Illustrate the following reactions:
(a) Hoffmann Bromamide degradation reaction.
(b) Coupling reaction.
(a) When an amide is made to react with bromine in the presence of aqueous or alcoholic solution of sodium hydroxide, the resulting product obtained is an amine with one carbon atom less as compared to the total number of carbon atoms present in the parent hydrocarbon. This reaction is termed as Hoffman’s Bromamide Degradation Reaction. The generalized reaction is as follows:
In the reaction R represent an alkyl group.
(b) The reaction which involves the joining of the two aromatic compounds with the help of –N=N- bonds to form diazonium compounds is called as coupling reaction. This reaction results in the formation of diazonium salts which on reacting with phenols or aromatic amines form coloured azo compounds. This reaction proceeds in forward direction through the mechanism of electrophilic substitution. The reaction is as follows:
