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JEE Main levelSingle correct optionDifficulty 2 of 3o2188

Vinylcyclohexane ( $CH X_{2} = CH - C X_{6} H X_{11}$ , a cyclohexane ring carrying a vinyl group) reacts with $HBr$ without peroxide. The major product is

A(1-bromoethyl)cyclohexane
B1-bromo-1-ethylcyclohexane
C1-bromo-2-ethylcyclohexane
D(2-bromoethyl)cyclohexane

Answer: B

Protonation gives the secondary cation

C X_{6} H X_{11} - CH X^{+} - CH X_{3}

. A 1,2-hydride shift from the ring carbon gives the tertiary 1-ethylcyclohexyl cation. Bromide adds to give 1-bromo-1-ethylcyclohexane.

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