Sciencemadness Discussion Board - picramic acid from picric

picramic acid from picric

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Rosco Bodine - 14-4-2014 at 14:37

Quote: Originally posted by Hennig Brand

Found some more good stuff for hydrogen sulfide generation I see.

Yeah I also have a couple of references requested to add to the database we have already. There are quite a few one page communications in the journals about small scale H2S generators using various schemes convenient for occasional experiments where H2S is needed mainly for analytical procedures not requiring large amounts of H2S as would be used in synthesis. The scale of interest to us is intermediate so it may be adaptable from either scenario of larger or smaller scale methods. There are likely several different valid approaches to making H2S or derivatives in intermediate scale quantities using generally commonly available materials so the choice may come down to using what materials are most convenient. This topic and the associated DDNP should probably achieve sticky status as it reaches maturity.

The article by Hodgson and Ward did not identify DDNP specifically as the material they used for the analytical determination of yield for their synthesis of picramic acid. But from the H&W description it would seem that their yield calculations for picramic acid were ultimately based upon the amount of DDNP resulting from diazotization, with their presuming the yield of DDNP would be quantitative and therefore mirror the yield of the precursor picramic acid. If that interpretation is correct then there is some distinction lost between this picramic acid thread and the DDNP thread, which is a small distinction anyway like part A and part B of an overall synthesis with part A being the precursor material picramic acid for DDNP that is the tongue in cheek "yield determination" part B.

There is no indication that in the alternative that H&W were investigating the effectiveness of a red hair dye, but what they were doing is making DDNP.

[Edited on 15-4-2014 by Rosco Bodine]

Hennig Brand - 17-4-2014 at 02:55

I did notice a while back that the yield determination from the Hodgson and Ward article involved titration of sodium picramate by conversion to DDNP. They most likely were focused on DDNP, and the article was just discussing production of the intermediate (sodium picramate).

Rosco Bodine - 17-4-2014 at 06:04

I have been looking at the various schemes for H2S generators to see what can be done as the most easily improvised method using over the counter materials. It is something I mentioned earlier in the thread that when the "dry method" type of polysulfides mixture is acidified that H2S will be produced but free sulfur will also be a byproduct.
So using a polysulfides mixture is not as efficient as using ferrous sulfide, but the economy is probably comparable since things like hydrated lime, washing soda or baking soda, and garden sulfur are cheap raw materials. There have been patented commercial process reaction schemes for producing what are "lime-sulfur" solutions that contain 27% soluble sulfur in various forms where the process is run under mild conditions, and I haven't finished my calculations on what part of that 27% soluble sulfur would actually convert to H2S on acidifying and what percentage would simply be precipitated as free sulfur. A possible scheme of interest is one where the polysulfides solution used is an equimolar mixture of sodium and calcium polysulfides. It would require some experiments to sort out what is the optimal mixture. What I have been thinking is it is possible that similarly as the mixture of iron filings and sulfur will react in the presence of H2O without it being necessary for igniting the mixture and performing the reaction at high temperature, that possibly a similar reaction may occur in a mixture of sodium bicarbonate and hydrated lime and sulfur mixed with water in a measured restricted quantity, with a similar reaction proceeding as when the dry method of mixing NaOH and S is done with minimal H2O just suffficient for conducting the reaction where the mixture becomes liquified from the exotherm. With NaHCO3 plus Ca(OH)2 the NaOH should form in situ and then react with the S and if the quantity of H2O used is correct, then the liquified Na polysulfides mixture resulting should be able to be decanted from the insoluble CaCO3 byproduct. This Na polysulfides liquid should produce H2S when it is acidified. Or it may serve better to use this Na polysulfides as a source of soluble sulfur residing in its polyulfide component to react with additional Ca(OH)2 which will ( I think ) tend to form CaS by reaction with the sodium polysulfide values that are only soluble sulfur, converting them to compound sulfur as CaS which increases the proportion of sulfides to what is convertible to H2S when acidified. Ca(OH)2 should react differently in a two stage reaction so that the soluble sulfur values convertible to H2S upon acidification is doubled to tripled ( if what I am thinking is correct ) above what would occur using only the "dry method" which is really a "wet method" only having carefully limited H2O to keep the reaction mixture highly concentrated, based upon only use of the Na polysulfides mixture. The CaS requires only one mole of Ca in relation to each S whereas the Na requires 2 moles Na to form the normal sulfide Na2S in the same scheme. So for an equimolar mixture of Na2S and CaS formed by the scheme described, I am thinking it could be a cheaper and more efficient precursor for production of H2S upon acidification. I have thought that once a scheme modeling the manipulations is worked out using smaller test quantities in sample bottles or flasks that the method could be scaled up easily to whatever scale is needed. Of course if NaOH is available easily, the first reaction could be changed to accomodate and there would be no CaCO3 byproduct.

The Na and Ca indefinite sulfides mixture could also serve directly as a kind of enhanced Zinin reagent which could be used as is for a reducing agent, apart from being useful as a source for H2S in a generator scheme.

With regards to the high temperature generation of H2S from the thermal cracking of hydrocarbons like vaseline or paraffin, I found a reference also that a heated mixture of pine rosin and turpentine 50/50 with sulfur reportedly freely evolves H2S and is a convenient source. What is the temperature required and if it is high enough to cause sublimation of sulfur as occurs with the petroleum hydrocarbons is not known. I suspect that there are hydrocarbons that will easily crack at lower temperatures than petroleum and produce H2S but I don't know what materials may be useful in that regard. Finding a combination or single material that reacts easily at gentle heat would be a winner for that method, and would probably be the easiest way to go. Even the vaseline and sulfur method has simplicity to commend it, but requires some accommdation for the sublimed sulfur which can complicate things. There it may be useful to have a dual output which
serves to trap sublimed sulfur, and cycle the output flow alternating through one trap or the other, heating the sulfur condensing trap that is idle to remelt trapped sulfur it contains and return it back into the heated mixture. When that substantially cleared trap has cooled again, then the H2S flow is diverted through it, while heating is applied to clear its parallel trap now encrusted with sublimed sulfur, with the cycle being repeated in alternating fashion, so that a recently cleared sulfur trap is in use continually. Such a scheme would allow for the "cracking reactor" producing H2S to run for hours if necessary without becoming plugged with sublimed sulfur in the output tube. Using a single larger tube
maybe as a coil of a few turns of 5/8 ID copper could be simpler and remain unobstructed through the duration of any single batch run. And then it could be cleared before the next use by simply heating it to above the mp of the sulfur it has trapped so that it would flow out of the coil and return back into the reactor. Anyway these are two ideas for how a scaleup could be done to make use of the thermal cracking scheme for H2S generation.

