Aromatic Hydrocarbons

Sheldon, Roger A.

doi:10.1016/b978-0-12-639380-4.50016-6

Cited by 17 publications

(12 citation statements)

References 44 publications

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“…Oxidation of Alkylbenzenes Using NHPI Combined with Co(acac) 2 . Various alkylbenzenes are known to be oxidized with dioxygen in the presence or absence of transition metals …”

Section: Resultsmentioning

confidence: 99%

“…The same oxidation with 26 by NHPI alone produced only a trace amount of 27 (run 2). Toluene ( 26 ) has been reported to be oxidized with air in the presence of cobalt(II) 2-ethylhexanoate at 140−190 °C and up to 10 atm of pressure to give 27 in about a 80% yield at 40−65% conversion 15a. Consequently, the NHPI/Co(acac) 2 system is thought to be a useful catalytic system for the aerobic oxidation of 26 .…”

Section: Resultsmentioning

confidence: 99%

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Alkane Oxidation with Molecular Oxygen Using a New Efficient Catalytic System: N-Hydroxyphthalimide (NHPI) Combined with Co(acac)_n(n= 2 or 3)

et al. 1996

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A novel class of catalysts for alkane oxidation with molecular oxygen was examined. N-Hydroxyphthalimide (NHPI) combined with Co(acac)(n)() (n = 2 or 3) was found to be an efficient catalytic system for the aerobic oxidation of cycloalkanes and alkylbenzenes under mild conditions. Cycloalkanes were successfully oxidized with molecular oxygen in the presence of a catalytic amount of NHPI and Co(acac)(2) in acetic acid at 100 degrees C to give the corresponding cycloalkanones and dicarboxylic acids. Alkylbenzenes were also oxidized with dioxygen using this catalytic system. For example, toluene was converted into benzoic acid in excellent yield under these conditions. Ethyl- and butylbenzenes were selectively oxidized at their alpha-positions to form the corresponding ketones, acetophenone, and 1-phenyl-1-butanone, respectively, in good yields. A key intermediate in this oxidation is believed to be the phthalimide N-oxyl radical generated from NHPI and molecular oxygen using a Co(II) species. The isotope effect (k(H)/k(D)) in the oxidation of ethylbenzene and ethylbenzene-d(10) with dioxygen using NHPI/Co(acac)(2) was 3.8.

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“…Oxidation of Alkylbenzenes Using NHPI Combined with Co(acac) 2 . Various alkylbenzenes are known to be oxidized with dioxygen in the presence or absence of transition metals …”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Alkane Oxidation with Molecular Oxygen Using a New Efficient Catalytic System: N-Hydroxyphthalimide (NHPI) Combined with Co(acac)_n(n= 2 or 3)

et al. 1996

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“…When a catalyst is used, the following redox mechanism is also involved: , The presence of catalysts enhances both propagation through the formation of alkoxy radicals (reaction 5) and decomposition of the hydroperoxides (reaction 6). The effectiveness of the catalyst according to the above redox mechanism is closely linked to the redox potential of the Me n + /Me ( n -1)+ couple.…”

Section: Discussionmentioning

confidence: 99%

Alumina-Supported Noble Metal Catalysts for Destructive Oxidation of Organic Pollutants in Effluent from a Softwood Kraft Pulp Mill

Chuang

1998

Ind. Eng. Chem. Res.

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The effectiveness of alumina-supported noble metal catalysts for the destructive oxidation of organic pollutants in effluent from a softwood kraft pulp mill was evaluated in a slurry reactor at 463 K and an oxygen pressure of 1.5 MPa. The effects of catalyst preparation procedures, such as metal loading, calcination, or reduction treatment on the catalytic activities, were also tested. Alumina-supported palladium catalysts were found to be more effective than supported manganese, iron, or platinum catalysts. The rate of oxidation over Pd/alumina catalyst was significantly higher than that of the uncatalyzed reaction. Adding Ce on the alumina support was found to promote the activity of alumina-supported Pt catalyst but inhibit the activity of alumina-supported Pd catalyst. The reaction mechanisms for the catalytic wet oxidation process and the roles of Ce on catalytic activity for destructive oxidation of organic pollutants in wastewater are discussed.

