The role of dissolved oxygen in the decomposition of aliphatic acids by hydroxyl radicals

摘要

The aim of this work was to study the oxidation of aliphatic acids by hydroxyl radicals resulting from the photolysis of hydrogen peroxide. Experiments carried out in dilute aqueous solutions of mono and dicarboxylic acids with 1 to 4 carbon atoms showed i) the oxidation of the carboxylic group is slow ii) the hydroxyl group of hydroxylated acids activates the adjacent C-H bond and leads after hydrogen atom abstraction, O_2 addition and HO_2° removal to the carbonyl group iii) a C-C bond cleavage occurs after hydrogen atom abstraction and oxygen addition for unsubstituted dicarboxylic acids. Excepted for oxalic acid, the mechanism of oxidation into CO_2 of the acids studied involves oxygen consumption and O_2°-/HO_2° releasing.