From carbonyl compounds
(i) By reduction of aldehydes and ketones: Aldehydes and ketones
are reduced to the corresponding alcohols by addition of
hydrogen in the presence of catalysts (catalytic hydrogenation) The usual catalyst is a finely divided metal such as platinum,
palladium or nickel It is also prepared by treating aldehydes
and ketones with sodium borohydride (NaBH4) or lithium
aluminium hydride (LiAlH4) Aldehydes yield primary alcohols
whereas ketones give secondary alcohols