Cyanides when reduced by means of stannous chloride* and hydrochloric acid in absolute ether followed by hydrolysis yield aldehydes. This reaction is known as Stephen reduction.
\(\underset {Methyl\,eyanide}{CH_3.C \equiv \\}+2H \xrightarrow[HCl]{SnCl_2} \underset {Aldimine}{CH_3CH\\}=NH\)
\(\xrightarrow {H_2O} \underset {Acetaldehyde}{CH_3CHO\\}+NH_3\)
Ketones cannot be prepared by this method.
