Which of the following acids, does NOT undergo Hell-Vohlard-Zelinsky reaction?

Which of the following acids, does NOT undergo Hell-Vohlard-Zelinsky reaction?
  1. Butanoic acid
  2. Propanoic acid
  3. Ethanoic acid
  4. Methanoic acid

Solution

Carboxylic acid which contain a – hydrogen atom reacts with chlorine or bromine in presence of red phosphorus to give a – chloro or a – bromo acids. This reaction is called H.V.Z (Hell Volhard Zelinsky ) reaction. CH3COOH ? CCl3COOH(trichloroacetic acid). CH3CH2COOH ? CH3CBr2COOH (a,a-dibromopropionic acid) Due to absence of a – H atom HCOOH does not undergo HVZ reaction.

Asked in: MHT CET 2020 (13 Oct Shift 1)

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