual " is a complete fraud based on my impression of excerpts mentioned by others who reference it ....another crap book of misinformation written by some asshole who doesn't know WTF he is talking about , but pretends that he does , just to make a buck , while endangering the lives of anyone who trusts the information .... a real slimy kind of lowlife is what such authors are

I'll give away better information for free , and accurately provide references and explanations as best I can , along with some unpublished stuff of my own invention as a bonus ...all for free

GOD....You can't see how much I am smiling because that song IS my little quirk song.....it buzzes in my head when I start getting nuts with all sorts of crazy crap around my house. My wife thinks I have "unique hobbies" and asks that I never share my interests with our friends (Like I am going to discuss acid distilltion with an asst. American History prof. who always calls her classes "HER-STORY"

.
You know that Lagard has published some very seriously dangerious garbage. The other one I remember (but did not buy, of course) was some crap about chem-weapons! No BS! The guy had stuff in there about seriously deadly poisons (real WMDs). And undoubtly he documented them as well as he did his work on energetics. That is a time-bomb waiting to have some tragic repercussions. The whole thing with him that really ticked me off is that one needs to actually have the book in one's possession to find the discrepencies, the typos, and the omissions. Thus paying money for the privlege of frustration and annoyance. The damnist thing about it is that it doesn't seem like a crap book from a casual glance. That's the nastiest thing. - Confession time... - I actually bought it when it first came out.

No bullshit stroke here but you DO have some strong background and commumication skills. That is what leads to success in both writting and teaching. ---- Lord knows you know your shit. But you can communicate. THAT, is a rare thing. I know a bunch of folks with Grad and Post-grad backgrounds that can't communicate. Maybe you -should- write.
- - And actually I don't mean some "explosives_book" ( you could actually write an "explainitory-explosives" book detailing all the pitfalls of other authors; that would be a help; as well as entertaining)......I mean a money maker like a high school chemistry book that pulls kids in. That makes them not only understand but enjoy reading & practicing chemistry. A "Tutor text", not a text book per se'. We know that all the lab shit that was done when I went to school (70's) can't be done now, so a lot of kids find chem dull. If you could find stuff that intregues them using examples that would get past a school board you could pull down about a hundred grand for essentially writting a thesis if the publisher pushes the book to a big school system.
Hell when I was in high school we had a teacher that blew crap up in class and no one thought a thing about it. He grew crystals (all sorts of toxic stuff) and was a great communicator. And even jocks past his class because it was fun. Or you COULD do some antithisis-of-the-explosives book genre'.....it would certainly sell as much as Lagard's stuff after folks find all the holes in the work.
Anyway, my Email is on the board, if you EVER want to bounce an idea around I would be very happy to check out what you're cookin' up.

[Edited on 19-10-2005 by quicksilver]

picric acid from ASA , NaNO3 and 92% H2SO4

Rosco Bodine - 19-10-2005 at 08:32

The most recent synthesis is one where some temperatures were closely watched and refined , and the nitration went very smoothly with absolutely no surging nor red fume production , resulting in an exceptionally pure end product in 90% yield based on ASA . So the conditions are a good baseline reference for any fine tuning of the process in efforts to get a little better efficiency . I believe it may be ultimately possible to get yields up around 98% using some adjustments , but a 90% yield process provides a good place to start .

The synthesis followed my rule of thumb proportions which have always produced a good result , for each 1 gram purified ASA , 4 ml 92% H2SO4 , 1.8 grams purified NaNO3 .

In a 1 liter Erlenmeyer 24/40 flask was placed a 10 X 35 mm stirbar and 750 ml of
92% H2SO4 heated with stirring to 80 C .
187.5 grams of purified ASA was added in small portions as fast as it would dissolve in the stirred mixture over the course of 45 minutes , the temperature gradually rising to about 105 C by the heat of reaction as the ASA dissolved . The flask was loosely stoppered with a hollow glass 24/40 stopper . Supplemental heating gradually raised the temperature to 118 C at the end of 90 minutes and the heating was discontinued . After standing overnight the sulfonated ASA mixture had cooled and solidified to a dark colored transparent gel filled with small tan cubical? crystals of sulfonated ASA . The mixture had to be reheated to 115 C to melt and with stirring redissolve so the mixture could be poured into the nitration flask .

Into a 4,000 ml Erlenmeyer flask was placed a heavy ( 62 gram ) 3 inch oval stirbar , and was set upon an old Type 1000 Thermolyne 7.5 X 7.5 stirrer hotplate . Dry , sifted free of lumps , NaNO3 , 339 grams total was divided into three equal 113 gram portions in preparation for the nitration and kept in sealed containers .

The hot sulfonated ASA mixture was poured into the 4L Erlenmeyer , the 900 ml of hot liquid not quite deep enough to completely cover the stirbar . An 18 inch thermometer , 260 C 75 mm immersion , was leaned diagonally in the flask with its tip sitting in the curved bottom outer edge inside the flask . A 4 inch flexible ventilation duct mounted in an extension ring was positioned next to the flask opening for removal of any fumes by the
remotely located blower whose intake air is drawn through the 4 inch hose and discharged outdoors . A second larger fan was situated next to the low workbench to pull a gentle draft in the same general direction as the higher velocity intake adjacent the opening of the flask . These sorts of precautions are essential for safely conducting a nitration on a molar scale . The nitration was conducted outdoors in an area shaded from direct sunlight .

The stirrer was started and run just below the speed where splashing of the shallow liquid occurred , with portions of nitrate begun with the mixture at 95 C ,
the decarboxylation foaming occurring instantly on contact from the first addition of nitrate . The additions were made steadily in portions using a teaspoon ,
adding the nitrate in heavy sprinkles into the vortex , the reaction temperature rising and maintained in the range of 100 to 103 C by regulating the rate of additions of the solid nitrate . The effervescence of CO2 from decarboxylation
occurred freely with no persistent foaming through the end of the addition of the first of the three portions of nitrate , and midway into the second portion at 1 hour from the beginning of the nitration . At this midpoint , the effervescence becomes more sluggish and the viscosity of the mixture is increased , the foaming from decarboxylation causes a volume increase for the mixture , and the additions must be slowed considerably . At the end of the addition of the second portion , the heat of reaction alone is insufficient and very gentle supplemental heating is added to maintain 103 C . About 15 grams into the final portion of nitrate , the time from the beginning of nitration will be 1 hour 45 minutes and some picric acid will begin to precipitate in the thickening mixture , greatly slowing the remaining additions . The stirring speed is increased and the heating is raised to 106 C by 2 hours from the beginning of nitration . The remaining nitrate additions go very slowly and will require as much time as all of the nitrate previously added . The temperature is very gradually allowed to increase over the remaining additions of nitrate , the following observations were made for
reference concerning the elapsed times from the beginning of nitration , and the total amount of the third portion of nitrate having been added .
@ 2 hours 15 minutes , 30 grams ,
107-108 C
@ 2 hours 30 minutes , 40 grams ,
109 C
@ 2 hours 45 minutes , 45 grams ,
111 C
@ 3 hours , 55 grams , 113-114 C
@ 3 hours 10 minutes , 60 grams , 114 C

At this point the mixture has become a very thick slurry and additions are suspended for a time . There is an accumulation of solids upon the walls of the flask and the thermometer is used to scrape the material into the vortex so the mixing can be accomplished . This manual assistance is required several times during the course of the remaining nitration . Close temperature control is essential to limit temperature to 114 C , as there are indications of an induction point for decomposition at about 116 C .

