INTERACTION OF 7,7´-DIOXO-7H, 7´ H-3, 3´ -BENZIMIDAZO[2,1-a]BENZO[de]ISOQUINOLINE-4, 4´ -DICARBOXYLIC ACID WITH SODIUM DITHIONITE IN WATER-ALKALINE SOLUTION

Abstract

Using the spectrophotometric method, the interaction of 7,7´-dioxo-7H, 7´ H-3, 3´ -benzimidazo[2,1-a]benzo[de]isoquinoline-4, 4´ -dicarboxylic acid with sodium dithionite in an aqueous-alkaline solution in aerobic and anaerobic conditions has been studied. It is found, that in the initial stage of process very rapidly formation of a tetraanion is observed due to the addition of two electrons. In the future, depending on the conditions of the reaction (aerobic, anaerobic atmosphere, small or large concentrations of the reducing agent), the tetraanion transition to the initial compound is observed due to its oxidation with air oxygen or sulfite anion formed from dithionite anions, as well as at sufficiently high concentrations of the reducing agent. A subsequent chemical stage of cyclization is possible with the cleavage of two carboxyl groups from the reduced form of the initial compound. It has also been established that the cyclization product is N,N'-di(benzimidazole)diimides of perilen-tetracarboxylic acid, which is isolated from a solution in a solid state. Its elemental composition is analyzed, IR- and electronic absorption spectra were obtained. The reversible nature of the initial stage of the interaction of 7, 7´-dioxo-7H, 7' H-3, 3´-benzimidazo[2,1-a]benzo[de]isoquinoline-4,4´-dicarboxylic acid with sodium dithionite is indicated by the fact that under aerobic conditions the concentration of the intermediate product present in the form of tetraanion decreases faster than the anaerobic atmosphere. The transition of the reduced form of the initial compound to the original, non-restored one is also observed during bubbling of air through the reaction mixture. It has been established by cyclic voltammetry that reversible reduction of the initial compound is also possible due to an electrochemical reaction occurring on a carbon-metal electrode in an aqueous-alkaline solution. The analysis of the voltage dependences showed that two electrons participate in the electrode reaction. For citation: Polenov Yu.V., Egorova E.V. Interaction of 7,7´-dioxo-7H, 7´ H-3, 3´ -benzimidazo[2,1-a]benzo[de]isoquinoline-4, 4´ -dicarboxylic acid with sodium dithionite in water-alkaline solution. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 6. P. 80-87. DOI: 10.6060/ivkkt.20246706.7056.