Which of the following will not undergo Hell-Volhard-Zelinsky reaction

Options

(a) Acetic acid
(b) Formic acid
(c) Propionic acid
(d) 2-Methyl propionic acid

Correct Answer:

Formic acid

Explanation:

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