[Edited on 17-4-2014 by Rosco Bodine]

Hennig Brand - 17-4-2014 at 10:07

Hydrogen sulfide reacts with copper and produces corrosion products. I didn't look into it in much depth to see how much of a problem it would be. I went with steel, since steel is resistant to hydrogen sulfide and cheaper too.

One of the attachments you provided a few posts back had a diagram of a lab scale hydrogen sulfide generation system, with inline bulbs designed to trap the sublimed sulfur. When I saw it I thought it looked like a simple solution to one of the only flaws with the heavy hydrocarbon and sulfur, hydrogen sulfide generation method. I think what I am going to do is use a large diameter steel U-tube to attached the generator to another vessel and from that second vessel lead the nearly sulfur free hydrogen sulfide off through the small diameter tube I am currently using to the bubbler. The second vessel (deposition vessel) wouldn't need to be nearly as large as the generator vessel. This is a very simple solution that I think would work. As far as wasting sulfur, it is quite cheap as you have pointed out. Actually, most of the deposited sulfur could likely be collected from the deposition vessel and used again. The large diameter U-tube wouldn't plug nearly as quickly and could be cleaned out between uses much more easily than a small diameter tube.

[Edited on 17-4-2014 by Hennig Brand]

Rosco Bodine - 17-4-2014 at 10:57

Stainless is passivated by H2S according to what I understood from a brief description I read in an article and I'll try to dig up that reference again.

Edit: Here it is, passivation of stainless steel by H2S

http://books.google.com/books?id=Rlq-812ED10C&pg=PA33&am...

I have on hand some malleable stainless tubing that is used similarly as soft copper. I think I have a couple of 2 liter wide flange inconel reaction kettles with heating mantles in storage somewhere, too.

Now where did I put my inconel resin kettles? or maybe they are 316, I forget

And hey if inconel or 316 won't do it then grade 1 titanium I have on the shelf too. I'm kidding a little bit here. Actually copper should work fine, and even glass or ceramic. 250C is not too extreme, a bit under 500F, and getting up there towards damn hot but still pretty manageable. For fluorocarbon mp references PFA 306C FEP 260C and PTFE 327C so PFA or certainly PTFE could be used for plumbing.
I think copper is also passivated by sulfiding and can be used even for the reaction kettle itself.

Also I am making another reference request for an article that should be illuminating about some technical aspects of the use of petroleum derivatives for H2S generation. This can be sorted out further, but there is useful information even on the first preview page where they show the optimum temperature as 250C.

Hydrogen Sulfide Production from Sulfur and Hydrocarbons.

http://pubs.acs.org/doi/abs/10.1021/ie50425a024?journalCode=...

Early references about paraffin say that asbestos was used as a catalyst and some patent references say that limited porosity silica or alumina is used for some hydrocarbon dehydrogenaton by sulfur reactions, so some chunks of silica cat litter "crystals" could help the reaction, I don't know. Some of that mineral fiber felt like is used for high temperature insulation for ceramic kilns might substitute for asbestos.

Another reference here reports that the reaction of sulfur with alkanes producing H2S begins in the range of 140-150C
so it would seem the higher temperature of ~250C may not be an absolute figure, and it could vary what is the temperature depending upon the C value of the alkane.
C14 alkanes bp is 250C and fp is 0C, C15 bp 270C fp 5C
and continuing in the same direction with increasing C value alkanes having higher bp and fp temperatures. My guess would be the lower C value lighter alkanes would begin reacting with sulfur to for H2S at the lower temperatures, and the more wax like higher C value alkanes are less reactive and require the higher temperatures to react with sulfur to form H2S.

http://pubs.acs.org/doi/abs/10.1021/ja00277a002?journalCode=...

Thanks to leu for the attached article
Hydrogen Sulfide Production from Sulfur and Hydrocarbons

BTW A.P.I. 20.5 = sp. gr. .930921

Mineral Oil should be an entirely adequate substitute,
vaseline would be next, and paraffin next among the substitutes that may be easier to find than heavy fuel oil.

Attachment: Hydrogen Sulfide Production from Sulfur and Hydrocarbons, R.F.Bacon, E.S.Boe, Ind.Eng.Chem.,1945.pdf (339kB)
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[Edited on 18-4-2014 by Rosco Bodine]

Hennig Brand - 19-4-2014 at 03:06

Quote: Originally posted by Rosco Bodine

C14 alkanes bp is 250C and fp is 0C, C15 bp 270C fp 5C
and continuing in the same direction with increasing C value alkanes having higher bp and fp temperatures. My guess would be the lower C value lighter alkanes would begin reacting with sulfur to for H2S at the lower temperatures, and the more wax like higher C value alkanes are less reactive and require the higher temperatures to react with sulfur to form H2S.

Sounds right, I didn't always pay attention as much as I should have in chemistry class, but what I remember is that in general the more carbon atoms an alkane has the more stable it is.

Paraffin wax bp >370^oC
Vaseline bp ~343^oC

Though paraffin wax and Vaseline are less reactive than the lighter (shorter chain) hydrocarbons, their lower volatility is probably an asset.

