Ketones are reduced to secondary alcohols by sodium borohydride (NaBH4) or lithium aluminum hydride (LiAlH4) as well as by catalytic hydrogenation.
(R−
R
|
C
|
R
−O)4Al−+4H+(aq)→R−
R
|
C
|
H
−OH+Al3+(aq)
Carbonyl carbon of ketones are reduced to −CH2− group in treatment with zinc amalgam and conc. HCl (Clemmensen reduction) or with hydrazine followed by heating with sodium or KOH in high boiling solvent such as ethylene glycol (Wolff-Kishner reduction).