Effective catalysis of simple metalloporphyrins for cyclohexane oxidation with air in the absence of additives and solvents

Guo, Can‐Cheng; Chu, Ming-Fu; Liu, Qiang; Liu, Yang; Guo, Dong-Cai; Liu, Xiaoqin

doi:10.1016/s0926-860x(03)00061-9

Cited by 130 publications

(43 citation statements)

References 34 publications

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“…As the conversion (ca. 6%) is also similar to that obtained from current industrial processes [11,12], this makes MB a promising catalytic system for the oxidation of cyclohexane. Indeed, this is a crucial step for the manufacture of nylon fibres, with cylohexanol used as precursor for nylon-6,6 and cylohexanone as precursor for nylon-6.…”

Section: Introductionsupporting

confidence: 80%

Insights into the Reaction Mechanism of Cyclohexane Oxidation Catalysed by Molybdenum Blue Nanorings

et al. 2015

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Molybdenum blue (MB), is a polyoxometalate with a nanoring structure comprising Mo 5+ -OMo 6+ bridges, which is active for the catalytic oxidation of cyclohexane to cyclohexanol and cyclohexanone. However, little is known about the mechanistic features responsible of this catalytic activity. In the present work, the Mo 5+ -O-Mo 6+ moieties embedded in the MB nanoring structure were characterized using diffuse reflectance-UV-Visible spectroscopy and solid state EPR spectroscopy. The amount of Mo 5+ centres was then varied by thermal treatment of the polyoxometalate in the absence of oxygen, and the resultant effect on the catalytic activity was investigated. It was observed that, an increased amount of Mo 5+ centres preserved the conversion of cyclohexane (ca. 6%) but led to a loss of selectivity to cyclohexanol giving cyclohexanone as the major product, and the simultaneous formation of adipic acid. To rationalise these results the catalysts were studied using EPR spin trapping to investigate the decomposition of cyclohexyl hydroperoxide (CHHP), a key intermediate in the oxidation process of cyclohexane. This analysis showed that CHHP has to be bound to the MB surface in order to explain its catalytic activity and product distribution.

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Section: Introductionsupporting

confidence: 80%

Insights into the Reaction Mechanism of Cyclohexane Oxidation Catalysed by Molybdenum Blue Nanorings

et al. 2015

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“…meso-Tetraarylporphyrin-derived systems are the most popular synthetic porphyrin class because of their facile synthesis and derivatization [9,10]. Cobalt(II)/(III) complexes of meso-tetraarylporphyrins have been utilized as oxidation catalysts [1,11], small molecule activation and transfer catalysts [12], and as electro-catalyst in, for instance, the four-electron reduction of dioxygen [13,14].…”

mentioning

confidence: 99%

Axial Imidazole Binding Strengths in Porphyrinoid Cobalt(III) Complexes as Studied by Tandem Mass Spectrometry

Mishra

Worlinsky

Gilbert

et al. 2012

J. Am. Soc. Mass Spectrom.

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The Co(II) complexes of twelve meso-tetraaryl-porphyrins, -chlorins, and chlorin analogues containing non-pyrrolic heterocycles were synthesized and converted in situ to the corresponding Co(III) complexes coordinated to one or two imidazoles. Electrospray ionization tandem mass spectrometry (ESI-MS/MS) in conjunction with the energy-variable collision-induced dissociation (CID) technique was used to compare the relative gas-phase binding strength of the axially coordinated imidazoles to the octahedral and square planar Co(III) porphyrinoid complex ions. The observed binding energies of these ligands were rationalized in terms of the effects of porphyrinoid core structure and meso-substitution on the electron density on the central Co(III) centers. Some of these trends were supported by DFT-based computational studies. The study highlights to which extend porphyrins vary from chlorins and chlorin analogues in their coordination abilities and to which extraordinary degree meso-thienyl-substituents influence the electronic structure of porphyrins. The study also defines further the scope and limits CID experiments can be used to interrogate the electronic structures of metalloporphyrin complexes.

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“…During the last several decades, a vast amount of work has shown that substituted metallo-porphyrins are efficient catalysts for alkane oxidations by molecular oxygen or air without co-catalysts or stoichiometric oxidants to give alcohols and/or carbonyl compounds at unprecedented rates under very mild conditions (Guo et al, 2003). However, there still exists a great distance from the industrial application of metalloporphyrin catalysts because of their defects, including low catalytic activity, poor stability and troublesome recoverability.…”

Section: Metallo-deuteroporphyrin Derivativesmentioning

confidence: 99%

Synthesis of Metallo-Deuteroporphyrin Derivatives and the Study of Their Biomimetic Catalytic Properties

Hu¹,

Sun²,

Xu³

et al. 2011

On Biomimetics

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Effective catalysis of simple metalloporphyrins for cyclohexane oxidation with air in the absence of additives and solvents

Cited by 130 publications

References 34 publications

Insights into the Reaction Mechanism of Cyclohexane Oxidation Catalysed by Molybdenum Blue Nanorings

Insights into the Reaction Mechanism of Cyclohexane Oxidation Catalysed by Molybdenum Blue Nanorings

Axial Imidazole Binding Strengths in Porphyrinoid Cobalt(III) Complexes as Studied by Tandem Mass Spectrometry

Synthesis of Metallo-Deuteroporphyrin Derivatives and the Study of Their Biomimetic Catalytic Properties

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