Vinylcyclohexane, $CH X_{2} = CH - C X_{6} H X_{11}$ (cyclohexyl group attached to the vinyl), reacts with HBr in the absence of peroxide. Assume the free carbocation rearranges completely before bromide captures it. The major product is:

A1-bromo-1-ethylcyclohexane
B(2-bromoethyl)cyclohexane
C1-bromo-2-ethylcyclohexane
D(1-bromoethyl)cyclohexane

Answer: A

Proton addition gives the secondary 1-cyclohexylethyl cation. A hydride on the ring carbon next to it shifts, giving the tertiary 1-ethylcyclohexyl cation. Bromide capture gives 1-bromo-1-ethylcyclohexane.

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Vinylcyclohexane, CHX2​=CH−CX6​HX11​ (cyclohexyl group attached to the vinyl), reacts with HBr in the absence of peroxide. Assume the free carbocation rearranges completely before bromide captures it. The major product is:

Answer: A

More questions on Carbocations: formation, stability, rearrangements

Vinylcyclohexane, $CH X_{2} = CH - C X_{6} H X_{11}$ (cyclohexyl group attached to the vinyl), reacts with HBr in the absence of peroxide. Assume the free carbocation rearranges completely before bromide captures it. The major product is: