Question

Write chemical equations to illustrate the following named reaction:

Hell-Volhard-Zelinsky reaction

Answer 1

Carboxylic acids react with chlorine or bromine in the presence of (red) phosphorus to give compounds in which the α-hydrogen atom is replaced by a halogen atom.

\[\ce{\underset{Acetic Acid}{CH3COOH} + Cl2 ->[Red P][H2O] \underset{Chloroacetic acid}{ClCH2 - COOH} + HCl}\]

\[\ce{ClCH2COOH + Cl2 ->[Red P][H2O] \underset{Dichloroacetic acid}{Cl2CHCOOH + HCl}}\]

\[\ce{Cl2CHCOOH + Cl2 ->[Red P][H2O] \underset{Trichloroacetic acid}{Cl3CCOOH + HCl}}\]