Sciencemadness Discussion Board

Picric acid: different instructions

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Quince - 21-8-2005 at 00:32

I got my replacement thermometer a few days ago. I noticed it had a small gap in the mercury column, so I was shaking it, and of course it broke, right where my thumb was. Took me ten minutes to stop the bleeding. That's the second thermometer I break in a couple of weeks. :( Worst is no one sells them here, so I have to wait and pay for shipping from the US...

HCl is excellent crystallization enhancer

Rosco Bodine - 28-8-2005 at 16:29

Earlier in the thread I mentioned the difficulty which can be encountered in
getting a good clean crystallization of picric acid , and I have rediscovered the secret I had learned once before and then forgotten , concerning the usefulness of a small amount of HCl as a crystallization modifier for aqueous solutions of picric acid . The solubility of picric acid in hot , even boiling hot water is
dramatically reduced by even a small percentage of HCl , which radically alters also the entire temperature solubility curve , so that the picric acid may be precipitated readily from very hot and more dilute solutions , in a controlled manner by small portionwise additions of HCl . The precipitated crystals are the
dense gritty freeflowing and readily filterable form having a sparkling fine
mesh just coarse enough to result in a freeflowing microcrystalline form when dry . The crystals precipitated in the presence of a small percentage of HCl are
light in color and highly pure , more consistent in granulation size than are the range of crystals which precipitate from plain aqueous solutions which are slowly cooled . The temperature range is smaller over which the bulk of the crystallization occurs and the temperatures at which crystallization begins and is mostly completed is much higher in solutions containing a small amount of HCl . Freeing the more concentrated solutions of dark colored impurities is also facilitated by adding small amounts of HCl sufficient only to effect a small precipitation which drops out mostly the impurities , which redissolve more slowly on reheating and may be filtered from the picric acid solution . Reboiling will drive off some of the HCl and increase the solvency , and the level of saturation can be manipulated with additions of water and HCl to accomplish the selective precipitation of dark tea colored impurities , lightening the color of the purified solution from which the picric acid may be precipitated . A boiling hot solution of picric acid in water which is no more than perhaps two thirds saturated , will show the dramatic effect of a small amount of HCl added to the boiling hot and well stirred solution . Adding one sixtieth to one fiftieth the volume of the aqueous solution , of 31.45% HCl into the vortex of the rapidly stirred solution at just below the boiling point by a half degree , the solution will cloud upon cooling by another 2 degrees and the precipitation of glittering crystals will begin . The precipitation of glittering crystals of picric acid will develop steadily
and nearly all of the precipitation will occur
in the narrow yet elevated temperature range of 95 downwards to 75 C , below which little further precipitation will occur .

Contrast this sharp precipitation range at
an elevated temperature which favors consistent crystal formation , in the presence of a small percentage of HCl ,
with the rather broad and sluggish precipitation for plain aqueous solutions .
The HCl containing solution is for the most part finished precipitation at a temperature where the plain aqueous solution is at about the midpoint of a rather wide range for crystallization which goes much more slowly and forms a wide range of crystal sizes getting smaller and smaller with decreasing temperature .

So the usefulness of HCl is established for forcing the crystallization of picric acid from hot aqueous solutions in a desirable crystalline form . HCl in this use could be thought of as a crystallization catalyst .

In COPAE , Davis hinted at the usefulness of HCl in producing light colored and pure crystals of picric aicd , but Davis did not elaborate on the usefulness of HCl as a solubility modifier and the mechanism for accomplishing the crystallization .

Quince - 28-8-2005 at 17:26

That's great! I'm going to try this in my next batch, as soon as I get my Gregar extractor finished so I can purify more aspirin.

However, upon reboiling, if the solution is boiling, how can you refilter? Or is it sufficient to just decant the PA solution from the precipitated impurities?

[Edited on 29-8-2005 by Quince]

Rosco Bodine - 28-8-2005 at 19:02

The cloud point of the solution is possible
to be maintained stable enough at a moderately warm temperature by adding the HCl in very small amounts and waiting a minute or two to observe the change .
The clouding is in my estimation largely the impurities which can be filtered both
as precipitated solids or as the suspended
matter at the cloud point , or some of both simultaneously . The use of temperature and the carefully added small amounts of HCl can be used to manipulate the solubility of warm and hot solutions so you can conveniently work with the solutions across a wider range of concentrations and temperatures . There is different solubility for the impurities and the picric acid , and you can selectively precipitate the impurities and or redissolve
any also precipitated picric acid by cycling the solution with temperature changes ,
and additions of water or hydrochloric acid . You will see when you work with the technique how the presence of HCl can be used to facilitate the selective precipitation of the picric acid or the impurities . Once you understand from observation how the solubilities can be manipulated , using HCl will become routine . The color and or physical form of the precipitated impurities is quite different from the sharply crystalline crisp form of picric acid crystals , and tar or heavy oily material which redissolves on resumed heating and dilution more slowly than any picric acid which may also precipitate and comingle with the impurities as a melt . This is the sort of
separation that has to be finessed with
a bit of skill , but having the HCl to use as a tool makes the process much simpler .
The first crystallization from a good nitration procedure is not difficult because the impurites are not at sufficient concentration to complicate things . But when the residual liquid from the first crop is boiled down to perhaps a third or less of its volume is when the impurities will begin to be troublesome and precipitate on cooling . Being able to accomplish the precipitation in hotter and more dilute solutions , by use of the HCl , by itself reduces the problem significantly of precipitated impurities in the second crop of crystals . It also reduces the length of time and energy requirement for not having to boil down the residual solution from the first crystallization to as small a volume as would be required without the added HCl . The technique can likely be generalized to a step by step which works well for a given batch size , but I can give no more details except to say try it , and learn from what you see occur with the solutions , the fuzzy logic of solubility manipulations ,
which applies to your particular batch .
I cannot yet describe a standard method because I am still working it out myself
the best technique . But even the not fully developed idea in experimental practice is a huge improvement over no idea at all , that a little HCl makes much shorter and rewarding work of your picric acid crystallizations .

chemoleo - 28-8-2005 at 19:17

That's very interesting.
What is the basis of precipitation? I can't quite figure it out, the precipitate has to be the full acid (including the proton), so what is causing the picric acid ion to protonate? The excess H+ I suppose. Still odd. I never understood these issues (common ion effect and such) too well :(

The_Davster - 28-8-2005 at 19:36

Is the batch that the HCl precipitated from a KNO3/H2SO4 batch or a HNO3/H2SO4 batch? I have had difficulties with the KNO3 method for a reason I believe to be because potassium picrate had formed. I have a feeling Rosco's HCl idea would have fixed it.

Rosco Bodine - 28-8-2005 at 20:02

Memory fails me on where I read it first , but I know later that Philou Zrealone also has mentioned that picric acid can exist in different forms depending upon the pH of the solution .

A lower pH favors the less soluble and less colored form of picric acid , IIRC it is called an enol form , and I don't recall the other form . A similar solubility and pH relationship exists for sulfuric acid added to solutions of picric acid , and Urbanski and PATR have that solubility relationship charted with minimal solubility at 18% H2SO4 . But of course H2SO4 would also tend to contaminate the crystals with its
low volatility residue , and HCl probably does the same thing more effectively in recrystallization scenarios . The H2SO4 data is useful for efficent quenching of nitration mixtures to determine the optimum dilution for the first crystallization of the crude material , with least loss in the dilution water , washings
from the first filtration . Industrial practice recycles everything , including that wash water , using it in subsequent nitrations .

Anyway , yes the picric acid was made using the nitrate and sulfuric acid method .
It may be possible that an alkali-trinitrosulfonic intermediate is formed
and that somehow HCl catalyzes the decomposition to picric acid ....I wondered about that myself , but then the observations on solubilities don't reconcile with that idea of what is occuring when HCl is present .

I'll have to go with the pH sensitivity / enol formation idea , and wish I could learn more about this . A possible clue
is in the formation of different colored forms of ammonium picrate , one yellow and one red . This may be a different aspect of the same pH sensitivity causing a different crystal form and color for a picric acid salt , while the effect is being manifested from the picric acid itself .

picric acid as indicator dye for pH 0.3 to pH 0.4 transition

Rosco Bodine - 29-8-2005 at 03:16

According to Merck , picric acid is not only
a dye , but is a pH sensitive indicator dye with a change from yellow to colorless at
pH decreasing below pH of 0.4 , listed in the attached table as the indicator shown
seventh down the list . So for sure there is a sharp transition point in pH which results in a fading of color from the solutions of picric acid , and indeed I have observed literally chalk white crystals clinging to the stirbar , which are probably
the fully transitioned material mentioned by Davis in COPAE . This information squares with my own observations and sheds light on what is occurring with added HCl . Picric Acid is itself a very strong acid , about as strong as phosphoric acid , so solutions of picric acid alone approach the transition point if they are strong enough , but don't quite get there to achieving the low enough pH to make the transition to the colorless and lower solubility form . Adding HCl nudges the pH still lower the little extra needed for the transition to occur , and that changes the entire nature of the system solubility , in favor of crystallization .

All in all a very neat trick :D

Attachment: table_phindic.pdf (100kB)
This file has been downloaded 1369 times

GODhack - 3-9-2005 at 12:43

ahh I know that it is almost totally offtopic but please help. Also sorry for my not very good english. So I maked TNP, NC, NG, EG... and it was realy fun. Two weeks (or ewen more) ago I had contact with NO2. I holded TNP reaction bath in my hand (~100ml) and NO2 fumes cames out. I droped all in large amont of water and moved avay for about10 minutes. Because I am silly I camed back and vorked in same plase for another few hours. Evrything was ok same day, another day...

But yesturday my body teprerature reached 37.3C and lots of red spots occured on skin. Yesturday also I tassed some exotic food so I buyed and drinked some antihistamin (not shure how it is colled in english) drugs. They helped me a lot. This day skin is red again and I drinked even double dose. I begin to think that it is not alergy but I am poisoned. Because I am realy scared few hours ago I asked my good frend and he dumped ALL chemicals in my lab that I produced.
Questions:
Am I realy poisoned?
How long skin will be red-spoted?
Is it serious?
How much is it seriuos?

Quince - 3-9-2005 at 19:35

I'd think that NO2 won't cause red spots on your skin. I've had several times nitrated my skin by accident, and it turns brown. After accidental releases of NO2, I took a breath of ammonia to neutralize it. Sounds like you have a rash, either allergic reaction to some chemical, or some sort of infection. The NO2 causes lung damage instead, and possibly death.

[Edited on 4-9-2005 by Quince]

Taaie-Neuskoek - 4-9-2005 at 01:08

Quote:

After accidental releases of NO2, I took a breath of ammonia to neutralize it.


:o You took a breath of ammonia?? I cannot advise this method, NO2 is already taken up in your lungs when you have breathed a couple of times more... It goes in your blood and does nasy things, I've read some literature on it.
Red spots on the skin is not something usual for NO2, if you've inhaled NO2 you feel sick, and your lungs hurt... no symptoms concerning the skin (exept from dying maybe) are described.

Thanks for the recristalising info Rosco, very helpfull. (I'm about to make some TNP...)

