Uses of Nucleophilic Substitution

Nucleophilic substitution is useful in organic synthesis because it swaps the halogen for a new functional group. Halogenoalkanes are therefore important intermediates in making other compounds.Warm aqueous hydroxide ions turn halogenoalkanes into alcohols. Alcohols are used as solvents and fuels, and can be oxidised to aldehydes, ketones and carboxylic acids.Cyanide ions turn halogenoalkanes into nitriles. This adds one carbon atom to the chain, which is one of the few ways to lengthen a carbon chain. Nitriles can then be converted into other compounds such as amines and carboxylic acids.Excess ammonia turns halogenoalkanes into amines. Amines are used to make dyes and pharmaceuticals.To plan a route, choose the nucleophile that provides the group you need, for example CN^- to make butanenitrile from 1-bromopropane.