Reduction of Esters via Aldehydes to Alcohols
Reduction of Esters to Alcohols via Aldehydes: Laboratory Application
Lithium aluminum hydride (LAH) and DIBAL (Diisobutylaluminumhydride) are the most frequently used reagents for the reduction of carboxylic esters to alcohols. Sodium borohydride, a much milder reducing agent, reduces aldehydes and ketones only .
The disadvantage of DIBAL is its high price and the fact that only one hydride ion is being transferred. Therefore, the reduction of "simple" carboxylic esters is preferentially carried out with lithium aluminum hydride.
The hydrolysis of lithium aluminum hydride reaction mixtures yields voluminous and difficult to filter precipitates. The isolation of the desired alcohols requires dissolving these precipitates in aqueous acids or bases.