Transformations of dimethylcyclohexanes in presence of a nickel-alumina catalyst and hydrogen under pressure

Summary

• 1. An investigation was made of the catalytic transformations of 1,2-, 1,3-, and 1,4-dimethylcyclohexanes at 460° in presence of a nickel-alumina catalyst and hydrogen at pressures of 25 and 50 atm.

• 2. The main reaction occurring in the transformations of the dimethylcyclohexanes was dehydrogenation to the corresponding xylenes, and the extent to which this occurred diminished with increase in the pressure of hydrogen.

• 3. Dehydrogenation was accompanied by the hydrogenolysis of methyl groups with formation, on the one hand, of toluene and benzene and, on the other, of methylcyclohexane and cyclohexane.

• 4. In the catalytic treatments of 1,3- and 1,4-dimethylcyclohexanes under the given conditions, 32–36% of toluene on the catalyzate was formed. The transformations of 1,3-dimethylcyclohexane went still further and were accompanied by the formation of about 30% of benzene on the catalyzate.