COOXIDATION REACTIONS DURING OXIDATIONS OF SUPEROXIDE WITH POLYHALIDES, CO2, PHOSPHATES, AND ACYL HALIDES

Superoxide (O2 ⋅-) reacted with polyhalides, CO2, phosphates, and acyl halides to form the corresponding peroxy intermediates, which could be used as reactive oxidants. Polyhalides reacted with O2 ⋅- to cause cooxidation of olefins to the corresponding oxides in good yields. The yields of the oxides correlated well with the reactivities of polyhalides with O2 ⋅-. The reactions of CO2 and phosphates with O2 ⋅- caused cooxidation of sulfides to the sulfoxides and that of sulfoxides to the sulfones, respectively, in high yields. The mechanisms of these reactions were examined with the use of K18O2. Acyl halides were found to have nucleophilic attack of O2 ⋅- to generate acylperoxy radicals and anions. On the other hand, CC14 as a polyhalide, CO2, and phosphates in the reaction with O2 ⋅- seemed to form CC13 ⋅-, CO2 ⋅-, and phosphate anion radicals, respectively, which were followed by addition of O2 to form the corresponding hydroperoxides or peroxy anions as potent oxidants. These results seem to indicate that O2 ⋅- acts as a nucleophile and a one-electron reductant. Also, the relative rate constants were measured by the rotating ring-disk voltammetric method. The orders of magnitude for pseudo-first-order rate constants K1/[s], were 4, 103, and 101 in the reactions of O2 ⋅- with acyl halides, CC14, and phosphates, respectively. There was a good correlation between k1/[s] and product yields in the cooxidation of trans-stilbene by systems of O2 ⋅- and acyl halides or anhydrides. © 1990, American Chemical Society. All rights reserved.