[Edited on 4-9-2005 by Taaie-Neuskoek]

quicksilver - 7-9-2005 at 18:38

Quote:
Originally posted by Rosco Bodine
-=snipped for brevity=-

All in all a very neat trick :D


Rosco: I have been following your posts for years now (mr. anonymous) and as I have been such a lurker have never told you that much of what you have experimented with / such have I..... indeed much of what you have expounded upon tracks with what I have worked with in-so-far as crystal growth, etc.
Some years back I posted a styphnic acid sulphonation and worked with styphic acid as you have picric. My experiences have been much the same in-so-far as crystal size, shape, and temp issues. I was lucky to have some kg of resorcinal...so I just went at it. Most of the styphic acid patents didn't provide for sulphonization in a manner that could be scaled up or down. Eventually I was able to reproduce beautiful, large yellow crystals of a variety of shapes. I have also made an attempt at picric using indigo, as I found a dye mfg that had some for pennies. Being a solid I did not have the challenges that oil of wintergreen presented and am possably going to use that next.
That being said I wanted to thank you for the work you have posted as I save much of the notes and experiences of others and even remember the clathrate post for some years back!
I have found that the toughest thing is to record mp temp when completing an experiment as I am limited as to equipment and have wondered if you have a "kitchen- fix" or some methodology regarding mp temp....(?)
I have found a method to change crystal shape from needle to a more pourable (cube, etc) without sacrificing size or consistency.
My issues with crystal growth are such that I found that the investment in a quality hotplate was nesessary.... as you have said that temp control was virtually primary; other factors being equal. And I simply wanted to add that your posts through out the years have been apprieciated.

quicksilver - 7-9-2005 at 21:04

Quote:
Originally posted by chemoleo
That's very interesting.
What is the basis of precipitation? I can't quite figure it out, the precipitate has to be the full acid (including the proton), so what is causing the picric acid ion to protonate? The excess H+ I suppose. Still odd. I never understood these issues (common ion effect and such) too well :(


I do now believe that it (and much of the "red goo" issue) _WAS_ H+. This was discussed several years ago and I believe that it was a member here who brought about some proofs. I can't remember who it was but I remember some of the remarks.

The final form is a bit stabilised by hydrogen bonding between the H of
=N(O)-OH and theO of O=C.

Orange color sometimes comes from NH3, or another base which produce a
tiny amount of the cetonitronic form (possibly more sensitive!)
You know the process for CH3-NO2 (uncolored but yellow to dark
brown when exposed to bases:
CH3-NO2 + NaOH -- H2C=N(O)-ONa
Thus
H3C-NO2 <==-- H2C=N(O)-OH (proton jump from the CH3 to the O)

Excessive Hydrogen may also account for same color.

Same occurs in TNT when subjected to alkaline fusion...a sensitizor
colored form appears:
-C(CH3)=C(NO2)- <==---- -C(=CH2)-C(=N(O)OH)-


Same phenomenon occurs with mono, di and trinitrophenol.

Rosco Bodine - 8-9-2005 at 23:15

The red goo is one of several byproduct impurities attendant to the synthesis of picric acid which are analogous to the byproducts formed with styphnic acid , and described in several patents . There are also other byproducts not mentioned ,
which tend to form a melt with some of the picric acid , which dissolves more slowly than the pure picric acid does when
forming a * saturated * solution in water gradually heated to boiling . The removal of the red goo impurity is best accomplished by fractional dissolution , sacrificing whatever picric acid is entrapped as a melt and slow to dissolve in boiling water , decanting the more nearly pure saturated or nearly saturated picric acid solution from the red goo which will solidify as a single solid chunk adhering to the bottom of the flask set upon a cool surface for a minute or two , allowing the still nearly boiling hot picric acid solution to be decanted . This is really the only effective way of removing the impurities which will otherwise discolor and adhere to the picric acid which precipitates if gotten from a mixture where " all is in solution " including the impurities . The precipitate of impure picric acid will on redissolving in
water gradually heated again to boiling leave the bulk of the impurities as the last thing to dissolve , again forming a melt which puddles on the bottom of the vessel . By cycling the dissolution and precipitation , nearly all of the impurity may be removed . Pure picric acid solutions are pure yellow in color without a trace of orange or brown . Even the saturated boiling solution will be pure primary color yellow . And the crystals
which separate from these pure yellow solutions will be more nearly perfect in purity than the crystals which form in more
orange colored impure solutions . These observations still apply to the solutions where HCl is used as a solubility modifier .
I have noticed that the more desirable crystals tend to drop out while the solution is still warm and this is really where the added HCl has benefit by shifting higher the temperature range over which most of the crystallization completes , and leaving much less remainder to be gotten from the filtered solution if it is boiled down for a second crop . Instead of 10% of the yield having to be gotten by boiling down the residual solution from the first recystallization , there is only maybe an additional 2 or 3 % there , which makes the second crystallization hardly even worthwhile for smaller sized batches .

Rosco Bodine - 9-9-2005 at 14:49

To get a more pure crude picric acid product from the first filtration of the diluted nitration mixture , I have underway an experiment which appears to be working . The experiment at early purification of the product is being done on a 1 mole scale according to a slight variation of Experiment 2 above using 1 mole of methyl salicylate for the nitration .
The sulphonation was done at a higher temperature ( 169 C ) for a longer time ,
several hours , using 40% the amount of sulfuric acid , and then adding more sulfuric before the nitration , but using only 90% the total amount H2SO4 on a molar basis as in Experiment 2 . An extra amount 20 grams of solid NH4NO3 was added to the spent nitration mixture before it was raised to 120 C for a half hour in finishing the nitration . After standing overnight , the two thirds solidified mixture of lumpy solids and spent acid was diluted with 1150 ml distilled water and heated to 110 C to redissolve the bulk of the crystals , but leaving a layer of darker melt and impurities at the bottom of the hot mixture . As the gentle boiling proceeded , the saturated solution gradually lightened and clarified above the melt pooled on the bottom , as small globules would rise and fall in the saturated solution " lava lamp style " .
There was a considerable amount of the melt at the bottom of the flask containing the spent nitration mixture total volume now about 2250 ml . The 3 liter Erl containing the boiling hot saturated solution was removed from the hotplate stirrer and set on a stack of newspaper
with one edge of the bottom of the flask raised slightly by a 1" thick block of wood ,
in order to tilt the flask so the melted material and the stirbar would roll across the bottom and settle at the low spot . The low spot was rested on a damp paper towel to more rapidly cool the puddled melt and stirbar . The flask was rocked gently to observe when the melt solidified , and when this occured , the saturated solution was clouding and
was quickly decanted from the solidified impurities , into a 4 liter beaker . A stirbar was placed into the beaker to keep the hot solution stirred as it precipitated the
crystals of picric acid .

The solidified chunk of impure picric acid encased the stirbar , and it was half the size of a fist , containing much picric acid ,
though contaminated with impurities . The impure material was covered with a fresh portion of 1500 ml distilled H2O and reheated to boiling . The similar effect as observed in the first dissolution repeated ,
only this time , a small volume of much darker melt was the result , estimated to be maybe 5 or 6 grams of impurity . The
1500 ml of boiling hot solution was handled exactly as was done before , decanted away from the impurity melt
just as it solidified clinging to the stirbar .
The hot saturated solution was decanted into a 2 liter beaker , and the residual 5 ot 6 grams of impurity was discarded .
The contents of the 2 liter beaker were
then added to the product from the first
decantation in the 4 liter beaker , total
volume of the combined material is about
3700 ml .

The crude material having been freed from probably 90% of its impurity
by this workup of the nitration mixture ,
should give a very fine quality end product
after subsequent recrystallization from
boiling water and HCl .

I wanted to describe this process since
no complete details of how this is done have been described before .

The quantities for the process described are for 1 mole of precursor , so it should be easy math to determine quantities for other batch sizes .

my first picric acid synth, did I do something wrong?

((Blasta)) - 12-9-2005 at 14:17

So I tried to create phenolsulfonic acid by first heating my concentrated sulfuric acid to around 300C. I then allowed the acid to cool off to 210C then I added my 100 extra strength Asprin tablets, at 32.5 grams. The solution began to attack the asprin quite quickly and within several minutes the acid-asprin solution went very dark and a few white fumes evolved. The end solution after cooling is still very dark but when I turn the flask to the light the acid-asprin solution appear to have a dark redish copper color to it. Did I overcook my solution? Is this normal? The smell of this liquid reminds me of photographic grade acetic acid...

update* I wonder if I used too little sulfuric acid? After adding in 100ml more acid the solution began to lighten some what...

[Edited on 12-9-2005 by ((Blasta))]

Quince - 12-9-2005 at 18:25

Isn't that too hot?

[Edited on 13-9-2005 by Quince]

Mumbles - 12-9-2005 at 19:59

That sounds normal to me. Everytime I have seen the phenol(or substitute) reacted with sulfuric acid it takes on a dark red color, to a black color if th sulfuric acid is impure. I assume the phenol-4-sulfonic acid has a dark red to black color. As far as the lightening, it could be because you had too little. I feel there is a much stronger chance that it is because of simple dilution. If you have a colored solution, and you add more solvent it tends to lighten in color.

As far as the acetic acid smells that is normal. The asprin is hydrolysed to salicylic acid and acetic acid. It is then decarboxalated and sulfonated. The heat you had on the sulfuric acid/asprin mix was probably high enough to boil off some of the acetic acid thus explaining the odor.

[Edited on 9-13-2005 by Mumbles]

Rosco Bodine - 13-9-2005 at 18:00

The phenolsulfonic acids are dark red and appear nearly black in anything but a thin layer which allows some light to reveal the color . Aspirin sulfonates easily and rapidly and at a fairly low temperature . It may be beneficial to actually leave as much of the acetic acid as possible by not sulfonating aspirin for too long or too hot ,
as its solvent properties and its evaporation is probably helpful to the nitration particularly in the first half of the nitration .

Using plain aspirin tablets will reduce your yield and result in purification problems if your experience follows mine . Picric acid can be difficult to isolate in pure form since any impurities tend to get trapped in the crystals . The difference can be whether one or three recrystallizations will be needed if the pure material is what is desired .

((Blasta)) - 13-9-2005 at 19:06

humm, I'll try nitrating the mixture and see how much Picric acid I recieve... I'll let you all know.

Quince - 15-9-2005 at 17:33

I want to save on solvent, so I'm wondering if an extraction using a solvent apparatus is usable for aspirin extraction, or would the filter be too clogged by the fine solids for this to work (or can I perhaps use a layer of several filters of increasing fineness to decrease the clogging effect)?

...pleasently surprised

((Blasta)) - 15-9-2005 at 17:55

Well, the experiment wasn't a loss after all. The black phenolsulfonic acid nitrated easily and produced a bright yellow crystalline precipitate. The crystals were washed in deionised water and dried. The end product was fairy pure after filtration. I estimate that the yield was ~60%, so I don't think it was terriable for my first try. I've since made
Ammonium Picrate and tested a COB device at the firing range. Quite powerful stuff and quite easy to make too!

Rosco Bodine - 20-9-2005 at 20:52

My initial optimism about methyl salicylate being a good precursor for picric acid is much in question now after three experiments have each failed to produce nearly as good yields of simply isolated pure product compared to the use of aspirin as the precursor . The process using methyl salicylate goes much more slowly both in the nitration and doubly slowly in the purification . It may be that the optimum conditions for the sulfonation and nitration have simply not been identified , but indications are that the problem is more involved than just that . The methyl group of the ester is what appears to itself be causing problems , possibly due to a byproduct during sulfonation which then causes losses during nitration , along with way too much of an oily contaminant in the end product which is difficult to eliminate .

Future experiments may refine the method for methyl salicylate to a point it will become useful , but presently the yield of purified end product is only about half the amount obtained using aspirin , and the quality is not as good . If I make any progress at refining the method to a point it is worthwhile , I will share the information . But from what I have observed with three experiments so far the methyl salicylate is much inferior to aspirin as a precursor for picric aicd .

I am considering saponifying the methyl salicylate with NaOH and then acidifying with HCl to convert it to salicylic acid , and eliminate the methyl group which I believe is the source of the trouble .

quicksilver - 21-9-2005 at 06:48

Quote:
Originally posted by Rosco Bodine
My initial optimism about methyl salicylate being a good precursor for picric acid is much in question now after three experiments have each failed to produce nearly as good yields of simply isolated pure product compared to the use of aspirin as the precursor . The process using methyl salicylate goes much more slowly both in the nitration and doubly slowly in the purification . It may be that the optimum conditions for the sulfonation and nitration have simply not been identified , but indications are that the problem is more involved than just that . The methyl group of the ester is what appears to itself be causing problems , possibly due to a byproduct during sulfonation which then causes losses during nitration , along with way too much of an oily contaminant in the end product which is difficult to eliminate .


