Sciencemadness Discussion Board

Synthesis of thioacetone?

panajotovicn - 1-1-2018 at 14:27

I was just wondering if it would be possible to synthesise C3H6S (thioacetone) form acetone and hydrogen sulfide under catalyst - aluminium chloride?
Yes/no? And, any other way?

[Edited on 1-1-2018 by panajotovicn]

Chemi Pharma - 1-1-2018 at 17:49

However Wikipedia supports your theory, I didn't find any workup treating about reacting acetone, H2S and AlCl3.

There are a few methods to produce thioacetone that can be found on Google. An interesting way is reacting acetone with PSCl3 and Triethylamine using water as a solvent and microwave radiation:

Thioacetone.jpg - 19kB

But while I was researching about Alprazolam synthesis, I found a preparation described at a Patent that covers the substitution step of the oxigen molecule of a ketone for sulfur, using phosphorus pentasulfide in an easier workup way:

Sulfur replacement of Ketones with P4S10.jpg - 143kB

I hope it helps!

j_sum1 - 1-1-2018 at 18:13

Don't do it man!
“Recently we found ourselves with an odour problem beyond our worst expectations. During early experiments, a stopper jumped from a bottle of residues, and, although replaced at once, resulted in an immediate complaint of nausea and sickness from colleagues working in a building two hundred yards away. Two of our chemists who had done no more than investigate the cracking of minute amounts of trithioacetone found themselves the object of hostile stares in a restaurant and suffered the humiliation of having a waitress spray the area around them with a deodorant. The odours defied the expected effects of dilution since workers in the laboratory did not find the odours intolerable … and genuinely denied responsibility since they were working in closed systems. To convince them otherwise, they were dispersed with other observers around the laboratory, at distances up to a quarter of a mile, and one drop of either acetone gem-dithiol or the mother liquors from crude trithioacetone crystallisations were placed on a watch glass in a fume cupboard. The odour was detected downwind in seconds.”

clearly_not_atara - 1-1-2018 at 23:21

As far as I know this molecule defeats all known containment procedures; there is no reported way of producing thioacetone without causing severe discomfort to everyone in a kilometer radius. So this is one of the worst syntheses you could attempt: it cannot succeed by any reasonable measure of "success".

Radium212 - 2-1-2018 at 03:00

Yeah, I'd avoid thioacetone. Have you heard of the Freiburg incident, where an entire block of the city had to be evacuated due to the stench from some accidentally produced in a soap factory. If you're making some kind of stinkbomb maybe just use cadaverine or putrescine.

Chemi Pharma - 2-1-2018 at 03:48

I agree with the other members of this Forum that said it's a horrible stink chemical reagent.

But I think my duty here is just analyse the chemical reactions and the ways to do that with the better yields and in an OTC manner. Who knows if you're intending to make exactly thioacetone or another thioketone?

People here often ask for a synthesis or a product that's not always is the real target of their questions. I'm used to see that, here, in this Forum.

If you want to know how to substitute the oxigen molecule of a ketone by sulfur, the way is follow the directions I've given. But If you really just want to produce thioacetone to do a revenge against your enemies, like a skunk does, you're on the right way:D

PirateDocBrown - 2-1-2018 at 09:58

For a stink bomb, it'd be best to have a device that can make it in situ, like from two reactants that combine with each other.

Radium212 - 2-1-2018 at 14:21

I suggest doing it microchemistry style in an ampoule. Seeing as it's a stink bomb you're not looking for something pure, just disgusting.

Radium212 - 3-1-2018 at 11:54

I suggest using cadaverine or putrescine for a stink bomb.

Tellurium - 9-1-2018 at 04:02

You can use Acetone with some HCl and bubble H2S gas into this mixture. This will produce the trimer: Trithioacetone.
I already done this and even the trimer stinks terrible when concentrated, got a tiny drop of the liquid onto my hand and even days later people were complaining about the smell.:D But please don't try to crack the Trithioacetone to thioacetone - that stuff is far far worse!:o

