Preparation
The nitrile function can easily be introduced by reaction of cyanide, either by substitution or addition.
Nucleophilic substitution
The substitution of a good leaving group by cyanide is a simple and general reaction to get nitriles.
Click here to remember the competition between substitution and elimination.
Displacement of diazonium salts
Diazonium salts are prepared by the action of nitrous acid on anilines.
With copper(I) cyanide, the diazonium group is replaced by CN: this is the Sandmeyer reaction.
Cyanide addition to aldehydes and ketones
The perhaps simplest carbon nucleophile, cyanide, adds to aldehydes and ketones to render cyanohydrins.
Conjugate addition to α,β-Unsaturated compounds
Cyanide adds to α,β-unsaturated aldehydes, ketones, esters, amides, etc in a totally conjugated manner (Michael addition).
Aldoxime dehydration
Aldoximes are obtained by reaction of hydroxylamine with aldehydes. Their dehydration with a dehydrating agent such as an anhydride leads to a nitrile.
Amide dehydration
Primary amides can be dehydrated with strong dehydrating agents like phosphorus pentoxide yielding nitriles.