Rosco Bodine - 19-4-2014 at 05:45

Maybe next time you run your H2S generator, try white mineral oil instead of vaseline and see if the H2S does come off at a lower temperature with the more mobile hydrocarbon having a lower C value alkane series like white mineral oil.
IIRC it is about C15 lower end fraction for white mineral oil, but I'll have to check that. Also if you have a scrap of that mineral wool "kaowool" or other trade name, maybe pull apart some of that mineral wool fiber to loosen the matting a bit and put a "cotton ball" chunk of that mineral based fiber in with the mineral oil and sulfur to see if it has any effect as a promoter like a physical catalyst scaffold / wick. If it works to help the H2S produce more easily at a lower temperature this could be a significant improvement. The lower temperature that the reaction can be run the less sublimation of sulfur will occur. So the generator may run cleaner. It is a tradeoff at a point because the oil has volatility too, but the oil would tend to reflux, while the sulfur would accumulate and plug the outlet tube eventually. There are many different specialty grades of mineral oil and there is probably a particular grade that is "perfect" but which one is best I don't know. But I think the most common grade of white mineral oil like is available everywhere is probably workable. I found a reference that is putting the alkane value for mineral oils as beginning at C17 for the lightest, so this should be okay, as that would put the boiling point well above the 250C minimum recommended by that reference attached earlier. It looks like it should work.

Here is another reference that says carbon is catalytic. Earlier I had mentioned it was reported that rosin and sulfur equal parts heated together evolve H2S and was mistaken about the turpentine. That mixture is just the two things sulfur and rosin.

Attachment: Production of Hydrogen Sulfide by heating Paraffin and other Hydrocarbons with Sulfur.pdf (356kB)
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Attachment: Hydrogen Sulfide pages chemicalengineer24news.pdf (450kB)
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[Edited on 20-4-2014 by Rosco Bodine]

Hennig Brand - 23-4-2014 at 13:58

I was at a home improvement center a couple days ago and found some stone wool. It is very popular right now it seems judging by the variety and quantity available. It is used for insulation and soundproofing and is very fire resistant of course. I didn't want to buy a huge bundle, for $50 or so, so I pinched a very small amount off the corner of one of the batts from a bundle. I don't really agree with shoplifting, but I don't think the tiny amount I took will hurt anyone especially since a whole bundle looked to be enough to insulate a small shed.

Rosco Bodine - 23-4-2014 at 15:33

Those last couple of references show that lampblack carbon is catalytic and lowers the reaction temperature and increases the yield, however for the heavier black oils that already have a free carbon content, lampblack isn't needed
and has no substantial effect. What I think may occur is that if some of the carbonized residue of asphalt is saved from an initial run using just a white mineral oil and sulfur mixture that is rich in oil so it doesn't end up with a solid chunk of carbon as byproduct, that a portion of the residual asphalt oil can be saved and mixed in as a catalyst with any fresh batch of mineral oil to blacken it with free carbon containing asphalt as a catalyst for the subsequent batches. That would avoid having to buy lampblack separately. Also the "black oil" mentioned being a lubricating oil sounds possibly like what would commonly be 90 weight or better and it may be that stinky diesel like odor gearbox oil, or something heavier.

[Edited on 23-4-2014 by Rosco Bodine]

Hennig Brand - 25-4-2014 at 14:06

I got the following equation, from the webpage linked to below which has fairly exhaustive information regarding the physical properties of sulfur.

http://www.ogj.com/articles/print/volume-93/issue-42/in-this...

ln(p) = 89.273-13453/T-8.9643lnT

where,
p = vapor pressure of sulfur in pascals
T = temperature in kelvins

According to the above website this equation agrees very well with experimental values for the vapor pressures of sulfur. I have included a jpg of a graph with the temperatures and corresponding vapor pressures of greatest interest for this process (between ca. 200-300^oC). I have also included a pdf of all three graphs made. There is a broad range graph in kelvins as well as one in degrees Celsius and the narrow range graph in degrees Celsius previously mentioned.

Sulfur Vapor Pressure versus Temperature.jpg - 27kB

Attachment: Sulfur Vapor Pressure versus Temperature Graphs.pdf (161kB)
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It is obvious that relatively small reductions in temperature in the hydrogen sulfide generator would drastically reduce the rate of sulfur sublimation. Regarding the carbon catalyst idea, now that I stop and think about it very early on in the process a lot of carbon is produced as a product in the reaction between the heavy hydrocarbon and the sulfur.

I think I have found another good use for the stone wool; insulating the delivery tube from the generator to the sulfur trap (deposition vessel). I found a bit of steel refrigeration tubing which is very thinned walled and much larger in diameter than the brake line. The tube could be insulated or even heated, for instance by an electric resistance heating element, but really I think it is big enough that it won't plug during the run time I will be using. A picture of the simple set-up suggested is shown below. The picture does not show any insulation on the large diameter steel tube connecting the two vessels. Also, the sulfur trap vessel could be placed in an iced bath if it was felt extra cooling was needed to assist sulfur deposition. The large diameter tube running into the sulfur trap also should have gone nearly to the bottom. The piece of large diameter tubing I have is not exactly the right length, so it may be replaced in the future.

Small diameter steel tubing (brake line) is ~3.1mm inside diameter
Large diameter steel tubing (refrigeration line) ~ 8mm inside diameter

Therefore, the large diameter steel tube has about 6.7 times the cross sectional area as the small tubing. It will take much longer to plug especially if insulated and/or heated. It will also be very easy to clean between uses.

H2S Generator with Sulfur Trap.jpg - 238kB

[Edited on 26-4-2014 by Hennig Brand]

Rosco Bodine - 27-4-2014 at 08:44

Your observation about the geometric increase in cross sectional area pertinent to the aspect of "clogging" of a tube by sublimed sulfur is directly translatable to the clogging and quenching of a detonation wave at near the critical diameter, and shows the thermodynamic effect and energy multiplication for increased area of a wavefront that can be enormous difference for what is an only slight increase in diameter. Small increase in diameter can change things drastically at a certain scale, while the geometric difference is not so great as the scale increases well beyond the dimensions that are near to critical. This is pretty general in all engineering as a transport phenomena or transfer / translational phenomena. Open up a design constraint bottleneck and there things get much easier fast. Tighten the specs and things get dicey and uncertain as the ceiling for allowable deviation from optimum is lowered.

