Oxidations of C–H Compounds Catalyzed by Metal Complexes

Shul’pin, Georgiy B.

doi:10.1002/9783527619405.ch5b

Cited by 58 publications

(48 citation statements)

References 186 publications

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“…Direct conversion of largely available alkanes into more valuable products is a subject of great interest. − An example with industrial significance concerns the oxidation products of cyclohexane, cyclohexanol, and cyclohexanone since they are used for production of adipic acid and caprolactame involved in the manufacture of nylon-6,6′ and nylon-6, respectively. − The industrial process uses homogeneous cobalt(III)–naphtalenate as catalyst and dioxygen as oxidant at high temperature (150 °C), forming cyclohexanone in low yield (4%) to achieve good selectivity (85%). Hence, alternative approaches to transform alkane efficiently and selectively under relatively mild conditions are necessary.…”

Section: Hemicryptophanes: Supramolecular Catalystsmentioning

confidence: 99%

Emergence of Hemicryptophanes: From Synthesis to Applications for Recognition, Molecular Machines, and Supramolecular Catalysis

2017

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In the wide area of host-guest chemistry, hemicryptophanes, combining a cyclotribenzylene (or cyclotriveratrylene CTV) unit with another different C-symmetrical moiety, appears as a recent family of molecular cages. The synthesis and recognition properties of the first hemicryptophane were reported in 1982 by Collet and Lehn, but the very little attention received by this class of host compounds in the 20 years following this first promising result can account for their apparent novelty. Indeed, in the last 10 years hemicryptophanes have aroused growing interest, and new aspects have been developed. Thanks to the rigid shaping unit of the north part (CTV) and also the variable and easily functionalized south moiety, hemicryptophanes are revealed to be inherently chiral ditopic host compounds, able to encapsulate various guests, including charged and neutral species. They also enter the field of stimuli-responsive supramolecular systems exhibiting controlled functions. Moreover, endohedral functionalization of their inner cavity leads to supramolecular catalysts. The confinement of the catalytic center affords nanoreactors with improved catalytic activities or selectivities when compared to model systems without a cavity. The current trend shows that reactions in the confined space of synthetic hosts, mimicking enzyme behavior, will expand rapidly in the near future.

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Section: Hemicryptophanes: Supramolecular Catalystsmentioning

confidence: 99%

Emergence of Hemicryptophanes: From Synthesis to Applications for Recognition, Molecular Machines, and Supramolecular Catalysis

2017

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“…A radical mechanism of ) in the open circuit were not taken into account. In this regard, the authors considered that it is necessary to give here a corrected expression for the decomposition rate of hydrogen peroxide, taking into account both reactions (i3) and (6 ). The analysis of the reaction mechanism presented in Scheme 1 in the quasistationary approximation with respect to the concentration of chain carriers Fe 2+ , OH, and HO 2 (O 2 −• ) led to Expression (A) for the rate of decomposition of H 2 O 2 .…”

Section: (A)mentioning

confidence: 99%

“…Compounds of iron, copper, manganese, chromium, vanadium, and some other transition metals showed high catalytic activity in the oxidation of hydrocarbons with peroxides. The saturated nature and high chemical inertness of alkanes create noticeable difficulties in their activation; therefore, the interaction of both saturated and unsaturated C-H compounds with metal complexes is an extremely interesting theoretical problem [1][2][3][4][5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Metal Complexes Containing Redox-Active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review

