SYNTHESIS OF SOME NOVEL 3-[(2-HYDRAZONO) BENZIMIDAZOLYL]-2-INDOLINONES AS POSSIBLE AZODYES

Indole-2,3-diones have been condensed with 2-hydrazinobenzimidazole to yield 3-[(2-hydrazono)benzimidazolyl]-2-indolinones (III). Structural investigation showed that the title compounds exists in two tautomeric forms (III reversible III)', both being stabilized by hydrogen-bonding. The dark yellow colour and the structure indicates the possible use of these compounds as azodyes. Further, N-substituted derivatives have been synthesized by three different methods: (i) starting with N-substituted indole-2,3-dione, (ii) starting with N-substituted 2-hydrazinobenzimidazole and (iii) by carrying out the substitution on nitrogen after preparation of the title compound. The synthesized compounds have been characterised by elemental analysis, IR, H-1-NMR and mass spectral studies.