STUDIES ON THE ESR-SPECTRA OF DAWSON-MOLY BDOVANADOPHOSPHONIC COMPOUND IN THE PROCESS OF PHENOL HYDROXYLATION

ESR spectra of molybdovanadophosphonic compound with Dawson structure in the process of phenol hydroxylation with H2O2 were studied. Contras ting their ESR parameters at different reaction rime, the change of V4 + reversible arrow V5+ in the system was analyzed. The results indicat ed that in tile initial stage, a few V4+ were produced in the process of the catalyst synthesized, After two hours, the amount of V4+ increa sed quickly and two kinds of signals of V4+, V(I) and V(II) appeared. The ESR parameters of V(I) were the same as ones at the initial stage, but the signals of V(II) were newly appeared. The increasing amount o f V(II) is higher than that of V(I), We had calculated the delocalized extent of unpaired electrons by the method of Ahragam Pryce and assig ned that two kinds of V4+, V (I) and V(II) are all the active centre o f the reaction.