Fluorescein-photosensitized Furan Oxidation in Methanolic and Reversed Micellar Solutions, Part II Kinetic Analysis

Singlet Oxygen, Radicals, Fluorescein, Diphenylisobenzofuran, Reversed Micelles The 1,3-diphenylisobenzofuran oxidation was investigated in methanolic and dodecylammonium propionate reversed micellar solutions using fluorescein sodium as photosensitizer. The furan oxidation was caused by the singlet oxygen mechanism (Type II). Aniline enhanced remarkably the furan oxidation in methanolic solutions, but inhibited highly this oxidation in the reversed micellar solutions. This enhancement of the furan oxidation was considered to be brought about by the occurrence of a radical mechanism (Type I) besides Type II mechanism. No Type I reaction occurred in the micellar solutions. The rate constants concerning with both reaction processes were evaluated by kinetic analysis, employing various aryland alkyl-amines. The reaction mechanism of Type I and the quenching mechanism of singlet oxygen by amines were discussed from the relationship between the rate constants, and the ionization potential of amines and the solvent polarity.