Question

Compound a reacts with one equivalent of h2 in the presence of a catalyst to give methylcyclohexane. Compound a can be formed upon treatment of 1-bromo-1-methylcyclohexane with sodium methoxide. What is the structure of compound a?

Answer 1

Answer:

The compound a is 1-methyl cyclohexene (see attachment for structure).

Explanation:

The reaction of 1-Bromo-1-methylcyclohexane with sodium methoxide is a second-order reaction since the methoxide ion is a strong base and also a strong nucleophile. This ion attacks the alkyl halide faster than the alkyl halide can ionize to produce a first-order reaction. However, we can not see the product of nucleophilic substitution. The SN₂ mechanism is blocked due to the impediment of the 1-Bromo-1-methylcyclohexane. The main product, according to the Zaitsev rule, is the 1-methyl cyclohexene, thus forming a double bond.

Then, this cyclohexene is hydrogenated to form the cyclohexane.