Question

Benzoic acid to benzoyl chloride conversion is achieved by:

• A. \( \text{Cl}_2, \text{hv} \)
• B. \( \text{SO}_2\text{Cl}_2 \)
• C. \( \text{PCl}_5 \)
• D. \( \text{Cl}_2,\text{H}_2\text{O} \)

Hint:

Phosphorus-based chlorinating agents are effective in converting carboxylic acids into acid chlorides for further synthetic transformations.

Answer 1

The Correct Option is C

Phosphorus pentachloride (PCl\(_5\)) reacts with benzoic acid to form benzoyl chloride via nucleophilic substitution. It replaces the hydroxyl group in benzoic acid with a chloride, yielding benzoyl chloride. This reaction is widely used in acylation and organic synthesis.