@ 3 hours 30 minutes , nitrate additions cautiously resumed , 113 C reaction temperature
@ 3 hours 45 minutes , 70 grams , 112 C
@ 4 hours , 85 grams , 112 C
@ 4 hours 30 minutes , 113 grams completion of addition 110 C , Supplemental heating very slightly reduced , reaction allowed to continue
@ 5 hours , slowly finishing reaction has cooled to 100 C and reaction appears complete , the temperature is subsiding
and the mixture is thinning as the temperature falls . Supplemental heating discontinued completely .
@ 5 hours 10 minutes , 97 C , mixture is now much thinner and is a free stirring smooth slurry with no foam whatsoever ,
a suspension of fine yellow reflective crystals of picric aicd suspended in a water clear colorless supernatant liquid of spent acid and bisulfate in solution
@ 5 hours 20 minutes , 92 C , cautious and gradual dilution of the stirred mixture was begun by streaming water from a wash bottle onto the inner walls of the flask and allowing the stirred mixture to be gradually diluted , limiting the temperature rise to 100 C , a total of about 1 liter of water was added . The dilution was accompanied by a fair amount of red fumes being evolved , believed to be the result of decomposition of nitrosylsulfuric aicd present in the spent nitration mixture .

The total volume of the diluted mixture was at the 2,000 ml graduation on the flask .

@ 6 hours , 74 C , ice is added to bring volume of diluted mixture to 2800 ml ,
and to speed cooling .

@ 6 hours 15 minutes , 23 C

Flask is placed in refrigerator to complete the precipitation .

The crude picric acid is filtered and blottered , and the still damp crystals are redissolved in 5200 ml boiling distilled water . On slow cooling , excellent crystals are formed , which after filtering and drying , are obtained 198 grams from the first crystallization , 83% yield based upon ASA , of exceptional quality picric acid .

An additional second crop of crystals ,
16 grams is obtained by boiling down the filtered liquid from the first crystallization to a volume of 1300 ml , and allowing to cool .

Yet a third crop of maybe 2 grams can be obtained by concentrating to 300 ml and cooling .

There was absolutely no dark colored impurity produced to tint the solutions or to precipitate and contaminate the product . The picric acid produced was
absolutely free from any contamination byproducts .

ordenblitz - 19-10-2005 at 09:36

Thank you very much...

I was wondering when you were going to post:

Rosco's Good Old Country Recipe for TNP

Rosco Bodine - 19-10-2005 at 10:33

@ordenblitz

You are very welcome , as is everyone
who has also been interested in PA from ASA by way of the modern variation on the ancient process using NaNO3 and the
sulfonation mixture .

It's overdue that I paid close attention to the temps and times and set forth the details for a clean nitration . I will probably experiment further in refining the process . The possibility of increasing the amount of H2SO4 by 10% or so may
have merit for yields and safety . This
process which I have worked out is still very much EXPERIMENTAL , even though it has produced the results I have described , it is possible the reaction may not * always * follow exactly the same course every time for me or for others .

I will emphasize that those temps are already " pushing " the reaction to cut down on the time requirement , and are
not far below safe limits , but at the same time are about right for what is needed to get the job done . Sorry there's not more headroom allowed for getting sloppy with the additions , but such is the reality for the thermodynamics of this particular nitration . You need to be familiar with the heating response of your hotplate and not overshoot the mark , because the mixture absolutely won't forgive it ,
and may require the expansion room afforded by a large reaction flask .

A minor error * may * result in a foaming which itself lowers the concentration of the reaction mixture and self regulates the reaction to oppose a potential runaway , so that the reaction subsides on its own and the nitration can be resumed . However , this is not guaranteed and depends on just how
" minor " is the error outside of the window conditions . I am not about to deliberately cause a runaway out of curiosity to explore the parameters of such a scenario , not without remote manipulation and a good solid bunker
from where I can watch what happens on a video monitor

There are inherent dangers in all nitrations , but this one appears to be reasonably predictable and safe , if the process is carefully done .

quicksilver - 20-10-2005 at 06:53

Quote:

Originally posted by Rosco Bodine

There are inherent dangers in all nitrations , but this one appears to be reasonably predictable and safe , if the process is carefully done .

I have not heard much about runaway reactions w/ nitration of phenols, I have heard about it w/ amines and the typical nitric-ester issues. but not with Phenols. I know it's possable w/ any nitration but yet I have heard little spoken of it.
You have been on these boards a long time; have you ever heard about someone having a runaway w/ PA?
The reason I ask is that during the "red-goo" issue I heard many people push the limit with phenol nitrations and the runaway / safety issue was rarely discussed.

Rosco Bodine - 20-10-2005 at 08:28

There have been reports of runaway reactions which have been quenched to avoid further " complications " . Think about it and you will realize that the potential is there for a thermally induced
" cook-off " , when the batch size is large and the proportions of materials present is not a safe mixture to be subjecting to a sudden temperature spike which can sometimes keep right on going to reach the ignition point . Picric acid is probably the safest trinitration of an aromatic , but I personally wouldn't ever perform its synthesis operating on the assumption that there is no danger about the process . One safety enhancement is provided by keeping the temperature high enough to guarantee that the nitration reaction proceeds without accumulation of unreacted nitrate or nitric acid which would aggravate the danger if the reaction suddenly surged and became uncontrollable , going into an oxidation decomposition mode which is autocatalytic and therefore self-accellerating . That uncontrolled process is limited only by the quantity of material present , and so it becomes a matter of
whether or not there is " critical mass " for the reaction mixture .....and if that condition is present , then the geometry lesson for the day pertains to " blast radius "

Rosco's TNR procedure

pdb - 5-2-2006 at 05:58

I prepared TNR using Rosco's procedure (page 1 of this thread) and same starting quantity, i.e. 10 gr commercial grade resorcinol. I thorougly followed the times and temperatures indicated, just taking some liberty from the recipe by accelerating somewhat HNO3 addition (68%, then 100%) after having observed than the temperature rise would be much weaker after dropwise addition of the first 10 ml of 68% HNO3. But at no time did the temperature overpassed 22°C.

After slow crystallisation from boiling distilled water, the crop of dry crystals was 16,2 gr iso 20 gr expected. However, I didn't try to recover the part of TNR still dissolved in the cold solution, although by evaporating a few ml of it, it left crystals in a non neglectable amount. Although TNR is notably less soluble in water than picric acid, the literature mentions 0,45 gr per 100 ml at 15°C. As I separated the crystals when the solution had reached 4°C, I assume that about 2 gr remained in the discarded 900 ml liquid... which would makes a total crop around 18 gr, still 2 gr short compared to Rosco's record.

