Reactions of hydroxyl radicals with polymerizable olefins

Grant, Richard D.; Rizzardo, Ezio

doi:10.1039/p29850000379

Cited by 26 publications

(17 citation statements)

References 6 publications

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“…На sp 2 -гібридизований атом вуглецю гідразо-ну в умовах опромінення також може бути спря-мована атака кисню, внаслідок чого утворюють-ся гідропероксиди, які використовувались для ге-нерування гідроксирадикалів [15][16][17][18] (схема 6).…”

Section: Issn 2308-8303unclassified

Reactions of N-alkylhydrazones of aliphatic ketones

Kurpil¹,

Ivonin²,

Volochnyuk³

2014

J. org. pharm. chem.

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Section: Issn 2308-8303unclassified

Reactions of N-alkylhydrazones of aliphatic ketones

Kurpil¹,

Ivonin²,

Volochnyuk³

2014

J. org. pharm. chem.

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“…Most importantly for studies of arene substrates, aminoxyl radicals have been reported to undergo hydrogen abstraction (disproportionation) reactions with cyclohexadienyl radical systems, leading to aromatization of the ring, and formation of reduced hydroxylamines such as 2 (TEMPOH; Scheme 1). [ 27,33,34 ] In fact, TEMPO and its derivatives can be reduced by 1,4‐cyclohexadiene via a sequence of allylic abstraction and disproportionation reactions. [ 35 ] Even if the coupling of cyclohexadienyl radical and TEMPO is near diffusion limited, the weak O–C bond leads to substantial reversibility even under moderate temperatures, and the reaction proceeds under thermodynamic control.…”

Section: Introductionmentioning

confidence: 99%

“…In the case of hydroxyl radical reactions with arenes, formed hydroxycyclohexadienyl radicals are oxidized to phenols, which with appropriate derivatization, were amenable to product analysis by gas chromatography–mass spectrometry (GC/MS) techniques. Previously, [ 27 ] we were able to measure the distributions of phenols generated by the reaction of hydroxyl radicals generated thermally from decomposition of azohydroperoxide 4 (Scheme 2) [ 33,37 ] with variously substituted arenes. The tert ‐butyl radical generated from 4 is rapidly scavenged by 1 to yield the alkoxylamine 5 .…”

Section: Introductionmentioning

confidence: 99%

Reaction of hydroxyl radical with arenes in solution—On the importance of benzylic hydrogen abstraction

Waggoner

Abdulrahman

Iverson

et al. 2021

J of Physical Organic Chem

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The regioselectivity of hydroxyl radical reactions with alkylarenes was investigated using a nuclear magnetic resonance (NMR)‐based methodology capable of trapping and quantifying addition and hydrogen abstraction products of the initial elementary step of the oxidation process. Abstraction products are relatively minor components of the product mixtures (15–30 mol%), depending on the magnitude of the overall rate coefficient and the number of available hydrogens. The relative reactivity of addition at a given position on the ring depends on its relation to the methyl substituents on the hydrocarbons under study. The reactivity enhancements for disubstituted and trisubstituted rings are approximately additive under the conditions of this study.

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“…The advantages of 2 over some other nitroso spin traps are that it is monomeric in solution to at least 0.03 M (5), and that it is stable to visible light and is, therefore, not by itself a source of nitroxyl radicals. a-Hydroperoxyalkyl diazenes (R'R~c(oOH)N=NR~) and some cyclic analogues have been known for some time as sources of free radicals (6)(7)(8) including the hydroxyl radical (9). However, some of them afford diazonium ion intermediates instead (10) and others cause oxygen atom transfers that convert olefins to epoxides (1 1) and thioethers to sulfoxides (12) by non-radical mechanisms under neutral conditions.…”

Section: Introductionmentioning

confidence: 99%

Thermolysis of α-hydroperoxyalkyl diazenes. Spin trapping of radical intermediates and spin trapping kinetics

Mathew¹,

Osei-Twum²,

Warkentin³

1991

Can. J. Chem.

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a-Hydroperoxyalkyl diazenes (Me2C(OOH)N=NR, 1, R = CH2CF3, CH2CH20Me, CH(Me)2, CMe3, CH2Ph, Ph, CH2CH20Ph, and c-C3HSCD2) decompose in benzene, at 50°C or less, by a mechanism involving free radical (Re) intermediates. The radicals were trapped with 1-methyl-4-nitroso-3,5-diphenylpyrazole, 2, to afford spin adducts (nitroxyls) that were observed by ESR spectroscopy. When the solvent was ethyl vinyl ether, radicals from 1 (R = CH2CH20Ph) were trapped by the solvent and the adduct radicals so formed were spin trapped by 2. These observations support free radical mechanisms for thermolysis of 1 and for the hydroxyalkylations that occur when 1 are decomposed in solutions containing en01 ethers or other unsaturated substrates. The ring-opening of cyclopropylmethyl radicals (cpm) to 3-butenyl radicals was used to estimate the rate constant for radical trapping by 2. For cpm the rate constant is given by log kcPm = (10.7 =t 0.4) -(3.9 =t 0.5)/9 where 9 = 2.3 RT kcal mol-'. At 25"C, the spin trapping rate constant has the value 6.9 x lo7 M-' s-l. Les a-hydropCroxyalkyldiazbnes (Me2C(OOH)N=NR, 1, R = CH2CF3, CH2CH20Me, CH(Me)2, CMe3, CH2Ph, Ph, CH2CH20Ph et c-C3HSCD2) se dCcomposent dans le benzbne B une tempCrature Cgale ou infkrieure B 50°C selon un mkcanisme impliquant des radicaux libres (Re) intermediaires. On a piCgC les radicaux libres avec le rnCthyl-1-nitroso-4-diphCnyl-3,5-pyrazole, 2, pour obtenir des adduits de spin (nitroxyles) que l'on a observis par spectroscopie de ESR. L'tther ethylvinylique utilisC comme solvant piege les radicaux provenant du composC 1 (R = CH2CH20Ph) et les adduits radicalaires ainsi formCs sont captCs par le composC 2. Ces observations tendent ti prouver que la thermolyse du compost 1 et l'hydroxyalkylation, qui se produit lorsque le compost 1 se dCcompose dans des solutions contenant des Cthers Cnoliques ou d'autres substrats insaturis, impliquent un mecanisme radicalaire. On s'est bas6 sur l'ouverture du cycle des radicaux cyclopropylmtthyles (cpm) qui conduit aux radicaux butCnyl-3 pour Cvaluer la constante de vitesse de la capture des radicaux par le compost 2. Pour le cpm, la constante de vitesse est donnCe par la rklation : log kcpm = (10,7 =t 0,4) -(3,9 =t 0,5)/9 ou 9 = 2,3 RT kcal mol-I. On Cvalue la constante de capture de spin B 6,9 x lo7 M-I s-' 2 25°C.

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Reactions of hydroxyl radicals with polymerizable olefins

Cited by 26 publications

References 6 publications

Reactions of N-alkylhydrazones of aliphatic ketones

Reactions of N-alkylhydrazones of aliphatic ketones

Reaction of hydroxyl radical with arenes in solution—On the importance of benzylic hydrogen abstraction

Thermolysis of α-hydroperoxyalkyl diazenes. Spin trapping of radical intermediates and spin trapping kinetics

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