2019

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Ligands are innocent when they allow oxidation states of the central atoms to be defined. A noninnocent (or redox) ligand is a ligand in a metal complex where the oxidation state is not clear. Dioxygen can be a noninnocent species, since it exists in two oxidation states, i.e., superoxide (O2−) and peroxide (O22−). This review is devoted to oxidations of C–H compounds (saturated and aromatic hydrocarbons) and alcohols with peroxides (hydrogen peroxide, tert-butyl hydroperoxide) catalyzed by complexes of transition and nontransition metals containing innocent and noninnocent ligands. In many cases, the oxidation is induced by hydroxyl radicals. The mechanisms of the formation of hydroxyl radicals from H2O2 under the action of transition (iron, copper, vanadium, rhenium, etc.) and nontransition (aluminum, gallium, bismuth, etc.) metal ions are discussed. It has been demonstrated that the participation of the second hydrogen peroxide molecule leads to the rapture of O–O bond, and, as a result, to the facilitation of hydroxyl radical generation. The oxidation of alkanes induced by hydroxyl radicals leads to the formation of relatively unstable alkyl hydroperoxides. The data on regioselectivity in alkane oxidation allowed us to identify an oxidizing species generated in the decomposition of hydrogen peroxide: (hydroxyl radical or another species). The values of the ratio-of-rate constants of the interaction between an oxidizing species and solvent acetonitrile or alkane gives either the kinetic support for the nature of the oxidizing species or establishes the mechanism of the induction of oxidation catalyzed by a concrete compound. In the case of a bulky catalyst molecule, the ratio of hydroxyl radical attack rates upon the acetonitrile molecule and alkane becomes higher. This can be expanded if we assume that the reactions of hydroxyl radicals occur in a cavity inside a voluminous catalyst molecule, where the ratio of the local concentrations of acetonitrile and alkane is higher than in the whole reaction volume. The works of the authors of this review in this field are described in more detail herein.

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“…Organic and inorganic peroxides and especially hydrogen peroxide are widely employed for the oxidation of various organic compounds. Alkanes are also among these organic substrates, although saturated hydrocarbons exhibit very high inertness in reactions in solutions under mild conditions [1][2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

New Oxidovanadium(IV) Complexes with 2,2′-bipyridine and 1,10-phenathroline Ligands: Synthesis, Structure and High Catalytic Activity in Oxidations of Alkanes and Alcohols with Peroxides

et al. 2019

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Reactions of [VCl3(thf)3] or VBr3 with 2,2′-bipyridine (bpy) or 1,10-phenanthroline (phen) in a 1:1 molar ratio in air under solventothermal conditions has afforded polymeric oxidovanadium(IV) four complexes 1–4 of a general formula [VO(L)X2]n (L = bpy, phen and X = Cl, Br). Monomeric complex [VO(DMF)(phen)Br2] (4a) has been obtained by the treatment of compound 4 with DMF. The complexes were characterized by IR spectroscopy and elemental analysis. The crystal structures of 3 and 4a were determined by an X-ray diffraction (XRD) analysis. The {VOBr2(bpy)} fragments in 3 form infinite chains due to the V = O…V interactions. The vanadium atom has a distorted octahedral coordination environment. Complexes 1–4 have been tested as catalysts in the homogeneous oxidation of alkanes (to produce corresponding alkyl hydroperoxides which can be easily reduced to alcohols by PPh3) and alcohols (to corresponding ketones) with H2O2 or tert-butyl hydroperoxide in MeCN. Compound 1 exhibited the highest activity. The mechanism of alkane oxidation was established using experimental selectivity and kinetic data and theoretical DFT calculations. The mechanism is of the Fenton type involving the generation of HO• radicals.

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Oxidations of C–H Compounds Catalyzed by Metal Complexes

Abstract: For Abstract see ChemInform Abstract in Full Text.

Cited by 58 publications

References 186 publications

Emergence of Hemicryptophanes: From Synthesis to Applications for Recognition, Molecular Machines, and Supramolecular Catalysis

Emergence of Hemicryptophanes: From Synthesis to Applications for Recognition, Molecular Machines, and Supramolecular Catalysis

Metal Complexes Containing Redox-Active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review

New Oxidovanadium(IV) Complexes with 2,2′-bipyridine and 1,10-phenathroline Ligands: Synthesis, Structure and High Catalytic Activity in Oxidations of Alkanes and Alcohols with Peroxides

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