August 10, 2022, 07:00:55 AM
Forum Rules: Read This Before Posting


Topic: Removing triethylamine hydrochloride (NET3 HCl) from reaction  (Read 35063 times)

0 Members and 1 Guest are viewing this topic.

Offline asa029

  • Regular Member
  • ***
  • Posts: 64
  • Mole Snacks: +1/-0
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?

Offline Doc Oc

  • Chemist
  • Full Member
  • *
  • Posts: 564
  • Mole Snacks: +48/-12
Re: Removing triethylamine hydrochloride (NET3 HCl) from reaction
« Reply #1 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.

Offline enahs

  • 16-92-15-68 32-7-53-92-16
  • Retired Staff
  • Sr. Member
  • *
  • Posts: 2179
  • Mole Snacks: +206/-44
  • Gender: Male
Re: Removing triethylamine hydrochloride (NET3 HCl) from reaction
« Reply #2 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.

Offline Honclbrif

  • Chemist
  • Full Member
  • *
  • Posts: 659
  • Mole Snacks: +58/-10
  • Gender: Male
Re: Removing triethylamine hydrochloride (NET3 HCl) from reaction
« Reply #3 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
Individual results may vary

Offline Mobius1988

  • Regular Member
  • ***
  • Posts: 38
  • Mole Snacks: +2/-0
Re: Removing triethylamine hydrochloride (NET3 HCl) from reaction
« Reply #4 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?

Offline fledarmus

  • Chemist
  • Sr. Member
  • *
  • Posts: 1676
  • Mole Snacks: +203/-28
Re: Removing triethylamine hydrochloride (NET3 HCl) from reaction
« Reply #5 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.

Offline Mobius1988

  • Regular Member
  • ***
  • Posts: 38
  • Mole Snacks: +2/-0
Re: Removing triethylamine hydrochloride (NET3 HCl) from reaction
« Reply #6 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?

Offline fledarmus

  • Chemist
  • Sr. Member
  • *
  • Posts: 1676
  • Mole Snacks: +203/-28
Re: Removing triethylamine hydrochloride (NET3 HCl) from reaction
« Reply #7 on: April 27, 2012, 03:59:55 PM »
exactly!  ;D

Offline Mobius1988

  • Regular Member
  • ***
  • Posts: 38
  • Mole Snacks: +2/-0
Re: Removing triethylamine hydrochloride (NET3 HCl) from reaction
« Reply #8 on: April 29, 2012, 11:53:09 AM »
Cheers

Sponsored Links