Rhodanide - 9-1-2018 at 07:26

If you're looking for something stinky or strange smelling, I'd suggest going with Phenyl Isocyanide. Its toxicity is very low, and the synthesis is very simple. It requires the following:
An Erlenmeyer flask
Equal amounts of both Aniline and Chloroform
Ethanol + Water in a 80/20 or 90/10 ratio (the less water the better, but enough to enable the reaction)
and finally, a smaller amount of Sodium Hydroxide (the amount depends on how much Aniline and Chloroform you use)
Dissolve the Aniline in the EtOH/H2O solvent, and dissolve the Sodium Hydroxide in to this. Add the Chloroform all at once, and stir to dissolve. Put a thermometer in the flask, make a hole for the thermometer in some Saran wrap, and seal the top of the flask with it. Heat-seal the wrap with a hairdryer or Heat gun on low heat. Gently warm the mixture to between 20-26 C for half an hour. You could distill the PhNC off under vacuum if you wanted to, just make sure your ventilation system is top of the line, or you live way out there, like me. It's nauseatingly pungent, and in the words of some, described as "highly specific, almost overpowering', 'horrible', and 'extremely distressing" (this was the description of other, more volatile Isocyanides, but this goes for Phenyl as well).

James Nilep - 9-1-2018 at 08:34

I have attempted the H2S Acetone method before using a hydrochloric acid catalyst with a large excess of acetone on a relatively small scale, but it didn’t seem to yield any trithioacetone, just a smelly solution of H2S, although I did not attempt to crack the trimer, after all I didn’t want the whole neighborhood to potentially vomit simultaneously

Melgar - 9-1-2018 at 12:34

Every time I've made H2S, it's been by accident. I'm not sure how one might make it deliberately. However, the accidental syntheses have typically involved dissolving metal reduction of sulfate, or the reaction of metal with sulfur and subsequent acid hydrolysis. It's kind of hard to tell how much is being produced though, just because it stinks a similar amount no matter how much or how little is produced.

Fyndium - 20-7-2021 at 11:06

So apparently a solution of acetone and HCl that is bubbled with H2S will produce trithioacetone. This can then be concentrated, and distilled in vacuum through a furnace tube at 500-650C to produce thioacetone.

What a lovely process. Would not touch it with a 10 meter pole. Although, if I were ever even hypothetically be interested in studying it, I would obtain a miniature disposable equipment, walk kilometers deep to the woods and attempt it there - and discard everything afterwards. And the day after read the news about strange rotten hell smell complaints all over that area. :D

But, a hypothetical question: if someone were to be able to produce it in useful quantities, could it be stored in sealed glass ampoules or would it still diffuse through eventually? Ampouling stuff seems to be the only viable method to prevent very volatile or smelly stuff getting around.

Isopropylamine isn't bad btw. It has a very strong ammonia odor, much more organic though, with sort of rotty-sweetish tone like what isopropanol can smell like in some quantities, but it's no way uncontrollable and it dissipates rather quickly. I'd rather handle it much more than phenylacetaldehyde or phenylacetic acid, because those smells seemed to be hugely more persistent, I've still got some plastic canisters that smell like of it after over a year sitting outdoors. On the other hand, cleaning equipment after handling isopropylamine left zero traces of odor.

[Edited on 20-7-2021 by Fyndium]

Ormarion - 24-8-2021 at 10:14

From my side i made some of the trimer by bubbling H2S into a acetone and anhydrous AlCl3 mix, haven't worked on it again but i think it worked with the smell it made

macckone - 24-8-2021 at 12:26

This is definitely something to be done during a heavy snow miles from the nearest human.
The animals may not appreciate it but at least you won't get arrested by them for possession of a chemical weapon.

Thioacetone is not technically a chemical weapon but try convincing a judge of that.

Ormarion - 24-8-2021 at 12:50

I'm lucky to leave km away from any humans so i can work peacefully in the lab :) also the trimer smell is strong but not super volatile, i could only smell it from one or 2m of the lab

macckone - 24-8-2021 at 20:34

The trimer is harmless, until you heat it to decomposition to the monomer.

Fyndium - 25-8-2021 at 10:04

It looks to me that it could be made in situ by preparing the more stable trimer, and when needed, distilling it through pyrolysis tube to form the monomer. I'm not sure if it would decompose further unless vacuum is used?

draculic acid69 - 25-8-2021 at 18:32

After reading this I don't know how anyone could possibly want to do this synthesis

Triflic Acid - 25-8-2021 at 19:31

Well, I mean, if you lost your nose in some bizarre industrial accident, it probably would be a good way to enforce 6 mile social distancing :P

Tsjerk - 26-8-2021 at 00:39

I'm very curious about this compound, especially about how bad it really is. But I'm definitely not going to try it, I'm just waiting for a news paper to report about it once someone else did.

