Magnetic field effects on the catalytic oxidation of 2,6-di-tert-butylphenol

Perito, Richard P.; Corden, Barry B.

doi:10.1021/ja00248a061

Cited by 13 publications

(2 citation statements)

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“…Though it is clear that at least some metalloporphyrins remain paramagnetic, the reduction in the paramagnetic shifts may be an indicator of antiferomagnetically coupled oxo-bridged dimers. [77] In principle these oxidation reactions can be influenced by a magnetic field if there are paramagnetic species, porphyrin or organic intermediate, in the rate-determining step in the reaction mechanism,[78, 79] but we observed no differences in the product ratios between reactions stirred magnetically (ca. 800 G) or mechanically by a shaker.…”

Section: Resultsmentioning

confidence: 74%

Enhanced Catalytic Activity and Unexpected Products from the Oxidation of Cyclohexene by Organic Nanoparticles of 5,10,15,20‐Tetrakis‐(2,3,4,5,6‐pentafluorophenyl)porphyrinatoiron(III) in Water by Using O₂

Smeureanu

Aggarwal

Soll

et al. 2009

Chemistry A European J

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The catalytic oxidation of alkenes by most iron porphyrins using a variety of oxygen sources, but generally not dioxygen, yields the epoxide with minor quantities of other products. The turnover numbers for these catalysts are modest, ranging from a few hundred to a few thousand depending on the porphyrin structure, axial ligands, and other reaction conditions. Halogenation of substituents increases the activity of the metalloporphyrin catalyst and/or makes it more robust to oxidative degradation. Oxidation of cyclohexene by 5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorophenyl) (tppf 20 )] with a diameter of 10 nm, formed by host-guest solvent methods, catalytically oxidize cyclohexene with O 2 to yield only 2-cyclohexene-1-one and 2-cyclohexene-1-ol with approximately 10-fold greater turnover numbers compared to the non-aggregated metalloporphyrin in acetonitrile/methanol. These ONPs facilitate a greener reaction because the reaction solvent is 89% water and O 2 is the oxidant in place of synthetic oxygen sources. This reactivity is unexpected because the metalloporphyrins are in close proximity and oxidative degradation of the catalyst should be enhanced, thus causing a significant decrease in catalytic turnovers. The allylic products suggest a different oxidative mechanism compared to that of the solvated metalloporphyrins. These results illustrate the unique properties of some ONPs relative to the component molecules or those attached to supports.

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Section: Resultsmentioning

confidence: 74%

Enhanced Catalytic Activity and Unexpected Products from the Oxidation of Cyclohexene by Organic Nanoparticles of 5,10,15,20‐Tetrakis‐(2,3,4,5,6‐pentafluorophenyl)porphyrinatoiron(III) in Water by Using O₂

Smeureanu

Aggarwal

Soll

et al. 2009

Chemistry A European J

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“…It is worthwhile to mention in this section the MFE study in the dark oxidation reactions of 2,6-dialkylphenols into p-quinones and diphenoquinones catalyzed by Co(II) (S = 3/2; V2) and Mn(II) (S = 5/2). [187][188][189] The singlet RP, which has a metal-centered radical is formed in a magnetosensitive step. The analysis of field dependences in the spirit of ref 180 (see above) enables one to estimate relative contributions of SOC and HFC to S-T evolution of the RP under investigation.…”

Section: [3*"x1mentioning

confidence: 99%

Spin-orbit coupling in free-radical reactions: on the way to heavy elements

Khudyakov¹,

Serebrennikov²,

Turro³

1993

Chem. Rev.

192

191

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Spin-catalysis phenomena

Минаев

Ågren

1996

Int. J. Quantum Chem.

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DOn the grounds of results from quantum chemical calculations, we introduce spin-catalysis as a new concept, and classify different types of chemical reactions according to this concept. We propose a general definition of spin-catalysis as phenomena in which chemical reactions are promoted by substances which assist in overcoming spinprohibition or in which the activation barrier is lowered through spin uncoupling induced by a paramagnetic catalyst. A number of known phenomena fall into this definition and can be classified according to two main categories: (1) spin-orbit coupling induced and (2) paramagnetic-exchange induced spin-catalysis. Other types of spincatalysis are also discussed: (3) processes with participation of substances which assist in (a) photochemical and Cb) thermal or electrochemical generation of active particles by energy and-by electron transfer [radicals, diradicals, O,(' La,1, etc.], reacting further without spin-prohibition: (4) processes induced by an external magnetic field. Processes (3) and (4) are quite general and well known; their inclusion in the spin-catalysis classification does not introduce any new findings for the chemical kinetics, but the general features, which unite them with the important catalytic processes of the first two types, serve as a useful guide in catalysis theory. Few models of spin-catalytic processes have been simulated for the purpose of illuminating the principles of spin-catalysis; the cis-trans isomerization of ethylene catalyzed by molecular oxygen, the external heavy atom effect in ethylene photochemistry, and some others.

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Magnetic field effects on the catalytic oxidation of 2,6-di-tert-butylphenol

Cited by 13 publications

References 0 publications

Enhanced Catalytic Activity and Unexpected Products from the Oxidation of Cyclohexene by Organic Nanoparticles of 5,10,15,20‐Tetrakis‐(2,3,4,5,6‐pentafluorophenyl)porphyrinatoiron(III) in Water by Using O₂

Enhanced Catalytic Activity and Unexpected Products from the Oxidation of Cyclohexene by Organic Nanoparticles of 5,10,15,20‐Tetrakis‐(2,3,4,5,6‐pentafluorophenyl)porphyrinatoiron(III) in Water by Using O₂

Spin-orbit coupling in free-radical reactions: on the way to heavy elements

Spin-catalysis phenomena

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Magnetic field effects on the catalytic oxidation of 2,6-di-tert-butylphenol

Cited by 13 publications

References 0 publications

Enhanced Catalytic Activity and Unexpected Products from the Oxidation of Cyclohexene by Organic Nanoparticles of 5,10,15,20‐Tetrakis‐(2,3,4,5,6‐pentafluorophenyl)porphyrinatoiron(III) in Water by Using O2

Enhanced Catalytic Activity and Unexpected Products from the Oxidation of Cyclohexene by Organic Nanoparticles of 5,10,15,20‐Tetrakis‐(2,3,4,5,6‐pentafluorophenyl)porphyrinatoiron(III) in Water by Using O2

Spin-orbit coupling in free-radical reactions: on the way to heavy elements

Spin-catalysis phenomena

Contact Info

Product

Resources

About

Enhanced Catalytic Activity and Unexpected Products from the Oxidation of Cyclohexene by Organic Nanoparticles of 5,10,15,20‐Tetrakis‐(2,3,4,5,6‐pentafluorophenyl)porphyrinatoiron(III) in Water by Using O₂

Enhanced Catalytic Activity and Unexpected Products from the Oxidation of Cyclohexene by Organic Nanoparticles of 5,10,15,20‐Tetrakis‐(2,3,4,5,6‐pentafluorophenyl)porphyrinatoiron(III) in Water by Using O₂