High Yield Sodium Picramate Synthesis - Experimental

Hennig Brand - 30-4-2014 at 03:28

Just to make sure that the results from the last synthesis were reproducible, and to get rid of the last of the sulfide solution before moving, I ran another experiment. The experiment was performed the same way as last time except that the temperature was a few degrees lower, ~37^oC as opposed to 40^oC, at the end of the sulfide-bicarbonate solution addition. After addition was complete supplemental heating had to be added to bring the temperature up to 40^oC or so where the temperature rose quite quickly mostly on its own to ~60^oC. This reaction started much more slowly than it did for the last experiment and overall the reaction time was at least double.

While air drying the sample mass was periodically checked over the course of more than two days and it was found that the mass did not change at all for the last 12 hours or more at which point the sample was considered to be dry. From 7.52g of picric acid 7.28g of sodium picramate was obtained or a quantitative yield. The yield is actually about 0.3% over 100%, which just means that there are small amounts of impurities or water still present. This may not be the best method to measure yield accurately, but I think it is safe to say that the yield is at least very nearly quantitative.

[Edited on 1-5-2014 by Hennig Brand]

Sulfur Trap Model

Hennig Brand - 11-5-2014 at 17:34

Here is my idea for a sulfur trap. The trap/vessel could be set in cold or iced water to aid sulfur deposition. The center divider forces the gas to travel down one side of the trap and up the other before exiting the trap. The center divider could also be hollow and have cooling water flowing through it. A nichrome resistance wire electrically heated delivery tube could be used to connect the hydrogen sulfide generator to the sulfur trap, which could eliminate or significantly reduce sulfur buildup between the generator and the trap. I think this arrangement would allow fairly continuous hydrogen sulfide production. The generator would still need to be recharged with sulfur and hydrocarbon, and cleaned out, from time to time of course. An alternative to shutting down to recharge and clean could be to simply have more than one generator and swap them out as needed.

I created a simple sketch using Google Sketchup which should illustrate the sulfur trap concept. Attached is a jpg of a top angle view and a bottom angle view.

Sulfur Trap Model (Bottom View).jpg - 71kB

[Edited on 12-5-2014 by Hennig Brand]

Praxichys - 13-5-2014 at 06:19

Why bother with the hydrocarbon/sulfur method to H2S? You mentioned methods using iron/sulfur earlier, but why not use that just for H2S generation?

Heat iron filings and sulfur in a soup can or something until the reaction starts. Let it cool, then just drip an acid on the FeS with a gas generator setup. There are no sulfur clogs or messy/stinky organosulfur leftovers to scrape out of glasware, etc.

Rosco Bodine - 13-5-2014 at 07:35

There are many valid approaches to generation of H2S and there are many valid alternative reductions of sodium picrate or other picrate to a picramic acid salt. It would become a matter of convenience what methods would have most appeal based upon what materials are available to then choose how to proceed with what course for synthesis. There are advantages and disadvantages to various approaches so which methods are best for any particular scenario would depend on the circumstances of most easily available materials defining the most convenient approach to synthesis for that individual case.

Hennig Brand - 13-5-2014 at 10:26

Quote: Originally posted by Praxichys

Why bother with the hydrocarbon/sulfur method to H2S? You mentioned methods using iron/sulfur earlier, but why not use that just for H2S generation?

Heat iron filings and sulfur in a soup can or something until the reaction starts. Let it cool, then just drip an acid on the FeS with a gas generator setup. There are no sulfur clogs or messy/stinky organosulfur leftovers to scrape out of glasware, etc.

I think I just solved the sulfur clogging issue and really if one is only interested in making enough sulfide solution to reduce ten or twenty grams of picric acid then simply using a delivery tube that is large enough to not plug during the short run time needed would be adequate. I was using a brake line for the experiments I posted about in this thread, which was only 3.1mm inside diameter, and while there were some clogging issues I still managed to produce enough sodium (hydro)sulfide solution for a lot of testing. Obviously glassware which is dedicated for this purpose or disposable should be used. For instance, I have been using mason jars with a hole cut in the metal lid, using an electricians knockout tool, for the stopper. In most cases I found that removing the chunk of carbon and organic material from the bottom of the reaction vessel was not that difficult.

The hydrogen sulfide produced by this method is very pure, according to the literature, and it uses very common, cheap materials. The setup I proposed above would be suitable for producing quite large quantities of hydrogen sulfide, say for example to make a large quantity of sodium (hydro)sulfide reducer or a large quantity of hydriodic acid.

Like Rosco said, there are many different materials and methods to choose from and their suitability depends on your goals, material availability and equipment availability, etc.

[Edited on 13-5-2014 by Hennig Brand]

nitro-genes - 22-6-2014 at 13:56

Hi Henning Brand, congrats with your work on the reduction of picric acid to picramic, some serious progress in this thread!. I must admit I haven't read every detail of it yet, though I was wondering about one of the earlier articles you posted. Here again they mentioned "sulfur dyes" formed, especially from aquous solutions and with higher alkalinity. Anyone knowns what exactly they are referring to and to what extent it makes up the final product after NaS redution? Could't help thinking that it could explain apprent more than 100% yields?

No luck on ascorbic acid/Fe method yet, yields were terrible, almost no precipiation of sodium picramate or picarmic acid after acidification. Seen the yields the sulfide reduction definitely seems the way to go, though I'm hesitant in directly producing H2S.

Another brainfart that I had was to maybe ignite a 1:1.7 mixture of sulfur and aluminum in a closed crucible to produce Al2S3. Al2S3 in contact with water produces H2S and Aluminum hydroxide (precipiates). Could you treat the solid Al2S3 with NaOH or NH3 solution and filter to get rid of the Aluminum hydroxide to produce ammonium of sodium sulphide solution?

