Sciencemadness Discussion Board

Solvents for acid/base workups of amines?

horribilis - 20-1-2020 at 15:26

What is a suitable and accessible solvent for acid/base workups of amines in general? DCM is the gold standard, I imagine, but it's no longer legal in my country. Diethyl ether and ethyl acetate would both undergo hydrolysis in strongly alkaline solutions, I think.

Would chloroform work? My only concern is the isocyanide reaction on primary amines, but I can't find much information on this.

Obviously something like toluene would work and be pretty much inert to strongly basic solutions, and it is easy to obtain, but I'd like to avoid high boiling point solvents as much as possible. Maybe toluene for initial extractions and chloroform for takeup of acidic washes followed by evaporation of chloroform to yield the amine? Would that risk the isocyanide reaction?

[Edited on 20-1-2020 by horribilis]

UC235 - 20-1-2020 at 16:38

Ether does not undergo hydrolysis and would be fine.

monolithic - 20-1-2020 at 17:02

I've used chloroform on tertiary amines, worked great. No clue about primary amines.

Quote: Originally posted by UC235  
Ether does not undergo hydrolysis and would be fine.

Isn't it risky to evaporate to dryness (well, to yield the freebase amine) in an amateur setting? Peroxides and such.

draculic acid69 - 21-1-2020 at 00:08

You should test the ether for peroxide before using it.if your going to store,possess,use or make ethers learning how to test for and destroy
peroxides is something that shouldn't be skipped.

Amos - 21-1-2020 at 07:38

If you are fine with the idea of obtaining your amines as pure hydrochloride salts, which usually provides much easier handling, ether, xylenes, and toluene all work fine. A stream of HCl gas can simply be passed in to crystallize these out. There may be some variability as to the solubility of these salts in that group of solvents.

[Edited on 1-21-2020 by Amos]