Synthesis of Some Novel 3-[(2-Hydrazono) BenzimidazolyI]-2-Indolinone as Possible Azodyes.

Abstract

Indole-2,3-diones have been condensed with 2-hydrazinobenzimidazole to yield 3-[(2-hydrazono)benzimidazolyl]-2-indolinone (III). Structural investigation showed that the title compound exists in two tautomeric forms(III–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, (iii) by carrying out the substitution on nitrogen after preparation of the title compound. The synthesized compounds have been characterised by elemental analysis, IR, ¹H-NMR and mass spectral studies.