Fyndium - 26-8-2021 at 07:57

If we compare thioacetone to tert-butyl isocyanide, what scale are we talking about?

It seems that the stuff has never been studied because of it's foul properties. Perhaps one could make it in very, very minute quantities in a more desolate location by using a gasoline lamp type device and place it over a heat source like simple campfire, where the trimer is first vaporized by the heat, and led into tube that bends and goes through the flame, heating the tube sufficiently to decompose the trimer. Even if majority is lost, even traces should be enough to prove the very nature of the stuff. Apparently free thioacetone is somewhat reactive so it will quickly cease into a more stable form, so any long term harm should not occur, presuming the location is remote enough.

[Edited on 26-8-2021 by Fyndium]

Fery - 3-3-2022 at 05:30

this thread is very old, but here I found the method and experiments how to crack trimer to monomer. Not easy (ketene lamp, 1 mm Hg vacuum argon flow)

Attachment: phplX10sb (1002kB)
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Keras - 4-3-2022 at 00:35

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

macckone - 4-3-2022 at 11:39

Interesting paper on the working conditions.
glove box and destroying any vapors in situ.

Fery - 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 - 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.

Tsjerk - 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.

wg48temp9 - 27-12-2022 at 02:14

I suppose it was inevitable that someone like NileRed would try to make it and post a video on it:

Apparently not the first youtuber. LabCoatz beat him to it:

PS:Happy new year everyone

[Edited on 12/27/2022 by wg48temp9]

Tsjerk - 27-12-2022 at 02:42

The famous NileRed that rents an island to make the stuff but later admits the nearest houses are only a couple hundred meters away...

gemar14 - 27-12-2022 at 22:06

It should be possible, but please don't. You'll stink up your entire neighborhood.

thioacetone - 28-12-2022 at 02:05

i like this topic.
i really want to make it

zero - 16-1-2023 at 20:34

Both NileRed and LabCoatz did not follow the original procedure that produced the infamous odor. In both the Freiburg incident [1] and Whitehall Soap Works [2] the procedure was to bubble H2S into a mixture of Acetone and HCl. It is likely the next step was taken immediately after which is to steam distill the trithioacetone. This is important because free thioacetone is not stable [3] and will likely polymerize shortly in storage.

Another error is smelling it up close. It is reported to smell worse in more dilution so it would be better to have a person far away walk towards where it is being produced to have a true sense of the odor.

I will attempt the synthesis when I can with both of these in mind and report the result.

An alternate method to produce monomeric thioacetone that does not involve cracking is bubbling H2S into an acidic solution of acetone ketal [3] [4]. Produces more monomer than cracking and seems easier.


For each mole of the corresponding ketal or enol ether, double the amount by weight of glacial acetic acid and about 1 g of hydroquinone are added, 3 drops of concentrated sulfuric acid are added and a trickle of hydrogen sulfide is introduced until the theoretical amount is absorbed. As a rule, the reaction is completed after 15-20 min. Final temperature about 35 deg. The mixture is then poured into ice water, the insoluble organic phase is rapidly taken up in petroleum ether, purified and distilled in a column. The following aliphatic thioketones are extremely unpleasant and pervasive smelling, indeterminate, deep red oils. We report separately on thioacetone and on the chemistry and spectroscopic properties of the thiones.

[2] pg. 219

Fery - 16-1-2023 at 22:27

Hi zero, very useful information! Starting from acetone + HCl + H2S there is a side reaction producing 2,2 propanedithiol (30-40% dithiol while trimer of thioacetone 60-70%). As you wrote - it is necessary to column distil, otherwise you could smell this dithiol with a false hope that it is monomer of thioacetone. One of the mentioned youtubers whose knowledge as well practical skills in chemistry were inversely proportional to his courage even did not distill either did not apply vacuum to crack the trimer. The other who was more careful and has years of practical chemistry skills, at least used steam distillation in lab, but I do not know whether his vacuum pump running on electrical battery on the island produced sufficient vacuum level to crack the trimer (if the steam distillation was not sufficient to get rid of gem dithiol and vacuum level too weak then he could again smell the propane-2,2-dithiol instead of monomer of thioacetone). Anyway I appreciate that both were brave enough to try this experiment! One PhD student who is focused on organosulfur chemistry discouraged me to do such experiments if I would like to avoid contact with a team of professionals dressed in spacesuits arriving in big red truck with loud siren horn. He also told me a story how his university schoolmate mistakenly used acetone to clean a glass with remainders of P4S10-pyridine complex, the washings were poured into a waste container with acetone so an undesired product was cooked spontaneously. Acetone is the most commonly used solvent to clean a glass but in organosulfur chemistry I should use methanol.
If the reaction from acetone ketal you mentioned produces more monomer, that could be very interesting route.
Personally I would be more happy for the trimer of thioacetone which should have scent of some tropical fruit and is used in some candy. So far I was brave to synthesize only trimer of thioformaldehyde which I did outside of my house during night when there were no passersby on street and neighbors were inside their houses. The scent of H2S produced at 0,5 mol scale during few hours from which circa one half did not react and was vented into atmosphere, was terrible. I did not bother to trap the H2S into an alkaline / hypochlorite / permanganate solution and just did the trithioformaldehyde synthesis outside.

