Activation of superoxide with organophosphorus halide compounds

Abstract

Phosphorus oxychloride, phenylphosphonic dichloride, diphenylphosphinic chloride, and other diarylphosphinic chloride were used to develope new peroxyphosphorus inter mediates which showed stronger oxidizing ability than superoxide itself. Various sulfides and sulfoxides were readily oxidized to the corresponding sulfoxides and sulfones respectively by peroxyphosphorus intermediate which is generated $\underline{in}$ $\underline{situ}$ by the treatment of phosphorus oxychloride with potassium superoxide. It was found that phenylphosphonic dichloride reacted with superoxide to form a peroxyphosphorus intermediate to convert the various aryl and alkyl thioamides into the corresponding amides in excellent yields. Various sulfoxides which have a α-hydrogen gave the corresponding sulfones and α-chlorosulfoxides in same system and the ratio of α-chlorination was depended upon by the p-substitutents of sulfoxide in aromatic ring. Oxidation of a series of p-substituted phenyl methyl sulfides was carried out to compare the relative reactivities of oxidation. The relative reactivity order was p-methoxyphenyl- ＞ p-methylphenyl- ＞ phenyl- ＞ pchloro- phenyl methyl sulfide (ρ =-1.14, γ =0.994 against $\sigma_ρ^+$ values). The value shows a strong electrophilicity. Both trans- and cis-stilbene were treated with the peroxyphosphorus intermediate to give only transstilbene oxide (from trans-stilbene ; 28%, from cisstilbene ; 12 %) through the electrophilic radical epoxidation. The spin trapping studies were carried out for the system, $O_2\cdot$+2-nitrobenzenesulfonyl chloride, 2-nitro-benzenesulfinyl chloride, diphenylphospinic chloride, diphenylphosphoryl chloride, 2-nitrobenzoyl chloride. The DMPO spin adducts have the coupling constants, $a_N$ = 12.6-12.8 G and $a_H$ = 10.0-10.3 G in agrement with those of the DMPO spin adducts of alkylperoxy radicals. The spin trapping studies with the use of DMPO have revealed that organic chlorides readily react with $O_2\ba...