EDIT: made pic slightly smaller and rotated it to avoid page stretching

[Edited on 8-23-2010 by Polverone]

TNR_smaller.jpg - 340kB

quicksilver - 5-2-2006 at 08:13

Your picture collection is very well done. I was looking at various methods of styphnic acid production just now and found a "NITRITE" synth. I have a collection of material from patents and sources that have proven to be worthwhile keeping (Roscoe's stuff, etc) and this had an old date and no lab notes....For what it's worth, I don't know it's background (what patent it came from, etc) but since this thread has had so much material added to it over the months...here it is:

Step 1. Preparation of Dinitroresorcinol monohydrate

To 16 liters of water add and dissolve 440 grams of resorcinol, then 452 grams of 98% sulfuric acid. Immediately thereafter, add 6800 grams of crushed ice to mixture, and then stir the mixture vigorously until the internal temperature of the mixture reaches about 0 Celsius. Then prepare a solution by dissolving 600 grams of sodium nitrite into 3200 milliliters of water, and then add this sodium nitrite solution to the sulfuric/resorcinol mixture over a period of 6 minutes while vigorously stirring the mixture and maintaining its temperature below 5 Celsius. After the addition of the sodium nitrite solution, continue to stir and cool the reaction mixture below 5 Celsius for 30 minutes. Note: A precipitate will begin to form. After the 30 minute period, filter-off the precipitated dinitroresorcinol monohydrate, and wash with several hundred milliliters of cold water (use gravity filtration).

Step 2. Preparation of Styphnic acid

Place 3000 milliliters of 40% nitric acid into a beaker, and then gently heat this mixture to about 30 Celsius. Thereafter, carefully mix the moist filter cake, prepared at the end of step 1 to the nitric solution over a period of about 30 minutes, while stirring the nitric acid and keeping its temperature around 30 Celsius. Immediately after the first addition of the filter cake, nitrogen oxide gases will be evolved, followed by the formation of a foam (the foam will dissipate after about 10 minutes). After the addition, raise the temperature of the mixture to 95 Celsius, and then hold this temperature for 1 hour. After heating for 1 hour, remove the heat source and allow the mixture to cool to room temperature. Note: A precipitate will form. When the reaction mixture reaches room temperature, filter-off the precipitated product, wash with 300 milliliters of 2% nitric acid, and then with 600 milliliters of cold water. Then air-dry the product. The result will be pale yellow crystals, well suitable for use in preparing lead styphnate, or Styphnic acid compositions.

As you can see it was designed to lab production size. I do not know if scaling it down would intail problematic issues but if it worked on a smaller scale it would be interesting as it cuts down on materials, etc.

Rosco Bodine - 5-2-2006 at 13:07

Quote:

Originally posted by pdb
I thorougly followed the times and temperatures indicated,

Really ?

Quote:

But at no time did the temperature overpassed 22°C.

Then your cooling was too agressive for the reaction to
proceed from its own exotherm . The way to patch things
would have been to remove all cooling and even nudge the
reaction with a little supplemental heat . When I use the term " keeping below a certain temperature " that is not to say that any temperature way below that will be fine , but
it is usually a temperature limit very near where you want to be with the reaction , but observing it as a point where
the reaction may not self-regulate very well or may show signs of decomposition byproducts . Generally for nitrations
you want to stay just under that temperature to keep the reaction rate steady , but not to exceed that temperature
during that time when the reaction is being regulated by rate of addition . When the reaction is not maintaining its
temperature , then you have to adjust the conditions so
that it does stay on track , understanding that there is
an optimum thermal curve the nitration should follow for
best results .

pdb - 6-2-2006 at 01:24

I do understand your point and agree. However, in my mind, 22°C was not that far from 25°C... Maybe this would deserve a wording precaution next time

BTW, isn't it a characterisation of a major difference between O- and C- nitrations ? E.g., NG is prepared while keeping temperature under 25° or 30°C (depending on authors) as a safety precaution, and good yields are still obtainable at quite lower temperature, while, in order to secure high yields, phenol-like nitrations have to navigate as close as possible of an upper limit, beyond which the likelihood of runaway is too high.

[Edited on 6-2-2006 by pdb]

Rosco Bodine - 6-2-2006 at 09:06

Quote:

Originally posted by pdb
I do understand your point and agree. However, in my mind, 22°C was not that far from 25°C... Maybe this would deserve a wording precaution next time

Indeed I could have done a better job of writing up the
details , but just had a paragraph in a lab notebook to
reference . Next time I do the synthesis I will be more thorough with my notes . A few minutes is not very specific
for example , and the minutes do count on a finite curve
where a reaction is affected by temperature and time .

Quote:

Yes good yields can be obtained at lower temperatures
with things that are easily nitrated but also easily oxidized ,
but the reaction rate slows so it becomes something of a tradeoff to choose a good working temperature . But it generally requires driving aromatic nitrations pretty hard to
effect their complete nitration , on the order of 3 times the temperature you would need for completely nitrating an aliphatic . Even at the elevated temperature , it is safer
for the nitration of the aromatic . You actually can completely nitrate an aromatic at the lower temperatures , if you don't mind waiting three days or even a week for the nitration to complete

I never actually tested this but it would seem so .

BTW the picture file you posted above won't completely download for me , maybe a corrupt file or the forum server
is dropping out . It has been acting wierd for a couple of days , dropping out completely at times . Could you maybe reattach the file and see if that helps anything .

Quince - 6-2-2006 at 16:16

Something's wrong on your side, Rosco, as his photo loads just fine on my machine.

[Edited on 7-2-2006 by Quince]

Rosco Bodine - 6-2-2006 at 22:12

The pictures are loading fine for me now so the file
is okay . I think it was the server acting out a bit
from time to time and I just tried during a temporary glitch .

It does load the first picture and then jump to a blank screen
until I wave the cursor of my mouse around a bit in the upper right part of the blank field and see that box for
resizing the image . When I click that box then the first
frame reappears and all is well scrolling to the other pictures also .

ppoowweerr - 31-8-2007 at 16:03

I am working on some physical properties of lead styphnate, and since TNR is somewhat difficult to purchase, I had to make some before I can begin working with it. I have had some difficulty getting a decent product but thanks to rosco, I have now achieved very nice pale yellow hexogonal crystals. The only problem is that I am not sure about the best means to prepare it for impact detonation. I think I have too much h2o present. I used an ATR IR and got an awesome spectra with even the fingerprint region is all accounted for compared to a spectra I found online. So now my questions: Will simply using a vacuum oven work to dry? What does the dinitro version look like on IR and to the eye? And thanks again to rosco and othersw who have posted on this thread.