My attempt yielded a slightly darker yellow (but indeed the yield was low. I am in the process of working w / HCI and that attempt at salvage.
However....I live in a very rural area and if you have access to a vet supply or a feed & grain store there is a product that is Asprin (pure) for cattle that sells for $8. It is made by Priority Care (it is Asprin for Cattle) called Asprin Boluses. This is pure ASA for $8 and it is 2.5 lbs of asprin....yes; one Kg of ASA for $8. It has been my source for experiments for a few years now.
You can find it on the web as well (Re-order #1OM010PCARE - second digit is the letter o the fourth is a zero). Thus you could spend about $20 (including shipping and get two kilos of ASA !
And that, my friend is VERY inexpensive. I have made a list of OTC sources in the USA and some items are unusally low cost; asprin is one of them.

Rosco Bodine - 21-9-2005 at 09:32

Yeah I think ASA is definitely the better precursor and it does produce a very pure picric acid in high yield by a fast process .

I haven't yet tested the ASA nitration using the nitrate as a concentrated solution of ammonium nitrate . Another
idea I want to try is a mixed solution of ammonium nitrate with some sodium nitrate , which may allow a more concentrated solution . I know there is an optimum water content and an optimum spent acids composition , any departure from which can be adverse to the yields . It can be a lot of work testing the variables and finding the conditions which work best , but I have seen it happen that the quality of the process can make a huge improvement when the details are worked out just right .

One thing I am getting with methyl salicylate is a clear oily precipitate which contaminates the end product , and also there is a soapy detergent like byproduct of sulfonation which results in a persistence to the foaming , at times the nitration is like trying to stir whipped cream or shaving cream , which is very annoying and troublesome , making the additions go tediously slow to allow continued mixing . There are very significant viscosity problems to manage
during the nitration , much worse than is the case for ASA .

ordenblitz - 21-9-2005 at 17:49

Priority Care aspirin boluses contain a small amount of urea as well as microcrystalline cellulose as a compression aid.

A better choice is to use their aspirin powder sold in one pound bags that is pure ASA.

http://farmvet.com/farmvet/shop/shopdisplaydetailfarm.asp?pr...

quicksilver - 21-9-2005 at 18:09

Quote:
Originally posted by Rosco Bodine
One thing I am getting with methyl salicylate is a clear oily precipitate which contaminates the end product , and also there is a soapy detergent like byproduct of sulfonation which results in a persistence to the foaming , at times the nitration is like trying to stir whipped cream or shaving cream , which is very annoying and troublesome , making the additions go tediously slow to allow continued mixing . There are very significant viscosity problems to manage
during the nitration , much worse than is the case for ASA .

When you said that I just thought of something..... Salicylic acid with heat source converts to carbolic acid (phenol) and
carbon dioxide; (in presence of water from 98% H2SO4)
The formed phenol just sulfonates rapidly. The wintergreen oil would need to jump through hoops to get to that point.
-SO3H group will do as -NO2 or -OH groups in accelarating the evolution of CO2 at lower temps.....perhaps....the meer fact that one is dealing with an "oil" would account for the soapy by-product...(?) Let's say that the sulfonation process is too fast (just a guess) and in a solid with a closer phenol structure it's OK...but in a product like oil of wintergreen it takes a much longer time because we don't have
C7H4O2 + H2O --- C6H6O + CO2
-C7H6O3 -- C6H6O + CO2
to start from. (I hope I wrote that correctly: but you get the idea)...
I have used Indigo....had a lot of problems....so once I let it sit in H2SO4 for a full day (24hrs)....final product came out lemon - white yellow and looked great. Used it in a reaction - it was the real thing. Of course I have yet to use horn or wool, or some damn thing....:P

Mumbles - 21-9-2005 at 18:45

Quote:
Originally posted by ordenblitz
Priority Care aspirin boluses contain a small amount of urea as well as microcrystalline cellulose as a compression aid.

A better choice is to use their aspirin powder sold in one pound bags that is pure ASA.

http://farmvet.com/farmvet/shop/shopdisplaydetailfarm.asp?pr...


Thats not pure ASA.

Quote:
1 level tablespoon is approximately 1/2 oz. 1/2 oz. contains approxiamtely 7080 mg of Aspirin.


1/2 oz is ~14g. 7080mg is only 7.08g. This puts it at 50% ASA.

Rosco Bodine - 22-9-2005 at 06:17

With alternative precursors in mind , it may be of interest that red gum may be nitrated to picric acid . I have never tried this method but it seems worth noting for any who may wish to experiment with unconventional precursors .

P.S.

Damn ESPACENET for going to encrypted files which are more difficult to assemble and decrypt for saving and sharing , and the stupid new user interface which they have substituted for the more functional one which has been recently removed from service . It adds 10 useless minutes of difficulty to handling any .pdf file they offer compared to what used to be so straightforward . And besides that , anybody with half a mind can recompile
the document in an unencrypted intelligent form ...so what have they accomplished really but to piss off their clients with their stupid new " document wrapper " interface ????

Attachment: GB104352 Picric Acid from Red Gum ( gum accaroides ).pdf (307kB)
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quicksilver - 22-9-2005 at 06:41

Quote:
Originally posted by Rosco Bodine
Damn ESPACENET for going to encrypted files which are more difficult to assemble and decrypt for saving and sharing , and the stupid new user interface which they have substituted for the more functional one which has been recently removed from service . It adds 10 useless minutes of difficulty to handling any .pdf file they offer compared to what used to be so straightforward . And besides that , anybody with half a mind can recompile
the document in an unencrypted intelligent form ...so what have they accomplished really but to piss off their clients with their stupid new " document wrapper " interface ????


IT'S ABOUT TIME SOMEONE SAID THAT....I simply stopped working with British patents at that site because ESPACENET has become a vacuous shambles of what it was supposed to be....Lord in Heaven! that site is a pain in the ass.
-=However; thank you for hasseling the file.=-

Please note that it needs to be renamed to "xxxxx.pdf" due to the above issues. But it IS a great example of the issues discussed.

quicksilver - 23-9-2005 at 08:00

Quote:
Originally posted by Rosco Bodine
With alternative precursors in mind , it may be of interest that red gum may be nitrated to picric acid . I have never tried this method but it seems worth noting for any who may wish to experiment with unconventional precursors .


After reviewing the patent there are some very important issues discussed. First of all is temp that they mention; the use of 40C (104 F) and time of nitration. This has been a real stumbling block for many. If the temp is raised, the nitration proceeds and if monitored can be successful but the yield falls. If nitration temp raises to the point wherein the solution has a "Yellow Froth" (temp unk.) the tri-nitration usually results BUT the trick is to MONITOR the solution for an overall orange colour NOT red! This colour issue is a real important one, I believe. It gives some clues where resources are not available - EXCEPT for appearence.[We can't just stop and use an old fashoned NitroMeter] And the solution must appear clear (as you mentioned). If cloudy and red the nitration has brought about the resultant "red-goo". This appears (to myself at least) to be a temp vs time issue. One can go as high as 200+C but the solution MUST be monitored. I have heard it said that if time were not at issue and one wanted to allow the synth to stretch over several days that 40C would be just fine (the patent points to this as well, in effect). But very few folks want a lab to proceed over days and on a production scale it would be problematic. Therefore monitoring the solution for colour is manditory.....due to a varience in ratio of temp vs. size of synth.
This has applied to BOTH my use of Indigo & plain old asprin.
I have worked with ounces (rather than grams) in my PA synths because I want to have a useful amount of reagent available after I'm all done. But that involves monitoring the thing constantly as I have found out that the temp/colour issue will change when I am at 1 OZ vs 8 ounces.....etc.
The patent speaks of sulfonation at the 10 hour level. I believe at 30C... I have not kept it that low myself....but I have brought the the temp to boiling (230C + or -) monitoring it constantly; I personally have had success but with a low yield. They mention 48 hours which leads me to believe they are working with the multi- pound or Kg level of product perhaps.
As you have mentioned I ALWAYS let the solution set for 12 hours after nitration and allow the cooling off to proceed without any interference (or a sudden plunge in cold) & my crystals have been fantastic!
On another topic therein they speak of purificication of the starting material. They mention purification in the cold! I have always done so. Even when many have said to use heated alcohol....I have used cold etoh and the product has been excellent. I have found a useful little trick with asprin. I use a solution of ethyl alcohol and acetone in my initial step of grabbing the ASA from the store bought material. I use 2/3 etoh to 1/3 acetone. This has two important effects. The 1st is that the product appears to be MUCH purer and forms very strong well formed crystals (I am not sure why but it is very different from using alcohol alone) and it also evaporates MUCH faster. The product is thus made has been THE BEST I have ever used. When comparing mp and it's appearence under a microscope to mfg reagent grade PA from a major suppier; it appears to be the SAME! All in all the patent agrees with what I have found experimenting over 6 months with PA alone. I have never seen this patent (due to the problems with that damn patent web site) yet it tracks with what I have found by trial & error! All in all it is an important patent as it outlines what many have had to learn by trial and error...IF...you know what you are looking for in both the patent and the synth itself.:D

[Edited on 23-9-2005 by quicksilver]

ordenblitz - 30-9-2005 at 15:36

Mumbles said:
__________________________________________________
That’s not pure ASA.

1 level tablespoon is approximately 1/2 oz. 1/2 oz. contains approximately 7080 mg of Aspirin.

1/2 oz is ~14g. 7080mg is only 7.08g. This puts it at 50% ASA.
__________________________________________________

Well actually it is pure ASA crystals.
Beside the fact I get quite pure TNP using it as received, I decided to alleviate any doubts...

I measured out 1 tablespoon, obviously a very inaccurate form of measure, and got 9.42 gm.

The package states:
Active ingredients - each pound contains Acetylsalicylic Acid (Aspirin)......1 lb.

To be sure I checked it on the FTIR.
(Kbr, transmittance)
Omnic full library search calls it as:
2-(acetyloxy)-Benzoic acid U.S.P
CH3COOC6H4COOH

This is definitely pure ASA crystals and the best $8.00 your going to spend.

chemoleo - 30-9-2005 at 19:20

Awesome your FTIR. You should create a thread on this, the uses of FTIR in amateur chemistry. While people submit either the methods or even the samples to you for analysis.
Did you ever get round to comparing AP vs 'DPPP'?
Sorry that's way off topic, and please dont respond to this, Ordenblitz, except in the correct thread....
So much for being an example eh :P

ordenblitz - 25-10-2005 at 18:06

Working from Roscoe's good old country recipe as was posted in another thread, I made some TNP this weekend.

The materials…
http://img58.imageshack.us/img58/9658/asacrystals7bj.jpg
http://img58.imageshack.us/img58/4581/h2so48hp.jpg

93.75 grams of ASA were sulfonated in 375ml 80º, ~96.5% H2SO4
http://img58.imageshack.us/img58/8198/hotsulfasa8lv.jpg

Strangely enough, upon cooling overnight the solution remained clear with no sulfonated material precipitating.
http://img58.imageshack.us/img58/6996/coldsulfasa4gw.jpg

The mixture was placed in a 1000ml flask and the temperature raised to 95º. The additions of granular sodium nitrate commenced. The NaNO3 was obtained from a commercial fireworks chemical supplier and is of high quality but the actual purity is unknown.
http://img58.imageshack.us/img58/1463/beginnitra0wo.jpg
http://img58.imageshack.us/img58/9098/1stadd6oj.jpg

The solution began to slightly darken with each subsequent addition.
http://img58.imageshack.us/img58/627/3rdadd3sl.jpg
http://img58.imageshack.us/img58/9339/7thadd2jo.jpg
http://img58.imageshack.us/img58/2308/10thadd1uv.jpg

As the crystals of TNP formed the mix began to thicken and lighten again.
http://img58.imageshack.us/img58/5044/14thadd6gb.jpg

At this point there was considerable foaming upon the addition of the solid nitrate and the timing between same had to be greatly increased as was suggested.
http://img58.imageshack.us/img58/6453/22ndadd9zj.jpg

Stirring was very difficult and the viscous mix moved but slowly with my poor 2" stir bar. Roscoe mentioned a big 3"oval stir bar and It's surely needed! Next time I will use more sulfuric to lower the viscosity. No sense being stingy.
http://img58.imageshack.us/img58/6875/26thadd8se.jpg

Although it looks like foam, it’s a viscous crust of TNP sitting on the top of the acid. It was making the additions of the nitrate almost impossible to work into solution. This was the final addition of the nitrate.
http://img58.imageshack.us/img58/5117/28thfinal9bd.jpg

An evil looking brew as 500ml of water was being added from a wash bottle as the dilution began.
http://img58.imageshack.us/img58/7987/startdilution9mq.jpg

Some ice and some time and viola'
http://img58.imageshack.us/img58/634/dilutedandcooling4nd.jp...

