New Insights into the Mechanisms of O−O Bond Cleavage of Hydrogen Peroxide andtert-Alkyl Hydroperoxides by Iron(III) Porphyrin Complexes

2000 ◽  
Vol 122 (36) ◽  
pp. 8677-8684 ◽  
Author(s):  
Wonwoo Nam ◽  
Hui Jung Han ◽  
So-Young Oh ◽  
Yoon Jung Lee ◽  
Mee-Hwa Choi ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Bond Cleavage ◽  
Alkyl Hydroperoxides

Spin trapping by use of nitrosodurene and its derivatives

1982 ◽  
Vol 60 (12) ◽  
pp. 1532-1541 ◽  
Author(s):  
Ryusei Konaka ◽  
Shigeru Terabe ◽  
Taiichi Mizuta ◽  
Shigeru Sakata
Keyword(s):  
Hydrogen Peroxide ◽  
Esr Spectra ◽  
Spin Trapping ◽  
Nitroso Compounds ◽  
Spin Adduct ◽  
Spin Traps ◽  
Spectral Pattern ◽  
Alkyl Radicals ◽  
Alkyl Hydroperoxides ◽  
Tert Butyl Hydroperoxide

In spin trapping the N-methyl-N-phenylaminomethyl radical with nitrosodurene, an esr spectmm exhibiting line width alternation was observed despite the normal spectral pattern found with the use of nitroso-tert-butane. Nitrosodurene derivatives, N-duryl nitrone and methyl N-duryl nitrone, have been revealed to be other excellent spin traps for the N-, 0-, and S-centered radicals. Spin adducts of these radicals, which can be independently prepared by spin trapping with nitrosodurene, are stable and can be easily discriminated by large differences in β-hydrogen splittings or characteristic patterns. Methyl N-duryl nitrone reacted with tert-butyl hydroperoxide to give a spin adduct which could be clearly distinguished in the esr spectra from the tert-butoxy adducts prepared independently from other sources. Accordingly, it seems to be the tert-butylperoxy adduct. Similarly, hydrogen peroxide gave a different spectrum from the hydroxy adducts. Alkyl hydroperoxides caused molecule-induced homolysis with the nitroso compounds to produce alkoxy adducts of the respective nitroso compounds. Some phenyl and duryl alkoxy nitroxides undergo decomposition to give alkyl radicals which were trapped by the nitroso compounds.

Reactivity of Hydrogen Peroxide, Alkyl Hydroperoxides, and Peracids

1992 ◽  
Author(s):  
Donald T. Sawyer ◽  
R. J. P. Williams
Keyword(s):  
Hydrogen Peroxide ◽  
Low Energy ◽  
Bond Energies ◽  
Alkyl Hydroperoxides

The reactivity of hydroperoxides is primarily dependent upon their unique bond energies (e.g., H-OOH, 90 kcal; HO-OH, 51 kcal; H-OOBu-t, 91 kcal, HO-OBu-t, 47 kcal), which allow low-energy rearrangements to give (HO·) and (·O·).

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

Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1046 ◽  
Author(s):  
Georgiy B. Shul’pin ◽  
Yuriy N. Kozlov ◽  
Lidia S. Shul’pina
Keyword(s):  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Hydroxyl Radicals ◽  
Oxidation States ◽  
Acetonitrile Molecule ◽  
Oxidation Of Hydrocarbons ◽  
Alkyl Hydroperoxides ◽  
Redox Active ◽  
Tert Butyl Hydroperoxide ◽  
Saturated And Aromatic Hydrocarbons

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.

Chemical Basis for High Activity in Oxygenation of Cyclohexane Catalyzed by Dinuclear Iron(III) Complexes with Ethereal Oxygen Containing Ligand and Hydrogen Peroxide System

1997 ◽  
Vol 52 (6) ◽  
pp. 719-727 ◽  
Author(s):  
Sayo Ito ◽  
Takashi Okuno ◽  
Hiroki Itoh ◽  
Shigeru Ohba ◽  
Hideaki Matsushima ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Oxygen Atom ◽  
Bond Cleavage ◽  
Structural Features ◽  
Active Species ◽  
Electronic Interaction ◽  
Ligand System ◽  
Dinuclear Iron ◽  
Binuclear Iron ◽  
Ethereal Oxygen

