CARBON-DIOXIDE PRODUCTION IN THE OXIDATION OF ORGANIC-ACIDS BY CERIUM(IV) UNDER AEROBIC AND ANAEROBIC CONDITIONS

The stoichiometry of CO2 production during the eerie oxidation of vari ous organic acids is measured under conditions with organic acid exces s: Measurements utilize a photometric methodology. For anaerobic condi tions stoichiometries [CO2](produced): [Ce(IV)](reduced) of about 0 (m alonic acid), 0.5 (e.g., glyoxylic acid), and 1.0 (oxalic acid) are fo und. Oxalic acid showed an oxygen-induced decrease of CO2 production, while other compounds such as malonic acid increased the amount of pro duced CO2 or showed no changes (e.g., tartronic acid). In the case of mesoxalic acid the stoichiometry is increased from about 0.5 to 2.0 du e to the presence of molecular oxygen. The results are discussed on th e basis of simple reaction mechanisms demonstrating that useful inform ation on reaction pathways and intermediates can be extracted from the se simple measurements. (C) 1998 John Wiley & Sons, Inc.