Nitration of Diphenylmethane and the Isomeric Nitrodiphenylmethanes in Dichloromethane

Diphenylmethane could be mononitrated to 2- and 4-nitrodiphenylmethane by nitric acid in dichloromethane. Adjustment of experimental conditions gave a mixture of 2,2‘-, 2,4‘-, and 4,4‘-dinitrodiphenylmethane. The occurrence of side reactions was negligible, and the conversions were quantitative in the latter reaction. In both processes conventional separation of the pure isomers appeared realistic from a practical point of view. The reactions ran smoothly and did not necessitate stringent controls against dangerous runaways. This nitration procedure was applied also to the three isomeric mononitrodiphenylmethanes which underwent quantitative mononitration in the unsubstituted ring.