CHARACTERIZATION OF COMPOUNDS OBTAINED BY CHEMICAL OXIDATION OF CAFFEIC ACID IN ACIDIC CONDITIONS

Sodium periodate oxidation of caffeic acid was investigated in aqueous solutions with pH ranging from 2 to 7. Products formed from quinone e volution were monitored by HPLC. It was found that they were affected both qualitatively and quantitatively by the conditions of the reactio n. The rate and the yield of the reaction increased with the pH. In pa rticular, two products obtained at pH values lower than 4.6 approximat ely, were analysed and isolated by reverse phase HPLC. By using H-1 an d C-13 NMR and mass spectrometries, these compounds were shown to be t wo stereoisomers of 2,5-(3',4'-dihydroxyphenyl)tetrahydrofuran 3,4-dic arboxylic acid.