Write short notes on the following: (i) Coupling reaction (ii) Gabriel phthalimide synthesis

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Coupling Reactions of Arene Diazonium Salts
Arenediazonium ions are weak electrophiles; they react with highly reactive aromatic compounds with phenols and tertiary arylamines to yield azo compound. This electrophilic aromatic substitution is called a diazo coupling reaction occurring mainly at p-position.

Couplings between arenediazonium cations and phenols take place most rapidly in slightly alkaline solution. If the solution is too alkaline (pH > 10), however, the arenediazonium salt itself reacts with hydroxide ion to form a relatively unreactive diazohydroxide or diazotate ion.

Gabriel Phthalimide Synthesis

This method is used for the preparation of primary amines.Phthalimide on treatment with ethanolic potassium hydroxide formspotassium salt of phthalimide which on heating with alkyl halidefollowed by alkaline hydrolysis produces the corresponding primaryamine.