Selective production of a p-alkyltoluene or 4,4'-alkylmethylbiphenyl

A method for producing (a) a p-alkyltoluene, wherein the alkyl group is methyl or ethyl, from benzene, toluene, ethylbenzene, or a mixture of benzene and toluene as the feed or (b) a 4,4'-alkylmethylbiphenyl, wherein the alkyl group is methyl or ethyl, from biphenyl, 4-methylbiphenyl, 4-ethylbiphenyl or a mixture of biphenyl and 4-methylbiphenyl as the feed, comprising:

• reacting the feed in the liquid phase with at least one of 1,2,4,5-tetramethylbenzene, pentamethylbenzene or hexamethylbenzene as the methylating agent, at a level of from about 1 to about 10 moles of the methylating agent per mole of the feed, in the presence of a catalyst comprising a Lewis acid or Bronsted acid alkylation catalyst or a mixture thereof that is more acidic than ferric chloride and at least as acidic as ferric bromide, at a level of from about 0.01 to about 1 mole of the catalyst per mole of the feed and at a temperature in the range of from about -40.degree. C. to about 80.degree. C.