4-HYDROXY-2-ALKENALS AND OTHER PRODUCTS FORMED BY WATER-MEDIATED OXIDATIVE DECOMPOSITION OF ALPHA,BETA-UNSATURATED ALDEHYDES

Water-mediated (pH 6.5) model experiments were carried out with (E)-2-hexenal (1), (E)-2-octenal (2), and (E,E)-2,4-decadienal (3) under oxygen atmosphere. After complete degradation of the alpha,beta-unsaturated aldehydes 1-3 and solvent extraction of the products formed, separation into neutral and acid fractions was performed by bicarbonate treatment. Subsequent HRGC, HRGC-MS, and HRGC-FTIR analyses revealed predominant formation of acids from 1 and 2, while for 3 the neutral fraction prevailed. In the neutral fractions 3-hydroxyhexanal was the major product formed from 1 and 1-hydroxy-2-heptanone and hexanal were found to be the major products formed from 2; the dienal 3 predominantly yielded hexanal and hexanoic acid. As minor products the toxicologically relevant compounds 4-hydroxy-(E)-2-hexenal, 4-hydroxy-(E)-2-octenal, and 4-hydroxy- (E)-2-nonenal arising from 1-3, respectively, were detected.