Rosco Bodine - 31-8-2007 at 23:35

Somebody needs to edit the image widths above
to about 550 pixels , and post the images sequentially ,
so they scroll vertically , instead of the horizontal panorama that appears now
and screws up the text formatting for the whole page .

Good pictures .....but the formatting stinks .

[Edited on 1-9-2007 by Rosco Bodine]

tito-o-mac - 8-9-2007 at 07:10

Was the residue crude or pure?

ppoowweerr - 3-10-2007 at 20:24

my residue was pure. It was pale yellow hexagonal crystals and i have been drying it in a low temp oven.
The IR was perfect and the MP was 177-181 C. I was very happy with the small range and Merck 12th Ed
says 180 MP. I am going to run it through a bomb calorimeter just for fun, tomorrow I hope. If not tomorrow then next week. Oh and by the way fuming red nitric is expensive. Thanks

ppoowweerr - 4-10-2007 at 15:07

I havent done any math yet so I dont have any numbers but I did get to run about .75g of TNR
in the bomb calorimeter. It yielded a net change of 0.8 C degrees in 2 L of h20. when I get the
numbers worked out tomorrow (or this weekend) I will be able to compare to published numbers
with mine for another test of purity.
What is the best method adding lead to make lead styphnate?

ppoowweerr - 11-10-2007 at 13:52

Thanks for all of your help, guys. I have finally made a satisfactory product of lead styphnate that yielded a surprisingly large detonation. thanks all

reciprocal solubility NH4NO3 - NaNO3 and NaNO3 - KNO3

Rosco Bodine - 5-8-2010 at 10:56

Quote: Originally posted by quicksilver

Quote:

Here are some reciprocal solubility charts for a couple of the binary systems of mixed nitrates which indicate the co-solubility enhancement which occurs at certain temperatures anyway for certain unique proportions of salts in mixture in water solution. There are definitely other binary and tertiary and possibly quaternary systems where a peculiar increase in water solubility occurs for certain specific proportions of particular nitrates in mixture. Calcium nitrate and ammonium nitrate exhibit reciprocal solubility, and I think it is also true for magnesium nitrate with other nitrates which would be very interesting. Where the indexing of such reciprocal solubility data is to be found I do not know.
To anyone who may be helpful with reciprocal solubility data references for nitrates, please add to these references.

Attachment: Reciprocal Solubility of NH4NO3 and NaNO3.pdf (119kB)
This file has been downloaded 895 times

Attachment: Sodium Nitrate Solubility and Reciprocal KNO3 Solubility.pdf (129kB)
This file has been downloaded 959 times

quicksilver - 5-8-2010 at 13:50

RB - Thank you very much for those.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Our page format is falling off the ends of the earth....

To those who post pictures: PLEASE reduce your size level if you see it distorts the page format. This has implications of both "read-ability" and if someone else happens (look how far you have to go to get to the "edit" button!)
to do that, the page can become totally illegible.
It's best not to "TILE" the pictures in any event.
Post one after another or drop them to 400/600 but
keep the sharp synthesis photo separate so everyone
can see the color.

[Edited on 5-8-2010 by quicksilver]

nitrate reciprocal pairs, double salts, and eutectics

Rosco Bodine - 23-8-2010 at 11:38

The use of specific combinations of nitrates in a specific proportion appears to be a valid strategy for loading up of solutions with the highest content of total nitrates in solution for a given temperature. And it also appears that specific combinations of nitrates do form double salts and eutectics which are capable of exluding some or all of the water of hydration which would normally have such great affinity for one or more of the nitrates that it would otherwise be impossible to obtain that nitrate in anhydrous form by heating to drive away the water and leave the completely dry salt. Magnesium nitrate is the nitrate of particular interest. While this is not fully described as being verified by weighing and moisture analysis figures, some references are indicating that Magnesium Nitrate forms anhydrous double salts and/or eutectic melts with Ammonium Nitrate, with Sodium Nitrate, with Potassium Nitrate, and other nitrates. Some combinations are of particular interest having potential value with regards to nitration mixtures where the dehydrating property of the nitrate and / or the sulfate which may be produced as a byproduct, can improve the nitrating power of the acid by sequestering H2O already present or H2O produced as a nitration or nitrolysis byproduct. Information in the literature is not very extensive concerning this potentially valuable technique which could be applied not only to nitration and nitrolysis mixtures, but could also have value in formulation of oxidizer melt mixtures for pyrotechnic compositions. There are a few mentions of this scattered among the patent references for fertiliziers, and pyrotechnic related compositions, and for energy storage by phase change salt systems, but there is very little information found pertaining to the usefulness for nitrations. I have found a few more references that I can share concerning the reportedly anhydrous melts. I also found a more extensive solubility table for different temperature aqueous solutions related to the reciprocal solubility of KNO3 and NaNO3. I will add to these mixed nitrates references as I find any more.

Attachment: Reciprocal Solubility KNO3 and NaNO3 warm solutions.pdf (132kB)
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Attachment: Ammonium Magnesium Nitrate solubility.pdf (118kB)
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Attachment: US3729351 Eutectic Oxidizer mixtures for FLARE_COMPOSITION.pdf (103kB)
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Attachment: GB382368 Anhydrous NaNO3 - Mg(NO3)2 - Ca(NO3)2 tertiary eutectic 138C.pdf (341kB)
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Mg(NO3)2 - NH4NO3 double salts and eutectics

Rosco Bodine - 29-8-2010 at 19:01

Here is some additional data from a Monsanto patent US3173756 and a journal article by the inventor regarding the anhydrous binary system Mg(NO3)2 - NH4NO3 double salts and eutectic mixtures. Also attached is the US1952849 patent parallel issue to the British patent already posted above. Example 3 which is 65% anhydrous Mg(NO3)2 - 35% KNO3 is interesting. Example 4 which is 51.8% anhydrous Mg(NO3)2 - 48.2% NaNO3 is also very interesting.

I have found mention that there exists a ternary anhydrous eutectic system of slightly lower melting point for Mg(NO3)2 - KNO3 - NaNO3 but I have not found the ratios stated.

Also it would seem that a quaternary system with those three and NH4NO3 would be likely, as well as ternary systems of Mg(NO3)2 - NH4NO3 - NaNO3 (or) KNO3 , but I have not found any of them published. There are mentioned also systems where urea is an added component which can substantially decrease the melting point and also result in anhydrous mixtures. Heating along with vacuum may be required for complete dehydration of some of these mixtures at reasonably low temperatures, while vacuum may not be strictly required for others. I have no specific information what is the spread on that, however vacuum appears to be a drying rate increaser more than an absolute requirement.

Attachment: US3173756 Griffith Magnesium Nitrate Ammonium Nitrate Anhydrous Double Salt and Inventor Journal article.pdf (884kB)
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Attachment: US1952849 Mg(NO3)2 Anhydrous Eutectics.pdf (185kB)
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[Edited on 30-8-2010 by Rosco Bodine]

grndpndr - 27-1-2011 at 02:42

US PATENT 1840229, jan5,1932. (double salts)
Aimed primarily @ producing less hygroscopic,high nitrate fertilizers incorporating a wide variety of nitrates.
FWIW excuse the nonexistent link I have a hard copy of the patent

"I have now found that nitrogenous products which do not have said objections are obtained in a simple manner by combining the said basic nitrates with the nitrates of alkali metals such as potassium,or monovalent radicles such as ammonium or urea radicals to form double salts.

