Reaction of VOSO(4)center dot 5H(2)O with a methanol solution of the HQ proliganc1 (HQ= 1-R(1)-4-R(2)(C=O)pyrazol-5-one in general, in detail: HQ(nPe), R(I) = phenyl, R(2) = neopentyl; HQ(Me.Me), R(I) = R(2)= methyl; HQ(Me.naph), methyl, R(2) = naphthalen-1-yl; HQ(naph), R(1) = phenyl, R(2) = naphthalen-1-yl; HQ(PH), R(1) = R(2) = phenyl; HQ(CF3), R(1) = phenyl, R(2) = trifluoromethyl; HQ(py.CF3), R(1) = pyriclin-2-yl, R(2) = trifluoromethyl) gave seven novel VO(Q)(2)(H(2)O) complexes which have been characterized by elemental analyses, IR, ESI-MS, electronic spectroscopy and magnetic susceptibility measurements and, in the case of derivative VO(Q(CF3))(2), also by EPR spectroscopy. The X-ray diffraction study, carried out on derivative VO(Q(nPe))(2)(H(2)O), evidenced a distorted octahedral environment with the two pyrazolonates in anti configuration and the vanadium atom 0.2914(7)angstrom away from the least-squares plane defined by the four equatorial oxygen atoms. The catalytic activity of these new oxovanadium(IV) complexes has been exhaustively tested for the oxidation of styrene, alpha-methylstyrene and cis-beta-methylstyrene, in the presence of H(2)O(2) as primary oxidant. The effects of oxidant to substrate molar ratio, catalyst amount, solvent and temperature have been studied. Overall, the vanadium complexes showed high activity and high to moderate selectivity toward the benzaldehyde (acetophenone) formation, depending from both the type of starting substrate and experimental reaction times. (C) 2010 Elsevier B.V. All rights reserved.

Synthesis and characterization of novel Oxovanadium(IV) complexes with 4-acyl-5-pyrazolone donor ligands: evaluation of their Catalytic Properties in the H2O2 promoted Selective Oxidation of Styrene derivatives

CRUCIANELLI, MARCELLO;A. DI GIUSEPPE
2010

Abstract

Reaction of VOSO(4)center dot 5H(2)O with a methanol solution of the HQ proliganc1 (HQ= 1-R(1)-4-R(2)(C=O)pyrazol-5-one in general, in detail: HQ(nPe), R(I) = phenyl, R(2) = neopentyl; HQ(Me.Me), R(I) = R(2)= methyl; HQ(Me.naph), methyl, R(2) = naphthalen-1-yl; HQ(naph), R(1) = phenyl, R(2) = naphthalen-1-yl; HQ(PH), R(1) = R(2) = phenyl; HQ(CF3), R(1) = phenyl, R(2) = trifluoromethyl; HQ(py.CF3), R(1) = pyriclin-2-yl, R(2) = trifluoromethyl) gave seven novel VO(Q)(2)(H(2)O) complexes which have been characterized by elemental analyses, IR, ESI-MS, electronic spectroscopy and magnetic susceptibility measurements and, in the case of derivative VO(Q(CF3))(2), also by EPR spectroscopy. The X-ray diffraction study, carried out on derivative VO(Q(nPe))(2)(H(2)O), evidenced a distorted octahedral environment with the two pyrazolonates in anti configuration and the vanadium atom 0.2914(7)angstrom away from the least-squares plane defined by the four equatorial oxygen atoms. The catalytic activity of these new oxovanadium(IV) complexes has been exhaustively tested for the oxidation of styrene, alpha-methylstyrene and cis-beta-methylstyrene, in the presence of H(2)O(2) as primary oxidant. The effects of oxidant to substrate molar ratio, catalyst amount, solvent and temperature have been studied. Overall, the vanadium complexes showed high activity and high to moderate selectivity toward the benzaldehyde (acetophenone) formation, depending from both the type of starting substrate and experimental reaction times. (C) 2010 Elsevier B.V. All rights reserved.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11697/11906
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