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Author: Subject: picramic acid from picric
Hennig Brand
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[*] posted on 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]




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[*] posted on 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! :D

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




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[*] posted on 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.
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[*] posted on 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...:D

" 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]
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Rosco Bodine
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[*] posted on 26-6-2014 at 10:18


A Malthusian catastrophe is what the arithmetic portends. Soylent green is people! :P
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[*] posted on 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. :D

[Edited on 26-6-2014 by nitro-genes]
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[*] posted on 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.




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[*] posted on 15-2-2018 at 10:05


bumped thread for reference to recent discussions in related threads
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15-2-2018 at 11:31
Rosco Bodine
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[*] posted on 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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