Explain briefly: (a) Carbylamine reaction (b) Gabriel phthalimide synthesis

Aliphatic and aromatic primary amines on heating with chloroform and ethanolic potassium hydroxide form isocyanides or carbylamines which are foul-smelling substances. /\[\mathrm{R}-\mathrm{NH}_2 + \mathrm{CHCl}_3 + 3\,\mathrm{KOH} \xrightarrow{\text{Heat}} \mathrm{R}-\mathrm{NC} + 3\,\mathrm{KCl} + 3\,\mathrm{H}_2\mathrm{O}\]

Isocyanide with an offensive smell is formed.

(Explanation or reaction)

Phthalimide on treatment with ethanolic potassium hydroxide forms potassium salt of phthalimide which on heating with alkyl halide followed by alkaline hydrolysis produces the corresponding primary amine /