Illustrated Glossary of Organic Chemistry

Hell-Volhard-Zelinsky reaction: A reaction between a carboxylic acid and PBr3 (or Br2 with PBr3 catalyst) resulting in the corresponding alpha-bromocarboxylic acid.

In this sample Hell-Volhard-Zelinsky reaction, phenylacetic acid is reacted with PBr3 to produce 2-bromo-2-phenylacetic acid.