Abstract: A biphenyl compound is produced from a corresponding aromatic monocyclic compound at a high yield thereof and a high percent selectivity thereto, by dehydrogenatively dimerizing the aromatic monocyclic compound with molecular oxygen in the presence of oxalic acid together with a organic palladium salt catalyst, under a pressure higher than the atmospheric pressure.

Abstract: Aromatic hydrocarbons are contacted under hydroalkylation conditions and in the presence of hydrogen, with a catalyst comprising an iridium compound supported on a calcined, acidic, nickel and rare earth-treated crystalline zeolite.

Abstract: A decarboxylation process for coupling aromatic compounds wherein cyclic hydrocarbons and heterocyclic compounds having at least one labile ring hydrogen are reacted with the mono silver salts of aromatic carboxylic acids, or mono silver salts of unsaturated compounds such as .alpha.,.beta.-ethylenically unsaturated acid compounds, or silver trifluoroacetate, or the mono silver salts are reacted with themselves, by heating to temperatures of 100.degree. to 500.degree. C. at pressures of 0.1 to 10 atmospheres, or by irradiating the reactants with ultraviolet light of 200 to 400 nanometers at temperatures of -30.degree. to 150.degree. C. The resulting dimers, trimers, polysubstituted polyphenyls, polyheterocyclics and trifluoromethylated aromatics are useful as heat transfer media, as intermediates for high molecular weight polymers, pesticides and petroleum additives, and as scintillation counters.