HVZ Reaction

When a carboxylic acid that contains α - Hydrogen is treated with Cl_2, Br₂  

In the presence of phosphorus, th e α - Hydrogen atoms are replaced by chlorine or bromine atoms. this reaction is known as "Hell-Volhard-Zelinsky or HVZ Reaction"

 α- Hydrogenated acids are convenient starting materials for preparing other α- Substituted acids.

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