Sciencemadness Discussion Board

Is it possible to prepare ethanethiol in this way?

math - 4-8-2013 at 18:42

Hello,

I've read that ethanethiol can be prepared by the reaction of ethylene with hydrogen sulfide over a catalyst or by the reaction of ethanol with hydrogen sulfide gas over an acidic solid catalyst, such as alumina (though I dunno at which temperature)[1].

Wouldn't it be possible to make it by bubbling H2S directly into ethanol?

Is there a simpler way for the hobbist-chemist to prepare it rather than by a halide displacement reaction, where ethyl halide is reacted with aqueous sodium bisulfide?

Or would my best bet to synthetize some ethyl chloride and proceed from there?


Thank you



[1] Norell, John; Louthan, Rector P. (1988). "Thiols". Kirk-Othmer Concise Encylclopedia of Chemical Technology (3rd ed.). New York: John Wiley & Sons, Inc. pp. 946–963. ISBN 978-0471801047.

Nicodem - 4-8-2013 at 22:57

Quote: Originally posted by math  
Wouldn't it be possible to make it by bubbling H2S directly into ethanol?

No.
Yet, in principle, it is possible to imagine catalytic conditions where this reaction could occur in the liquid phase in ethanol at close to ambient temperatures. H2S is still fairly nucleophilic even without deprotonation and might react with with EtOH2+ at useful rates, so that such conditions would require an acid catalyst (a strong acid that does not react with H2S). More realistically though, even with a proper acid catalyst, you would likely still need autoclave conditions. If you are that interested, I suggest you to search the literature for possible examples. Otherwise, this does not appear a good option, if you aim at a preparative synthesis. Even if it would be viable, it would give a mixture of EtSH and Et2S (and who knows what else).
Quote:
Is there a simpler way for the hobbist-chemist to prepare it rather than by a halide displacement reaction, where ethyl halide is reacted with aqueous sodium bisulfide?

The simplest way is via the S-ethylation of thiourea with ethyl bromide or ethyl iodide (plenty of literature examples) and then the hydrolysis of the thiuronium salt. But in any case, it is not the reactions themselves that are the difficult part, it is the isolation of ethanethiol that is difficult. I suggest you trying first with something simpler, like n-dodecanethiol or other such higher mercaptans. Ethanthiol cannot be properly made unless you have a very efficient fume hood - the higher mercaptans are much more manageable.
Quote:
Or would my best bet to synthetize some ethyl chloride and proceed from there?

That sounds like the worst possible route. Already preparing ethyl chloride is a challenge, then handling it...

math - 5-8-2013 at 04:20

Thanks for your reply. I may have understimated ethanethiol synthesis due to its above-room temperature BP and thought it'd be my easiest choice for thiol synthesis due to ethanol availability.

At this point I should switch to something else and be happy with the most feasible thiol I'd try, since I'd have made some just as novelty for its strong odour. Unfortunately I don't have a source for dodecanol.


Thank you

Metacelsus - 5-8-2013 at 13:55

Would ethanol and aluminum sulfide react to form ethanethiol at room temperature? I've heard of ethanol and Al2S3 reacting at high temperatures to produce diethyl sulfide and ethanethiol, but I'm not sure if the same thing would happen at 25 C.
https://en.wikipedia.org/wiki/Aluminium_sulfide
http://books.google.com/books?id=BPcxrmIgLKMC

Another way would be sodium hydrosulfide and an ethyl halide:
https://en.wikipedia.org/wiki/Ethanethiol

Finnnicus - 5-8-2013 at 17:23

What about ammonium hydrosulfide? Its only stable in solution though, but can be prepared from H2S and NH3.

math - 6-8-2013 at 14:47

Quote: Originally posted by Finnnicus  
What about ammonium hydrosulfide? Its only stable in solution though, but can be prepared from H2S and NH3.


I don't understand if this is a statement or a question :)

sonogashira - 7-8-2013 at 02:14

Quote: Originally posted by Nicodem  
The simplest way is via the S-ethylation of thiourea with ethyl bromide or ethyl iodide (plenty of literature examples) and then the hydrolysis of the thiuronium salt. But in any case, it is not the reactions themselves that are the difficult part, it is the isolation of ethanethiol that is difficult. I suggest you trying first with something simpler, like n-dodecanethiol or other such higher mercaptans. Ethanthiol cannot be properly made unless you have a very efficient fume hood - the higher mercaptans are much more manageable.

For dodecane thiol preparation, as described above, see:
http://www.orgsyn.org/orgsyn/prep.asp?prep=cv3p0363

Thiocyanides and thiosulphates may be used similarly, I believe.

I read a paper recently where dodecane thiol was promoted as an odourless replacement for EtSH in organic reactions. I haven't worked with either, but if a reaction called for EtSH I would certainly try to make dodecane thiol work in its stead.

Sodium lauryl sulphate is easily obtained, and would be a suitable precursor.

[Edited on 7-8-2013 by sonogashira]

Methyl.Magic - 15-9-2013 at 08:09

You can make thiols by adding elemental Sulfur to a grignard reagent. You will form the R-S-MgX and you can keep it as the magnesium salt form to avoid the foul smell and use it as the nucleophile for the next reaction.

AndersHoveland - 16-9-2013 at 10:41

Quote: Originally posted by Cheddite Cheese  
Would ethanol and aluminum sulfide react to form ethanethiol at room temperature?

There might be a very slow reaction with methanol. Methanol is known to be corrosive to aluminum. I think that would just form H2S, however.

It may be possible to dehydrate H2S with ethanol. Perhaps by gassing it with HCl. Or passing HCl into Al2S3 with ethyl ether and a little ethanol.