Hell–Volhard–Zelinsky halogenation
The Hell–Volhard–Zelinsky halogenation reaction is a chemical transformation that involves the halogenation of a carboxylic acid at the α carbon. For this reaction to occur the α carbon must bear at least one proton. The reaction is named after the German chemists Carl Magnus von Hell (1849–1926) and Jacob Volhard (1834–1910) and the Russian chemist Nikolay Zelinsky (1861–1953).
| Hell–Volhard–Zelinsky halogenation | |
|---|---|
| Named after | Carl Magnus von Hell Jacob Volhard Nikolay Zelinsky |
| Reaction type | Substitution reaction |
| Identifiers | |
| Organic Chemistry Portal | hell-volhard-zelinsky-reaction |
An example of the Hell–Volhard–Zelinsky reaction can be seen in the preparation of alanine from propionic acid. In the first step, a combination of bromine and phosphorus tribromide (catalyst) is used in the Hell–Volhard–Zelinsky reaction to prepare 2-bromopropanoic acid, which in the second step is converted to a racemic mixture of the amino acid product by ammonolysis.