CATALYTIC ACTION OF NITROGEN-CONTAINING BASES ON KINETICS OF ZINC AND HEXA- (m-TRIFLUOROMETHYLPHENYL)BENZOPORPHYRAZINE COMPLEX FORMATION

Abstract

A complexation reaction of hexa(m-trifluoromethylphenyl)benzoporphyrazine with zinc acetate in the system “morpholine (piperidine) – benzene” was studied. Preliminary studies have shown that at concentrations of morpholine and piperidine in benzene less than 0.95 and 0.2 mol/l respectively, the reactions between hexa(m-trifluoromethylphenyl)benzoporphyrazine and zinc acetate not observed. The reaction takes place only at the range of concentrations of morpholine of 0.95 to 8.70 mol /l in benzene and at the range of concentrations of piperidine of 0.2 to 7.74 mol /l in benzene. The changes in the electronic absorption spectrum do not depend on the nature of the nitrogen-containing base, and accompanied by π - chromophore molecules from D2h to D4h symmetry increase. It was shown that complexation describes with the total kinetic equation of the third order. That is there is the first order on every reagent -hexa (m-trifluoromethylphenyl) benzoporphyrazine, zinc acetate and the base. A possible scheme of the mechanism in which the acid - base interaction of hexa (m-trifluoromethylphenyl) benzoporphyrazine with morpholine (piperidine), leading to the H – complex formation is the rate-limiting step of the process proposed. This complex unlike molecular form posseses higher reactivity at interaction with zink cation since an expenditure of energy for breaking intracyclic NH bonds is essentially lower. It was found that rate of hexa (m-trifluoromethylphenyl) piperidin benzoporfirazina coordination by zinc is higher in system “piperidine – benzene”. At replacement of piperidine with morpholine рКа of bases decreases by a factor of about 2.5. It results in the decrease in complexation rate judging by values of k298 by a factor of ~7 on the background of constancy of activation parameters of reaction. This fact is not surprising since less pronounced proton acceptor ability of morpholine complicates removal of intracyclic proton of NH - groups with formation of N - complex and, consequently, complicates zinc cation entrance into the coordination plane of the macrocycle.For citation:Petrov O.A., Sadovskaya I.N. Catalytic action of nitrogen-containing bases on kinetics of zinc and hexa (m-trifluorome-thylphenyl) benzoporphyrazine complex formation. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 3. P. 36-41.