[Edited on 22-6-2014 by nitro-genes]

nitro-genes - 23-6-2014 at 16:04

Couldt edit my previous post, but some initial optimistic results with aluminumsulfide produciton. 20g Aluminium powder was mixed with 34 grams of sulfur (slight excess aluminium) and ignited in a stainless steel vessel with small opening to relfief the pressure, that was closed with dry sand to eliminate oxygen as much as possible (immediately after the reaction). The stainless steel barely survived the reaction, glowing almost white orange for a full minute after completion. After cooling, the aluminum sulfide was removed from the container with a hammer (this stuff is incredibly tough!). Then in a narrow glass container, 8 grams NaOH was dissolved in 75 ml of destiled water, after which 10 grams of Al2S3 chunks were added. Took a couple of hours for the Al2S3 to decompose completely in the NaOH solution, after which a fine layer of presumably Al(OH)3 remains at the bottom. The decomposition of Al2S3 in water is clearly audible as pronounced H2S bubling can be heard as long as the reaction is not complete. After filtering a clear, slighty yellow solution of NaHS was obtained. Quick test indicate direct formation of red colour after introducing to small amount of PA. When kept absolutely dry, the Al2S3 could be stored as a on demand reducing agent.

Cannot believe how easy this seems to work after obtaining Al2S3, I was afraid that the Aluminium hydroxide would form a sort of gel or otherwise difficult to seperate fine precipitate, but it can actually be filtered out really easy.

Will try larger scale reduction tomorow.

Edit: The reaction vessel used for the Al+S reaction containing remaingin Al2S3 is best filled with strong NaOH solution to eliminate H2S formation, don't use water!

[Edited on 24-6-2014 by nitro-genes]

Hennig Brand - 24-6-2014 at 05:41

Thanks for the high praise. I am more of an explosives and science/technology enthusiast than a chemist, but I will point out a couple things that seem relevant.

This first attachment called "Communications" provided by Rosco, talks about yield and how the reduction should be carried out between 50 and 60 Celsius for best yields of the purest product. High temperatures (e.g. 70^oC) as well as the presence of excess hydroxide ion in the reaction mixture are also reported to reduce yield. Possible undesirable by-products are also described. There are at least two or three sources posted in this thread which describe by-product dye formation during the reduction, and they all describe them differently. What they all seem to describe, though, is a lessening of product weight recovered from the reaction mixture and a darkening of the solution as the quantity of by-product formation increases.

See article titled “Communications” posted as attachment.
http://www.sciencemadness.org/talk/viewthread.php?tid=433&am...

See Hodgson and Ward article posted as attachment.
http://www.sciencemadness.org/talk/viewthread.php?tid=433&am...

I am sure that there are other ways to produce an effective reducer for picric acid. Except for the serious poison danger, generating hydrogen sulfide by heating a heavy hydrocarbon and sulfur is very advantageous. It allows very pure hydrogen sulfide to be produced and as long as high purity sodium hydroxide is used the sulfide reducing agent produced will also be very pure. The composition of the reducing solution produced can be easily determined by taking the weight of the sodium hydroxide solution before H₂S absorption and after. The old expression, “garbage in, garbage out” I think applies here. Most of the reducing agents, I have seen used, seem to be a mixture of various reducing agents and unreacted material, etc. I do understand the desire to avoid the use of hydrogen sulfide gas though. It is quite unpleasant material and it can be downright dangerous if not handled properly. Your method of reacting aluminum and sulfur seems good. Interesting to see what kind of results you get when reducing picric acid.

[Edited on 24-6-2014 by Hennig Brand]

nitro-genes - 24-6-2014 at 06:48

Today I tried the reduction of picric acid to picramic on a larger scale, it seems Al2S3 is realy conveniant for the production of NaHS solutions.

Al2S3 was produced from direct reaction of Al with S as desribed earlier. It appears as black chunks in the picture, probably due to contaminants from the dark german aluminium used. (aluminium carbide, carbon etc)

8 grams of NaOH was dissolved in 75 ml of destilled water. To this was added 10 grams of Al2S3 chunks. The Al2S3 immediately starts to decompose as conitnued bubling can be observed opon adding the NaOH solution (photo). It takes several hours to decompose the Al2S3 completely and was kept in the fridge overnight. After complete reaction, the resulting NaSH solution smelled slighlty of H2S, indicating that mostly NaHS and a small amount of free H2S were in solution.

After overnight in the fridge, the aluminium hydroxide/oxide and contimants were mostly at the bottom of the beaker (photo) and could be filtered of easily. A small amount of wash water was used to retrieve all of the NaHS. After filtering off the precipitate, a slighly yelowish solution is obtained (photo).

Next, 15g of recrystallized picric acid was dissolved in 100 ml's of NaOH solution (2.62g NaOH). This was heated to 50 deg C to dissolve all of the SP and prevent precipitation from solution upon addition of the NaHS solution. Slow additions of the NaHS solutions were made, so that the temperature of the solution remained between 50 and 55 deg C. A slight amount of what appears to be sulfur was forming on the boundary of the solution and air, visible as a slight opaque film on top of the solution.

After 3-4 minutes most of the sodium picramate precipitated. The solution was kept in the fridge untill at 5 deg C. The resulting sodium picramete was washed twice with an icecold 10% salt solution, and finally icecold water. Yield looks pretty good, though it needs to dry first. Upon heating it puffs off pretty violent, only the slightest smell of buring sulfur can be noticed.

7- Sodium picramate precipiation.jpg - 168kB

3 - Al2S3 after completion decomposition.jpg - 157kB

[Edited on 24-6-2014 by nitro-genes]

nitro-genes - 24-6-2014 at 07:35

Regarding the dark brow solutions upon alkalinity increase... Noticed similar dark brown colour of the solution after attemped 8 hour ascorbic acid/Fe redution and hardly any precipiation of picramate/picramic acid. I'm beginning to suspect that what they call sulfur dyes may actually be nothing more than over reduction of picramate into di ,-and triaminophenols. Ascorbic acid is certainly capable under certain conditions to produce the diamino variant, it has even been patented if I'm not mistaken.

