# Reduction of Aldehydes and Ketones to Alcohols

## Reduction of Aldehydes and Ketones to Alcohols: Selectivity

Since sodium borohydride is a milder than lithium aluminum hydride, only aldehyde or ketone can be reduced selectively (Luche reduction).

Aldehydes are more reactive, because transition of the $sp2$ hybridized carbonyl carbon to the $sp3$ hybridized alkoxy form is sterically less hindered. Therefore, at low temperatures only the carbonyl group of aldehydes is reduced. Because of the ,+I- effect of the two alkyl groups, the oxygen of the keto carbonyl group is a stronger than that of the aldehyde. The addition of , such as CeCl3 , generates a more stable complex of the ketone carbonyl resulting in a stronger activated keto group.

Fig.1
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