New congeners of 1-picryl-2-phenyl-2-(para-picramidophenyl)-diazenium betaine whose picramido groups are replaced by 4-cyano-2,6-dinitrophenyl analogs

By analogy with our previously described 1-picryl-2-phenyl-2-(para-picramid ophenyl)-diazenium betaine (4a), three new congeners were synthesized in wh ich either one, or the other, or both of the picryl groups have one 4-nitro group replaced by a cyano group. The spectral properties of these new comp ounds are described, and they prove that the cyanodinitrophenyl group behav es like a slightly less powerful electron-withdrawing group than a picryl g roup. The dipotassium salt of 1-picryl-2-phenyl-2-(4-picrylamino-phenyl)-hy drazine (5a) forms a supramolecular complex, 13, with 18-crown-6 ether, whi ch can be mono- or dialkylated with methyl iodide, resulting in a monomethy l and dimethyl derivative 14 and 15, respectively. The monomethyl derivativ e, 14, has the methyl attached to the diarylamino nitrogen atom, since oxid ation by potassium permanganate converts it into a stable hydrazylic radica l, 17. A byproduct in the synthesis of betaine 4a, when an excess of DPPH i s used over N-methoxypicramide, was proved to be 2-(4-methoxyphenyl)-2-phen yl-1-picrylhydrazine, 12. In order to avoid the formation of such byproduct s and to allow simpler purification procedures, it is recommended to use eq uimolar ratios of reactants, in the presence of potassium permanganate.