Aromatic amines and their derivatives. Part 3. The synthesis and crystal structure of 4,4′-NN′-tetramethyl-NN′-dinitroso-2,2′-methylenedianiline
The synthesis of 4,4′,N,N′-tetramethyl-NN′-dinitroso-2,2′-methylenedianiline (1) by the route p-MeC6H4NH2+ HCHO + OH–→(p-MeC6H4NMe)2CH2(7b); (7b)+ acid at 70 °C → 4,N-dimethyl-6-(N-methyl-p-toluidinomethyl)aniline (4b); (4b)+ acid at 130 °C → 4,4′,NN′-tetramethyl-2,2′-methylenedianiline (3b); (3b)+ HNO2→(1), is described. Aspects of the 1H n.m.r. spectra of the above and related compounds are discussed. A crystal-structure analysis of compound (1) shows one of the N-nitroso-groups to be disordered with the endo-form being in preponderance (4 : 1) over the exo-form. The other N-nitroso-group is exclusively exo in the solid state. There is little or no resonance between the benzene ring and the nitroso-group attached to the ring, the two groups being almost perpendicular to each other. In one of the N-nitroso-groups, the nitrogen atom deviates significantly from the plane of the benzene ring to which it is attached. Both amide nitrogen atoms show some pyramidal character.