What is HVZ reaction ? Give equation.

Explanation

Carboxylic acids having `alpha`-hydrogens or halogenated at the `alpha`-position on treatment with chlorine or bromine in presnce of small amount of red phosphorus to give `alpha`-halo carboyxlic acids.
This reaction is named as Hell-Volhard-Zelinsky (HVZ) reactions.
`R-CH_(2)-COOH underset("i)"H_(2)O)overset("i)"x_(2)//"Red" 'p')to R-CH-COOH`
`" "X`
`" "X=Cl, B r`
`" "alpha`-Halo Carboxylic acid