19.17: Preparation of Amines: Reduction of Amides and Nitriles
Nitriles can be reduced to primary amines using reducing agents like lithium aluminum hydride or catalytic hydrogenation. The reduction introduces an amino group with an extra carbon in the skeleton. Nitriles are formed from the reaction between alkyl halides and sodium cyanide through the SN2 mechanism. Primary alkyl halides are the preferred substrates to prepare nitriles.
Amides can be reduced to primary, secondary, and tertiary amines using catalytic hydrogenation, active metals like Fe, Zn, Ni, and strong reducing agents like lithium aluminum hydride. The reaction introduces only the amino group without extending the carbon skeleton.
Amide reduction is useful in the last step of monoalkylation of arylamines.