Chemical Forums

Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: asa029 on May 09, 2011, 01:38:38 PM

Title: Removing triethylamine hydrochloride (NET3 HCl) from reaction
Post by: asa029 on May 09, 2011, 01:38:38 PM
One of the biproducts of a reaction is the hydrochloride salt of triethylamine. This must be removed for characterization of the product. Recrystalization is not a good idea (DCM or EtOH) since the compound has similar solubility. I was wondering if anyone knew if the NEt3.HCl could be removed simply by allowing the reaction mixture to wander through a plug of silica?
Title: Re: Removing triethylamine hydrochloride (NET3 HCl) from reaction
Post by: Doc Oc on May 09, 2011, 01:44:55 PM
It depends on how well your compound will run on silica, but yes, Et3N is very stationary in flash chromatography.

However, it's about 100x easier to just wash your product with 1M HCl.  I'm assuming your product doesn't have free amines on it, or else you'll have difficulty running that on a flash column.  But if it doesn't, then just take it up in solvent (ether or EtOAc should be fine) and wash it a couple times with mild HCl, I do that all the time to get rid of amine bases from my crudes.
Title: Re: Removing triethylamine hydrochloride (NET3 HCl) from reaction
Post by: enahs on May 09, 2011, 01:45:36 PM
Also, if your compound is soluble in say THF, well the triethyl amine salt is not, so you can just filter it off.
Title: Re: Removing triethylamine hydrochloride (NET3 HCl) from reaction
Post by: Honclbrif on May 09, 2011, 02:29:32 PM
Or if you compound isn't base labile, you could add some 1M KOH to regenerate the free base, vac off the volatile amine, and extract the organics into solvent
Title: Re: Removing triethylamine hydrochloride (NET3 HCl) from reaction
Post by: Mobius1988 on April 27, 2012, 05:03:05 AM
Hi,

Ive just accidently added like 15 equivs of triethylamine to an SN2 reaction (was supposed to be adding a solvent and picked up the wrong bottle). My product has two amines in it and is normally purified on an aminopropyl modified silica cartridge with flash column chromatography. Will the excess triethylamine run with my product on this and not be removed?

I cant use the HCL trick mentioned above since it will protonate my amines, any other ideas? Will it come off on a rotary evaporator?
Title: Re: Removing triethylamine hydrochloride (NET3 HCl) from reaction
Post by: fledarmus on April 27, 2012, 08:58:49 AM
What is the boiling point of triethylamine and how does it compare to your products?

With no acid to protonate it, triethylamine is pretty volatile.
Title: Re: Removing triethylamine hydrochloride (NET3 HCl) from reaction
Post by: Mobius1988 on April 27, 2012, 11:41:16 AM
The boiling point is 89 degrees C, and my products have very high boiling points so I should be able to vac it off I believe?
Title: Re: Removing triethylamine hydrochloride (NET3 HCl) from reaction
Post by: fledarmus on April 27, 2012, 03:59:55 PM
exactly!  ;D
Title: Re: Removing triethylamine hydrochloride (NET3 HCl) from reaction
Post by: Mobius1988 on April 29, 2012, 11:53:09 AM
Cheers