Carboxylic Acids and their Derivatives 2 Question 58
58. Give reasons for the following in one or two sentences.
“Acetic acid can be halogenated in the presence of $\mathrm{P}$ and $\mathrm{Cl}_{2}$, but formic acid cannot be halogenated in the same way.” Why?
(1983, 1M)
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Solution:
- $\mathrm{CH}{3}-\mathrm{COOH}+\mathrm{Cl}{2} \xrightarrow{\text { Red- } \mathrm{P}} \underset{\mathrm{Cl}}{\mathrm{CH}_{2}}-\mathrm{COOH}$ (HVZ reaction)
For this reaction to occur, presence of a $\alpha-\mathrm{H}$ is essential requirement. Formic acid does not has any $\alpha-\mathrm{H}$, fails in HVZ reaction.
