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

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.

1982 ◽  
Vol 60 (12) ◽  
pp. 1597-1597 ◽  
Author(s):  
Walter Kremers ◽  
Grant W Koroll ◽  
Ajit Singh

Azide radicals (N3·) are formed in aqueous solutions by the reaction of hydroxyl radicals (·OH) with azide anions (N3aq−). Azide radicals have been spin trapped with three nitroso spin traps: nitrosodurene (ND), 2,6-dideutero-3,5-dibromo-4-nitrosobenzene sulfonate (DDNBS), and 2-methyl-2-nitrosopropane (MNP). The electron spin resonance (esr) spectra show the presence of two molecules of the spin traps in the spin-trapped species.


1982 ◽  
Vol 60 (12) ◽  
pp. 1602-1609 ◽  
Author(s):  
Th. J de Boer

The radical scavenging properties of nitroso compounds were discovered accidentally during investigations of photochemical nitrosation of hydrocarbons with alkyl nitrites. Depending on the nature of substrates and nitrosating agent, various nitroxides can be generated. Identification of these nitroxides by their esr spectra has triggered the development of the spin-trapping technique which has been useful in the elucidation of many organic radical reaction mechanisms. Recent studies have shown that the behavior of nitrosocyclopropanes and α-chloro-nitroso alkanes is unorthodox upon irradiation. Dark reactions of α-chloro-nitroso alkanes with Grignard reagents lead to nitrones by a polar mechanism and to oximes by electron transfer. In the latter case high yields of hydrocarbon dimers are sometimes obtained from the Grignard and other organometallic reagents, despite the presence of nitroso compounds. In the postulated reaction mechanism dimers and higher associates from the organometallic reagent play an essential role.


Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1046 ◽  
Author(s):  
Georgiy B. Shul’pin ◽  
Yuriy N. Kozlov ◽  
Lidia S. Shul’pina

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.


1982 ◽  
Vol 60 (12) ◽  
pp. 1594-1596 ◽  
Author(s):  
Harparkash Kaur ◽  
M John Perkins ◽  
André Scheffer ◽  
David C Vendor-Morris

Nitrosotriptycene is found to be a potentially useful spin trap when used in organic solvents; the esr spectra of its spin adducts are simple, but they may show marked temperature dependence due to restricted rotation. Nitrosotriptycene traps primary alkyl radicals with a rate constant of ca. 2 × 107 L mol−1 s−1 at 40°C in benzene.


1982 ◽  
Vol 60 (12) ◽  
pp. 1587-1593 ◽  
Author(s):  
M John Perkins ◽  
Harparkash Kaur

A personal view of early experiments which led to the use of C-nitroso-compounds as spin traps is presented, and it is shown how these experiments resulted in the first isolation, and subsequent investigation, of acyl nitroxide radicals: the use of 1-methyl-4-nitroso-3,5-diphenylpyrazole as a spin trap, and the preparation and preliminary investigation of its water-soluble analogue (1) are described.


1982 ◽  
Vol 60 (12) ◽  
pp. 1549-1559 ◽  
Author(s):  
Kamil V Ettinger ◽  
Alexander R Forrester ◽  
Charles H Hunter

The chemical origin of lyoluminescence has been probed using spin trapping techniques. Radicals derived from amino acids and saccharides by γ-irradiation in the solid state have been identified after trapping with aliphatic and aromatic nitroso compounds. Most of the radicals trapped were secondary alkyl radicals. Reaction of peroxyl radicals derived therefrom are thought to produce the emitting species (excited carbonyl compound and/or singlet oxygen). The effect which thermal annealing of the solids after γ-irradiation has on (a) the concentration of radicals in the solid, (b) the concentration of trapped radicals, and (c) the light yield has been investigated. One new water-soluble spin trap has been prepared.


1982 ◽  
Vol 60 (12) ◽  
pp. 1463-1473 ◽  
Author(s):  
Brenda Walker Griffin

The use of the spin traps nitrosobenzene and 2-methyl-2-nitrosopropane has established that metmyoglobin and liver microsomal cytochrome P-450 initiate a radical decomposition of cumene hydroperoxide. With metmyoglobin and the alkyl nitroso compound, the only radical product of cumene hydroperoxide trapped was the methyl radical formed by β scission of the cumyloxy radical. With both hemeprotein initiators, nitrosobenzene trapped only the cumyl radical, considered to be a decomposition product of the unstable spin adduct phenylcumyloxynitroxide. Support for this proposal includes: (1) previous spin trapping studies of the chemical decomposition of cumene hydroperoxide; and (2) significant inhibition by nitrosobenzene of the one-electron oxidation of aminopyrine and the autoxidation of unsaturated membrane lipids resulting from addition of the hydroperoxide to liver microsomes. Aminopyrine altered the epr signal amplitudes of the spin adducts produced with both nitroso compounds, indicative of oxidation of aminopyrine by the methyl radical and reduction of cumene hydroperoxide by the aminopyrine radical. The participation of hydroperoxide-derived radicals in the low peroxidatic activities of certain hemeproteins is quite distinct from the catalytic function of the true hemeprotein peroxidases, which bring about an efficient two-electron reduction of specific hydroperoxides.


Sign in / Sign up

Export Citation Format

Share Document