Filtering out the raw TNP crystals. I cooled quickly, so the result is a voluminous fine crystal.
http://img58.imageshack.us/img58/8335/filteringtnp2kq.jpg

The raw material was suctioned well and dissolved in 2200 ml of boiling water and then allowed to cool again.
http://img58.imageshack.us/img58/7097/recrycooling2uk.jpg

The first crop was dried and weighed in at 84.2 grams or 70.5% of theoretical.
http://img58.imageshack.us/img58/2767/firstcrop6ff.jpg

The mother liquor was boiled down to ~500ml and a second crop was obtained. After filtering and drying a further 24.16 grams was obtained.
http://img58.imageshack.us/img58/9192/secondcropcooling9df.j...

The remaining TNP in solution was neutralized with K2CO3 then chilled and the crystals of potassium picrate were collected. They were then re-crystallized from acetone which yielded 3.56 grams, corresponding to 3.053 grams of picric acid in the final liquor.
http://img58.imageshack.us/img58/6001/ktnp7um.jpg

Final tally was 111.41 grams of C6H3N3O7, 93.38% based on ASA.
It was a good day. Thanks Roscoe.


Kinda perty aint she?

pretty.JPG - 15kB

Quince - 25-10-2005 at 18:12

That's funny. The sulfonation makes my liquid a very dark color which clears up during nitration, nothing like your images.

Rosco Bodine - 25-10-2005 at 19:33

Looks like the right stuff and the right yield . Before I had a magnetic stirrer ,
I used about 20% more H2SO4 for a thinner mixture so it could be manually swirled in a 1.5 liter glass tea kettle .
IIRC the product was not quite as good , but the process followed about the same general track otherwise and was workable .

The higher temperature of 115-118 for the sulfonation will produce the disulfonate which is much darker and will gel solid on cooling overnight to a suspension of crystals in a gelled acid matrix , like dark red-black sand jello full of light colored sand . My acid isn't reagent grade so the color is probably off , but the physical consistency should be the same . The disulfonate nitrates more easily and decarboxylates vigorously from the start so it is better I think from a reaction management standpoint to use the higher sulfonation temperature and get the disulfonate ,
but whatever works for you ...the mono and the disulfonate both lead to picric acid
upon nitration , only the reaction proceeds a little differently and decarboxylation is finished later in the nitration for the monosulfonated ASA .

Personally , I like to get most of the effervescence over with early , while the mixture is thinner in the mononitration and dinitration stage , but there is some overlapping of the reactions across the whole time of nitration , giving variations on a theme depending on temps and rates , stirring efficiency , as well as the sulfonation state of the precursor .

Give the mixture some slow cooling time , with stirring continued , after the plain water quenching , and a bit larger crystals will come out of the warmer mixture before it is cooled more quickly with the ice , and then discontinue the stirring as the ice is completely melted .
If you hit it just right the crude picric acid will all be like fine beach sand , microcrystalline a bit finer than table salt , and it will filter quickly even without suction by a plain gravity filtration .
The filter paper has limited life wet with the diluted nitration mixture , a couple of hours is okay , but it shouldn't be left all
day or it will possibly disintegrate when
rinsing off the crude crystals into the flask for boiling and recrystallization .

ASA really does give a nice grade of picric acid in good yield by this method . I have made it from time to time for about 25 years using basically the same old country recipe ...er , I mean synthesis :D

ordenblitz - 25-10-2005 at 20:24

Roscoe,
I followed your sulfonation profile fairly closely but the hold time at 118 was only about 5 minutes as I needed to do some other things. So I shut off the hotplate and put the flask up for the night. I'm going to try that again with a longer hold to see if I get the change in color.

>Give the mixture some slow cooling time
>with stirring continued , after the plain
>water quenching , and a bit larger crystals
>will come out

My solution was so thick that the stir bar just quit working. I had to stir the last portion of nitrate in with the thermometer. I would like to try your cooling profile but, I need to get a better bar!

[Edited on 26-10-2005 by ordenblitz]

Rosco Bodine - 26-10-2005 at 01:09

After the midpoint of the addition of the total nitrate , the viscosity gets a bit tricky
and practice makes perfect when it comes to adjusting the addition rate and temperature to find the range where the
mixture is least viscous and stirs fairly well . It looks to me as if the mixture stirs most freely just after a bit of nitrate is added and some foam is helping to loosen the mixture , but if the foaming becomes greater then it decreases the stirring efficiency greatly . So you have to watch for the good working volume and pace the additions of nitrate to keep it stirring freely . The progress of the reaction follows a sort of curve instead of being linear , and you will get skilled at the manipulation of the conditions with some practice . Feel free to adjust the proportions and test your own ideas , as the synthesis is not necessarily optimized , though it is pretty good and probably not far off the mark . It is a good working method but good stirrer torque and a heavy stirbar is definitely needed , and the additions of nitrate can get tedious when hours are involved .
If I was intending many experiments with this , I would likely get a stepper driven auger feeder for addition of the nitrate and automate the process . A control program could be devised for large batches , if any large scale production was intended . About the limit for my own equipment and manually done batches would be a 2 mole scale , and that would require my 12 liter Florence being nearly filled for the first crystallization :D
Not exactly microscale .

I have one dedicated electrical branch for the 1.6 Kilowatt hotplate to which that humungus flask is paired . When it gets to the point of needing pouring cradles and pumps for emptying your reaction vessels , you know you have a serious experiment underway :D

Joeychemist - 26-10-2005 at 08:10

Quote:
Originally posted by Rosco Bodine
Memory fails me on where I read it first , but I know later that Philou Zrealone also has mentioned that picric acid can exist in different forms depending upon the pH of the solution .

A lower pH favors the less soluble and less colored form of picric acid , IIRC it is called an enol form , and I don't recall the other form .

I'll have to go with the pH sensitivity / enol formation idea , and wish I could learn more about this . A possible clue
is in the formation of different colored forms of ammonium picrate , one yellow and one red . This may be a different aspect of the same pH sensitivity causing a different crystal form and color for a picric acid salt , while the effect is being manifested from the picric acid itself .



I have been performing my own experiments with Picric Acid lately and have some very interesting findings to share.

Rosco touched on this a little a while back but more proof was needed for me to be sure.

I have had several 5g batches of Picric Acid (Which were recrystalized into very light yellow/white crystals and precipitated using HCl) sitting out on and evaporating dish now for about two months and I have noticed that the Picric Acid crystals are clearly changing back into the brighter “canary yellow” color that we all attribute to Picric Acid. The surfaces of the samples and crystals which are exposed to the air revert back much quicker than the crystals at the bottom of the sample but the color change is still noticeable (It is very noticeable on the larger crystals at the bottom of the sample).

These observations (Along with Rosco’s observations) lead me to believe that there is infact both an Enol and Keto form of 2,4,6-TNP like Rosco suggested!

Mmmm….Keto-Enol tautomerisms :D

This is very interesting and is a giant step forward in my eyes. What do you guys think?

Rosco Bodine - 26-10-2005 at 10:17

The pH sensitive color transition is very real not only for picric acid but also for sodium picrate . And I believe it was the light colored form which was gotten from the diluted nitration mixture , in a nearly insoluble form of fine crystals , which at
a partial dilution did not even really tint the supernatant spent acid , nor did the liquid stain the filter paper yellow when filtered . That is definitely an observable difference when a strong dye has lost its ability to dye , presumably from residual acidity of HNO3 and / or HNO2 which can be smelled on the damp nearly white crystals .

I would not use the HCl for the final crystallization , in any significant concentration , as the crystals do absorb
some of the HCl and you can smell it on the crystals for days of airing out . Use plain distilled water with very little or no HCl for the final crystallization and the color is still very pale for the highly purified product .

ADP - 26-12-2005 at 13:55

I am also in the works of performing a Picric acid synth and my sulfonation produces a very dark colored liquid. I am using the following reagents:
10g of purifyed ASA
20ml of H2SO4 (ACS)
35ml of 70% HNO3 (ACS)

Do these quantities seem reasonable? I heated my ASA/Sulf acid mix at 100dC for 1 hour and it turned from yellow, orange, then red, to deep brown and then a thin blackish color. It has now cooled to room temp and I intend on chilling it to 0dC, adding HNO3, stirring, and then heating once more.
Quote:
Originally posted by Quince
That's funny. The sulfonation makes my liquid a very dark color which clears up during nitration, nothing like your images.

I was just now doing some thinking and realized that my asprin from which I procured ASA has polyethylene glycol, starch, and polyproprylene glycol in it. I used acetone as means of purification and am worried that what I thought was pure ASA may have glycols in it. Should I be worried about this? How would these react with H2SO4?

IPN - 26-12-2005 at 14:20

The amounts look quite reasonable to me but I don't think you need to cool the sulfonated product so much before adding it to the nitric acid, room temp should be fine. Then just add it slowly with good stirring keeping the temp below 40C-50C and heat to ~120C for about 30-45 minutes after addition. That will finish the nitration.
Beware of the NOx gasses that develop during the reaction!

Oh, and 10-15min should be enough (at 100C) for the sulfonation part.

ADP - 26-12-2005 at 14:59

Many thanks IPN, I will post results later.

Sucessful Procedure

ADP - 26-12-2005 at 22:15

I used the following reagents in my procedure:
10g ASA (purifyed via acetone)
20ml H2SO4 (98% ACS)
35ml HNO3 (70%)

I added the sulfuric acid to a 250ml beaker and added the ASA at once. The mixture turned a deep wine color and then went black but remained thin and easy to stir. (on a side note I wonder if my ASA had polyproproylene glycol in it? soluble in acetone?)

Allowed to sulfonate for 1 hour at 100dC. Cooled to room temp (at this point the phenol-4-sulfonic acid was visible from the thickness and color of the mixture) and then ice bathed at 10dC added 35ml of HNO3 and stirred.

I brought this mix to room temp and put in a steam bath at 50dC for like 20 min. I then raised the temp to 90 and 100dC and the water was boiling and heavy NO2 was produced and the mixture was starting to boil. I was kinda worried about this and only let the mix remain this hot for like 5min.

The color changed to a light milky yellow and I removed heat and brought to room temp. I could clearly see picric acid at this point and added 200ml of ice water and stuck in fridge to cool to -5dC for least solubility. Filtered and set to dry; here are my pics... :D













My one question of improvement is: How do I nitrate the phenol mixture at 120dC for 30-45min if my nitric acid is boiling and decomposing? Is this supposed to happen and will a runaway ensue? Thanks a ton.

kABOOM! - 27-12-2005 at 01:06

Yep...this is how I too made Picric Acid, ADP. I kept the temperature slightly lower...say 65C for a slower reaction but still I got the same product. I got a fairly decent sized yield too.

Quince - 27-12-2005 at 03:05

Quote:
Originally posted by kABOOM!
I got a fairly decent sized yield too.

What the fuck does this mean? Ever heard of numbers, measurements? "say 65 degrees"?! Did you even use a thermometer, or just stuck your finger in and it seemed warmer than your mother's twat? What made you choose that particular temperature? Why not 50, or 80? No, wait, let me guess: it just 'felt right'. For fuck's sake, I thought this forum was about chemistry, not fucking medieval alchemy! This forum is being taken over by the k3wls, it would seem! Hey, I've got an idea, let's just start mixing up random shit in proportions determined by the dice roll/cards/stars!

