A reaction for making primary amines from amines using bromine or chlorine and sodium hydroxide:RCONH2 → RNH2 The halogen replaces a hydrogen atom from the amido group to form a halo-amide. This then reacts with the alkali to produce an isocyanate, which decomposes into the amine and carbon dioxide. The amine has one carbon atom fewer than the amide from which it is produced. This technique is used to reduce the length of carbon chains in molescules (the Hofmann degradation). The reaction is named after the German chemist August Wilhelm von Hofmann (1818–92).
RCONH2 → RNH2