[Edited on 27-1-2011 by grndpndr]

otonel - 15-4-2011 at 11:17

I try to make styphnic acid and lead styphnate like in that site powerlabs but the result was a brown "misery" not yellow, I dissolved that in a mixture of water with ethanol and heated with intention to make more pure but all was a black colored mixture and I add some lead oxide and in the attachment picture is my disastrous result.
Can extract and purify lead styphnate or styphnic acid from my final result or is good to drop to garbage?
What was wrong with my synthesis, I follow procedure from powerlabs but I don`t have thermometers and anyway I don`t leave the mixture to become too hot,next time I will use your procedure from first page for my 4 grams of remaining resorcinol

quicksilver - 15-4-2011 at 11:38

Obviously it's not possible to comment on your synthesis as you didn't post it. However whatever you did, did not have the desired result.

otonel - 15-4-2011 at 12:18

Here is my synthesis :
-8grams of powdered resorcinol are weighted and added to the 250ml beaker containing the 10ml of concentrated sulfuric acid.
-the mixture is stirred for several minutes untill the resorcinol dissolves and forms into a yellow liquid and heated for 30 minutes during which it quickly solidifies into a pink - brown cream
- the resultant product is than chilled to -5C on a water bath with salt added, and 15ml of nitric acid are added
-the mixture react very slowly but when I heated on the hotplate reaction become more fast with NO2 fumes
-after complete reaction the mixture color become brown-black and I added 100ml distilled water
-the mixture is cooled to 5C so as to precipitate styphnic acid (or what I make) , and than was quickly filtered and washed with 400mL of cold distilled water
-I dissolve the resultant filtrate in a boiling mixture of 1 volume ethanol and 2 volumes water and I add some amount of lead monoxide
You see the result , and that was synthesis followed by me

quicksilver - 16-4-2011 at 07:00

Periods of time and crystal "set-up" periods were not outlined so I will assume nothing but what had been written. However the idea is that the styphnic acid be allowed to form, crystallized and dry prior to moving onward to the synthesis of the lead salt. If that period of time and formation is missed it's possible that is why the synthesis failed. There needs to be ordered "steps" in this process and it should not be rushed. Since I was not looking over your shoulder; I certainly cannot say for sure but the progression has some important time elements to it.
From what I have seen the "powerlabs" synth was not a notably successful one; that's why there have been many other designs implemented. It's not too difficult & many have had great results but the general lab to lead styphnate must progress in stages wherein the synthesis is well defined. I've seen great success with both trinitro and lead-trinitroresorcinol labs which offered good "repeat-ability" but they had strong emphasis on time and temperature. Very often when a nitration fails those two factors play a powerful role in the failure.

Whenever one has a problem with nitration/esterfications or where there is a sulfonation prior to the process one should always make every attempt to look to temperature, timing, addition of precursor. & consistency. These are the major issues that result in success or failure.

[Edited on 17-4-2011 by quicksilver]

otonel - 1-5-2011 at 11:29

Quicksilver I try your synthesis on the first page and the resultant product was a yellow- red crystals, not very pure stypnic acid but my first accomplish synthesis and I don`t have thermometer or something else to control temperature.
Tomorrow will try a recrystallization and next step will be to make lead stypnate and silver stypnate

quicksilver - 2-5-2011 at 06:45

Unless you can control elemental conditions such as temperature, you'll never get a very pure product in many synthesis. Controls of variables such as time, exposure, temperature, volume, & density are vital.

You can get yourself a lead salt and see if you can produce a functional lead styphnate; that would tell you something. The synthesis I use produces a remarkably potent product & resultant lead stypnhate is of high quality, good yield & brisant (for lead styphnate anyway). The emphasis on a careful sulfonation was suggested to another fellow's web site as his synth for the same had recurrent troubles.

[Edited on 2-5-2011 by quicksilver]

Here is a useful book

Rosco Bodine - 13-9-2011 at 12:49

This book should be put in the forum library but I am not sure how to upload it to that destination, so at least temporarily I have placed the pdf file here for the book

Aqueous Solution And The Phase Diagram

http://sciencemadness.org/scipics/Aqueous%20Solution%20And%2...

This book helps understanding the physical chemistry that comes into consideration with solutions, presented as an introductory level sort of text. Really for our interests with regards to nitrates, much more comprehensive studies and charts of highly concentrated mixed nitrate solutions and substantially anhydrous or low hydration eutectic melts is needed, but this particular book is a start and could be a helpful guide into understanding and charting ones own experiments if published references are not available for
nitrate salt systems of interest.

Here is a page that offers a free program having a Microsoft excel template for triangular diagrams which may be useful not only for nitrate solution calculations but possibly may be adaptable for workups of nitration diagrams. I have not tried this program so I can offer nothing further about it at this time. On second glance it appears the ions of particular interest are not included with the free version of this software. A fully functioning program covering the nitrates
of NH4+ Na+ K+ Mg++ Ca++ Zn++ Al+++ Cu++ Mn++ ect.
for systems up to quinary level would be more like what we would find interesting.

http://www.phasediagram.dk/index.htm

@ Anders Hoveland it appears Kaj Thomsen is in your neighborhood, so maybe you can facilitate getting us all a free trial program for the nitrates and mixed nitrates

[Edited on 13-9-2011 by Rosco Bodine]

85C 1% H2O nitrate brine 70.7% NH4NO3 28.3% NaNO3

Rosco Bodine - 14-9-2011 at 17:27

Quote: Originally posted by Rosco Bodine

Quote: Originally posted by quicksilver

Quote:

More on reciprocal solubility of the sort that is interesting in regards to potential usefulness in nitrations, where the nitrate may be added as liquid from a heated addition funnel. See the attached patent US3734709 on the last page, last paragraph just before the claims, where a concentrated mixed brine of ammonium nitrate and sodium nitrate is specified liquid at 85C which contains only 1% H2O
and has a solid nitrates content of 99% ...which is the kind of very low H2O content mixed nitrate system being sought.

There are probably others, but this looks like probably a very good combination.

If the patent's reported composition is accurate, the ratios would correspond on a dry basis of a total 100 parts for the nitrates, 28.55 parts NaNO3 71.45 parts NH4NO3

The dramatic effect of lowering the liquid temperature caused by the 1% H2O can be seen by considering the eutectic point for the anhydrous salts mixture is 35C higher. See attached articles which describe the eutectic for the anhydrous salts mixture. Also attached is an article describing the solubility in H2O for NH4NO3 alone.

