Question

Two different compounds having the molecular formula $C_8{H}_{15}Br$ are formed when $1,6-$dimethylcyclohexene reacts with hydrogen bromide in the dark and in the absence of peroxides. The same two compounds are formed from $1,2-$dimethylcyclohexene. What are these compounds?

Answer 1

The two compounds are (1R,2R)-1-bromo-1,2-dimethylcyclohexane and (1R,2S)-1-bromo-1,2-dimethylcyclohexane. These can be obtained by the addition of a molecule of HBr to carbon carbon double bond in 1,2-dimethylcyclohexene.
They can also be obtained by the addition of a molecule of HBr to carbon carbon double bond in 1,6-dimethylcyclohexene. However this involves rearrangement.