LiAlH4 on carboxylic acid

May 2013
2
0
I've read that when a carboxylic acid reacts with LiAlH4 it gives two alcohols (just like an ester).

But when I try to think of the mechanism, I get stuck here:

LiAlH4 produces H-, since H- is a strong base it should immediately abstract a proton from carboxylic acid to give the corresponding carboxylate ion (Just like reaction of carboxylic acid with grignard reagent), instead of undergoing nucleophilic addition to give alcohol.

How do I resolve this? Thanks in advance!
 

Unknown008

CHF Hall of Fame
May 2010
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Mauritius
The Li^+ ion substitutes the OH in COOH first. The C=O is then reduced by AlH3 to give an aldehyde. See below:



Another LiAlH4 then reduces the aldehyde to alcohol:


I found the pictures here.
 
May 2013
2
0
Thank you!
So that means LiAlH4 is so strong that it even can reduce the carboxylate ion
 
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