Attachment: US3734709_AMMONIUM_SODIUM_NITRATE.pdf (110kB)
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Attachment: The Properties of Ammonium Nitrate. Part III. Ammonium Nitrate and Sodiurn Nitrate.pdf (430kB)
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Attachment: The System Ammonium Nitrate-Sodium Nitrate.pdf (543kB)
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Attachment: The properties of ammonium nitrate. Part II. Ammonium nitrate and water.pdf (309kB)
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[Edited on 15-9-2011 by Rosco Bodine]

Picric acid turned black?

Amos - 30-4-2014 at 08:29

I'm familiar with the synthesis of picric acid(trinitrophenol) and have successfully made it twice using aspirin, concentrated sulfuric acid, and KNO3. The most recent synthesis I conducted was in a much larger volume than the previous two. I dissolved 42g aspirin in 200ml of ~96% sulfuric acid, let it sit at about 90 degrees celsius until all aspirin was dissolved and a black colour was achieved. Next I slowly added 80g KNO3 in parts to the mix, carefully keeping the temperature low enough so as to evolve minimal nitrogen dioxide fumes. When this was done, and the solution was rapidly cooled in an ice bath, I got, as usual, lots of crude picric acid and a lot of yellow solution. Everything seemed fine. But when I filtered it out and added the crude TNP to boiling water in an attempt to purify and remove the excess acids, something funny happened. Some of the impurities came out as a red foam, which is normal in my experience, but after a while the entire contents of the beaker turned very dark yellow/black. I'm afraid I may have ruined my batch, but can anyone tell me for sure, and if so, how not to do it again? Sorry for the long post; I ramble.

Motherload - 30-4-2014 at 08:53

Did you purify the ASA out of the pills ?

Amos - 8-6-2014 at 17:17

In fact I did; I keep a large amount of it already purified as a reagent. In the end, after my first couple of ideas didn't work, I ended up adding some sodium bicarbonate to the solution, which miraculously seemed to clarify it back to a more acceptable red color, and after filtering/boiling/recrystallizing, ended up with a decent amount of clean picric acid.

nitro-genes - 14-6-2014 at 15:43

Just an observation that I wanted to share, not really of added value to this thread.

Just recrystallized a batch of PA for picramic synthesis, Normally I let the water solution cool and don't give it a closer look untill the next day or so. I never noticed how beautifull this process is. Upon a closer look the feather like crystals beginning to grow also introduced pronounced turbidity (dont know if this is the right word), probably due to the energy of their formation. Almost looked like the solution was on a hotplate, or mixing ethanol and water. Reminded me of a black smoker. It is somewhat visible in the top right of the photo. :-)

Maybe I just inhaled too much NO2...

[Edited on 14-6-2014 by nitro-genes]

Rosco Bodine - 15-6-2014 at 09:40

Things that have been seen cannot be unseen

On page 1 of this thread
http://www.sciencemadness.org/talk/viewthread.php?tid=4457&a...

Quote: Originally posted by Rosco Bodine

In near saturated solutions very near the boiling point , I have observed nascent crystals of picric acid first appearing as merely a pinpoint of reflected light grow to flat rectangular plates with pointed ends attain 10 mm length in 5 minutes . In bright light , a spiraling ribbon " mirage effect " in the liquid off the pointed ends of the crystals can be observed as the telltale sign of current in the liquid dragged along by the depositing molecules which build the crystal larger at a barely perceptible visible rate . The rate slows down drastically at lower temperatures and you cannot actually watch an individual crystal grow in length .

nitro-genes - 19-6-2014 at 11:40

How could I think this had escaped the attention of the SMDB picric acid expert himself?

Regrettably however, I must admit that (despite the usually highly interesting and detailed content of mr. Bodines posts), I have not read all 5146 of them.

Anyway, I gave the ascorbic acid reduction a shot to picramic (small scale). Characteristic red colour developed after prolonged boiling Sodium PA with slight excess of sodium ascorbate, the colour very much resembles that of (poly)sulfide reduction, a really dark red, almost black. Now the funny thing, whereas immidate precipitation is evident with (poly)sulfide reduction, nothing crystallizized after the ascorbic acid reduction. Not even after 2 days at 4 deg C. Volume was boiled to 1/3 of original, 2 days 4 deg C, nothing. Then added 10% HCl, no picramic acid precipitation. What is going on here? Is the SPA reduced further to more produce more soluble products or does picramic acid under some condition refuse to crystallize from super saturated solultions? Solubility is like 1-2 g/l at RT IIRC. Opinions/suggestions?

Rosco Bodine - 20-6-2014 at 08:49

It is essential that the stoichiometry be based upon reduction involving the sodium salt of picric acid, because that is actually what is done. The reduction is pH dependent.
The reduction of sodium picrate to sodium picramate using sodium ascorbate I haven't done so I can't share any comparison observation. But I would expect the reduction to occur quickly at well below boiling, like at 60C should be fine.
At boiling, I am not sure how stable the picramic acid would be and it could be decomposed by an unfavorable pH. If the amount of reducing agent isn't limited, the reduction could also go further and reduce more than the 1 desired nitro group so you could end up with diamino or even triaminophenol instead of the desired picramic acid. The solubility of the sodium salt of picramic acid is not very great and the solubility of free picramic acid from acidification is extremely small. The sodium picramate is however an intense dark maroon red "oxblood" color dye even appearing almost black in concentrated solution, but should color fade to almost clear very pale yellow tint on acidification, precipitating the nearly insoluble free picramic acid, which should be a dull brownish color, IIRC. You sure wouldn't need to concentrate the solution to isolate any free picramic acid because it is virtually insoluble the solubility is so low.

[Edited on 20-6-2014 by Rosco Bodine]

nitro-genes - 21-6-2014 at 02:12

Reaction conditions and quantities were initially used from the attached article where they indeed mention preferential reduction of only one nitro group. It was however on a less than a gram scale and pH was not monitored, so afr from ideal indeed. :-) The reduction, as judged by the rate of colour change is surprisingly slow even at 70-80 degrees, since I also had other things to do that day, I heat it to the boiling point to speed things up. The article (if you can call it that) mentioned however that the redcution products from dinitrobenzene reduction using AA could not be isolated. Could it be that the dehydroascorbate from the reduction acts as a solubility modifer? It is unclear where they refer to exactly. Might be a good test to see whether isopropanol would be able to precipiate the sodium dehydroascorbate while keeping Sodium picramate in solution, maybe extraction? Suitable solvent?

