CATALYTIC ACTIVITY OF MANGANESE(II)-GLUCONATE COMPLEX IN REACTIONS OFHYDROGEN-PEROXIDE

Kinetic studies of the hydrogen peroxide decomposition catalyzed by th e dimeric Mn(II)-gluconate complex, in alkaline medium, showed evidenc e for the oxidative cleavage of the ligand, leading to the formation o f formaldehyde as one of the products. In the presence of a large exce ss of other hydroxylated substrates, such as methanol or ethylene glyc ol, a significant increase in the yield of formaldehyde was observed, corroborating the observed peroxidase activity in this system, in addi tion to the catalase activity. Oxygen free radicals were detected as i ntermediates of reaction, by ESR spectroscopy using the spin-trapping method, only under aerobic conditions. Therefore, a nonradical mechani sm was proposed for the reaction, based on the formation of a peroxo-M n(II) complex, and its further reduction to the previous Mn(II) specie s. (C) 1994 John Wiley & Sons, Inc.