The aqueous photochemistry of 2,6-dimethylphenol. Evidence for the fragmentation of the α C-C bond

Abstract A study of the photochemical behaviour of 2,6-dimethylphenol in aerated aqueous solution upon excitation at 270 nm has been undertaken. High-performance liquid chromatography (HPLC) analyses indicated the primary formation of 2,6-dimethylbenzoquinone and the para-para coupling dimer as major products; two isomeric products resulting from α C-C scission were also observed. They account for about 20% of the conversion. Only the dimer was observed when the irradiation was carried out under deaerated conditions. The photoreaction has been shown to result from an electron ejection process leading to phenoxyl radical and solvated electron. The results indicate that O 2 − and HO 2 are among the species involved in the formation of the oxidized products and particularly those arising from the cleavage of the aromatic ring.