Photoinduced Decomposition of Peracetic Acid in Xylenes. Orientation in Aromatic Substitution of Methyl and Hydroxyl Radicals

Article abstract of DOI:10.1021/jo01293a004

The photolysis of peracetic acid (1) in o-,m- or p-xylenes (2) has been carried out using 2537-Angstroem or >2900-Angstroem light at 20-22 deg C.The yields of ethyltoluenes (3), trimethylbenzenes (4), and dimethylphenols (6) are higher at 2537-Angstroem than those at >2900-Angstroem photolysis, but the reverse is true with the yield of methylbenzyl alcohol (5).The isomer distribution of trimethylbenzenes (4) formed from o- (2a) or m-xylene (2b) suggests that an attack of methyl radical at the position meta to the methyl group is favored with 2537-Angstroem light, while an attack at the ortho position is preferential with >2900-Angstroem light.On the other hand, the isomer distribution of dimethylphenols (6) at 2537 Angstroem suggests that an attack of hydroxyl radical is favored at positions ortho and para to the methyl group.These orientations of radical attack are briefly discussed.