[Edited on 24-6-2014 by nitro-genes]

nitro-genes - 24-6-2014 at 12:23

oh, almost forgot... it also makes some realy fast DDNP

Attachment: P1030094.avi (4.1MB)
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Hennig Brand - 24-6-2014 at 12:52

Nice pictures, looks like you have had success. That's a pretty clever idea using Al2S3. Interested in hearing what kind of yield you got.

nitro-genes - 24-6-2014 at 13:46

Won't be able to weigh the sodium picramate for yield... I didn't want to store the sodium picramate itself since it deflagerates pretty violent and for the DDNP synthesis picramic acid was needed. So I went ahead and dissolved al of the wet sodium picramate in the least amount of 80 deg C water. Used the suggestion of Rosco, by slowly (while stirring) adding 10% HCl solution to precipitate the picramic acid over the course of about 15 minutes. The picramic acid precipitated this way does not form the usual mud like substance but filters more easily. Still pretty fine crystals but a closeup look seems to suggest ~0.2 mm long needle like crystals that glitter in reflective light. There is a pretty sharp point at which most of the picarmic acid will come out of solution, could have been more patient in the HCl addition to maybe produce even larger crystals. To my surprise, the picramic acid obtained definitely looks more red than brown as I obtained usually, don't know if this is a purity issue or relates to crystal size as well.

The picramic acid will be weighed tomorow (or the day after), when it is dry.

[Edited on 24-6-2014 by nitro-genes]

Rosco Bodine - 24-6-2014 at 21:51

About this I am not certain, but possibly it is worth experiments to see if picramic acid is useful as a gasoline additive for dissolving and reducing levels of rust trapped in fuel filters and fuel tanks corroded by ethanol or methanol or other oxygen containing fuel additives and moisture contaminated fuel. A related patent GB1574297 is attached.
And the U.S. issue patent US4145190 is also attached.
Also attached is US4073626 which specifically mentions picramic acid, column 3 line 18.

Attachment: GB1574297 Ferrous Picrate Fuel Additive.pdf (516kB)
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Attachment: US4145190 Ferrous Picrate Fuel Additive.pdf (423kB)
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Attachment: US4073626 Ferrous Picrate Fuel Additive.pdf (331kB)
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[Edited on 25-6-2014 by Rosco Bodine]

Hennig Brand - 25-6-2014 at 06:19

Quote: Originally posted by nitro-genes

After complete reaction, the resulting NaSH solution smelled slighlty of H2S, indicating that mostly NaHS and a small amount of free H2S were in solution.

I found that all the sulfide solutions I encountered including those with sodium hydroxide in solution stunk of H₂S. Even if you started out with pure sodium sulfide in solution small amounts of H₂S are formed by decomposition and is detectable in extremely small amounts (according to Wiki: 0.0047 ppm is the recognition threshold, the concentration at which 50% of humans can detect the characteristic odor of hydrogen sulfide, normally described as resembling "a rotten egg".)

The sodium (hydro)sulfide solution you prepared appears to be much less yellow than the ones I prepared using the H₂S generator and passing the gas through a bubbler. I suppose I could have flushed the generator head space and delivery tube, etc with inert gas, or let the generator produce for a short while before starting to produce the sodium (hydro)sulfide reducing solution. I am not sure that small amounts of oxygen and the small amounts of polysulfides produced from it are much of a problem anyway though.

Sodium Picramate Monohydrate?

I have seen reference to the monohydrate of sodium picramate in a couple of places, but on searching I have found no detailed information about it. Does anyone know if sodium picramate does form a hydrate and/or have any specific information regarding it.

Rosco posted this Zinin screen shot article earlier in this thread. http://www.sciencemadness.org/talk/viewthread.php?tid=433&am... The same passage can be found in this text: "Speciality Chemicals: Innovations in Industrial Synthesis and Applications, edited by B. Pearson"

It states, "During the reaction, the reaction mixture changes from yellow to deep red as the product gradually precipitates as fine red crystals of the monohydrate.", but doesn't say anything more about it. Would like to have some more information about this.

If what I have been getting is the monohydrate of sodium picramate, the 100.3% yield I obtained earlier was actually closer to 93%. As far as I know picramic acid does not form a hydrate, so conversion to picramic acid could be a better way of determining yield. At this point I think I prefer making DDNP directly from sodium picramate however.

[Edited on 25-6-2014 by Hennig Brand]

nitro-genes - 25-6-2014 at 08:40

Thanks for pointing that out, the difficult part (without pH meter) is indeed to know how much of the sulfide is present as HS- and S2-, this was one of the things that worried me, because there is no telling if the 10 grams of Al2S3 used translates directly to the theoretical amount of H2S produced. Agreed, H2S smell is not a really accurate (nor healthy) way of estimating alkalinity of the solution.

If my rusty molarity calculations were right, I would have ended up with 3 moles of NaHS for every mole of sodium picrate, not sure how a reduced, like 2.5-1 ratio would do in terms of yield.

[Edit]

Axt posted two articles describing metallic picrates in the thread below, most of the picrates seem to retain IIRC,as hydrates, not sure for sodium though

https://www.sciencemadness.org/whisper/viewthread.php?tid=87...

@ Rosco, do you end up with orange exhaust fumes? As a big fan of the Dutch soccer team, this would be really cool!

[Edited on 25-6-2014 by nitro-genes]

Rosco Bodine - 25-6-2014 at 09:50

Actually it is a very real serious and expensive issue that has been a continual headache for ethanol blended fuel users that plain steel gas tanks over time invariably do rust and it would be a great product that could form a fuel soluble compound with the colloidal ferrous "slime" that predictably accumulates and gradually plugs up fuel systems, causing expensive repairs. Whatever is saved by blending ethanol with gasoline as a government mandated environmental regulation supporting "renewable energy" has a huge downside in maintenance for the fuel system fouling that results. So far as I know, there is no commercial fuel additive that eliminates the issue, though some help prevent it. The combustion products would be such nanoparticulate ferric oxides or magnetite and at such trace amounts that it would be invisible and wouldn't likely cause any deposits and would likely be less building than the more coarse particles that come through the filter already, until accumulation obstructs the filter and requires a replacement filter, usually along with a new fuel pump and other components, along with the labor expense. The hidden costs for ethanol blended fuels are greater than any benefit and still too many vehicles are in daily use that are not designed for complete happy coexistence with corrosive and moisture laden oxygenated fuels that are inherently inferior many ways to straight hydrocarbon fuels.

