91Ó°ÊÓ

The Hell-Volhard-Zelensky reaction is a halogenation reaction and mostly involves the halogenation of carboxylic acid at the alpha carbon. The reagents used are phosphorus tribromide and dibromide.

The introduction of bromine at the position of a carboxylic acid is given by the Hell-Volhard-Zelensky reaction. In the first step of this reaction, a carboxylic acid is transformed into an $\mathrm{Î\pm }$Bromo-acid by using ${\mathrm{Br}}_2$and ${\mathrm{PBr}}_{3\left\{\right\}}$ . The second step of the reaction represents ${\mathrm{Sn}}^2$a reaction in which ammonia replaces bromine.

(a)

The synthesis of glycine by using bromination followed by amination is as shown below:

Formation of glycine

(b)

The synthesis of leucine by using bromination followed by amination is as shown below:

Formation of leucine

(c)

The synthesis of glutamic acid by using bromination followed by amination is as shown below:

Formation of glutamic acid