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Write short note on the following : (i) Carbylamine reaction (ii) Diazotization (iii) Hoffmann's bromide reaction (iv) Coupling reaction |
Answer» Solution :(i) CARBYLAMINE reaction : When primary amine(aromatic of aliphatic) warned with chloroform and alc. KOH, isocyanides are formed which can be identified by their OFFENSIVE smell. This test is used to identifythe presence of primary amine or chloroform  . (ii) Diazotization : When primary aromatic amine is treated with `NaNO_(2)` and HCI at 273-278 K, diazonium salt is obtained. This reaction is known as diazotization. Benzenediazonium chloride is a very important synthetic compound, which can be changed into heloarenes, phenol, cyanobenzene, BENZENE etc.  (III) Hoffmann.s bromide reaction : When any primary amide (alphatic or aromatic) is treated with bromine and alkali, it gives the amine with one less carbon atom.  This reaction is used to reduce one carbon atom from a compound. ## (iv) COUPLING reaction : When benzenediazonium chloride is treated with phenols or aromatic amines, azo dyes are produced in which diazo `(-N = N-)` group is retained. Coupling reactions generally take place at p-position of phenol or aromatic amines.  (v) Ammonolysis : Reaction of alkyl halides with ammonia is known as ammonolysis. Ammonolysis generally gives the mixture of `1^(@), 2^(@), 3^(@)` amines and quaternary ammonium salt. 
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