Keras - 17-1-2023 at 02:14

I suppose thioacetone acts on the smell receptors the same way hydrogen sulphide does: at too high a concentration, the receptors become saturated and ‘pass out’. That would explain why the smell is worse at low concentrations, where the receptors are still fully functional.

zero - 17-1-2023 at 07:49

Fery: Saw your synthesis of thioformaldehyde, very nice! Do you know how far you could smell the H2S from?
You are correct that the gem-dithiol is formed but it is only mentioned with the ZnCl2 modification, not with the original HCl. Not saying it wouldn't be formed, but the references I have only mention it when using ZnCl2. [1]
Another reason I doubt both Nilered and Labcoatz succeeded is also in [1]:

Thioacetone was prepared by pyrolyzing hexamethyl-s-trithiane on hot quartz rings under reduced pressure with subsequent quenching of the product as quickly as possible to -78°C. The pyrolysis temperature was fairly critical. Within the pressure range of 5-20 mm, a temperature below about 500°C permitted much of the trimer to survive. Above 650°C, decomposition to simpler compounds became excessive, and allene and hydrogen sulfide became important products. Under favorable conditions, 80% yield of red-orange, clear liquid monomer could be obtained, which could be redistilled quantitatively in a vacuum system.

The odor they describe is more like H2S, a thiol, or even the trimer evaporating unchanged. I don't think a blowtorch without argon or a vaccuum will produce much monomeric thioacetone.
According to the Esso researchers:

Two of our chemists who had done no more than investigate the cracking of minute amounts of trithioacetone found themselves the object of hostile stares in a restaurant and suffered the humiliation of having a waitress spray the area around them with a deodorant.

Surely if either Nilered or Labcoatz made thioacetone, they would have a similar experience with family or friends? To be clear these researchers were working in a fumehood so imagine how tiny the amount of thioacetone got on them. In both the Freiburg incident and the Esso researchers mention the smell travelled about 0.5 km. Nilered was much closer than that to houses which likely would have complained and Labcoatz reported the smell only travelled 200 ft. Again, more consistent with H2S or a thiol.

Keras: Agreed, it does seem to overpower much like H2S.

I will be focusing on producing monomeric thioacetone from the ketal method since it should bypass the temperature control issues and the hydroquinone will prevent polymerization.


[Edited on 17-1-2023 by zero]

[Edited on 17-1-2023 by zero]

Fery - 17-1-2023 at 09:33

zero - my trithiane was not completely odorless, I smelled something a little sulfurous, but definintelly only veeeeery weak... that could also be some impurity... traces of organosulfur compounds have strong enough scent...
you can scent H2S from distance, it just depends on its concentration (amount and how fast are you releasing it into air) and the direction of wind... there is some threshold of H2S which could be found in some literature, below this threshold you do not scent it (in my synthesis I scented it from few meters already and circa 0,25 mol was released into air during few hours)... you can avoid that by trapping gas into alkaline solution / hypochlorite / permanganate etc... the last 2 trap and oxidize also escaping organosulfur compounds which have worse scents than H2S but I was just lazy to trap H2S because I did the reaction outside
you are right, cracking thioacetone trimer into monomer is not so easy... strong enough vacuum, narrow window of temperature, quickly cooling into very low temperature - otherwise polymerization occurs quickly:
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anyway if any of the 2 youtubers yield of monomer was something like 0,00000001% they would be able to notice its scent at this very low but sufficient concentration

[Edited on 17-1-2023 by Fery]