Collect. Czech. Chem. Commun. 1980, 45, 3140-3149

Preparation of some trimethyl- and methylethylbiphenyls and reactivity of aromatic hydrocarbons in the Gomberg reaction

Jan Novrocíka, Marta Novrocíkováa and Miloš Titzb

a Research Institute for Coke Chemistry, Urxovy závody, 757 27 Valašské Meziříčí
b Research Institute of Organic Syntheses, 532 10 Pardubice-Rybitví


Trimethyl- and methylethylbiphenyls with the alkyl groups in the both phenyl rings have been prepared by the Gomberg reaction and identified by the capillary gas-liquid chromatography. Depending on choice of the aromatic hydrocarbon either individual isomers or their mixtures (three at the most) have been obtained which were contaminated with compounds of diarylmethane type in many cases. The methylethylbiphenyls have only been prepared as mixtures contaminated with diarylmethanes. These side products have been prepared by independent syntheses. A method has been developed for isolation and separation of mixtures of trimethyl- and methylethylbiphenyls from the reaction products containing tarry products. The method is suitable for preparation of small amounts of some analytical standards. The HMO method has been used for calculation of values of the radical superdelocalizabilities at individual centres in the molecules of o-, m- and p-xylene, toluene and ethylbenzene, and these values have been compared with composition of the Gomberg reaction products from these hydrocarbons. The competitive technique has been used for comparison of the reactivities of the mentioned aromatic substrates in the Gomberg reactions.