Stereochemistry of hydrogenation of 4-t-butylmethylenecyclohexane

Abstract

The catalytic hydrogenation of 4-t-butylmethylenecyclohexane has been studied in a search for selective catalyst systems which would produce largely cis- or trans-4-t-butylmethylcyclohexanes. Both soluble and insoluble catalysts have been employed. Chloroplatinic acid and stannous chloride in propan-2-ol containing aqueous hydrogen bromide catalyse the hydrogenation at room temperature and 1 atm., 95% of cis- and 5% of trans-product being formed. In contrast, when the complex RhCl[(2-MeC₆H₄)₃P]₂ is used in benzene–ethanol solution, 90% of cis- and 10% of trans-product are produced. Hydrogenation with 5% Rh–C in methanol produces 88% of cis- and 12% of trans-isomer.