Question

Alkyl diazonium salts decompose to form carbocations, which go on to form products of substitution, elimination, and (sometimes) rearrangement. Keeping this in mind, draw a stepwise mechanism that forms all of the following products.

Short answer

Any organic reaction involving the reaction of a primary aromatic amine with nitrous acid in the presence of an inorganic mineral acid to form the corresponding diazonium salt and a molecule of water.

This is known as the ‘diazotization reaction.’

Diazotisation reaction

Step-by-step solution

Diazotization reaction

Any organic reaction involving the reaction of a primary aromatic amine with nitrous acid in the presence of an inorganic mineral acid to form the corresponding diazonium salt and a molecule of water.

This is known as the ‘diazotization reaction.’

Diazotisation reaction

Mechanism

a. o-Methylaniline would undergo a diazotization reaction in the presence of nitrous acid and hydrochloric acid to form the diazonium salt. The salt would react with water to form o-cresol.

Formation of o-cresol

b. The 1,2-hydride shift of the cation, followed by the nucleophilic attack of a water molecule and deprotonation, would produce methyl cyclohexanol.

Formation of methylcyclohexanol

c. The deprotonation of the cation would produce methylcyclohexene.

Formation of methylcyclohexene