Attachment: Reduction of nitrobenzenes with ascorbic acid.pdf (155kB)
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[Edited on 21-6-2014 by nitro-genes]

Rosco Bodine - 21-6-2014 at 04:09

The use of ferrous sulfate is mentioned so it is entirely possible the actual reduction is accomplished by the ferrous hydroxide regenerated from the ferric by the ascorbate. Ascorbic acid is reported to reduce ferric sulfate to ferrous sulfate and similar reductions are reported where use of ferrous compounds is reported in schemes where there is regeneration of the spent ferric byproduct with it reduced back to the ferrous active reducing agent by various reducing agents. Iron or perhaps other metal filings, reducing sugars, or sulfides and ascorbate can all be used in such schemes where iron salts are catalytic and regenerated. This may be a key aspect for the reaction, but I'm not certain.
I think there is a similar catalytic reduction possible likewise using manganese and copper as regenerable catalytic reducing agents. What is operative for such schemes is I think the selectivity of the main reducing agent is better for rapid reaction regenerating the catalyst which reacts more readily with the nitro compound. It could be that the hybrid catalytic reduction scheme there is necessary for the reduction to proceed at moderate temperature. There is a dedicated thread for picramic acid where various processes are referenced.
The yield for the sodium sulfide reduction is very high and is reportedly high yield for some of the catalytic schemes also. If one reduction scheme fails to work well then there are several alternative schemes possible.

Nitrates Eutectic Mixtures

Rosco Bodine - 10-9-2014 at 05:32

Some mixtures found listed on use net 20 years ago

Nitrate Mixture Eutectics edit.bmp - 921kB

Edit: attached is the original source posting. I have edited and added some of the missing data in the K/Li/Na entry, gotten recently from other sources

Attachment: eutectic nitrate mixtures usenet.pdf (9kB)
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[Edited on 10-9-2014 by Rosco Bodine]

Magnesium Nitrate Mg(NO3)2 dehydration related

Rosco Bodine - 25-3-2015 at 16:26

More information provided here concerning dehydration properties of Magnesium Nitrate which is useful alone or in mixtures for oxidizer or nitration applications.

References attached relate to hydration states of Magnesium Nitrate and describe thermodynamic studies including vacuum dehydration of the hexahydrate to the dihydrate which is reported surprisingly to occur faster at a lower temperature of 40 - 45C range than at only moderately higher temperatures. What would occur at a much greater higher temperature as for increasing the rate of dehydration under vacuum is not described.

The magnesium nitrate - water binary system

From the following page
http://www.phasediagram.dk/binary/magnesium_nitrate.htm

The magnesium nitrate - water binary system exhibits a particular solubility behavior encountered in many aqueous salt systems: multiple solubilities at the same temperature. Between 50 and 90°C the solubility of magnesium nitrate can be one of three values, as it appears from the phase diagram at the right. The figure also shows that the Extended UNIQUAC model is able to reproduce this type of solubility behavior quite accurately. Three eutectic points and one peritectic point are found in this binary system.

The eutectic point where ice and magnesium nitrate nona-hydrate precipitate simultaneously is at -27°C and 33 % Mg(NO3)2. This is the cryohydratic point. A peritectic point appears at -21°C and 36 % Mg(NO3)2 marking the transition between the nona-hydrate and the hexa-hydrate of magnesium nitrate.

The hexa-hydrate and the di-hydrate of magnesium nitrate form a simple eutectic system with a eutectic point at 50°C and 67 % Mg(NO3)2. Finally magnesium nitrate di-hydrate and anhydrous magnesium nitrate form a simple eutectic system with an eutectic point at 129°C and 82 % Mg(NO3)2.

The fact that the transition at 129°C is a eutectic rather than a peritectic point has been documented in a number of experiments as for example the measurements carried out by Ewing, W. W., Brandner, J. D., Slichter, C. B., Griesinger, W. K. "The temperature-composition relations of the binary system magnesium nitrate-water", J. Am. Chem. Soc. 55(1933)4822-24.

(JACS article and related articles attached)

Attachment: Temperature Composition Relations of Binary System Magnesium Nitrate - Water.pdf (154kB)
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Attachment: THERMAL BEHAVIOUR OF Mg(NO3)2 6H20.pdf (444kB)
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Attachment: Vacuum dehydration Magnesium Nitrate.pdf (564kB)
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The fourth file attached describes a dehydration of Mg(NO3)2

Thermodynamic properties of potassium nitrate - magnesium nitrate compound [2KNO3 - Mg(NO3)2]

Attachment: Thermodynamic properties of potassium nitrate - magnesium nitrate compound [2KNO3 - Mg(NO3)2].pdf (321kB)
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[Edited on 26-3-2015 by Rosco Bodine]

"nitrous gases" useful for nitrations

Rosco Bodine - 1-8-2015 at 08:19

In a previous post the subject of nitrosylsulfuric acid was brought up as being an observed component of the nitration mixture producing picric acid.

http://www.sciencemadness.org/talk/viewthread.php?tid=4457&a...

There has been passing interest in this observation because it is not really known for certain if the nitrosylsulfuric acid is entirely just a byproduct accumulating in the nitration mixture or if it is actually an essential intermediate component which participates in the nitration and may be the actual nitrating agent derived in situ from the heated nitric and sulfuric acid mixture. There have been reported high yield nitration mixtures which have high water content but involve specific conditions which are difficult to reproduce not knowing the critical details which are now being better identified.

It is known that in the use of aspirin as a precursor first dissolved in sulfuric acid, a deacetylation and sulfonation occurs leading to salicylic acid sulfonate as the precursor for nitration. Reportedly this salicylic acid sulfonate should be easy to convert in quantitative yield to picric acid, via a modified nitration method where the nitration system is a high water content system. This suggests that indeed an aqueous solution of a mixture of nitrate and nitrite of sodium may be used to accomplish the conversion of the salicylic acid sulfonate in an acidified aqueous nitration mixture, with the additions of the nitrating agent mixture being possible to accomplished using an aqueous solution of the salts being added or injected rather than the more tedious method of adding a solid nitrate to a low water content concentrated sulfuric acid solution of the salicylic acid sulfonate.

JACS Vol 41 pg2045 Picric Acid from Salicylic Acid.bmp - 496kB

JACS Vol 41 pg2045 Picric Acid from Salicylic Acid.bmp - 496kB

Picric Acid related by Datta and Varma.bmp - 176kB

Attachment: JACS Vol 41 pg2039.pdf (414kB)
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Attachment: US1292266 Picric Acid patent by Datta and Varma.pdf (184kB)
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Attachment: blinded.mid (27kB)
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TGT - 3-8-2015 at 00:29

This is a little off topic, but recently I have made a batch of picric acid. I have done this numerous times before, but this last time things were different. When I recrystallize from hot water I usually get fine needles of picric acid after it has cooled. This time for the first time I got crystals formed okay, but they were not needle like, they just formed at the bottom a flat layer and they became very bulbous and solidified tight to the bottom of the beaker. Very pretty, but also very different than I am use to. Nothing was changed during the recrystallization. I am wondering possibly I didn't nitrate hot enough and produced dinotrophenol? Thanks in advance, this has been confusing.

TGT

[Edited on 3-8-2015 by TGT]

[Edited on 3-8-2015 by TGT]

Rosco Bodine - 6-4-2016 at 20:55

On the first page of this thread I posted a convenient method for a small scale high yield synthesis of very pure styphnic acid.

