Formation of radicals in the amine inhibited decomposition of t-butyl hydroperoxide

1969 ◽  
Vol 47 (2) ◽  
pp. 295-299 ◽  
Author(s):  
K. Adamic ◽  
K. U. Ingold
Keyword(s):  
Aromatic Amines ◽  
Peroxy Radical ◽  
Nitroso Compounds ◽  
Peroxy Radicals ◽  
Tertiary Amines ◽  
Chain Initiation ◽  
Butyl Hydroperoxide ◽  
Spin Resonance ◽  
Butoxy Radical ◽  
Radical Signal

The radicals formed in the amine inhibited, α,α′-azo-bis-isobutyronitrile initiated, decomposition of t-butyl hydroperoxide at 65° have been examined by electron spin resonance. In the absence of amine a strong peroxy radical signal is obtained. Amines with structures that do not correspond to those of conventional antioxidants (i.e. primary and secondary aliphatic amines and tertiary amines) generally have little or no effect on this signal. Nitroxide radicals are generated from secondary aromatic (diaryl and alkaryl) amines. The rate of conversion of these amines to nitroxides reached a maximum of 50–60% of the rate of chain initiation for some diphenylamines. A maximum concentration of nitroxide of about half the initial amine concentration was obtained with 4,4′-dimethyldiphenylamine.N,N,N′,N′-Tetramethyl-p-phenylenediamine is very rapidly oxidized by t-butyl hydroperoxide to give Wurster's Blue cation and, presumably, a t-butoxy radical. This amine is therefore an initiator of oxidation rather than an inhibitor as has commonly been supposed.Primary aromatic amines do not appear to form simple aryl nitroxides. It is proposed that arylamino radicals [Formula: see text] are directly oxidized to nitroso compounds by peroxy radicals.

The Influence of Irradiation Temperature on U.V. Induced Defect Creation in Dry Silica

1985 ◽  
Vol 61 ◽  
Author(s):  
R. A. B. Devine ◽  
C. Fiori ◽  
J. Robertson
Keyword(s):  
Oxygen Vacancy ◽  
Peroxy Radical ◽  
Irradiation Temperature ◽  
Threshold Temperature ◽  
Peroxy Radicals ◽  
Oxygen Hole ◽  
Spin Resonance ◽  
Dependent Growth ◽  
Dose Dependent ◽  
Annealing Curve

ABSTRACTElectron spin resonance measurements have been carried out on samples of Suprasil Wl (dry silica) subjected to ultraviolet laser radiation (λ = 248 nm, E = 5 eV/photon). Studies have been made for fixed irradiation temperature (room) variable accumulated ultraviolet dose and fixed accumulated dose (3000 J/cm2) at various irradiation temperatures in the range 110 K to 335 K. Three principal defect centers are observed. Non-bridging oxygen hole centers are created at all temperatures in the range studied with slightly higher efficiency at room temperature (ration 300 K/150 K ∼ 2.5). Comparison of the dose dependent growth curve of the 4.8 eV absorption and its isochronal annealing curve with those for the oxygen hole center clearly identify the origin of the absorption band with this defect. A threshold temperature ∼ 200 K is found for oxygen vacancy creation consistent with results on single crystalline quartz. Post irradiation annealing at 593 K eliminates the vacancy centers and the peroxy radical resonance appears. Its growth as a function of accumulated ultraviolet dose and irradiation temperature supports the hypothesis that peroxy radicals form by the trapping of diffusing, molecular oxygen at the oxygen vacancy center.

Ni-Catalyzed Oxidative Transamidation of Tertiary Aromatic Amines with N-Acyl Saccharin

Synlett ◽  
2021 ◽  
Author(s):  
Shengzhang Liu ◽  
Lingyun Yang ◽  
Jiasi Tao ◽  
Weijie Yu ◽  
Tao Wang ◽  
...  
Keyword(s):  
Aromatic Amines ◽  
Secondary Amines ◽  
Tertiary Amines ◽  
Butyl Hydroperoxide ◽  
Tert Butyl ◽  
Tert Butyl Hydroperoxide

Employment of tertiary amines as the surrogates for secondary amines has prominent superiority in stabilization and easy handle. Herein, a Ni-catalyzed transamidation of N-acyl saccharin amides with tertiary aromatic amines has been reported. By using tert-butyl hydroperoxide (TBHP) as the terminal oxidant, this reaction is featured with a selective cleavage of the C(sp3)–N bonds of the unsymmetrical tertiary aromatic amines depending on the sizes of the alkyl substituents.

Free radicals in the reaction between t-butyl hydroperoxide and titanous ion: Some observations by electron spin resonance spectrometry

1965 ◽  
Vol 18 (8) ◽  
pp. 1177 ◽  
Author(s):  
MFR Mulcahy ◽  
JR Steven ◽  
JC Ward
Keyword(s):  
Aqueous Solution ◽  
Free Radicals ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Peroxy Radicals ◽  
Methyl Radicals ◽  
Methyl Radical ◽  
Butyl Hydroperoxide ◽  
Spin Resonance ◽  
G Value

The reaction between t-butyl hydroperoxide and titanous ion in aqueous solution produces free methyl radicals detectable by electron spin resonance spectrometry (Dixon and Norman). However, the presence of titanous ion in concentrations greater than 0.01M broadens the spectrum of the methyl radical, causing it effectively to disappear at titanous concentrations greater than 0.1M. At hydroperoxide concentrations above 0.25M t-butyl peroxy radicals (identified by a strong single-line spectrum with g-value 2.0136) are produced by the reaction ���������� R. + (CH3)3COOH → RH + (CH3)3COO. Their concentration reaches a maximum about 1 sec after the concentration of the methyl radicals has fallen to an undetectable value and their half-life (≈ 5 sec) is about ten times that of the methyl radicals.

