FORMATION OF ACETALDEHYDE FROM L-ASCORBIC ACID AND RELATED COMPOUNDS IN VARIOUS OXIDATION SYSTEMS

摘要

The quantities of acetaldehyde formed from L-ascorbic acid, L-threonic acid, and D-erythrose upon oxidation with Fenton's reagent and upon UV irradiation were determined by gas chromatography. When 10 mu mol of L-ascorbic acid was oxidized with Fenton's reagent, 316 nmol of acetaldehyde was recovered. When 10 mu mol of L-ascorbic acid was irradiated (lambda = 300 nm) for 12 h, 297 nmol of acetaldehyde was produced. Upon oxidation with Fenton's reagent, L-threonic acid (10 mu mol) and D-erythrose (10 mu mol) produced 112 and 81.5 nmol of acetaldehyde, respectively. Acetaldehyde was formed from D-erythrose but not from L-threonic acid by photolysis, suggesting that acetaldehyde formation involved a Norrish type II reaction. Acetaldehyde was also formed from aqueous solutions of L-ascorbic acid (122 nmol/10 mu mol), D-erythrose (37.0 nmol/10 mu mol), or L-threonic acid (27.9 nmol/10 mu mol) with the presence of Fe2+ at 37 degrees C under an air stream. This study is the first to report formation of acetaldehyde from ascorbic acid.