Substituted diaryls

1,138,489. Substituted diaryls. IMPERIAL CHEMICAL INDUSTRIES Ltd. 28 Nov., 1967 [13 Dec., 1966], No. 55881/66. Heading C2C. Substituted diaryls are prepared by the oxidative coupling of aromatic compounds having at least one hydrogen atom and one or more electronegative groups attached to the aromatic ring, in the presence of a catalyst comprising one or more of the metals silver, copper, chromium, manganese, vanadium, iron, cobalt, nickel, palladium, rhodium and compounds thereof, a proton-accepting substance and an oxidizing agent. Suitable proton-accepting substances are ammonia, amines, metal alkoxides and alkali and alkali earth metal hydroxides and carbonates. The preferred oxidizing agent is oxygen and the preferred catalysts are copper compounds. Examples are given of the oxidation of nitrobenzene to 4,41-dinitrodiphenyl and methyl benzoate to 4,41-diphenyldicarboxylic acid dimethyl ester.