Question

α–halogenation of carboxylic acid is called

• A. Hell–Volhard–Zelinsky reaction
• B. Riemer–Tiemann reaction
• C. Gattermann reaction
• D. Sandmeyer’s reaction

Hint:

HVZ reaction occurs only in carboxylic acids having at least one α–hydrogen.

Answer 1

The Correct Option is A

Step 1: Understand α–halogenation.
α–Halogenation refers to substitution of a hydrogen atom at the α–carbon of a carboxylic acid by a halogen atom.
Step 2: Recall named reactions.
The Hell–Volhard–Zelinsky (HVZ) reaction specifically involves halogenation at the α–position of carboxylic acids in presence of red phosphorus and halogen.
Step 3: Eliminate other options.
Riemer–Tiemann reaction is used for formylation of phenols.
Gattermann reaction introduces –CHO or –CN groups.
Sandmeyer’s reaction replaces diazonium groups with halogens.
Step 4: Conclusion.
α–Halogenation of carboxylic acid is known as the Hell–Volhard–Zelinsky reaction.