TRANSFORMATION OF 2,6-DIMETHYLPHENOL PHOTOINDUCED BY EXCITATION OF [CO(NH3)(5)N-3](2+) AT 365 NM

Efficient induced oxidation of 2,6-dimethylphenol (DMP) occurred by ex citation of azidopentaammine cobalt(III) at 365 nm. The presence of DM P did not affect significantly the quantum yields. The azide radical N -3(.), produced on irradiation, efficiently reacted with DMP to yield phenoxyl radicals. In aerated as well as in deaerated solution, the co upling of such radicals yielded unequivocally 3,3',5,5'-tetramethyldip henoquinone as the predominant photoproduct. Trace concentrations of p ara-para coupling dimer together with polyphenyl ethers were also dete cted by mass spectrometry. The formation of the substituted diphenoqui none in the absence of oxygen was attributed to a subsequent oxidative pathway involving the starting Co(III) complex. No dimethyl-p-benzoqu inone or dimethylhydroquinone was formed, suggesting that the cobalt i ons play an important role in the observed reactions.