Chemical Forums

Please login or register.

Login with username, password and session length

Sponsored links

Pages: [1]   Go Down

Author Topic: Washing NaH (60% suspension in mineral oil)  (Read 1356 times)

0 Members and 1 Guest are viewing this topic.

ocvihwer

  • Very New Member
  • *
  • Mole Snacks: +0/-0
  • Offline Offline
  • Posts: 2
Washing NaH (60% suspension in mineral oil)
« on: December 09, 2016, 05:54:20 AM »

Background: I'm working on a Wittig reaction and I'm using NaH (60% suspension in mineral oil) to deprotonate

My product is very nonpolar and the grease in NaH might be a problem for workup. So I tried to use freshly distilled THF to wash away the grease. I add some THF to NaH/oil suspension and removed the liquid, hoping that THF will dissolve the grease away.

However, I cannot remove all the THF from the NaH solid. I decided to just leave it in there and added DMSO anyway.

Question:

Will the residual THF pose any potential problem?

Thanks!
Logged

rolnor

  • Full Member
  • ****
  • Mole Snacks: +21/-3
  • Offline Offline
  • Posts: 252
Re: Washing NaH (60% suspension in mineral oil)
« Reply #1 on: December 09, 2016, 09:06:49 AM »

I have worked with methylenetriphenylphosphorane and that reagent was in the original paper made with NaH/DMSO. I found that it can be generated with n-BuLi/THF instead wich I find more convenient.
To answer your question, no, THF will not be a problem.
Logged

Dan

  • Global Moderator
  • Sr. Member
  • ***
  • Mole Snacks: +465/-72
  • Offline Offline
  • Gender: Male
  • Posts: 4718
  • Organic Chemist
    • My research
Re: Washing NaH (60% suspension in mineral oil)
« Reply #2 on: December 09, 2016, 09:28:25 PM »

Absolutely agree. DMSO is a total hassle, BuLi or tBuOK in THF is much more convenient.
Logged
My research: Google Scholar and Researchgate

RedViper9

  • Regular Member
  • ***
  • Mole Snacks: +0/-0
  • Offline Offline
  • Posts: 9
  • Organic Chemist
Re: Washing NaH (60% suspension in mineral oil)
« Reply #3 on: January 20, 2017, 09:08:07 PM »

Assuming your THF is dry, it should not be a problem (See Williams and Lawton JOC, 2010, 8351.); however, I've always triturated NaH with dry hexane or dry pentane (very flammable!) since the trace solvent is inert and is easily removed after the reaction.
Logged

pgk

  • Full Member
  • ****
  • Mole Snacks: +49/-18
  • Offline Offline
  • Posts: 463
Re: Washing NaH (60% suspension in mineral oil)
« Reply #4 on: January 21, 2017, 07:21:58 AM »

I have used NaH (from mineral oil suspension) in diethyl ether, as a reaction medium. I have got better yields by preliminary washing NaH with petroleum ether (anhydrous, by keeping  over molecular sieves 3-4 Å), followed by washing with diethyl ether than washing with diethyl ether, only.
Logged

discodermolide

  • Chemist
  • Sr. Member
  • *
  • Mole Snacks: +404/-70
  • Offline Offline
  • Gender: Male
  • Posts: 5038
    • My research history
Re: Washing NaH (60% suspension in mineral oil)
« Reply #5 on: January 21, 2017, 09:20:33 AM »

You used to be able to buy 100% NaH from Aldrich.
Logged
Development Chemists do it on Scale, Research Chemists just do it!
My Research History

RedViper9

  • Regular Member
  • ***
  • Mole Snacks: +0/-0
  • Offline Offline
  • Posts: 9
  • Organic Chemist
Re: Washing NaH (60% suspension in mineral oil)
« Reply #6 on: January 21, 2017, 09:51:53 AM »

You used to be able to buy 100% NaH from Aldrich.

Is this similar to 60% H2O2? I expect in both cases Sigma would be happy to sell it to you, but the DoT won't ship it.

On a side note, has anyone used the KH suspended in a solid wax block?
Logged
Pages: [1]   Go Up
 

Mitch Andre Garcia's Chemical Forums 2003-Present.

Page created in 0.065 seconds with 25 queries.