A video has been posted which is a slight variation on the method I described tested by another experimenter. I think the process variation shown in the video would have an improved yield by using the 10 grams resorcinol I specified instead of 8 used for the variation, and the cooling and stirring reduced with the reaction allowed to run in the initial nitration at a higher temperature as I described.

http://www.sciencemadness.org/talk/viewthread.php?tid=4457&a...

Quote: Originally posted by Rosco Bodine

Here is a method which I used a few times for styphnic acid which would consistently produce a 90% yield of recrystallized pure product .

10 grams of resorcinol is swirled into and dissolved in 50 ml of concentrated H2SO4 .
The dissolution is moderately exothermic due to the spontaneous sulfonation . After a few minutes a lavender colored precipitate forms and the mixture is allowed to stand for 2 hours . Then the mixture is cooled to 0 C by ice bath and
nitrated by dropwise addition of 20 ml of HNO3 d 1.4 ~68-70% to the stirred mixture kept below 35C until all is in solution except for small amount of end product which may be appearing . On recooling to 10C , 20 ml fuming HNO3 d 1.5 ~ 97% is added dropwise to the stirred mixture keeping temperature below 25C . The stirring is stopped and the mixture allowed to stand in the cold bath for a few minutes . The reaction mixture is then removed from the cooling bath and the temperature allowed to rise
from the exotherm . Some end product should be seen precipitating at about 28C and the mixture will foam and increase in volume and temperature .
The temperature rise will accellerate at an induction point of about 38C , really accelerating at 45C and from there spiking upward to 75C . Only an intermittent stirring should be done during the exotherm because the gas bubbles actually dilute the volume density and tend to regulate the reaction . Stirring the mixture causes the temperature to spike again by reconcentrating the mixture . Only stir periodically when the reaction temperature is falling and stirring down the foam will kick the reaction and temperature back up again . Generally only stir the mixture if the temperature drops below 40C from the unaided exotherm of the reaction itself . When the reaction temperature ceases to rise above 35C when stirred , allow the mixture to stand without stirring for a half hour and then dump the reaction mixture onto 250 grams of ice cubes and rinse the flask with 200 ml ice water , everything added together in one crystallizing bowl .
After 30 minutes the mixture is filtered and the crystals rinsed on the filter with about 40 ml ice water . The crude styphnic acid is redissolved in about 900 ml of boiling water , and on cooling deposits about 20 grams of hexagonal plates of pure very pale yellow styphnic acid . Yield is 90% of theoretical based on resorcinol . This method works fine for small batches but is possibly not directly scalable upwards without some provisions for temperature control . For a batch this size , a 500 ml flask is sufficent ,
a 250 ml size is marginal and will threaten to overflow at the peak of the reaction , likely would overflow without any stirring down the mixture which at times forms a solids filled curd , more than being a liquid consistency . The mixture becomes more liquid again as the reaction completes .

https://www.youtube.com/watch?v=Jqfv8qyiKMk&nohtml5=Fals...

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NeonPulse - 7-4-2016 at 17:00

The styphnic acid produced in the video was far superior to the powerlabs procedure I tried before this one. The synthesis worked very well too and went pretty much just as you described. There was not a lot of Nox fumes either. The whole process was quite tame unlike The powerlabs procedure which fumed like all hell and the yield was small.- probably oxidised the shit out of it. I would have used the specified 10g resorcinol but I had only 8g left. I still have most of the TNR produced leftover and it is nice pale yellow and granular crystals. I expect it to store well and unchanged for a long time.

. If ever there's a synthesis I want to try I will always look to see if you have posted an optimised version first and your general input about them. Some of my other videos are based on methods you devised including the mighty Azo-clathrate primary. I think I got it right. I tried to get it as close as I possibly could at the time. That stuff is quite the primary!
You put alot of thought and effort into your methods and it's always a pleasure to read and try them. Can I ask roscoe what do you do for a living? I often wonder wher reading your material and think whatever it is you do you must excel at it.

Rosco Bodine - 7-4-2016 at 20:02

There is in an old Gmelin article reported an interesting double salt of nickel styphnate and potassium styphnate which you should take a look at.

There is a few posts above a description of the usefulness of "nitrous gases" as a nitrating agent, which can be an effect that happens in many different nitrations where the nitrous gases are supplied from nitrosyl sulfuric acid formed in situ and then controllably very gradually the nitrosyl sulfuric acid intermediate is decomposed by increasing nitration byproduct water content and temperature of the nitration mixture. On a small scale nitration it is a method that works very well. The foam collapses and dissipates to a liquid slurry as an indication the reaction is complete.

If the viscosity of the nitration mixture is sufficiently great it produces a stable enough foam, the nitrous gases are trapped and not being lost to the reaction, the nitration continues in a "blob" of foam that is self regenerating as the reactants are consumed.
That is actually the scheme for the reaction producing styphnic acid so the ratios of reactants are in a narrow range to produce the desired viscosity that results in that
stable foam as a kind of niche condition for the reaction to follow a specific course.

See the attachment to the linked post
http://www.sciencemadness.org/talk/viewthread.php?tid=11105&...

And another post of interest
http://www.sciencemadness.org/talk/viewthread.php?tid=13283&...

A basic lead styphnate possibly could form interesting clathrates and could also possibly form a neutral double salt with picric acid by boiling 1 molar equivalent of basic lead styphnate with 2 molar equivalents of picric acid. Using 1 molar equivalent of picric acid might result in a "hemi-basic" lead styphnate - lead picrate double salt. AFAIK such contemplated double salts are purely my conjecture, hypothetical and unreported compounds, but seem possible. If the "hemi-basic" variant exists, it could also be a clathrate substrate, and might complex with lead azide formed in situ from an added equivalent of lead nitrate to the reaction mixture followed by slow addition of an equivalent of sodium azide. And if a confirmed clathrate formation occurs it would possibly complex with more than 1 equivalent of lead azide with a limit of how many more possible, only to be found by experiment.

With regards to the nickel styphnate - potasium styphnate double salt, when you have basic nickel carbonate or nickel sulfate or other on hand, I have an idea that nickel hydrazine nitrate due to its extreme low solubility may be easily producible by a different method than usually described using free hydrazine and nickel nitrate. I think using hydrazine sulfate reacted with calcium nitrate a solution of hydrazine nitrate will be easily filtered away from the calcium sulfate precipitate, and should react with nickel nitrate in presence of gradually added sodium hydroxide, or sodium bicarbonate, or ammonium hydroxide, or ammonium bicarbonate used to neutralize the excess nitric acid value associated with the hydrazine nitrate and form sodium nitrate or ammonium nitrate byproduct remaining in solution. The contemplated reaction might require a separate disassociation of the hydrazine nitrate done first, freebasing the hydrazine first, using the base separately, before mixing with the nickel nitrate as a better and more specific sequenced preferential reaction and certain approach likelier to work. The NiHN might be an interesting complementary mixture with the double nickel - potassium styphnate if that double styphnate salt has the sass as reported by Gmelin.

[Edited on 4/8/2016 by Rosco Bodine]