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“…Phenol is an industrially valuable precursor material used to synthesize several chemical products. − Currently, it is manufactured only by a three-step cumene process from benzene and dioxygen (O 2 ) as oxidants, where the overall yield of phenol is ∼5%. − Phenol is also produced by the sulfonation and Dow processes. The main disadvantages of these processes are poor atom economy and high reaction temperature and pressure.…”

Section: Introductionmentioning

confidence: 99%

Benzene Hydroxylation by Bioinspired Copper(II) Complexes: Coordination Geometry versus Reactivity

et al. 2020

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A series of bioinspired copper(II) complexes of N 4 -tripodal and sterically crowded diazepane-based ligands have been investigated as catalysts for functionalization of the aromatic C−H bond. The tripodalligand-based complexes exhibited distorted trigonal-bipyramidal (TBP) geometry (τ, 0.70) around the copper(II) center; however, diazepaneligand-based complexes adopted square-pyramidal (SP) geometry (τ, 0.037). The Cu−N Py bonds (2.003−2.096 Å) are almost identical and shorter than Cu−N amine bonds (2.01−2.148 Å). Also, their Cu−O (Cu− O water , 1.988 Å; Cu−O triflate , 2.33 Å) bond distances are slightly varied. All of the complexes exhibited Cu 2+ → Cu + redox couples in acetonitrile, where the redox potentials of TBP-based complexes (−0.251 to −0.383 V) are higher than those of SP-based complexes (−0.450 to −0.527 V). The d−d bands around 582−757 nm and axial patterns of electron paramagnetic resonance spectra [g ∥ , 2.200−2.251; A ∥ , (146−166) × 10 −4 cm −1 ] of the complexes suggest the existence of five-coordination geometry. The bonding parameters showed K ∥ > K ⊥ for all complexes, corresponding to out-ofplane π bonding. The complexes catalyzed direct hydroxylation of benzene using 30% H 2 O 2 and afforded phenol exclusively. The complexes with TBP geometry exhibited the highest amount of phenol formation (37%) with selectivity (98%) superior to that of diazepane-based complexes (29%), which preferred to adopt SP-based geometry. Hydroxylation of benzene likely proceeded via a Cu II -OOH key intermediate, and its formation has been established by electrospray ionization mass spectrometry, vibrational, and electronic spectra. Their formation constants have been calculated as (2.54−11.85) × 10 −2 s −1 from the appearance of an O (π* σ ) → Cu ligand-to-metal charge-transfer transition around 370−390 nm. The kinetic isotope effect (KIE) experiments showed values of 0.97−1.12 for all complexes, which further supports the crucial role of Cu-OOH in catalysis. The 18 O-labeling studies using H 2 18 O 2 showed a 92% incorporation of 18 O into phenol, which confirms H 2 O 2 as the key oxygen supplier. Overall, the coordination geometry of the complexes strongly influenced the catalytic efficiencies. The geometry of one of the Cu II -OOH intermediates has been optimized by the density functional theory method, and its calculated electronic and vibrational spectra are almost similar to the experimentally observed values.

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Aromatic Hydrocarbons

Cited by 17 publications

References 44 publications

Alkane Oxidation with Molecular Oxygen Using a New Efficient Catalytic System: N-Hydroxyphthalimide (NHPI) Combined with Co(acac)_n(n= 2 or 3)

Alkane Oxidation with Molecular Oxygen Using a New Efficient Catalytic System: N-Hydroxyphthalimide (NHPI) Combined with Co(acac)_n(n= 2 or 3)

Alumina-Supported Noble Metal Catalysts for Destructive Oxidation of Organic Pollutants in Effluent from a Softwood Kraft Pulp Mill

Benzene Hydroxylation by Bioinspired Copper(II) Complexes: Coordination Geometry versus Reactivity

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Aromatic Hydrocarbons

Cited by 17 publications

References 44 publications

Alkane Oxidation with Molecular Oxygen Using a New Efficient Catalytic System: N-Hydroxyphthalimide (NHPI) Combined with Co(acac)n(n= 2 or 3)

Alkane Oxidation with Molecular Oxygen Using a New Efficient Catalytic System: N-Hydroxyphthalimide (NHPI) Combined with Co(acac)n(n= 2 or 3)

Alumina-Supported Noble Metal Catalysts for Destructive Oxidation of Organic Pollutants in Effluent from a Softwood Kraft Pulp Mill

Benzene Hydroxylation by Bioinspired Copper(II) Complexes: Coordination Geometry versus Reactivity

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Product

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Alkane Oxidation with Molecular Oxygen Using a New Efficient Catalytic System: N-Hydroxyphthalimide (NHPI) Combined with Co(acac)_n(n= 2 or 3)

Alkane Oxidation with Molecular Oxygen Using a New Efficient Catalytic System: N-Hydroxyphthalimide (NHPI) Combined with Co(acac)_n(n= 2 or 3)