Question

An alkene ‘X’ (C\(_4\)H\(_8\)) does not exhibit cis/trans isomerism. Reaction of ‘X’ with Br\(_2\)/CCL\(_4\), followed by reaction with reagent ‘Y’ gave ‘Z’ (C\(_6\)H\(_6\)). What are ‘Y’ and ‘Z’ respectively?

• A. aq.KOH ; CH\(_3\)CH\(_2\)C = CH
• B. alc.KOH ; CH\(_3\)C = CCH\(_3\)
• C. (i) alc.KOH, (ii) NaNH\(_2\) ; CH\(_3\)CH\(_2\)C = CH
• D. (i) alc.KOH, (ii) NaNH\(_2\) ; CH\(_3\)C = CCH\(_3\)

Hint:

Dehydrohalogenation reactions with NaNH\(_2\) lead to the formation of alkynes from vicinal dibromides.

Answer 1

The Correct Option is C

The reaction of ‘X’ with Br\(_2\)/CCL\(_4\) produces a vicinal dibromide. The subsequent treatment with alcoholic KOH causes elimination to form an alkene, which can undergo dehydrohalogenation with NaNH\(_2\) to give the required alkyne. Thus, the answer is (i) alc.KOH and (ii) NaNH\(_2\).