Structure and infrared spectrum of 2-hydroxyphenyl radical

Infrared spectrum of 2-hydroxyphenyl, C6H4-OH, produced from 2-iodophenol in a low-temperature argon matrix upon UV irradiation (λ>280 nm) was measured with an FT-IR spectrophotometer. This radical was found to be less stable by 120 kJ mol−1 than phenoxyl, C6H5-O, by a density functional theory calculation. Two final photoproducts were identified as cyclopentadienylidenemethanone and 4-iodo-2,5-cyclohexadienone in analogy with the photoproducts of 2-chloro and 2-bromophenols. A kinetic analysis shows that the latter is produced via 2-hydroxyphenyl by hydrogen migration and iodine recombination while the former is produced by Wolff rearrangement after elimination of hydrogen iodide.