Catalytic Oxidation of Alkylbenzenes with Molecular Oxygen under Normal Pressure and Temperature by <i>N</i>-Hydroxyphthalimide Combined with Co(OAc)<sub>2</sub>

Yoshino, Yūji; Hayashi, Yoshiaki; Iwahama, Takahiro; Sakaguchi, Satoshi; Ishii, Yasutaka

doi:10.1021/jo9708147

Cited by 308 publications

(176 citation statements)

References 35 publications

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“…[29] For example, the selective autoxidation of adamantane to adamantanediol [28] and/or -triol [Equation (3)] in the presence of a catalyst Table 1. O À H bond dissociation energies ( BDE ) in N-substituted hydroxylamines.…”

Section: ð2þmentioning

confidence: 99%

Organocatalytic Oxidations Mediated by Nitroxyl Radicals

2004

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The use of nitroxyl radicals, alone or in combination with transition metals, as catalysts in oxidation processes is reviewed from both a synthetic and a mechanistic viewpoint. Two extremes of reactivity can be distinguished: stable (persistent) dialkylnitroxyls, such as the archetypal TEMPO, and reactive diacylnitroxyls, derived from N-hydroxy imides, such as N-hydroxyphthalimide (NHPI). The different types of reactivity observed are rationalized by considering the bond dissociation energies (BDEs) of the respective N-hydroxy precursors, substrates and reaction intermediates. Reactive diacylnitroxyl radicals are generated in situ from the corresponding N-hydroxy compound. The protagonist, NHPI, catalyzes a wide variety of free radical autoxidations, improving both activities and selectivities by increasing the rate of chain propagation and/or decreasing the rate of chain termination. In the absence of metal co-catalysts improved conversions and selectivities are obtained in the autoxidation of hydrocarbons to the corresponding alkyl hydroperoxides. For example, cyclohexylbenzene afforded the 1-hydroperoxide in 97.6% selectivity at 32% conversion when the autoxidation was performed in the presence of 0.5 mol % NHPI, and the product hydroperoxide as initiator, at 100 8C. This forms the basis for a potential coproduct-free route from benzene to phenol. In combination with transition metal co-catalysts, notably cobalt, NHPI and related compounds, such as N-hydroxysaccharin NHS, afford effective catalytic systems for the effective autoxidation of hydrocarbons, e.g., toluenes to carboxylic acids, under mild conditions. In the case of the less reactive cycloalkanes, NHS proved to be a more active catalyst than NHPI which is attributed to the higher reactivity of the intermediate nitroxyl radical, resulting from the replacement of a carbonyl group in NHPI by the more strongly electron-attracting sulfonyl group. Stable dialkylnitroxyl radicals, exemplified by TEMPO, catalyze oxidations of, e.g., alcohols, with single oxygen donors such as hypochlorite and organic peracids. The reactions involve the intermediate formation of the corresponding oxoammonium cation as the active oxidant. Alternatively, in conjunction with transition metals, notably ruthenium and copper, they catalyze aerobic oxidations of alcohols. These reactions involve metal-centered dehydrogenations and the role of the TEMPO is to facilitate regeneration of the catalyst (Ru and Cu) and oxidation of the alcohol (Cu) via hydrogen abstraction or one-electron oxidation processes. Detailed mechanistic investigations, including kinetic isotope effects, revealed that oxoammonium cations are not involved as intermediates in these reactions. In contrast, oxoammonium cations are involved in the aerobic oxidation of alcohols catalyzed by the copper-dependent oxidase, laccase, in combination with TEMPO. This different mechanistic pathway is attributed to the much higher redox potential of the copper(II) in the enzyme. Similarly, N-hydroxy compounds such as ...

