Explain the Hoffmann bromamide degradation reaction.

Hoffmann developed a method for the preparation of primary amines by treating an amide with bromine in an aqueous or ethanolic solution of sodium hydroxide.
In this degradation reaction,migration of an alkyl or aryl group takes place from the carbonyl carbon of the amide to the nitrogen atom.
The amine so formed contains one carbon atom less than that present in the amide.
The general reaction is:
$R-CONH_2 + Br_2 + 4NaOH \rightarrow R-NH_2 + Na_2CO_3 + 2NaBr + 2H_2O$
Example:
$CH_3CONH_2 + Br_2 + 4NaOH \rightarrow CH_3NH_2 + Na_2CO_3 + 2NaBr + 2H_2O$
(Ethanamide to Methanamine)