Concept:Phosphorus pentachloride (\( \text{PCl}_5 \)) is a strong chlorinating agent that substitutes the hydroxyl (\(-\text{OH}\)) group of a carboxylic acid with a chlorine atom to form an acid chloride.
Formula:$$ \text{CH}_3\text{COOH} + \text{PCl}_5 \longrightarrow \text{CH}_3\text{COCl} + \text{POCl}_3 + \text{HCl} $$
Solution:- The \(-\text{OH}\) group in acetic acid is replaced by \(-\text{Cl}\), yielding acetyl chloride (\( \text{CH}_3\text{COCl} \)).
- The byproducts of this substitution are phosphorus oxychloride (\( \text{POCl}_3 \)) and hydrogen chloride (\( \text{HCl} \)).
Why other options are incorrect:Option A has an incorrect byproduct (\(\text{POCl}_2\)). Option B suggests cleavage of the C-C bond (forming methyl chloride), which does not happen. Option D lists \(\text{H}_2\) gas instead of \(\text{HCl}\).
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