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Section: ð2þmentioning

confidence: 99%

Organocatalytic Oxidations Mediated by Nitroxyl Radicals

2004

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“…[1][2][3][4][5][6][7][8] Cobalt complexes have received much attention recently due to the potential application of these complexes as oxidation catalysts for the oxidation of cyclic althenes, enolizable aldehydes, secondary alcohols, and other organic substrates. 9 -14 Previously we reported the synthesis and catalytic properties of a series of polymerbound iron, copper, and ruthenium complexes.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and catalytic oxidation properties of polymer‐bound cobalt complexes

Lei

Han

et al. 2000

J. Appl. Polym. Sci.

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Polymer-bound 2,2Ј-bipyridine cobalt complexes PSBPY-Co, PSBPY-Cobipy, PSBPY-Co-oxine, and PSBPY-Co-phen (where PSBPY: polystyrene bound-2,2Ј-bipyridine; bipy: 2,2Ј-bipyridine; phen: 1,10-phenanthroline) were synthesized and investigated by IR, X-ray photoelectric spectroscopy, thermogravimetry-differential thermal analysis, inductively coupled plasma atomic emission spectrometry, and elemental analysis. The complexes were found to be catalysts for the oxidation of alkylbenzenes and cyclohexene in the presence of molecular oxygen in the absence of solvent.

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“…Recently, it has been used as a catalyst in oxidation processes, via the phthalimide N-oxyl radical [5] (known as PINO). The PINO radical can be obtained in several ways [5][6][7], and has an important role in the oxidation of a large variety of compounds, including aliphatic hydrocarbons [7,8], alkylbenzenes [9,10], alcohols and aliphatic amines [11,12], benzylamines [13], N-alkylamides [14], etc. O-Substituted hydroxylamines have found applications in medicinal chemistry, having antihistaminic and bactericidal properties, as well as being used as prophylactic chemicals in protecting animals against ionizing radiations [15,16].…”

Section: Introductionmentioning

confidence: 99%

New N-aryloxy-phthalimide derivatives. Synthesis, physico-chemical properties, and QSPR studies

Tudose¹,

Badea

Cãproiu³

et al. 2010

Open Chemistry

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Abstract:Starting from N-hydroxyphthalimide 1 and the reactive fluoro-or chloro-nitroaryl derivatives 2, 3 and 4a-e (2-chloro-3,5-dinitropyridine; 3, NBD-chloride; 4a, 1-fluoro-2,4-dinitrobenzene; 4b, picryl chloride; 4c, 4-chloro-3,5-dinitrobenzotrifluoride; 4d, 2-chloro-3,5-dinitrobenzotrifluoride; 4e, 4-chloro-3,5-dinitrobenzoic acid) the corresponding N-(2-nitroaryloxy)-phthalimide derivatives 5a-e, or 6 and 7 were obtained and characterized by IR, UV-Vis 1 H-NMR and 13 C-NMR spectroscopy. The TLC behavior and the hydrophobicity of these derivatives have been experimentally evaluated by R M0 parameters (using RP-TLC). The experimental R M0 parameters were compared with the calculated partition coefficient, log P. A QSPR study was also performed to establish possible correlations between the structure and physical properties (λ max and R M0 ) of compounds 5a-e, 6, and 7.

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Catalytic Oxidation of Alkylbenzenes with Molecular Oxygen under Normal Pressure and Temperature by N-Hydroxyphthalimide Combined with Co(OAc)₂

Cited by 308 publications

References 35 publications

Organocatalytic Oxidations Mediated by Nitroxyl Radicals

Organocatalytic Oxidations Mediated by Nitroxyl Radicals

Synthesis and catalytic oxidation properties of polymer‐bound cobalt complexes

New N-aryloxy-phthalimide derivatives. Synthesis, physico-chemical properties, and QSPR studies

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Catalytic Oxidation of Alkylbenzenes with Molecular Oxygen under Normal Pressure and Temperature by N-Hydroxyphthalimide Combined with Co(OAc)2

Cited by 308 publications

References 35 publications

Organocatalytic Oxidations Mediated by Nitroxyl Radicals

Organocatalytic Oxidations Mediated by Nitroxyl Radicals

Synthesis and catalytic oxidation properties of polymer‐bound cobalt complexes

New N-aryloxy-phthalimide derivatives. Synthesis, physico-chemical properties, and QSPR studies

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Product

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Catalytic Oxidation of Alkylbenzenes with Molecular Oxygen under Normal Pressure and Temperature by N-Hydroxyphthalimide Combined with Co(OAc)₂