91Ó°ÊÓ

Cyclohexane cannot be directly converted to 1-methylcyclohexene. It undergoes several reactions.Initially, cyclohexane is treated with sodium hypochlorite in the presence of acetic acid. This reaction produces cyclohexanone and it is reacted with Grignard reagent followed by hydrolysis, which gives 1-methylcyclohexanol. This compound is then heated strongly with sulfuric acid so that it loses its water molecule, and 1-methylcyclohexene is formed. The reaction is given below.

Synthesis of (a)

Cyclohexane is converted to cyclohexanone as given below. This is treated with ethyl Grignard reagent followed by hydrolysis which produces 1-ethylcyclohexanol. The compound is heated with sulfuric acid which is followed by reduction using ${\mathrm{H}}_2/\mathrm{Pd}$, and ethylcyclohexane is formed. The reaction is given below.

Synthesis of (b)

Cyclohexanol is heated with hydrogen bromide which forms bromocyclohexane. This is further treated with magnesium metal in the presence of ether. This produces a Grignard reagent—cyclohexane Grignard reagent. It is then treated with propanal followed by hydrolysis which gives the final product, 1-cyclohexyl ethanol. The reaction is given below.

Synthesis of (c)