Explain the following ructions :
(a) Gabriel Phthalimide reaction
(b) Coupling reaction

Explanation

Gabriel.1 phthalimide synthesis : Phthalimide when treated with alcoholic potassium hydroxide is easily converted into potassium phthalimide which on treatment with alkyl halide followed by hydrolysis with acid or alkali yields phthalic add and a primary amine.

(b) Coupling reaction : It involves the reaction of bezene diazonium salts with phendols or aryl amines. Coupling of phenol takes place in mild alkaline solution while with aromatic `1^(@)` amines in mild acidic medium.