So, your mood shows as awesome, eh? Is that due to the holidays, or did you taste one too many of your witch's brews?

Any moderator care to check the IP of this tool, to see if it's another incarnation of Hideki, or just a cretinous copycat?

[Edited on 27-12-2005 by Quince]

12AX7 - 27-12-2005 at 04:49

Quote:
Originally posted by Quince


Did you happen to read the part of the Sulfuric Acid bottle that says "Do not drink", Quince?

Tim

ADP - 27-12-2005 at 06:42

When using HNO3 for the nitration of the phenol-4-sulfonic acid, what is the best temperature and nitration time from experience? I feel that my nitration would have been better had I held say 80dC for 30 or 40min.

I kept a lab journal and will reattempt the synthesis today for improvements. I havne't weighed my yield yet as it is still damp. I will do so shortly. :)

Quince - 27-12-2005 at 17:33

Quote:
Originally posted by 12AX7


Yo, whazaaap Timmy, haven't heard from you in a while.
Quote:
Did you happen to read the part of the Sulfuric Acid bottle that says "Do not drink", Quince?


It said no such thing on the label. :P

chemoleo - 27-12-2005 at 17:52

Please back to topic. I am well-tempted to just delete this little useless episode. I might do so at a later time nonetheless.

quince...show a little class!

kABOOM! - 27-12-2005 at 20:39

WTF, quince! What did I do to piss you off!? Sorry, I guess I need more information...I'll provide it--- provided that you get off my back pal. Thanks.

I used the following chemicals in my procedure:
25g ASA (purifyed via Ethanol)
35ml H2SO4 (96%)
50ml HNO3 (95% estimated- home brewed)

I added the ASA to 35ml of H2SO4 in a pyrex flask and allowed the temperature to rise using a hot water bath. The temperature was kept at 90 C for 1 hr 10 minutes. The ASA-sulphuric acid mixture was completely dark by this point- and sulphonated. I then chilled the liquid to -1C in the freezer for 35 minutes. I even packed a shallow water-bath which help keep the temperature down substantily then I added the 50ml of HN03. The temperature gradually rose....a few red NOx fumes evolved and I left the mixture to get up to room temperature... then I put the beaker back into a hot water bath. The temperature of the water never got above 70C ...lots of red NOx fumes evolving by this point. The digital thermometer gave me a reading of 65.5C for the water bath-- kept in for 15 minutes. The end product was creamy yellow, and filtered using distilled water and kept cool for several hours.

[Edited on 28-12-2005 by kABOOM!]

Quince - 27-12-2005 at 23:23

Quote:
Originally posted by chemoleo

Hey chameleon, you're letting all those stars besides your name get to your head. Or maybe it's all the fumes from your chemistry stash.

chemoleo - 27-12-2005 at 23:30

Stop being a petulant dickhead Quince. Cheap provocations won't get you anywhere.

You are off-topic for the last 3 posts, and you are flaming quite unnecessarily so, particulary in light of the fact that you are not quite in the position to flame, looking at your previous record.

Now STFU and CONTRIBUTE something WORTHWHILE rather than random flaming just to pat your ego.


[Edited on 28-12-2005 by chemoleo]

Nevermore - 27-12-2005 at 23:54

Quote:
Originally posted by Quince
What the fuck does this mean? Ever heard of numbers, measurements? "say 65 degrees"?! Did you even use a thermometer, or just stuck your finger in and it seemed warmer than your mother's twat? What made you choose that particular temperature? Why not 50, or 80? No, wait, let me guess: it just 'felt right'. For fuck's sake, I thought this forum was about chemistry, not fucking medieval alchemy! This forum is being taken over by the k3wls, it would seem! Hey, I've got an idea, let's just start mixing up random shit in proportions determined by the dice roll/cards/stars!

So, your mood shows as awesome, eh? Is that due to the holidays, or did you taste one too many of your witch's brews?

Any moderator care to check the IP of this tool, to see if it's another incarnation of Hideki, or just a cretinous copycat?

[Edited on 27-12-2005 by Quince]


having a bad day eh...
i suggest a good visit to gym, hitting the sack, or shooting some mice and finish em with a bat..
the net doesn't work for cooling off, and u know, u don't want your hand to shake when u are working with those substances, unless u have a few spare fingers.
Goodluck

[Edited on 28/12/2005 by Nevermore]

Quince - 28-12-2005 at 00:22

I'm no longer working with those substances; my pyromaniac's days are past. The only explanation I have for the continued experimentation with explosives by people on this forum is that they are compensating for being cursed with a smaller-than average manhood. For the asians like Hideki, though, that should be expected, so there must be another explanation for that particular individual. Happy holidays.

[Edited on 28-12-2005 by Quince]

vulture - 28-12-2005 at 09:25

You'd think that someone with that many posts would know better and that sanctioning would only be required for n00bies...

Apparently not. You've gotten enough warnings quincy, you're suspended for 14 days. Go shoot your guns and come back when you've blown off some steam.

[Edited on 28-12-2005 by vulture]

YT2095 - 25-9-2006 at 09:57

*BUMP*

sorry for that, but I AM interested, and although it`s taken me the best part of an aftrenoon Ive read all the posts in here, Rosco I`m Impressed!:o

I`m trying to do Similar but on a Micro scale with only single figure Gram quantities.
thus far I crushed 16 x 300mg aspirins, dissolved the lot in 100% pure Etoh, filtered and evaped.
put that in a boiling tube and added 20ml of 98% sulphuric.
at this point it warmed and went yellow orange and the powder turned gel like and slowly mixed into the acid.
upon careful heating I watched color changed as stated in this thread and stopped heating at the "Black" color.
(although not technicaly Black) there were a few White fumes emited also and a distinct Vinigar smell.
upon cooling however, the Mixture has solidified, and it`s not even down to room temp yet!

What have I done wrong?

or is it another case of YT makes yet MORE Black useless junk when trying to do Orgo chem :(

I`ll cap this tube and await a response before continuing further.

I`ll also point out that I only wish miligram quantities from this just to Look at, I have No interest in boom booms!

EDIT: I also plan on using 70% nitric acid as the O2N donor (if that makes any difference?).


[Edited on 25-9-2006 by YT2095]

Rosco Bodine - 25-9-2006 at 11:14

You haven't done anything wrong at all by having the
disulfonation product set up solid on cooling .....that is
exactly what it normally does . It will melt again when
you reheat it to the temperature where you will begin the nitration .

To keep the mixture more liquid you can use more sulfuric acid .

The nitration should work fine using 70% nitric , although
I haven't worked out the exact times and temps , and the
reaction may progress differently .

The nitration mixture will still require heating at least to boiling water bath temperatures and holding there for some time towards completion of the nitration to produce a most completely nitrated product .

BTW you need to do the nitration in a flask to allow for
some expansion room for the foaming which will occur .

[Edited on 25-9-2006 by Rosco Bodine]

YT2095 - 25-9-2006 at 11:21

well from I`ve learned from your posts thus far the Mono Nitration part may take place (and preffered if) it`s at a lower temp.

I`ll use a Hypo to deliver the nitric anyway, that way I can guage the exact amounts and literaly do drop at a time.

for now I`ll leave this as a solid until I get more time during the day tomorrow, you said also that the residual acetic may not present a problem also, and so I`ll leave it capped too.

thnx for the info :)

Rosco Bodine - 25-9-2006 at 12:46

Concerning theory and experiment .....

One thing you should consider doing is using solid nitrate
for the first third to one half of the nitration , since
that is so straightforward and can be done at a high
initial temperature with a good nitration rate .
And then use your 70% HNO3 for the remainder of
the nitration , where it would probably be of benefit
for not causing any further loading of the mixture with
solid byproducts , as would occur where the entire nitration is done using a solid nitrate .

Such a scheme could perhaps exploit the desirable
property of the solid nitrate in the first third or half
of the nitration where it works best , and would conserve
your 70% HNO3 for that later stage in the nitration where
it would possibly have advantage . However it is
not assured that the reaction itself will behave in accordance with the expectation , as it may or may not .

Also , in these sulfonation mixtures where the water content is low and the H2SO4 content high , in an undiluted sulfonation mixture , there is not really any distinct three stage reaction for the nitration products ....indeed there is some end product appearing already in the nitration mixture early during the nitration , even though the lower nitration products predominate , there is an overlapping of the
nitration products stages which is present throughout the process . So , even though only one third of the total nitrating agent is added , the conversion to mononitrated
product is not complete , but the mixture contains some
of the unreacted sulphonate , and all three nitration products , but the mononitrate
* theoretically * should predominate . What is the actuality on the proportions and the progress of this sort of nitration mixture is unknown . So to get fully past the mononitration stage , could require as much as half of the nitrating agent to have been added and reacted , since not all of the first third was reacting in a way to produce the mononitrate , but was diverted to formation of some of the dinitrated and trinitrated products .

[Edited on 25-9-2006 by Rosco Bodine]

quicksilver - 26-9-2006 at 06:32

One of the most valuable things I have picked up from you was temp control issues and proportions. the 1 to 4 ratio of H2SO4 & ASA (and the solid nitrate 1.8: 1) have seen me through some pretty fun experiments.In fact I was suprised to see this post up as I just got done following a solid nitrate / ASA nitration of 100 grams. You once said something about coping with foam that is a good deal.....takes a lot patients to SLOW down the introduction of a solid nitrate when the experiment will certainly take you the whole day...... :D It is pretty nice when one emulates an experiemnt and gets the same results in terms of yield % and product quality!

Rosco Bodine - 26-9-2006 at 08:25

Yeah it is a very gradual process of nitration which seems to resolutely resist efforts at speeding it up ,
which always seems to bring complications with foaming
and diminished yields , in my experience anyway .

The slow pace is one of the things I thought could be
addressed by using solid nitrate for the first half of the nitration , and then using 68-70% HNO3 for the second half .....hoping that the total time could be reduced by
a third to a half of what is required when only the solid nitrate is used .

The conversion of aspirin to picric acid in a most efficient
and optimized manner is a desirable synthesis to have
all the details established . Picric acid and several derivatives of it are for many reasons
" practical energetic materials 101 " , even though
the literature seems to focus greater attention on other materials , which tends to deemphasize the true significance and usefulness of picric acid . Because it
can be made from many different starting materials ,
and is so useful both directly , and as an intermediate for
other useful materials , it is and should remain a keen
interest for experimentation . Where it is written otherwise that picric acid is somehow archaic or has
no particlar usefulness or versatility , are words you can
attribute to someone who doesn't know what they are talking about .

YT2095 - 26-9-2006 at 09:12

well, I`ve completed the Next step, over the space of 30 mins the KNO3 was added spatula at a time.
this was done outdoors in a 250ml conical flask as you recommended, at 1`st there was little i the way of NO2 but white choking fumes instead, the NO2 didn`t really happen until about half way, I was trying to keep the heat up as you can imagine about 25ml in a large flask outside on a cool still day isn`t easy.
eventualy I was down to half a spatula at a time but faster feed until there was no visible reaction even with movement of the liquid.
the color was orange and perfectly transparent.
this liquid got thinker and crystals started to form up the flask, upon gentle heating LOADS of NO2 came away and everything dissolved again, the color is quite a bit lighter now and it`s also lke thick honey as it`s cooling and there are 2 crystals forming, and many less than hair thickness making "cobweb" paterns up the side of the flask, these are Lemon yellow, and LOOK like the product.

I`ll cease the reaction at this point now and let it cool until I get further advice from you Rosco.
I didn`t do the HNO3 70% idea in the end, I stuck to the "tried and tested" method for a 1`st go.

I know at Some point I`ll have to shift all the K2SO4 out the thing, and being such a tiny microscale synth, I daren`t crash in ice water else risk loosing the lot.

enhzflep - 26-9-2006 at 09:45

YT,
The first time I did this synth was also with 1 pk aspirin (24@300mg). I don't have any refferences handy, but it was something like 8gm ASA to start with. This was then sulphonated with boiled battery acid, before being nitrated with.. wait for it .. (I'm a bit embarrased about this one) Pottasium Nitrate that was extracted from comercial black powder :o - I know, I know - but it was the first nitrate source I had.

