Question

Reaction of HBr with 3-methylcyclohexene yields a mixture of four products cis-and trans-1-bromo-3-methylcyclohexane and cis-and trans-1-bromo-2-methylcyclohexane. The analogous reaction of HBr with 3-bromocyclohexene yields trans-1,2-dibromocyclohexane as the soul product.
Required:
Draw structures of the possible intermediates and mechanismfor the latter reaction.

Answer 1

Answer:

See explanation

Explanation:

The mechanism of this reaction including intermediates are shown in the image attached to this answer.

The reaction of  HBr with 3-bromocyclohexene yields trans-1,2-dibromocyclohexane as the sole product because; the proton first attacks the  3-bromocyclohexene  and a brominium ion is formed. This brominium ion is a cyclic intermediate as shown in the image attached.

Attack of a bromine ion afterwards must lead to the formation of trans-1,2-dibromocyclohexane as shown.