Modern friedel-crafts chemistry. Part-271. Alkylation of benzene with 1-benzyl-and 1-phenylcyclohexanols in the presence of H2SO4 and AlCl3/CH3NO2 catalysts

The alkylation of benzyene with 1-benzylcyclohexanol (3) gave a mixture of 2,3-benzobicyclo[3.3.1]nona-2-ene (8, 79%) and cyclohexyldiphenylmethane (10, 21%) with AlCl 3 /CH 3 NO 2 catalyst and a mixture of 1-benzylcyclohexene 5 (47.5%), 8 (8%), 10 (21.5%), 1-cyclopentyl-1,2-diphenylethane (12, 18%) and l-benzyl-1-phenylcyclohexene (13, 4%) with H 2 SO 4 catalyst. Treatment of 3 with AlCl 3 /CH 3 NO 2 in petroleum ether gave a mixture of 5 (26%) and 8 (62%). Attempted alkylation of benzene with 1-phenylcyclohexanol (4) in the presence of either AlCl 3 /CH 3 NO 2 or H 2 SO 4 catalyst gave l-(1-phenylcyclohexyl)-2-phenylcyclohexene (17) as sole product. Mechanistic interpretation of the results in terms of carbocation behaviour is offered.