Abstract The crystal structures of two binuclear iron(III) complexes with linear μ-oxo bridge, Fe2OCl2 (tfpy)2 (ClO4)2 ·2CH3CN and Fe2OCl2(epy)2(ClO4)2 were determined, where (tfpy) and (epy) represent N,N-bis(2-pyridylmethyl)-tetrahydrofurfurylamine and N,N-bis(2-pyridylmethyl)-2-ethoxyethylamine, respectively. Their structural features are essentially the same as that of the corresponding linear binuclear complex with (tpa)-complex, Fe2OCl2(tpa)2(ClO4)2, where (tpa) is tris(2-pyridylmethyl)amine; the ligands (tfpy) and (epy) act as a tetradentate tripod-like ligand, and Fe-O (ethereal oxygen atom; these are located at the trans-position of bridging oxo-oxygen atom) distances are 2.209(4) and 2.264(2) Å for (tfpy) and (epy) compounds, respectively. These two (tfpy) and (epy) complexes exhibited much higher activity for the oxygenation of cyclohexane in the presence of hydrogen peroxide than that of the (tpa) complex. In contrast to this, the former two complexes exhibit negligible activity for the decomposition of hydrogen peroxide, whereas the catalase-like function of the (tpa) compound is remarkable. These are indicating that an active species for oxygenation of cyclohexane, which is assumed to be an iron(III)-hydroperoxide adduct with η1-coordina­tion mode, should be different from that is operating for decomposition of hydrogen perox­ide; for the latter case formation of a (μ-η1:η1-peroxo)diiron(III) species being stressed. The EHMO calculation showed that electronic interaction between the monodentate hydroperox­ide adduct of the binuclear iron(IIl)-(tfpy) compound and the tetrahydrofuran ring of the ligand system may lead to facile peroxide-tetrahydrofuran linkage formation, and the interac­tion described above should promote the O-O cleavage of the peroxide ion heterolytically. Based on these discussions, it was concluded that heterolytic O-O bond cleavage of the iron(III)-hydroperoxide adduct caused by electronic interaction with organic moiety contain­ing an ethereal-oxygen and by approach of the substrate which donates electron to the perox­ide adduct should play an important role in producing a high-valent iron-oxo species in these systems. In the case of (tpa) complex, formation of a hydroperoxide adduct linking with the ligand system seems to be unfavorable because of both the steric and electronic reasons.

PHOTOOXIDATION OF PROPIONALDEHYDE AT LOW PARTIAL PRESSURES OF ALDEHYDE

1966 ◽  
Vol 44 (24) ◽  
pp. 2973-2979 ◽  
Author(s):  
A. P. Altshuller ◽  
I. R. Cohen ◽  
T. C. Purcell
Keyword(s):  
Hydrogen Peroxide ◽  
Carbon Monoxide ◽  
Oxygen Molecule ◽  
Radical Mechanism ◽  
Alternative Mechanism ◽  
Alkyl Hydroperoxides ◽  
Free Radical Mechanism ◽  
Partial Pressures ◽  
Peroxy Acids ◽  
Radical Disproportionation

Propionaldehyde at partial pressures of from 0.0006 to 0.04 mm was photooxidized at 3 100 Å in the presence of 150 mm of oxygen. The major products were ethyl hydroperoxide and carbon monoxide. Acetaldehyde was formed at intermediate concentrations and formaldehyde, ethanol, methanol, hydrogen peroxide, and ethane were minor products. No ozone, peroxy acids, or diacyl peroxides could be detected.The results can be explained on the basis of a free-radical mechanism. Certain radical disproportionation reactions which are often postulated are unimportant because of the low partial pressures of propionaldehyde. An alternative mechanism involving direct chemical reaction of an oxygen molecule with the triplet state of the propionaldehyde may be of some significance, but cannot account for all of the products obtained. The present results indicate the importance of alkyl hydroperoxides as products in photooxidations at low partial pressures of aldehyde in the presence of large excesses of oxygen.

scholarly journals Kinetics of Oxidation of Cobalt(III) Complexes ofaAcids by Hydrogen Peroxide in the Presence of Surfactants

2008 ◽  
Vol 5 (1) ◽  
pp. 43-51 ◽  
Author(s):  
Mansur Ahmed ◽  
K. Subramani
Keyword(s):  
Hydrogen Peroxide ◽  
Electron Transfer ◽  
Bond Cleavage ◽  
Micellar Medium ◽  
Hydroxy Acids ◽  
Peroxide Oxidation ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of

Hydrogen peroxide oxidation of pentaamminecobalt(III) complexes ofα-hydroxy acids at 35°C in micellar medium has been attempted. In this reaction the rate of oxidation shows first order kinetics each in [cobalt(III)] and [H2O2]. Hydrogen peroxide induced electron transfer in [(NH3)5CoIII-L]2+complexes ofα-hydroxy acids readily yields 100% of cobalt(II) with nearly 100% of C-C bond cleavage products suggesting that it behaves mainly as one equivalent oxidant in micellar medium. With unbound ligand also it behaves only as C-C cleavage agent rather than C-H cleavage agent. With increasing micellar concentration an increase in the rate is observed.

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