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Author: Subject: Synthesis of thioacetone?
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[*] posted on 4-3-2022 at 11:39

Interesting paper on the working conditions.
glove box and destroying any vapors in situ.
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[*] posted on 5-3-2022 at 00:28

Hi macckone, I'm not so brave to crack the trimer to monomer, but maybe I will try to synthesize the trimer. Cracking requires quite strong conditions. I found in literature that during the synthesis of trimer, there is a lot of side product propane-2,2-dithiol "with an intensely powerful, disagreeable odor" (60-70% trithioacetone and 30-40% propane-2,2-dithiol, see the experiment in the attached pdf, they had to perform vacuum distillation to separate them). This side product (geminal dithiol) worries me more than the trithioacetone itself which is quite stable and hard to crack to monomer. My friend who already does organic chemistry business (still studying PhD) told me, that the trimer is in equilibrium with monomer so traces of monomer are always present. He also told me that he is specialized in organosulfur chemistry and performed a lot experiments in organosulfur syntesis. In university lab they finally always washed equipment with methanol or isopropanol, but once his schoolfellow mistakenly used acetone to wash a glass with remainders of P2S5 so the thioacetone "was cooked". It happened inside fume hood but the whole building was full of very bad odor. My friend also pointed me out, that using P2S5 is best with pyridine complex, otherwise P2S5 is very strong dehydrating agent because P2O5 is formed.
Yet I still did not succeed with preparation of thioformaldehyde trimer (I tried Na2S2O3 to avoid H2S but it did not work in my case). My first step would be trimer of thioformaldehyde = 1,3,5 trithiane and I will have to bubble the nasty H2S into the reaction (or drip solution of Na2S but that will introduce sulfur contamination as my Na2S is not colorless but yellow so with impurities of disulfide/polysulfides which would decompose to sulfur in solution with excess of HCl). Maybe only then I'll try the trimer of thioacetone somewhere in wood few kilometers away from civilization, maybe not (distillation of propane-2,2-dithiol is quite distractive for me, but maybe it could be separated by creating its Na salt by reaction with NaHCO3 or Na2CO3? which should be soluble in water unlike trithioacetone which is almost insoluble).

Attachment: pol.1970.150080826.pdf (728kB)
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Lionel Spanner
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[*] posted on 10-3-2022 at 04:13

Quote: Originally posted by Keras  
What’s funny about thioacetone is that it seems to stink more in a diluted form (so far away from the source). I suspect, like H₂S, some sort of overload of the olfactory nerves when the concentration is too high.

Good target for a microscale experiment :p

Could also be down to its vapour pressure, i.e. it evaporates more quickly when diluted.

Industrial chemist rediscovering the practical pleasures of pure chemistry.
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[*] posted on 10-3-2022 at 04:50

No, because it is already evaporated when diluted. Also vapour pressure only starts playing a role in high relative concentrations, which I really hope no one is experiencing with thioacetone.
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