Mechanism of Formation and Decomposition of C6H5(O2•)C(OH)C6H4OH

In the present theoretical study, the thermochemical properties of Ph(O-2(center dot))C(OH)PhOH and considered products of its oxidation are calculated using the DFT approaches (M062X, B3LYP, wB97XD, M08HX, MN15) at the 6-311++G(d, p) level of theory. The DFT values of Delta H-ra(o)(Y-i) of the atomization of considered structures are corrected using the linear calibration dependencies reported for the peroxides as well as for the hydrocarbons (including aromatic and simple oxygenated compounds). The values of Delta H-f(o)(Y-i, CORR) +/- 3SD(i), derived from the corrected values of Delta H-ra(o)(Y-i, CORR), are coordinated by the intersection of their 3SD(i) intervals, determined previously. The values of Delta H-f(o)(Y, MEAN) +/- 2SD(Y) of the Ph(O-2(center dot))C(OH)PhOH (2F), Ph-center dot & horbar;OO & horbar;C(OH)PhOH (3G), HOPh center dot & horbar;OO & horbar;C(OH)Ph (2G), PhC(OH)(2)PhOH (1H), Ph(O2H)C(OH)PhOH (4G) and Ph(O-center dot)C(OH)PhOH (1G) (corresponded, respectively, to -159.4 +/- 6,-55.2 +/- 6,-61.5 +/- 3.7,-385.8 +/- 6,-293.4 +/- 1.4,-148.9 +/- 6 kJ/mol), as well as the values of E-a double dagger = 127.8 +/- 7, 121.2 +/- 8, 17.2 +/- 5, 19.4 +/- 3 kJ/mol, determined, respectively, for the reactions (R21a), (R21b), (R22a), (R22b) and the values of the rate constants of associated reactions, are reported for the first time. According to calculations, the replacement of >(CH)-H-center dot by OH group increases the values of dissociation energy (DE) of >C(X)& horbar;O-2(center dot), >C(X)O & horbar;O-center dot, >C(X)O & horbar;H, PhC(X)OO & horbar;(PhOH)-Ph-center dot, and HOPhC(X)OO & horbar;Ph-center dot bonds, but decreases those values of >C(X)O-2-H, HOPhC(X)Ph-OO center dot, and PhC(X)(PhOH)-Ph-OO center dot bonds. As a result of increased stability of the >C(X)& horbar;O-2(center dot) bond (X = OH), the higher temperatures can be used for the chain production of p-PhC(O2H)HPhOH and p-PhC(O2H)(OH)PhOH at high concentrations of p-PhCH2PhOH. On the contrary, the contribution of reactions (R21a) and (R21b) to the oxidation is significant under low concentrations of p-PhCH2PhOH. Its also found that the stable intermediate O-2 pi-pi cluster, predicted for the >C-center dot(H) radical, is not observed for the reaction of >C-center dot(OH) with O-2, due to the formation of a hydrogen bond between the OH group and partially charged O-2(delta-).