Question

Which among the following does NOT undergo Williamson's synthesis?

• A. \(\text{C}_2\text{H}_5\text{Br}\)
• B.

  

• C. \(\text{C}_6\text{H}_5-\text{Br}\)
• D. \(\text{C}_6\text{H}_5-\text{CH}_2-\text{Br}\)

Hint:

Williamson synthesis needs an alkyl halide that can undergo SN2; aryl halides cannot.

Answer 1

The Correct Option is C

Step 1: What the reaction needs:
A carbon bonded to the halogen that is sp3 hybridised and open to backside attack.

Step 2: Test each halide:
Ethyl bromide, isobutyl bromide (the figure shows $\text{CH}_3\text{-CH(CH}_3)\text{-CH}_2\text{-Br}$) and benzyl bromide all have sp3 carbons bearing Br. Bromobenzene has the halogen on an sp2 ring carbon, so it is unreactive. Answer (C).

Final Answer:
Bromobenzene. \[ \boxed{\text{(C)}} \]