Anyway.. The synth was carried out and was simply scaled down. I'm sure I dont, but IIRC it was about 100gms of ice and water that I crashed it in. Solubility's somewhere in the order of 2 or 3 gms per L (or was that per 100ml??)

I ended up with in the order of 4-5 gms of picric. Far from Ideal, but acceptable given the care (or lack therof ) exercised throughout

This was then succesfully used to make lead picrate - both normal and basic. Some went into a comp det and the remainder functioned as an extremely loud whistle - which, I er in-tended. Yeah, that's right - I wasn't trying to make a det with the powder pressed too tightly at all.. NOoooo. not at all. ;)

Too lazy to look it up, what about K2SO4's solubility in EtOH? If you're going to make PbPicrate, then there's the first step done too.

Rosco Bodine - 26-9-2006 at 09:51

A thermometer is helpful for this reaction if you are
trying to get good efficiency , because you are going to have to run it pretty hot and the thermometer will allow you to track what is going on in the mixture .

If you are using KNO3 , the K bisulfate byproduct is so much less soluble than the sodium analogue that you should be using more sulfuric acid , perhaps 5.5 to 6 ml of H2SO4 per gram of ASA . I'm not sure about the best ratio for KNO3 because it has been a long time since I used the KNO3 , switching to NaNO3 early on because of
the reduced quantity of H2SO4 required . I do recall that KNO3 did work well , it was just not as efficient in the utilization of acid .

That old thread

https://sciencemadness.org/talk/viewthread.php?tid=4457&...

See near the end of the page my post

" picric acid from ASA , NaNO3 and 92% H2SO4 "

It contains some details that ordenblitz was duplicating here in this thread . Maybe the process for NaNO3 can be interpolated for KNO3 . IIRC the KNO3 process also
could run at a bit lower temperature , maybe by 10C or so . Experiments with NH4NO3 solution were not done
on ASA , but observations on its use in other nitrations
indicated that it favored an even higher temperature for being effective particularly in the final stage of nitration .
It became clear that water content of the nitration mixture , the type of nitrate being used , and the ratio
of the acid mixture to the quantity of picric acid being attempted , time of reaction , and temperature range
for the reaction are all together interrelated factors which
affect the process . Change one thing and it changes everything else to some extent .

YT2095 - 26-9-2006 at 10:10

well Happily (I think) the liquid mass has now crystalised from the edges inwards with fine yellow crystals in an Orange syrup.

there`s no Red globs or sludge as has been reported by some in this thread, so I`m pleased with it thus far.

I`m in 2 minds now if to re-heat and crash onto ice and a little water, or Add ice water, I think the former would be safest as water to acid is Never good.
eitherway, it will be the bare Minimum of H2O irrespective of phase, and then put into the fridge, liquid poured off next day.

then do the same again with BOILING water at a minimum to dissolve all with a drop of HCl added, and then lagged to cool Very slowly.

pour off the liquid once more and then follow the purification proceedure as also outlined in this thread.

if anyone can see a flaw or a Better way to get my product out Please let me know!
that`s the reason I`m doing this single step at a time :)

but rem, I only started with 4g of Pure ASA!

EDIT: ok, I decided to "Wing it" after reading the link you provided, and added the cold water to the inside wall of the flask, and yes, there was heating and NO2 liberated also.
I took the water vol up to the 130ml region and kept the lot moving constantly, eventualy All the solid mass broke up and the color is now All a lemon yellow with white to yellow tiny crstals floating about.
Most stay on the bottom but there`s also about 10% on the top too and swishing makes them stick to the side walls :(
satisfied that no solid clumps exist, it`s now in the fridge to stay overnight.
I`ll decant where possible, if not I`ll just filter out and give a cold water rinse.
and then follow the rest of your proceedure in that link but with the HCl addition.


Interesting that you mentioned about picric being a lost art and Archaic, if you actualy knew what my plans were for it, you`de think I was archaic and out of the Ark! :o

[Edited on 26-9-2006 by YT2095]

YT2095 - 27-9-2006 at 04:32

ok, it`s all done, I have roughly Twice the volume of picric acid as the starting crushed asa (a pleasant surprise).
it`s been washed twice, filtered with a rinse and is now in plain water with a few drops of 38% HCl and back in my original boiling tube with a cork in it (I don`t want any to dry!)
I considered re-crystalising this but I don`t like the idea of large crystals of this stuff, so a fine sulpher like powder is ideal, especialy for my application as a Wool Dye.

I would like to know what the Ideal way to store this stuff is, under water is a given as is non metalic, but what sort of container ?
I`ve heard of this stuff crystalising around bottle stoppers and exploding when someone tried to open it, does it have vapor pressure issues like Iodine for instance?

Rosco Bodine - 27-9-2006 at 06:32

Picric acid is reasonably safe to store dry . It has no volatility at ordinary temperatures . A pill bottle
with a plastic cap is fine for storage .

It is such a powerful yellow dye that if one should even glance upon an uncontained sample without wearing safety glasses , that not only the researcher will be permanently dyed bright yellow , beginning with the white of the eye and permeating to even the soles of the feet .....but also ones children shall have the complexion of canaries even to the third generation ;)

quicksilver - 27-9-2006 at 06:39

There are a lot of idiocyncracies that fly by and are not noticed. A heavy stir-bar....a strong vortex, the use of NaNO3 rather than KNO3, (which solid nitrate to use is a whole thread in itself) a final inclution of HNO3 to boost the fluid volume and maintain the "freshness" of the nitration, the recording and attention to temp-altering the additions of solid nitrate to temp changes....these issues can help keep foam down and maintain a fine product time after time. I said this before; I keep a Hell of a lot of the things people write, I also maintain a lengthy written record myself. I worked on a 100 gram ASA synth and knew I was going to get very sharply deliniated, beautful crystals of reagent-grade TNP.

[img]null[/img]

[Edited on 27-9-2006 by quicksilver]

yield_6.jpg - 54kB

YT2095 - 27-9-2006 at 07:15

Nice Pic!

although it maybe the ambient light, but mine looks a little lighter yellow than that, but the liquid (dissolve PA in H2O) is insanely yellow, I`ve already dyed a strip of fleece in the leftovers (filter paper and washing sols), I think I`ll not dry this product though, I`m happy with it left in the bottom of the boiling tube under a layer of water, I used a tiny drop of Ammonia in the water to make sure all stronger acid traces are gone, and if some turned to Ammonium Picrate then that`s just fine too, in fact I considered doing that to the entire batch just for stability reasons.
Wool contains Amines though and so I decided against it as that`s probably what the PA reacts and bonds to in the wool.

I`m happy with my product now, Thank you All very much each and esp You Rosco, without your posts in this thread I feel that things may have turned out somewhat differently than they have!
more than likely yet another case of YT makes some More useless black organic junk.

Cheerz each, I`m satisfied now :)

[Edited on 27-9-2006 by YT2095]

Rosco Bodine - 27-9-2006 at 07:31

Quote:
Originally posted by quicksilver
There are a lot of idiocyncracies that fly by and are not noticed. A heavy stir-bar....a strong vortex, the use of NaNO3 rather than KNO3, (which solid nitrate to use is a whole thread in itself) a final inclution of HNO3 to boost the fluid volume and maintain the "freshness" of the nitration, the recording and attention to temp-altering the additions of solid nitrate to temp changes....these issues can help keep foam down and maintain a fine product time after time. I said this before; I keep a Hell of a lot of the things people write, I also maintain a lengthy written record myself. I worked on a 100 gram ASA synth and knew I was going to get very sharply deliniated, beautful crystals of reagent-grade TNP.


Yeah there are still yet to be worked out details for
finessing and tweaking the conversion of ASA to
picric acid , depending upon the variables encountered
with different approaches , to arrive at proven methods
that would be optimized . These variations which
are specific to the use of ASA as the precursor could
be the basis for a whole range of experiments which
could reveal exactly what combinations and proportions
work best .

It is good to have easy access by relatively simple synthesis for a valuable reagent like picric acid ,
eliminating dependance on some commercial supplier
whose pricing or other interest may be undesired .

quicksilver - 27-9-2006 at 22:11

Optimizing these labs is truely a "Labour of Hercules" as it seems that when one begins to really look at the variables....they just get longer and longer! And anoting the dynamics of what actually happens when these variables are tweaked gets to be a serious undertaking. I have a lot of fun studying this stuff.
The one synth that I have yet to work with is the catalytic via mercuric nitrate....That is something I would really like to play with. There is something about going back to the very root of benzene that may offer some outstanding elements of study and learning. I actually have some Hg(NO3) reagent but I'm figuring that nitric acid and metalic Hg could do it. (HgNO3 is EXPENSIVE stuff!) The challenge would be finding benzene now-a-days.....
And I am in TOTAL agreement that picric acid IS the most significant energetic material one could synthisize. While lead picrate has been cast as a less effective initiator I have no doubt that it would be just fine for the specific initiation of PA itself. As crude as it seems on the surface, I believe that a lead picrate-picric acid detonator could be opimized for mirroring the initation abilities of a #8 commercial cap. I have no doubt that in crude tests such as a "bent nail test" like that of the U.S B. o M. would yeild results that put it in the ballpark of standard commercial material.
One of the most unique experiments has been that of friction and impact sensitivity of PA. So much has been made of the dangers of dry PA I have found that crystal size, shape, and synthiziation have shown differing results in simple field testing. Friction testing is one of the more difficult to perform with less than professional apperatus. Maintaining accurate weight the test which could be duplicated, it appears Ithat of a block of steel upon another using gravity and angle as a propelling medium. PA appears NOT to be that friction sensitive when compaired to materials like ETN or MHN which seems to be as sensitive as many primaries. Falling hammer impact sensitivy however is very revealing. Showing freshly made, non-shaven crystals of large size to be quite sensitive; especially that of a large rhomboid shape. Cube-like, well compacting crystals are second in line for sensitivity.

[Edited on 28-9-2006 by quicksilver]

Rosco Bodine - 28-9-2006 at 01:06

To get picric acid to detonate from its derivatives used as an initiator is possible , but lead picrate alone is not going to do the job in any reasonable amount , in an unreenforced detonator anyway . More powerful derivatives like DDNP , or the 4/12 azo-clathrate will do the job , and the basic picrate or one of its multiple salts can be used as a flash igniter . A very storage stable , reliable and powerful detonator can be made where the base charge is picric acid and the initiator and igniter are derivatives . The critical diameter and mass for picric acid is a fair amount larger than for something like PETN ,
so picric acid performs better in larger devices , and requires fairly heavy initiator charges to cause its
complete detonation . But it is sufficiently sensitive
and brisant to be an efficient base charge in a detonator .

Sickman - 28-9-2006 at 03:10

Quicksilver,

I second what Rosco says about the basic metal salts of picric acid not being sufficient initiators of Picric acid.

I've done several experments in this regard with basic lead picrate, using even up to 15 grams with out a positive detonation of the picric acid.

However, and I'm frustrated I can't find the source to quote, but I remember distinctly reading that sulfur greatly sensitizes picric acid both to shock and to heat.

It would be great if we could find a suitable sensitizer to make picric acid detonate from basic lead picrate as it is easy and cheap to prepare.

I will try to find my source on this thought of using sulfur to sensitize PA, and better yet in the future I will conduct some tests as to various substances abilities to sensitize picric acid enough to cause it to respond to such things as flash powder and lead picrate.

I think if our goal is to get a salt of picric acid to detonate picric acid, we should not increase the amount of the salt or reenforce the cap more, but rather find a way to sensitize the picric acid to respond to the picrate salt!

YT2095 - 28-9-2006 at 05:04

IIRC (and I don`t remember the source) but it goes something like the More sensitive the picrate, the less brissant, the opposite applies whereby the least sensitive picrate (ie Ammonium picrate) will be the most brissant/powerfull.

