Remarkable effect of simple aliphatic alcohols on the controlled aerobic oxidation of toluene catalyzed by (T(p-Cl)PP)MnF/NHPI

The remarkable effect of simple aliphatic alcohols on the controlled oxidation of toluene with molecular oxygen over [5,10,15,20-tetrakis(p-chlorophenyl)porphinato]manganese fluoride (T(p-Cl)PPMnF) and N-hydroxyphthalimide (NHPI) was reported. The influences of reaction conditions such as the concentration and structure of alcohols, temperature and catalyst concentration on the promotion effect were also studied. UV-vis spectra were used to investigate the possible structure of reaction intermediate derived from the catalyst (T(p-Cl)PP)MnF in the toluene oxidation systems in the presence of methanol. The results showed that the added methanol interacted with catalyst (T(p-Cl)PP)MnF to form the coordination compound [(T(p-Cl)PP)Mn-III(ROH)(2)](+), which subsequently was transformed into a high valent manganese-oxo radical cation intermediate [(T(p-Cl)PP)Mn-IV(O)(CH3OH)](+center dot) in the oxidation systems. We deduce that the formation of [(T(p-Cl)PP)Mn-IV(O)(CH3OH)](+center dot) and its higher reactivity toward toluene may be responsible for the better results observed. On the basis of the results obtained, a possible mechanism of the controlled oxidation of toluene with dioxygen over (T(p-Cl)PP)MnF/NHPI in the presence of the aliphatic alcohols was proposed. (C) 2013 Elsevier B.V. All rights reserved.