Chapter 19: Carboxylic Acids
a
-Halogenation
(Hell-Volhard-Zelinsky reaction)
Reaction type: Substitution
Summary
Reagents most commonly : Br
2
and either PCl
3
, PBr
3
or red phosphorous in catalytic amounts.
Carboxylic acids can be halogenated at the C adjacent to the carboxyl group.
This reaction depends on the enol type character of carbonyl compounds.
The product of the reaction, an
a-
bromocarboxylic acid can be converted via
substitution reactions
to
a
-hydroxy- or
a
-amino carboxylic acids.
Related Reactions
a-
Halogenation of Aldehydes and Ketones
