Biphenylenes. Part XV. 3,7-Dimethyl- and 3,7-dimethoxy-1,5-dinitrobiphenylene

Abstract

The compound produced by reaction of 3.4-dibromo-5-nitrotoluene with copper bronze has been shown to be 3.7-dimethyi-1.5-dinitrobiphenylene. The analogous 3.7-dimethoxybiphenylene has been prepared similarly from 3.4-dibromo-5-nitroanisole.The dipole moment of the dimethyldinitrobiphenylene has been found to be about 2.4 D. This unexpected result is discussed.RECENTLY Corbett and Holt reported that the reaction of 3,4-dibromo-5-nitrotoluene with copper bronze in boiling NN-dimethylformamide gave a compound, in. p. 302", in 40% yield. This compound, C,,H,,N,O,, was considered to be either 3,6-dimethyl-1,8-dinitrobiphenylene (I) or the isomeric 3,7-dimethyl-l,5-dinitrocompound (11; R = Me), probably formed by the dimerisation of a benzyne intermediate. We have