The Hell Volhard Zelinsky reaction demonstrates a method for alpha addition with a carboxylic acid. The gist of the method is to convert the. Carboxylic acids can be brominated in the alpha position with a mixture of Br2 and PBr3 in a reaction called the Hell-Volhard-Zelinskii reaction. The classical method to convert carboxylic acids into α-haloacyl halides using phosphorus(III) halide is known as the Hell-Volhard-Zelinsky.

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Chemistry Stack Exchange works best with JavaScript enabled. The mechanism for the exchange between an alkanoyl bromide and a carboxylic acid is below. The reaction is initiated by addition of a catalytic amount hhell-volhard-zelinsky PBr 3after which one molar equivalent of Br 2 is added. The users who voted to close gave this specific reason: Home Questions Tags Users Unanswered.


Ch Halogenation

Reason behind conversion of acid to acid bromide in Hell-Volhard-Zelinsky reaction [closed] Ask Question. For help asking a good homework question, see: This question appears to be off-topic.

The phosphorus halides form the acyl halides readily because phosphorus has a huge affinity for oxygen. If an aqueous solution is desirable, a full molar equivalent of PBr 3 must be used as the catalytic chain is disrupted.

Hell-Volhard-Zelinsky Reaction – ChemistryScore

Substitution reactions Halogenation reactions Name reactions. PBr 3 replaces the carboxylic OH with a bromide, resulting in a carboxylic acid bromide. Unlike other halogenation reactions, this reaction takes place in the absence of a halogen carrier.

Sometimes, phosphorus tribromide is not hell-volhard-zelinskh to form the acyl halide but, since there is also bromine in the media, phosphorus pentabromide is formed which can form acyl halides even of solid acids.

How do you think the alpha-bromine is incorporated into the acyl bromide? From Wikipedia, the free encyclopedia.

Hell-Volhard-Zelinsky reaction

Raoul Kessels 3, 2 However, I hope it will serve others as well. Views Read Edit View history. Google is your friend!


The reaction is named after three chemists, the German chemists Carl Magnus von Hell — and Jacob Volhard — and the Russian chemist Nikolay Zelinsky — In other projects Wikimedia Commons. This page was last edited on 29 Augustat By using this site, you agree to the Terms of Use and Privacy Hell-volhard-zelijsky.

In practice a molar equivalent of PBr 3 is often used anyway to overcome the slow reaction hell-volhard-zelinsmy. How do I ask homework questions on Chemistry Stack Exchange? This was a question where AJ needed to make some effort in offering a solution.

Acyl halides lack the carboxylic acid hydrogen.