Gopal Mishra - Scorpionate complexes of vanadium(III or IV) as catalyst precursors for solvent-free cyclohexane oxidation with dioxygen

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      Abstract:

        The V-scorpionate complexes [VCl(3){HC(pz)(3)}] (pz = pyrazolyl)   and [VCl(3){SO(3)C(pz)(3)}] catalyze cyclohexane oxidation with   dioxygen, to cyclohexanol (the main product) and cyclohexanone,   under solvent-free conditions. [VCl(3) {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.

      Address (URL): http://stage.iupac.org/publications/pac/pdf/2009/pdf/8107x1217.pdf