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Author: Subject: Looking for the most convenient preparation of ethyl mercaptan. Via ethyl chloride/sulfate?
Merryp
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[*] posted on 9-2-2020 at 13:23
Looking for the most convenient preparation of ethyl mercaptan. Via ethyl chloride/sulfate?


The thiol formation seems pretty straightforward, making the adequate ethylating agent seems somewhat tricky.

The required temperature for hydrochlorination of ethano, in presence of zin chloride, is 110 – 140 °C, according to literature.
So, autoclav or gas phase.
Wikipedia lists the reaction between methanol, sulfuric acid and sodium chloride as a source for methyl chloride, but it's not otherwise specified whether that reaction happens at more ambient conditions.
I reckon the presence of H2SO4 in the solution may be beneficial/catalytic.

Ethyl hydrogen sulfate, and sodium ethyl sulfate have been featured in previous discussions; there seems to be some uncertainty about the conditions though.
With hydrolysis, and competing reactions, namely formation of diethyl ether, seem to be the primary problem for those.

So, I was wondering if there are sources with a bit more clarity on these issues. Any ideas?
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Boffis
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[*] posted on 10-2-2020 at 01:37


Smelly business but if you must!!

Easiest route is react with thiourea. Both ethyl halides and diethyl sulphate will react to form an ethyl isothiuronium salt These are isolatable and stable compounds so you can prepare a fair bit and then react a little at a time with a base such as NaOH, ammonia or hydrazine hydrate.

With ammonia you will have guanidine left in the solution and with hydrazine hydrate aminoguanidine.
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Tsjerk
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[*] posted on 10-2-2020 at 03:48


You are doing this in a very efficient fume hood or in the middle of nowhere right? You wouldn't want the fire department showing up to evecuate the block.



[Edited on 10-2-2020 by Tsjerk]
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Chemi Pharma
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[*] posted on 10-2-2020 at 06:58


See Prepchem.com to do that:

https://www.prepchem.com/synthesis-of-ethanethiol/

I personally think that you'd better use Ethyl bromide (cheap, easy to purchase and manageable chemical) and sodium sulfide (cheap and easy to purchase too), bubbling into the solution hydrogen sulfide, adaptating prepchem.com recipe given with ethyl chloride (much more difficult to manage cause it's lower B.P. and a watched chemical) and KHS.

The question is: what do you want to do with ethanethiol? may be using it's sodium salt to dealkylate phenol ethers to phenols (eg. eugenol, vanilin, anisaldehyde, etc.)? If so, I'm attaching a paper very instructive about demethylation (dealkylation) where dodecanethiol is used mixed with sodium methoxide, instead the smelly ethanethiol or it's sodium salt, who will give ethylmethyl sulfide as a byproduct (much more smelly).

I think it's a simple method that gives high yields of demethylation products and dodecanethiol is a cheap and affordable reagent sold by Sigma Aldrich, so as sodium methoxide.

Attachment: demethylation and dealkylation of phenol ethers.pdf (88kB)
This file has been downloaded 37 times

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Abromination
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[*] posted on 10-2-2020 at 08:45


Christ almighty, why would you want to make it? I do hope you understand how unbelievably overwhelming the smell will be. It is offensive at reportedly a few parts per billions.
The evacuation of the block isn't a joke.




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clearly_not_atara
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[*] posted on 10-2-2020 at 08:47


I'm pretty sure that the easiest way is to form the Bunte salt with thiosulfate and then subject this to acid hydrolysis, releasing the free thiol. The downside is that producing the thiol by acid hydrolysis means that it will be both volatile and warm, and for semi-obvious reasons many people would prefer to produce the immobilized thiolate or at least make it cold.

A descripton of the hydrolysis can be found here:

https://pubs.acs.org/doi/abs/10.1021/ja00974a039

A much less unpleasant method of production would be to react ethylmagnesium bromide with elemental sulfur in diethyl ether. The thiolate can then be extracted with aqueous KOH, keeping this horrible compound fixed in the condensed phases.

If you just want "a thiol", the above article is attached and describes the facile preparation of benzylthiol from benzyl halides. This is not quite as harmless as dodecylthiol but it is much less awful than ethylthiol.

(And if you just want to demethylate a phenol, may I have a few minutes of your time to discuss our Lord and Savior "Lithium Chloride in DMF?")

Attachment: phpKladrb (762kB)
This file has been downloaded 47 times

[Edited on 10-2-2020 by clearly_not_atara]




[Edited on 04-20-1969 by clearly_not_atara]
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draculic acid69
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[*] posted on 11-2-2020 at 03:35


Please preach to us of the lithium chloride in dmf u speak of.ive heard of lithium iodide breaking bonds of some sort but this sounds more interesting.
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fusso
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[*] posted on 11-2-2020 at 15:53


Cant open phpKladrb file.
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clearly_not_atara
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[*] posted on 11-2-2020 at 16:21


fusso: For some stupid reason SM tells your computer that it is an "application/binary" file but it is in fact a PDF. If you choose a PDF reader from the "Open With" menu, or if you save the file, open a PDF reader, and use the "Open" dialog within the PDF reader to select the file, it should display a PDF. It worked just now when I downloaded it, but I did have to do something weird.

I'm not sure why that happened, exactly.

Quote:
Please preach to us of the lithium chloride in dmf u speak of.ive heard of lithium iodide breaking bonds of some sort but this sounds more interesting.


"LiCl (292 g, 6.89 mol) was added to a solution of eugenol (354 mL, 2.30 mmol) in DMF (3.7 L), and the mixture was refluxed for 44 h, with additional portions of LiCl (292 g, 6.89 mol) being added after 4 h, 22 h and 29 h. The reaction mixture was allowed to cool down to room temp., and diluted with toluene (2 L). The formed precipitate was filtered off and washed with toluene, the washings were combined with the organic solution and concentrated in a rotary evaporator. Silica-gel FC (Et2O/pentane, 1:1,Rf = 0.37) provided 4-allylpyrocatechol(173 g, 50%)."


Attachment: Kraft.Eichenberger.Conception.Characterization.and.Correlation.of.New.Marine.Odorants.pdf (228kB)
This file has been downloaded 33 times





[Edited on 04-20-1969 by clearly_not_atara]
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