| Abstract |
The V-scorpionate complexes [VCl3\HC(pz)(3)\] (pz = pyrazolyl) and [VCl3\SO3C(pz)(3)\] catalyze cyclohexane oxidation with dioxygen, to cyclohexanol (the main product) and cyclohexanone, under solvent-free conditions. [VCl3 \HC(pz)(3)\] provides the. best activity (13 \% conversion into the ketone and alcohol, with high selectivity, at the O-2 pressure of 15 atm, at 140 degrees C, 18 h reaction time). The reaction is further promoted (to 15 \% conversion) by pyrazinecarboxylic acid (PCA). The use of C- or O-radical traps supports the involvement of a free-radical reaction mechanism. Several reaction parameters have been varied in a systematic study, directed toward optimization of the process. |
