PRODUCTION OF HYDROGEN-PEROXIDE FROM DIOXYGEN AND HYDROXYLAMINE OR HYDRAZINE CATALYZED BY MANGANESE COMPLEXES

Manganese(II) catecholate complexes efficiently catalyse the production of H2O2 from dioxygen in the range pH 7.5-8.6 using hydroxylamine or hydrazine as substrates; concentrations of hydrogen peroxide > 0.2 mol dm-3 and turnover numbers [H2O2]/[Mn(II)] > 10(4) can be obtained. The rate of production and yields are very sensitive to the electronic effect of the substituents on the catecholate ring with the best results being achieved using 4,5-dihydroxybenzene-1,3-disulfonate. Deuteriation studies (using ND2OD) indicated that the reduction of O2 occurs via an electron transfer from the substrate and a mechanism is proposed whereby both O2 and the substrate become bound to manganese and the electron transfer is mediated through the manganese catecholate complex.