The Hell-Volhard-Zilinsky Halogenation is a reaction in which the alpha carbon of a carboxylic acid is halogenated. This reaction is catalyzed by a necessary amount of PBr2, which replaces the OH, thus forming an acid bromide. The acyl bromide then tauteramerizes to form an enol. A molar amount of Br2 is also added, which bonds to the alpha carbon. This reaction differs from other halogenations in that it does not include a halogen carrier. The general reaction scheme of a Hell-Volhard-Zelinsky Halogenation is illustrated below.
A reaction involving the Hell-Volhard-Zelinsky Halogenation is the synthesis of 2-bromobutanoic acid, also called 2-bromobutyric acid, from butanoic acid.
Formula: C4H7BrO2
Molecular Weight: 167 g/mol
Melting point: -4 deg C
Boiling point 101 deg C
A reaction scheme of this reaction is illustrated below.
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