MECHANISM OF THE REACTION BETWEEN HYDROXY L RADICALS AND ALIPHATIC-ACIDS IN AQUEOUS-SOLUTION - EFFECTS OF HYDROXYL-GROUPS

The aim of this work was to study the mechanism of oxidation of dicarb oxylic acids by hydroxyl radicals resulting from the photolysis of hyd rogen peroxide. Experiments have been carried out with aqueous solutio ns (C-o approximate to 1 mmol.L(-1)) of malonic acid, hydroxymalonic, ketomalonic, succinic, melic and tartaric acids. Results showed that i n the presence of dissolved oxygen, OHo reacts with hydroxyacids by H- abstraction at the carbon atom carrying the hydroxyl group. The radica l formed fixes one oxygen molecule and then releases one HO2. radical. On the other hand, the reaction of OH. radicals with the unsubstitute d analogues leads to a C-C bond cleavage. In each case, the mechanism proposed involves oxygen consumption.