Hell-Volhard-Zelinsky Halogenation Reaction

This week in Organic Chemistry, we were assigned to find a piece of literature that has a Hell-Volhard-Zelinsky (HVZ) halogenation and talk about that specific reaction. I found this blog to be the most difficult one yet due to not being able to access most chemistry journal articles without paying a large fee. HVZ is when a carboxylic acid is treated with a tri-halogenated P (PCl3, PBr3, ect.), and this reaction halogenates the alpha carbon of the carboxylic acid. HVZ begins by replacing the OH group of the C.A. with a halogen. Then another halogen is added to the alpha carbon of the C.A. Finally, the original halogen is replaced with an OH group, thus making the molecule a C.A. again. The picture below is the mechanism for an HVZ reaction.

The specific HVZ that I found reacts cyclohexanecarboxylic acid with PCl3 to yield
1-chlorocyclohexanecarboxylic acid. The OH group of the C.A. is replaced with Cl, followed by chlorination of the alpha carbon. Then the molecule undergoes hydrolysis to form the final product. The reactant and product can be seen in example 1 below.

-The High School Chemist


































Sources
http://www.springerlink.com/content/t2ur113r36720270/
http://en.wikipedia.org/wiki/Hell-Volhard-Zelinsky_halogenation