April 20, 2024, 04:22:32 AM
Forum Rules: Read This Before Posting


Topic: Problem by the conversion of an ester to an alcohol by LiAlH4  (Read 2112 times)

0 Members and 1 Guest are viewing this topic.

Offline makkes

  • Very New Member
  • *
  • Posts: 1
  • Mole Snacks: +0/-0
Problem by the conversion of an ester to an alcohol by LiAlH4
« on: October 06, 2017, 03:09:38 PM »
Best chemist,

I'm currently doing research to self-healing polymers at NovAM (TU Delft). The reaction I did was a conversion of a di-ester (diethyl malonate) to a di-alcohol with AlLiH4 as catalyst (in THF). During my reaction (after 24h) I took a TLC and I saw 1 concentrated spot and 2 very small spots who were hard to see. I decided to work-up my reaction by quenching with water follows by the addition of 10% H2SO4 to dissolve the salts. After extraction I took another TLC and saw 2 bright spots and the two small spots. I'am really wondering what the second bright spot could be and I hope that someone can tell me what it could be.



This reaction is used to be a simple reaction, because ethanol is the only by-product. LAH is the strongest catalyst for this reaction, so I don't understand why there is a second product in nearly the same concentration as the major product.

I hope you can help me out!

Max Wempe

Offline phth

  • Chemist
  • Full Member
  • *
  • Posts: 528
  • Mole Snacks: +39/-4
Re: Problem by the conversion of an ester to an alcohol by LiAlH4
« Reply #1 on: October 06, 2017, 10:21:23 PM »
What is a catalyst: something consumed or preserved after a reaction?

Offline OrganicDan96

  • Full Member
  • ****
  • Posts: 268
  • Mole Snacks: +20/-1
Re: Problem by the conversion of an ester to an alcohol by LiAlH4
« Reply #2 on: October 11, 2017, 01:43:51 PM »
have you got an NMR, what is the structure?, I have heard of LiAlH4 reductions failing due to Li coordinating with the molecule (such is true with crown ethers), if possible you could consider using diisobutyl aluminium hydride in excess.

Offline clarkstill

  • Chemist
  • Full Member
  • *
  • Posts: 477
  • Mole Snacks: +77/-4
Re: Problem by the conversion of an ester to an alcohol by LiAlH4
« Reply #3 on: October 12, 2017, 05:45:53 AM »
I guess you might also worry about E1cb elimination of the beta-hydroxy ester intermediate? Or retro-aldol to give ethyl acetate and formaldehyde?

Sponsored Links