Carbonyl reduction

In organic chemistry, carbonyl reduction is the conversion of any carbonyl group, usually to an alcohol. It is a common transformation that is practiced in many ways.^[1] Ketones, aldehydes, carboxylic acids, esters, amides, and acid halides - some of the most pervasive functional groups, -comprise carbonyl compounds. Carboxylic acids, esters, and acid halides can be reduced to either aldehydes or a step further to primary alcohols, depending on the strength of the reducing agent. Aldehydes and ketones can be reduced respectively to primary and secondary alcohols. In deoxygenation, the alcohol group can be further reduced and removed altogether by replacement with H.

Two broad strategies exist for carbonyl reduction. One method, which is favored in industry, uses hydrogen as the reductant. This approach is called hydrogenation and requires metal catalysts. The other broad approach employs stoichiometric reagents that deliver H^- and H⁺ separately. This article focuses on the use of these reagents. Prominent among these reagents are the alkali metal salts of borohydrides and aluminium hydrides.