Question

Identify A and B in the given chemical reaction sequence : -

• A.
• B.
• C.
• D.

Answer 1

The Correct Option is C

The given sequence involves the following steps:
Step 1: Friedel-Crafts Acylation 
Benzene (\(\text{C}_6\text{H}_6\)) reacts with acetyl chloride (\(\text{CH}_3\text{COCl}\)) in the presence of \(\text{AlCl}_3\), an electrophilic catalyst. This forms acetophenone (\(\text{C}_6\text{H}_5\text{COCH}_3\)) as compound \(A\):
\[\text{C}_6\text{H}_6 + \text{CH}_3\text{COCl} \xrightarrow[\text{AlCl}_3]{} \text{C}_6\text{H}_5\text{COCH}_3 \, (A).\]
Step 2: Clemmensen Reduction
Acetophenone (\(\text{C}_6\text{H}_5\text{COCH}_3\)) undergoes Clemmensen reduction using zinc amalgam (\(\text{Zn–Hg}\)) and hydrochloric acid (\(\text{HCl}\)). The carbonyl group (\(-\text{CO}\)) is reduced to a methylene group (\(-\text{CH}_2-\)), resulting in ethylbenzene (\(\text{C}_6\text{H}_5\text{CH}_2\text{CH}_3\)) as compound \(B\):
\[\text{C}_6\text{H}_5\text{COCH}_3 \xrightarrow[\text{Zn–Hg, HCl}]{} \text{C}_6\text{H}_5\text{CH}_2\text{CH}_3 \, (B).\]
Step 3: Acidic Oxidation
Ethylbenzene reacts with \(\text{H}^+\) under oxidation conditions to form acetophenone again. This completes the reaction cycle.
Final Products:
\(A = \text{C}_6\text{H}_5\text{COCH}_3\) (Acetophenone).
\(B = \text{C}_6\text{H}_5\text{CH}_2\text{CH}_3\) (Ethylbenzene).
Conclusion: The correct identification of \(A\) and \(B\) is given in option \((3)\).
Final Answer: (3).