Kinetics of Zn-5,15-di(ortho-methyloxyphenyl)-2,8,12,18-tetramethyl-3,7,13,17-tetrabutylporphyrin oxidation by organic peroxides in o-xylene
作者:S. V. Zaitseva、O. R. Simonova、S. A. Zdanovich、O. I. Koifman
DOI:10.1134/s0036023610060215
日期:2010.6
A spectrophotometric and quantum chemical (PM3) study of the structure and properties of Zn-5,15-di(ortho-methyloxyphenyl)-2,8,12,18-tetramethyl-3,7,13,17- tetrabutylporphyrin (ZnP(I)) in its oxidation with organic peroxides in o-xylene at T = 295 K is presented. The kinetic parameters (k(app), k(v)) of this reaction are reported. The reactivities of strained zinc porphyrinates (ZnP(I), Zn-5,15-di(ortho-methyloxyphenyl)-2,3,7,8,12,13,17,18-octamethylporphyrin (ZnP(II)), and a zinc porphyrin with a 2,5-dimethoxyphenylene "cover" (ZnP(III))) are compared. The electronic and conformational properties of the macrocycle are significant factors in the interaction of the metalloporphyrins with the peroxides. The structures of the reactants and intermediates have been calculated by the PM3 method. The macrocycle of ZnP(I) has a distorted structure. The degree and type of distortion are estimated. When reacting with the peroxides, the metalloporphyrin changes its structure so that the macrocycle becomes still more strained, and this enhances its reactivity.