As for the sodium picramate being a hydrate or not a hydrate, it would be a simple titration of a weighed amount of the dry material that would settle that question since the color transition fading sharply to nearly clear endpoint is so obvious. Calculation should immediately reveal from the amount of HCl used to achieve transition from dark dye to abrupt color fade, what is the mole amount of the sodium picramate converted to sodium chloride, being equal.
Whatever was the weighed amount of dry sodium picramate used for the determination, will be the same mole fraction as the mole fraction of HCl used to produce the byproduct NaCl.
Solve for the unknown mole weight for sample titrated and if it comes out close to 221.11 then it is anhydrous and if the unknown solves out at 239.11 then it is the monohydrate.

[Edited on 25-6-2014 by Rosco Bodine]

Hennig Brand - 25-6-2014 at 11:58

Yes, a titration like was described in the Hodgson and Ward paper to determine yield. I still have some dry sodium picramate in storage, so the next time I make DDNP I will run the synthesis as a titration and kill two birds with one stone.

Ethanol has been causing a lot of problems, especially with small engines from what I have heard. Adding ethanol produces a fuel with lower energy density and results in corrosion related issues. I hope they will give up on this foolishness and go back to straight gasoline. I buy gas, whenever possible, at the stations that sell gasoline without ethanol. A fuel additive that deals with the associated issues of ethanol in fuel would be a real winner though you are right.

[Edited on 26-6-2014 by Hennig Brand]

Rosco Bodine - 26-6-2014 at 07:41

Yeah there are significant economic and technical issues that are ignored by overly enthusiastic regulators and environmental activists who want to change the world by administrative decree which fails to be pragmatic about what will be the measure for what is actual "progress" towards some not well defined goal of "healing" global warming or climate change, depending on the political as much or more than the actual atmospheric weather. It is a way of thinking that has caused disproportional cost increases in return for the dubious benefit derived where the only certain result has been that everyone is paying more and getting less back for what they spend because productivity has suffered on both sides for supply and demand in a world being crippled by burdensome regulations which really don't have a practical necessity, but have more of an ideological and philosophical motivation that is more metaphysics than science. Those who have joined the "green religion" cult may believe they are conscientious masterminds tasked with protecting the environment, but the disproportionate negative impact on consumers and producers is measurable and continual, while there is no observable or even predictable effect showing a return for that cost as any real improvement to the biosphere. Sometimes it seems like a paradox that we live on a world where billions of people are now computer literate but can't add and subtract to do the simple arithmetic and arrive at understandably reasonable and practical perspectives about what things are "righteously and ethically green" as a sensible stewardship of resources, as distinguished from what things are pie in the sky unrealistic and impractical burdensome constraints that are counterproductive in every way except for reenforcing some "feel good" delusion embraced by an ideology of "green extremism" that is essentially the mentality of a luddite who would have a happier existence if they were a potted plant, maybe a broccoli for example, living out their days as a specimen exhibit on an organic farm where everything is powered by solar panels and windmills in a world where the internal combustion engine and horseless carriages have been all replaced by less environmentally sinful horses who spend equally rewarding days eating renewable grass and converting it to renewable horse shit. The Amish are looking for a few good men. Aside from the foregoing rant about the slings and arrows of outrageous fortune, it was about 10 years ago I posted this interesting technology about picric acid derivatives possible usefulness as a "fuel combustion catalyst"
http://www.sciencemadness.org/talk/viewthread.php?tid=3683&a...
Given that the amount of fuel additive required would be so small and the economics favorable, it seems odd there is nothing in the way of followup. And the "mad science" aspect of this technology is intriguing given the easy improvisation of the required material and the potential benefit. There is provided also a legitimate experimental use for a material that may have value as an energetic material in alternative ways which provides a good explanation for any inquiring minds why a person might want to have on hand their own supply of what may otherwise be suspect, but has a legitimate use documented here that is benign.

nitro-genes - 26-6-2014 at 09:20

Dunno if you can blame the activist for increasing costs, fossil fuels are simply becoming scarcer and therefore more expensive to find and obtain, which translates to increasing costs for an ever increasing number (word population) of consumers. We have burned up most of the earths fossil fuel reserves in a matter of decades, the potential rammifications on the economic level are hard to estimate and may only become visible in the long term but numerous examples exist where fast and cheap solutions to boost economical productivity affected the environment in ways that lead to immense economical costs in the long term. Everything on this planet is connected in ways that are sometimes even hard to graps for geophysisits/biologists themselves but a general awareness of this is starting to sink in to the people in general, which I think is good. Surely, is has lead to spurious ideas and projects of questionable bennfits, like biofuels (that cost more conventional fuel than they produce) and are only possible due to government sponsoring but it is a start and can be optimized. Remember that one of the first ccombustion egines had like 8000cc and produced only a few horsepower, while todays combustion engines are much more efficient (well... maybe not in the US). Same for the use of ethanol, you cannot seriously believe that this is an unsolvable problem for the automotive industry that cant be prevented by some coating of the fueltank or whatever, that is maybe not implemented yet due to the relative new use of ethanol-fuels, what shoudl we do then...go back to tertraethyl lead as an anti-knock?

Combustion engines are a thing of the past anyway, within 10-15 years we will all drive electric vehicles and ITER will save us all...

" Sometimes it seems like a paradox that we live on a world where billions of people are now computer literate but can't add and subtract to do the simple arithmetic"

What does a yearly 2% growth of the word population mean in terms of arithmetic and consequences on needed resources and the environment over the next decades?

