IIT JEE , AIEEE Forum - Chemistry , Organic Chemistry

rash29

What is Hell Vohlard Zelinsky reaction?

shevchenko

halogenation takes place at the alpha carbon to the carboxylic acid in the presence of halogen and red phosphorous

kasirajan.1990

Hell-Volhard-Zelinsky Reaction

Treatment with bromine and a catalytic amount of phosphorus leads to the selective ?-bromination of carboxylic acids.

Mechanism

Phosphorus reacts with bromine to give phosphorus tribromide, and in the first step this converts the carboxylic acid into an acyl bromide.

An acyl bromide can readily exist in the enol form, and this tautomer is rapidly brominated at the ?-carbon. The monobrominated compound is much less nucleophilic, so the reaction stops at this stage. This acyl intermediate compound can undergo bromide exchange with unreacted carboxylic acid via the anhydride, which allows the catalytic cycle to continue until the conversion is complete.

tobeiitian

madmax

@ kasirajan.1990 If U copy some other site's material ,atleast have the courtesy to mention the site's name!!!

OUTRAGEOUS BLASPHEMY BRO!!!

http://www.organic-chemistry.org/namedreactions/hell-volhard-zelinsky-reaction.shtm

People come to Goiit for proper human replies not sites!!

kasirajan.1990

i didnt knw tht we hav to post the source frm were we get the soln in the reply....wld do it in the future mr."madmax" ...n thnx fr mentioning it.

Ask & Discuss Questions with Community & Experts