BENZALDEHYDE FORMATION FROM ASPARTAME IN THE PRESENCE OF ASCORBIC ACID AND TRANSITION METAL CATALYST

摘要

Benzaldehyde was produced from aspartame in aqueous acidic solutions containing ascorbic acid and Cu(II) or Fe(III) ion. Benzaldehyde was identified in the system by GC-MS. The yield of benzaldehyde decreases dramatically as the pH of the medium increases above 2.0. EDTA and DTPA completely inhibited benzaldehyde production, while desferrioxamine inhibited only the Fe(III)-catalyzed reaction. Benzaldehyde is not produced under anaerobic conditions unless H2O2 is added to reaction mixtures. H2O2 is produced by reduction of atmospheric oxygen under aerobic conditions. Benzaldehyde production was dependent on ascorbic acid concentration, but the yield of benzaldehyde decreased as the concentration of ascorbic acid exceeded that of aspartame. Addition of ethanol to the reaction mixture had little or no effect on benzaldehyde production, suggesting a mechanism that may not involve free hydroxyl radical. A mechanism is proposed for the reaction.