Selectivity in the photo-fries rearrangement of some aryl benzoates in green and sustainable media. Preparative and mechanistic studies

Abstract

Irradiation of a series of p-substituted aryl 10 benzoates under N2 atmosphere in homogeneous and micellar 11 media was investigated by means of steady-state condition and 12 of time-resolved spectroscopy. A notable selectivity in favor of 13 the 2-hydroxybenzophenone derivatives was observed in 14 micellar media. The benzophenone derivatives were the 15 main photoproduct. On the other hand, in homogeneous 16 media (cyclohexane, acetonitrile, and methanol) the observed 17 product distribution was entirely different, viz. substituted 2- 18 hydroxybenzophenones, p-substituted phenols, benzyl and 19 benzoic acid were found. The binding constants in the 20 surfactant were also measured and NOESY experiments showed that the aryl benzoates were located in the hydrophobic core of 21 the micelle. Laser flash photolysis experiments led to the characterization of both p-substituted phenoxy radical and substituted 22 2-benzoylcyclohexadienone transients in homogeneous and micellar environment.