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Author: Subject: Thiol preperation with Thiourea
Picric-A
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[*] posted on 23-12-2010 at 10:12
Thiol preperation with Thiourea


I am attempting to make n-propanethiol from n-propylbromide with thiourea according to vogel.

I do not have a magnetic stirrer so i am relying on the boiling to mix the biphase enough however after 2 hours the biphase has not formed a single phase as vogel says should happen after 30mins.

Has anybody had any experience with this procedure and if so why is my procedure not working?
Thanks,
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DJF90
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[*] posted on 24-12-2010 at 09:20


You changed the procedure and it didn't work. Am I suprised? No. Try following the instructions next time (i.e. use stirring), or just be thankful you didn't succeed. Thiols are notoriously smelly, especially the lower chain alkyls. Also worth bearing in mind that thiourea is itself carcinogenic; Many people don't realise that.
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[*] posted on 24-12-2010 at 11:59


After leaving it, cold overnight, i proceeded with the alkaline hydrolysis with NaOH(aq) and from around 20ml of 1-bromopropane i got just 5ml of propanethiol, however i did not acidify the aqeous phase and so a fair amount of product is present as the thiolate. I only needed 3ml and so i have plenty.

All glassware is now soaking in bleach, rendering it odourless.
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[*] posted on 26-12-2010 at 06:06


I tried ethanethiol a few weeks ago, just a single drop of EtBr in a huge excess of thiourea, then NaOH soln was added and it was boiled. No smell was noticed until it was boiling, then it stunk! so I wouldn't worry if the alkyl bromide isn't reacting with the thiourea straight away, it should get started once the NaOH is added and it's boiling.
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