Photolysis of diaryliodonium salts (UV/Vis, EPR and GC/MS investigations)

The photodecomposition of commercial lipophilic diaryliodonium hexafluoroan timonate SarCat(R) SR-1012 was investigated in acetonitrile (ACN) and ACN/H 2O mixed solvents by means of UV/Vis spectroscopy, an EPR in situ spin trap ping technique and GC/MS analysis. The application of the spin traps nitros odurene (ND) and 5,5-dimethyl-1-pyrroline N-oxide gave evidence for the pro duction of radical intermediates corresponding to the breaking of the carbo n-iodine bond, in addition to carbon-oxygen bonds in SR-1012 aryl substitut ion. The photolytic products analyzed in aprotic acetonitrile were iodobenz ene, acetanilide, biphenyl and C12H25CH(OH)CH3, while in ACN/H2O (1:1, vol. ) solution iodobenzene, biphenyl, C12H25CH(OH)CH2OC6H4OH and hydroxylated b iphenyls were identified. The influence of oxygen on the product distributi on in both solvent systems was inconsequential. The proton concentrations p hotogenerated in the irradiated SR-1012 ACN/H2O solutions were quantified s pectrophotometrically using bromophenol blue indicator. (C) 2000 Elsevier S cience S.A. All rights reserved.