Formation of diphenyl nitroxide in diphenylamine inhibited autoxidations

1969 ◽  
Vol 47 (2) ◽  
pp. 287-294 ◽  
Author(s):  
K. Adamic ◽  
M. Dunn ◽  
K. U. Ingold
Keyword(s):  
Electron Spin Resonance ◽  
Oxygen Atom ◽  
Electron Spin ◽  
Peroxy Radical ◽  
Peroxy Radicals ◽  
Alkoxy Radical ◽  
Oxygen Atom Transfer ◽  
Lower Efficiency ◽  
Alkoxy Radicals ◽  
Spin Resonance

The formation of diphenyl nitroxide in diphenylamine inhibited, α,α′-azo-bis-isobutyronitrile initiated, autoxidations at 65° has been studied by electron spin resonance. Diphenylamine is oxidized to a diphenylamino radical which is then converted to the nitroxide by an oxygen atom transfer from a peroxy radical. The initial rates of conversion of diphenylamine to diphenyl nitroxide and the maximum nitroxide concentrations attained are generally greater for oxidations with tertiary peroxy radicals than for oxidations with primary or secondary peroxy radicals. The lower efficiency of nitroxide formation by primary and secondary peroxy radicals is attributed to a cage disproportionation between alkoxy radical and nitroxide which leads to the formation of a carbonyl compound and diphenyl hydroxylamine. This reaction cannot occur with tertiary radicals. The rate of formation of diphenyl nitroxide is greater for tertiary peroxy radicals which give stable tertiary alkoxy radicals. Nitroxide formation is inhibited by secondary, but not by tertiary, hydroperoxides.

Effects of nitroso compounds and aromatic amines on fetal tracheal explants

1993 ◽  
Vol 45 (2-3) ◽  
pp. 81-86 ◽  
Author(s):  
C. Nowak ◽  
K. Gleier ◽  
M. Christ ◽  
K. Gorzelniak ◽  
H.-B. Richter-Reichhelm
Keyword(s):  
Aromatic Amines ◽  
Nitroso Compounds ◽  
Tracheal Explants

Absolute rate constants for hydrocarbon autoxidation. VI. Alkyl aromatic and olefinic hydrocarbons

1967 ◽  
Vol 45 (8) ◽  
pp. 793-802 ◽  
Author(s):  
J. A. Howard ◽  
K. U. Ingold
Keyword(s):  
Hydrogen Atom ◽  
Steric Hindrance ◽  
Rate Constants ◽  
Peroxy Radical ◽  
Electron System ◽  
Chain Termination ◽  
The Self ◽  
Hydrogen Atom Abstraction ◽  
Peroxy Radicals ◽  
Absolute Rate

Absolute rate constants have been measured for the autoxidation of a large number of hydrocarbons at 30 °C. The chain-propagating and chain-terminating rate constants depend on the structure of the hydrocarbon and also on the structure of the chain-carrying peroxy radical. With certain notable exceptions which are mainly due to steric hindrance, the rate constants for hydrogen-atom abstraction increase in the order primary < secondary < tertiary; and, for compounds losing a secondary hydrogen atom, the rate constants increase in the order unactivated < acyclic activated by a single π-electron system < cyclic activated by a single Π-system < acyclic activated by two π-systems < cyclic activated by two π-systems. The rate constants for chain termination by the self-reaction of two peroxy radicals generally increase in the order tertiary peroxy radicals < acyclic allylic secondary  [Formula: see text] cyclic secondary  [Formula: see text] acyclic benzylic secondary < primary peroxy radicals < hydroperoxy radicals.

scholarly journals Diel peroxy radicals in a semi industrial coastal area: nighttime formation of free radicals

2012 ◽  
Vol 12 (8) ◽  
pp. 19529-19570 ◽  
Author(s):  
M. D. Andrés-Hernández ◽  
D. Kartal ◽  
J. N. Growley ◽  
V. Sinha ◽  
E. Regelin ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Trace Gases ◽  
Peroxy Radical ◽  
Industrial Area ◽  
Diurnal Variations ◽  
Peroxy Radicals ◽  
Industrial Emissions ◽  
Air Masses ◽  
Volatile Organic ◽  
Organic Trace

Abstract. Peroxy radicals were measured by a PeRCA (Peroxy Radical Chemical Amplifier) instrument in the boundary layer during the DOMINO (Diel Oxidant Mechanisms In relation to Nitrogen Oxides) campaign at a coastal, forested site influenced by urban-industrial emissions in Southern Spain in late autumn. Total peroxy radicals (RO2* = HO2 + ΣRO2) generally showed a daylight maximum between 10 and 50 pptv at 13:00 UTC, with an average of 18 pptv over the 15 days of measurements. Emissions from the industrial area of Huelva often impacted the measurement site at night during the campaign. The processing of significant levels of anthropogenic organics leads to an intense nocturnal radical chemistry accompanied by formation of organic peroxy radicals at comparable levels to those of summer photochemical conditions with peak events up to 60–80 pptv. The RO2 production initiated by reactions of NO3 with organic trace gases was estimated to be significant but not sufficient to account for the concentrations of RO2* observed in air masses carrying high pollutant loading. The nocturnal production of peroxy radicals seems therefore to be dominated by ozonolysis of volatile organic compounds. RO2* diurnal variations were consistent with other HO2 measurements available at the site. HO2/RO2* ratios generally varied between 0.3 and 0.4 in all wind directions. Occasional HO2/RO2* ≥ 1 seemed to be associated with periods of high RO2* variability and with RO2 interferences in the HO2 measurement in air masses with high RO2 load.

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