Question

What will happen if I heat a solution of 1-bromo-1,2-dimethylcyclohexane in methanol?

Answer 1

The organic products are 1-methoxy-1,2-dimethylcyclohexane and 1,2-dimethylcyclohexene.

Explanation:

The structure of 1-bromo-1,2-dimethylcyclohexane is

This is a 3° alkyl halide, so the mechanistic possibilities are `"S"_"N"1` and `"E1"`.

I predict a mixture of both, with the `"S"_"N"1` being the major product at low temperatures.

The first step is loss of the bromine atom to form the tertiary carbocation.

Then the methanol can attack the carbocation to form 1-methoxy-1,2-dimethylcyclohexane.

As an alternative, methanol could act as a base and remove an α-hydrogen in an `"E1"` elimination to form 1,2-dimethylcyclohexene.

At higher temperatures, more molecules will have enough energy to get over the activation energy barrier for elimination, so the proportion of the cyclohexene product will increase.