I can`t be sure, but I think as a general rule-of-thumb this applies to Most explosive materials (there are exceptions such as AN).

this isn`t really my area though, so I could well be wrong!

quicksilver - 28-9-2006 at 06:29

The thing that nags away at me is the industrial accidents wherein metal picrates are formed within a large amount of picric acid and the whole mass is popped. :) Therefore it would seem that some method could be available but I have been known for ideas that "seemed" to work but fell on their face :(

Quite frankly, I d like to test it. (that's the whole reason for the thread on energetic test apperatus).....I also heard something about the sensitivity of picrates being related to some element of their energy; however I don't know if it's brisance or what.....don't quote me but I believe it's from a book published in 1918 on military explosives. One of the very first published by Wiley.

Rosco Bodine - 28-9-2006 at 08:39

I have tested the sensitivity of picric acid to initiation
by anhydrous crystalline normal lead picrate and
basic lead picrate , both with *negative results* in unreenforced detonators , where a 1.5 gram 9.5 mm
column of picric acid failed to be detonated by amounts
of the initiator increased even to 3 grams .... at which point I stopped the tests which appeared to be an exercise in futility . To secure reliable detonation of picric acid from its normal or basic picrate used as initiator could possibly require even tens of grams , and strong confinement . In any reasonable quantities as would be applicable in the size of a device acceptable for
use as a detonator , in an unreenforced configuration ,
the normal and basic picrates simply do not deliver
sufficient impulse to cause detonation of picric acid .
Perhaps for a 12.5 mm diameter column the threshold
would be crossed , or it could require even 19 mm or more , I am not really sure what would be the minimum
workable size .

Where a stronger confinement and larger amounts of materials is in play , then sure it is probable that the threshold amounts required are available at some point
to secure reliable detonation , but it will be one big fat cap not nearly as efficient as such a device should be in
terms of size or utilization of energetic materials , aside
from safety concerns , all of which make this arrangement
a poor choice when better combinations are known .

quicksilver - 28-9-2006 at 18:29

Yep....it's funny that we do the same stuff. I was just doing something similar. I couldn't get that stuff to pop. I am getting quite a collection of material, notes and 1st or sendhand experimental info that's quite accurate as well. After a period of calm testing and recording negitive results I put down the note book and decided to wing it (albiet safely in small amounts). Well, I smacked it with a hammer, scrapped it accross various friction bearing hard surfaces, & used a bit of basic lead picrate (some of the highest sensitivity I have worked with) .5gr....no go, full gram; no go, I finally gave up as I could not get more into the capsule I had. I am wondering what azides might do but I bet it wouldn't be a simple .01 gram as with ETN / PETN.
So I am thinking that the "accidents" that occur must be either large diameter column (as you suggest) or area in which a larger hot spot is created than that which I am familiar. frankly, I think that all energetic materials should be respected deeply for their potential but it seems that some of the horror stories that surround PA may be a bit inflated. I am certainly not suggesting that PA should be treated in a chavler fashon but it seems tough as TNT. Actually in the typical in a 6mm column I would bet that it would need something mighty hot to pop.
I was suprised at the results....I even thought that perhaps I had a blend of di & tri nitrated material - [...Now I know I'm working with the tri - nitrated material because I use a friend's mp machine and if I'm within about 3 degrees I think I have the real deal] PA is damn valuable stuff but it's not a clear and present danger to the lab outside of it's toxicity and annoying stain-making qualities IMO. Frankly the best reason for keeping it wet is to minimize the dust!



[Edited on 29-9-2006 by quicksilver]

Rosco Bodine - 28-9-2006 at 20:16

The first compound detonators which I ever made and tested were 1.5 gram picric acid base charges in a .25 inch (6.36mm) column diameter press loaded in 3 sequential 0.5 gram portions at 8,000 psi , then topped
with 0.4 gram microcrystalline PbN3 press loaded in one
increment at 15% reduced pressure of 6,800 psi . The capsules were 1/32" wall aluminum . A loading block
holder was made from two blocks of phenolic bolted
together and bored along the axis of the clamped together faces , so that the holder could be separated
and the capsule could be freed from the holder after loading , since the pressure of loading had been found to expand the capsule sufficiently to make it a nearly permanent assembly if held in a one piece tubular loading die .

Comparisons were made for caps loaded by this scheme
with both picric acid and styphnic acid used as base charges . The performance was very nearly identical ,
with the styphnic acid being estimated perhaps 3 % less powerful , but perhaps 20% more sensitive to initiation
by PbN3 . Threshold amounts of initiator for full detonation of the base charge in the unreenforced caps
appeared to be about 0.15 gram for the TNR and about
0.2 gram for the TNP . Reliable loadings providing some extra initiator for consistency of high output performance were decided to be 0.3 grams for the TNR and 0.4 grams
for the TNP .

From my own tests with these and other materials loadings , charge geometry is important to performance ,
and the scaling up of the base charge also requires a
scaling up of the initiator accordingly . I know this
experimental finding contradicts the literature , and
I don't much care as I trust my own experimental
results more than the results reported by others where
such contradictions arise . I think the larger scheme
devices is where the general rule applies concerning
there being no benefit in using larger than minimal
initiator charges , but in the scaling up of a compound
detonator that more general rule simply does not apply .
Simply put , to get oversized base charges to go at
highest velocity like they ought to , you have to overdrive the shit out of them with what is a correspondingly larger intitator . On a number scale
I suppose the compound dets I have tested would
range from #12 to #30 , since I tend to have a pretty
liberal view concerning what is a " cap sensitive "
composition . I sort of figure at a point where most
folks would resort to using a small booster , my preference is to just use a bigger cap and get straight to business without any middle man .

quicksilver - 29-9-2006 at 06:25

I'd say .4 gr of PbN3 is a damn strong kick start! When I experiment with heavy weight & strong initators I have a tough time telling if I am "getting my money's worth" from the base charge. But here we have a threshold amount of .15-.2 - Jeeze, it stiill seems like a lot from what I was used to (my 1st was PETN based and a damn small bit of azide; I think .05)... That one appeared better than a commercial #8 from my limited experience.
I take it that (your .4 azide) really DID overdrive and was satisfactory in proformance...? When I made a base charge of PA I used .8 fulminate and got results that I felt were better than a commercial #8 but not by much.
I did notice that if one uses aluminum that is hard rather than soft the caps seem to have a wee better proformance. Arrows made by EASTON-AlCOA are made of Al that is fantastic for caps! It is super brittle and shatters in a manner unlike simple soft Al tubing.

[Edited on 29-9-2006 by quicksilver]

Rosco Bodine - 29-9-2006 at 09:08

Generally what I would do is test increasing increments
of 0.05 grams until reaching the point of minimal amount for *consistently* producing a complete detonation with reliability .......and that is what I would call " threshold "
rather than the lesser minimum which would only sometimes produce a complete detonation . Then I would arbitrarily increase that amount by 50% usually
to feel comfortable with the figure as a " sure " loading ,
allowing headroom for degradation over time or whatever
" Murphy's Law " type factors might introduce .

1.5 grams in a 6.36mm column diameter is sort of a
tall and narrow column in a diameter that is near to the critical diameter for these materials , which causes an
unusual increase in the demand for impulse to sustain
a good detonation wave through the realatively tall
and narrow column of base charge , and using fairly
coarse crystals like I generally favor increases the
impulse requirement further . Both of these factors
being in play are further multiplied by the unreenforced
configuration which by itself can double the minimum
amount of initiator which is often stated in the literature
without regard to other factors , where the " bragging "
being done about how little initiator is required relates
to circumstances where *everything* has been optimized
in favor of minimum initiating charges , including the use
of reenforcing caps over the inititator , and particle sizes
for the base charge and geometry for the device that is
very different than what would be those parameters for
a * real world * device .

You have to write your own tables for the particular
device you have in mind and derive your own working
figures from experimental tests , because that is where
the transition from theory to reality occurs . The conditions which you implement in your own design
are not going to match the conditions for the tests
which were the basis for the figures given in the literature , so to an extent you can throw away the book and write your own , after discovering that it is your
data that applies to what you are doing better than
anybody elses data which applied to their own design .
The veracity of your own tests is unimpeachable with
regards to its relevance to your own design .

These trinitrated phenols are quite sensitive to critical diameter versus particle size and column geometry
( height to diameter ratio ) and loading density and confinement values for columns in the range of diameters 6-9.5mm as would be found in detonators , so they
are very good base charges for seeing the efficiency
differences of different initiators which may be tested .
Also any residue of undetonated material in a clean test chamber is easily revealed by misting with water spray
because the base charge is a dye , while the detonated
products are only a residue of soot in the chamber .
So you can quickly determine if a complete detonation occurred , simply by looking at the wash water :D ,
no yellow ....lucky fellow :D , the initiator did the job .

quicksilver - 30-9-2006 at 06:03

Some damn good ideas there ("no yellow" was cute)...I know this is a bit OT but I have some fine methods of making and woorking with capsules but I haven't found a method of making a re-enforcing cap....what do you use?
Going back to topic; I also use course crystaline material. Do you believe that the crushing of a compaction mechanism within the column has any effect? by that I mean that IF the crystals were smaller could a greater pressure yield a higher preformance: other factors being equal? (would crystal size ever have a bearing on preformance?)

Rosco Bodine - 30-9-2006 at 08:16

There certainly is an optimum mesh size and loading density for a specific column diameter . The work of
screening a dozen different mesh sizes and working out the loadings and output comparisons is more of the
task of a bean counter than I can stand . It is work that has probably been done by the commercial manufacturers
and is probably proprietary information what they have
developed as their own loadings , to wring out all the
efficiency which can be gotten with respect to the
economics of manufacture .

Actually it is my general practice of *not * using a reenforcing cap which has bearing upon my other
preferences and practices . The use of a reenforcing
cap when available enables a more efficient device to be made in terms of reducing the minimum loading for the
initiator . When a reenforcing cap is used , then the physical consistency of the crystals is less critical with regards to the crystals ability to form a stable compressed pellet , since the compressed column of material will be mechanically locked into place by
the reenforcing cap .

In the absence of the reenforcing cap , then the physical considerations which govern a highly pressed loading are
similar as apply to press forming a clay nozzle for a
rocket motor , where an aggregate of material which
has sufficient grit is required to form a stable pellet
after compression , which will not slowly separate again
and crumble on storage . Indeed a stable loading is
the requirement which becomes the governing parameter
to the influencing of all the other considerations . This
is something which early researchers recognized and
there have been several patents concerning small percentages of additives and schemes for depositing
films of certain pressure flowable binders upon crystals
of lead azide , to greatly enhance its pellet forming properties as is particularly desirable in nonreenforced
detonators . I have not experimented with such binders
but have relied upon capsule geometry and crystalline
form of the materials as the easiest solution , although it
admittedly is not the most efficient solution .

In my experience the crystalline form has very definitive substantial bearing on the explosive properties of a material , even aside from loading considerations for a plurality of crystals en masse , the crystal form being to the unit crystal , its own peculiar loading as a single crystal unit . The sensitivity to initiation and critical diameter and detonation velocity are all influenced
by the crystal form and mesh size . There is something
of a compromise between mesh size and maximum possible compressed loading density which relates to the
amount of interstitial space which will remain in the mass
after compression into a pellet . The higher the density
produced for the pellet , the higher will be the possible
velocity .....but it will also become more difficult to initiate . So there are a set of compromises involved
in the design considerations for a detonator , whether
it is of an open topped column unreenforced design ,
or otherwise designed for added confinement . The reenforced cap is certainly a more advanced design
but is also more difficult to manufacture .

Quince - 1-10-2006 at 00:46

So to generate the optimal crystal shapes, what recrystallization procedure do you recommend?

Rosco Bodine - 1-10-2006 at 05:25

For a crude product that has been produced in high yield and purity directly from nitration , like the very light colored product which I described , and which ordenblitz
duplicated and described on page 6 , shown here in
one of ordenblitz's pictures .....

http://img58.imageshack.us/img58/634/dilutedandcooling4nd.jp...

