Predict major product 'P': cyclopentyl methyl ketone xrightarrow text (i) HBr, benzoyl peroxide xrightarrow text (ii) KCN xrightarrow text (iii) Na(Hg)/C _2text H _5text OH P:

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NEET Chemistry QUESTION #1103

Question 1

Predict major product 'P': cyclopentyl methyl ketone \(\xrightarrow{\text{(i) HBr, benzoyl peroxide}}\xrightarrow{\text{(ii) KCN}}\xrightarrow{\text{(iii) Na(Hg)/C}_2\text{H}_5\text{OH}}\) P:

Cyclopentyl group with CH\(_3\) and NC substituents
NC–CH(CH\(_3\))–cyclopentyl
Cyclopentane ring with CH\(_3\) and CH\(_2\)NH\(_2\)
Cyclopentane ring with CH\(_3\) and CH\(_2\)NH\(_2\) (exocyclic)✔️

Correct Answer Explanation

(i) HBr with peroxide = anti-Markovnikov addition → CH\(_2\)Br at the end of the methyl chain (allylic/radical). (ii) KCN substitutes Br → –CH\(_2\)CN. (iii) Na(Hg)/EtOH reduces CN → –CH\(_2\)NH\(_2\). Major product: cyclopentyl group bearing –CH\(_3\) transformed to –CH\(_2\)NH\(_2\) substituent = option (4).

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