[Edited on 26-6-2014 by nitro-genes]

Rosco Bodine - 26-6-2014 at 10:18

A Malthusian catastrophe is what the arithmetic portends. Soylent green is people!

nitro-genes - 26-6-2014 at 10:35

A malthusion catastrophe is one way to describe certain, less wealthy, parts of the world. Pink-slime and "mechanically reclaimed meat" are not to far from Soylent green IMHO.

[Edited on 26-6-2014 by nitro-genes]

Hennig Brand - 27-6-2014 at 06:22

Yes, playing around with the exponential growth equation and using bacterial growth as an example makes it very obvious that we are in trouble. The big business types love the increase in population because it means more economic growth and money/power for them. It is time these people were forced to think about things other than just money, like the long term welfare of their country and the sustainable use of resources. I am very doubtful that the CO2 we are producing by burning fossil fuels is having the effect on climate that many of the environmental fanatics say it is, but I do think that petroleum is a very valuable raw material which can be used to make many, many other things and probably even more so in the future. It seems kind of sad that we are just burning this valuable material almost as fast as we can pump it out of the ground.

I think there is still lots of oil, it is just that we have picked a lot of the low hanging fruit so to speak. It is gradually getting more expensive to get the oil out of the ground. I also believe that the price we pay for things has very little to do with the cost associated with producing it much of the time. It is all about what people will pay, and especially in modern times they are very good at using propaganda to convince us about a lot of things to help justify higher prices for many things. If most of your neighbors are willing to pay $2 per liter for gasoline, then guess what, you will be forced to pay that too if you want that product. I think there are a lot of games played with the pricing of most items and services we consume. It is all a big game to extract the maximum amount of dollars from the mostly ignorant consumers.

Rosco Bodine - 15-2-2018 at 10:05

bumped thread for reference to recent discussions in related threads

Rosco Bodine - 6-3-2018 at 08:33

Quote: Originally posted by Hennig Brand

I said above that for my next experiments that I would save the methanol and go with water. This is apparently a bad idea if the reducer is sodium sulfide and the sodium bicarbonate buffer is used. From Hodgson and Ward, "while the addition of sodium bicarbonate to the sodium sulphide in alcohol greatly improved the reduction efficiency, this does not occur in water alone (see Table II, Experiment 6) since the water-soluble sodium carbonate formed (insoluble in the methanol medium) probably introduces the alkalinity necessary for by-product formation with 20% diminution in yield of picramic acid." Makes sense now that I stop and think about it.

I might try the following in water though. The idea, which came from the Zinin article, is to use a magnesium salt that would precipitate the hydroxide formed from the reduction reaction, as magnesium hydroxide, thereby keeping the pH of the reaction solution from rising and preventing undesirable by-product formation. Epsom salt is magnesium sulfate heptahydrate and would probably work fine.

MgSO₄ (aq) + 2NaOH (aq) -------> Mg(OH)₂ (s) + Na₂SO₄ (aq)

If it wasn't possible to separate the magnesium hydroxide and sodium picramate from each other after the reaction was complete, the sodium picramate could be precipitated as usually and then dissolved in water before filtering out the magnesium hydroxide. Acidifying the sodium picramate solution would then precipitate picramic acid. I think my next experiment may involve Epsom salt.

I am not sure how difficult it will be to remove the precipitated magnesium hydroxide from the sodium picramate solution. It seems like it may be difficult to filter. As long as it can be removed with a reasonable amount of effort, this process would likely be a good way of reducing bi-product formation and increasing yields.

[Edited on 9-4-2014 by Hennig Brand]

There is an article attached which may be useful in understanding more about what occurs for magnesium and possibly also for aluminum salts in reactions with sulfides and polysulfides.

The normal sulfides of magnesium and aluminum decompose in water with evolution of free H2S, but for magnesium and possibly likewise for aluminum there may also form a soluble and stable hydrosulfide that is stable in water solution even in hot water and may have value as a Zinin reducing agent. Perhaps in some scheme this may be useful in working up a Zinin reagent from a complex system of reducing sulfur compounds produced by mixing and reaction of a strong base and sulfur. The use of magnesium or possibly aluminum salts could have value in limiting the alkalinity in Zinin reduction mixtures. The article is from 100 years ago.

The reaction at the top of Journal page 542 of the article, page 4 of the pdf, is especially interesting

MgSO4 + Na2S + 2H2O ----> Mg(OH)2 + Na2SO4 + 2 NaSH

This is a similar buffering effect using magnesium to limit alkalinity.
Magnesium Acetate or citrate or perhaps glycinate should work similarly to buffer a system to limited alkalinity or acidity, as a scheme I described could be useful with other reducing agents where the intended product of reduction would be a picramate.

The buffering effect in a slightly acid reduction would leave the Magnesium organic acid salt intact and soluble as a spectator, but if the reaction system trended alkaline above pH 10.3 (some report a range of pH 9 to pH 10.5) the alkalinity would be limited by precipitation of the Magnesium as Mg(OH)2. [Note: The range of pH buffering is I think time related where there is a rapid response at achieving a buffered pH 9 and with passing time more slowly buffering to the higher value of 10.3, the low solubility of Mg(OH)2 delaying the higher 10.3 - 10.4 pH stable endpoint reached only very gradually and slowly] Conversely if the reduction reaction mixture trended too extremely acid, the buffer present as an organic acid salt of Magnesium would be disrupted and the Magnesium would mitigate the increasing acidity. An organic acid salt of Magnesium would have the desired effect of mitigating increasing acidity that would not be a desired buffering effect present for a mineral acid salt of Magnesium.

http://www.aqion.de/site/191 pH values of common compounds

http://cldfacility.rutgers.edu/content/reaction-suspension-m... experimental demo of effect for magnesium organic acid buffering and neutralization

Attachment: Pages from The_Journal_of_Industrial_and_Engineering page 539 article.pdf (430kB)
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[Edited on 3/6/2018 by Rosco Bodine]

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