Slow cooling undisturbed from a slightly less ( ~5% below saturation ) than saturated solution of the filtered and drained crude product in boiling distilled water gives
a product which is exceptional from the first water
crystallization . The product will be an acicular mass
of elongated hexagonal blades .

a_bab - 1-10-2006 at 06:11

The pure (recrystalized from HCl iirc) TNP looks like white, transparent crystals. They will slowly become yellow, apparently under the effect of the light.

Zinc - 24-10-2006 at 05:38

In the school lab me and my friend found a very old (the teacher said 20-30 years old) bottle containing picric acid. I have read on Megalomanias page that it will form a very unstable crystalline structure after many years.
So is it safe to open the bottle?

Rosco Bodine - 24-10-2006 at 05:52

Yes .

Of course if you reveal being informed enough to know
that the public exhibition of " daring and heroic duty "
displayed by the local bomb disposal unit is nothing
else but a publicity scam ......then it may arouse curiosity
about where you get your information and why you would know better .

[Edited on 24-10-2006 by Rosco Bodine]

Nitrojet - 24-10-2006 at 11:03

Picric acid can be manufatured in laboratory scale via the following route:

Place 10 g. of phenol in a dry 750 ml. or 1 litre flat-bottomed flask and
add 23 g. (12-5 ml.) of concentrated sulphuric acid, shake the mixture
(which becomes warm) and heat it on a boiling water bath for 30 minutes
to complete the formation of the o-and- p-phenolsulphonic acids, and then
cool the flask thoroughly in an ice-water mixture. Place the flask on a
non-conducting surface (e.g., a wooden block or an asbestos board) in a
fume cupboard, and, whilst the phenolsulphonic acids are still a viscous
syrup, add 38 ml. of concentrated nitric acid and immediately mix the
liquids by shaking for a few seconds. Allow the mixture to stand;
generally within 1 minute a vigorous but harmless reaction takes place
and copious red fumes are evolved. When the reaction subsides, heat
the flask in a boiling water bath for 1.5-2 hours with occasional shaking ;
the heavy oil, initially present, will ultimately form a mass of crystals.
Add 100 ml. of cold water, chill thoroughly in ice water, filter the crystals
at the pump, wash well with water to remove all the nitric acid, and drain.
Recrystallise from dilute alcohol (1 volume of alcohol : 2 volumes of
water) ; about 110 ml. are required. Filter off the recrystallised material
and dry between filter paper. The yield of picric acid (yellow crystals),
m.p. 122°, is 16 g.

Warning

Aqua_Fortis_100% - 19-1-2008 at 10:23

Today I tried the usual procedure, wearing gloves and goggles:

100mL 98% sulfuric acid,
20g ASA
50g KNO3

I started adding ASA slowly on sulfuric acid, while heating it on a oil-bath.. Then after 30-40 min the mix was pratically black.
So removed the mix from the oil bath , let some more time and started to add the KNO3 very slowly to avoid NOx and overflow of foam..

After all, the mix was clear-red and bubbling , because of the CO2 .. So I let this some more time bubbling and put again on the oil bath... After this the mix appeared clear orange/almost yellow..

I then removed of the oil-bath and let cooling slowly..

After some hours I came back and look a big mess on the floor.. The TNP crystals have ppt on the mix and for some reason the crystals increased greatly the volume of the mix and part of this go to overflow and did the mess... Was a big mistake I did, because I didn't used a larger vessel for the reaction..

So wearing new latex gloves and goggles I removed most of the "saved" material and with difficulties put on 500-600mL of ice/water. The yellow material ppt instantaneously , but some of it splashed on my arms (not due to heat, but improperly pouring the mix on the ice-water)...
After I washed my arms and other parts like a manic , but the yellow stain still seems to be unaffected..

I wish to dont have severe poisoning of picric/picramide or other nasty stuffs forming inside my body..

Has anyone similair misfortune?
Any words of what really happened to this mix?

The lesson I learned today is to use a large vessel to hold any overflow and to use proper gloves/safety wear before even thinking in play with this stuff..

[Edited on 19-1-2008 by Aqua_Fortis_100%]

[Edited on 19-1-2008 by Aqua_Fortis_100%]

quicksilver - 20-1-2008 at 09:08

Well you know what happened and why so there is no need to re-write what you know. However a clean up of a lab accident is an important issue in itself.
It seems that haste in a clean up can make a mess - into a problem. Nitrated benzenes are absorbed through the skin and they are toxic. Next time have a plan in place as to HOW to clean up in case you need to do more than simple carry on.

One thing that may help is to look at the synthesis and determine that if the procedure calls for 100ml of fluid and an additional fluid level or expansion, to think that the minimum container would be 25% larger than all concerned. Prior planning prevents poor performance. A lab coat is really an important part of general safety equipment, goggles should be of a quality that prevents fogging, gloves should be available in large amounts so as to be able to change into new ones to prevent contamination of product as well as personal contamination.

Benzenes are toxic to liver / kidneys and that may have a cumulative effect (just ask Mr Hurst). Single-level exposures are not that significant unless it's on a large level.

You know all this, I'm sure but what you said in the description is the MOST important...."After some hours I came back and" Personally, I don't leave experiments alone....especially of the type you describe!

[Edited on 20-1-2008 by quicksilver]

Leander - 23-2-2008 at 13:25

Could it be possible to produce a PBX containing picric acid?
Low sensitivity to initiation IMO doesn't immediately means it couldn't make a good plastic explosive. As far as I know, the key factor to a powerfull PBX is not meanly sensitivity or raw power, but having a small critical diameter.

When using pure, fine meshed picric acid, and a percentage of inerts below 10%, with additionally some MHN or PETN, I think it's definitely with a try. :)

Has anyone of you got any experience with this?

Rosco Bodine - 23-2-2008 at 13:33

It should be possible to make a gelled nitromethane containing perhaps 75% of picric acid as a colloidal jelly
and it would be cap sensitive , and certainly would have
adequate brisance for shaped and cutting charges .

a_bab - 26-2-2008 at 07:32

Actually it's a known odd fact that NM dissolves TNP like crazy.

rbick - 26-2-2008 at 11:14

Actually, the patent 5140908 goes into depth about sensitizing NM with picric acid.

It also mentions the addition of water to the mixture in some cases. The ratio added was up to 50% TNP 50% NM, although different percentages were tested. It is described as cap sensitive and quite powerful. Take a look at the patent, as they have tables describing results of various TNP percentages.

[Edited on 26-2-2008 by rbick]

grndpndr - 24-5-2008 at 07:45

Aqua fortis, rest assured, I witnessed a indivdual accidentaly contaminate himself (TNP)several times over a period of several months some 6-8 years ago and hs liver function tests reman normal at age 50.At least his product ws of his product was of high quality!LOL
I assume TNP and lead azide are compatible in a compound det?Approx how much lead azide is needed to RELIABLY detonate the TNP(1-2gr,1/4-3/8 al tubing.Thanks much!

Rosco Bodine - 24-5-2008 at 15:57

For TNP at 1/4" column diameter and a charge of 1.5 grams compressed in three half gram increments at 8,000psi , in an unreenforced configuration, 0.25 grams
of Pb(N3)2 compressed at 6,800psi is about the minimum
for initiation, at the medium to high velocity transition threshold. For a practical loading having guaranteed reliability at that diameter and compression, 0.4 grams
will do the job. For TNR you can drop that to 0.3 grams.

The pellet geometry of the loadings has great bearing on how small charges like detonators perform, more than initiator weight being any linear increase for larger diameters and/or heavier base charges. So to keep the performance on larger diameter columns of base charges, the initiator will have to be geometrically increased accordingly, in my experience. For reliability, the initiator
should be heavy in order to overdrive the shit out of the base charge, to guarantee it goes at highest velocity.
I also have a theory that there is a reflected wave sympathetic detonation somewhere intermediate in the column when a heavy initiating charge is used, which basically makes the middle of the column do a similar thing as the meeting opposing waves in det cord loops when the Dautriche method is used for calculating velocity in stick charges. You should see the hot spot signature
develop in the column of base charge on witness plates
at some point in the incremental increase of base charge
well above the amount required for ordinary mode initiation, at which point you have a "special" engineers cap:D . A 2 gram TNP base and that configuration will
make urea nitrate and probably a few other relatively insensitve secondaries which might more usually require a booster, go high order just fine from the cap alone, if it is inserted deep in the charge. A #12 cap maybe, but hey,
it works for me:D

grndpndr - 24-5-2008 at 18:24

Thanks Ive always felt caps that would seriousy overdrive the intended HE best, feeling a weak cap could waste much larger qantities of HE.Aprox. comm. equivalet of .4-.5 lead azide/1gr TNP -2gr TNP?In a 3/16 soft AL tubing w/epoxed end caps.

At the time what i saw used- FM, approx .5/.75gr pressd to ahieve somewhre round 4500mps and 1-2gr TNP with similr al tubing the results were as one would expect.Very litte doubt of detonaion unless problems were encountered with the main charge.By themselve thrown in a pond they made a satisfying thump in 6-8ft of water and rocked the dock.Unscientific to be sure but little doubt as to effectivenes.:)

[Edited on 25-5-2008 by grndpndr]

grndpndr - 25-5-2008 at 05:14

Hs anyone ever investigated concave detontor end caps hopefully to achieve a SC effect for the longer stick and rectangular mil TNT/C4 demolition block charges.FM5-25 has exellent cutaways of compound det to scale using lead styphnte as an ignitor and lead nitrate as the primary2.350 length x .241 OD M7 special military though wieghts arent mentioned and the lenghth is designed for fused use with near 1/2 the lenghth designed for the fuse.RDX is the base taking the vast majority of room.

Rosco Bodine - 25-5-2008 at 09:08

Quote:
Originally posted by grndpndr
Thanks Ive always felt caps that would seriousy overdrive the intended HE best, feeling a weak cap could waste much larger qantities of HE.Aprox. comm. equivalet of .4-.5 lead azide/1gr TNP -2gr TNP?In a 3/16 soft AL tubing w/epoxed end caps.

At the time what i saw used- FM, approx .5/.75gr pressd to ahieve somewhre round 4500mps and 1-2gr TNP with similr al tubing the results were as one would expect.Very litte doubt of detonaion unless problems were encountered with the main charge.By themselve thrown in a pond they made a satisfying thump in 6-8ft of water and rocked the dock.Unscientific to be sure but little doubt as to effectivenes.:)


There's no way I would drop below 1/4" diameter for a compressed charge with good confinement for TNP or TNR because of critical diameter coming into play. A column diameter of 5/16" would be better actually for the base charge, but of course that also increases the initiator weight requirement geometrically to maintain the same performance.
Do you follow what I am telling you about the geometric increase? I mean it is not a matter of a linear increase of 25% more initiator being needed when the diameter increases 25% from four sixteenths to five sixteenths, but is the volumetric increase required for maintaining the same relative heights of the compressed initiator pellet to the
compressed base charge pellet. Call it Rosco's rule for microcharges:D and no you won't find it in the books, like a few other of my observations, but you can try it and see
some experimental verification for charges in the near regions of critical diameter and critical mass where overdriving is required to reach maximum velocity in the
relatively short distances involved.

To illustrate Rosco's rule for microcharges in play, let's take
the case of the increase in column diameter from 1/4" to 5/16" which is a 25% diameter increase. You have to look at the area increase on the "end disc" of the column which is defined by pi times the square of the radius, so the area
increases by 56.25% as a result of that 25% diameter increase, and that's the amount of increase you have to apply to the weight of the initiator used for the increased
column diameter to maintain the geometry of the charges.

It's a common misunderstanding for people who would think,
well I have increased the column diameter by 25% so then
I should increase the initiator weight by 25%, when that will give a deficient amount, the increase actually being 56.25%.
So if 0.4 grams of Pb(N3)2 is the sweet spot loading for the
1/4" diameter, then going up by 25% diameter to 5/16", will require bumping up the initiator weight to 0.625 grams.

And to all the naysayers, try it and see if it doesn't work out that way for smaller charges that are in that region where
critical diameter becomes an influence on velocity.
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