Air Oxidation of Hydrocarbons.<sup>1</sup> II. The Stoichiometry and Fate of Inhibitors in Benzene and Chlorobenzene

Boozer, Charles E.; Hammond, George S.; Hamilton, Chester E.; Sen, Jyotirindra N.

doi:10.1021/ja01617a026

Cited by 223 publications

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“…(2) The volatility of the products from l a made it impossible to determine accurately the efficiency of l a by product analyses (5) as a check on the e determined by the induction period method with a phenolic inhibitor (33). (3) The question of the exact location of l a within the bilayer (5) is further complicated by its partial water solubility (vide infra) and this complicates the assessment of the bilayer cage effect on this initiator.…”

Section: [2] Ri = 2 [ a R O H ] /~mentioning

confidence: 99%

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Autoxidation of phosphatidylcholines initiated with dicumylhyponitrite in solution and in bilayers

Barclay¹,

Kong²,

VanKessel³

1986

Can. J. Chem.

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. 64, 2103 (1986). Dicumylhyponitrite (DCHN) was used as a thermal initiator of autoxidation of unsaturated phosphatidylcholines in o-dichlorobenzene and in mixed bilayers of dilinoleoylphosphatidylcholine (DLPC) with dimyristoylphosphatidylcholine (DMPC). Quantitative studies were made of the products, a,a-dimethylbenzyl alcohol (DMBA), acetophenone (AP), and dicumylperoxide (DCP) from DCHN. The ratio DMBAIA2DCHN (37 rt 6%) indicates the effectiveness of cumyloxy in hydrogen abstraction from the phospholipid in solution. The overall efficiency (e) of DCHN determined by the inhibitor method with a-tocopherol (a-T) was 84 * 596, close to the overall ratio (DMBA + AP)/A2DCHN (90 rt 6' 361, and indicates either significant initiation through the methylperoxy radical in o-dichlorobenzene solution or that a-tocopherol traps cumyloxy radical before @-scission occurs. The thermal decomposition rate constant of DCHN is greatly reduced in a medium of high viscosity; in DLPC to one-quarter, in Nujol to one-sixth that in isooctane and this is interpreted in terms of a one-bond scission of DCHN. In DLPC + DMPC mixed bilayers the effectiveness of the cumyloxy radical to initiate reaction varied from 30 to 19% depending on the amount of DLPC and in this medium there is little or no initiation by methylperoxy according to product analysis and a-T inhibition studies. In mixed bilayers, the rate of oxidation was directly related to the [DLPC] indicating that the classical rate law applies. The oxidizability of DLPC in mixed bilayers (0.046 M I J 2 s ' " ) is comparable to that of neat DLPC.LAWRENCE ROSS COATES BARCLAY, DAVID KONG et JOANN VANKESSEL. Can. J. Chem. 64. 2103 (1986).On a utilisC l'hyponitrite de dicumyle (HNDC) comme initiateur thermique pour l'autooxydation de phosphatidylcholines non-saturts dans le o-dichlorobenzene et dans des doubles couches mixtes de dilinolCylphosphatidylcholine (DLPC) et de dimyristoylphosphatidylcholine (DMPC). On a rCalisC des etudes quantitatives des produits : l'alcool a , a-dimCthylbenzylique [Traduit par la revue]

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Section: [2] Ri = 2 [ a R O H ] /~mentioning

confidence: 99%

“…Ri must be measured, for example, by the inhibitor method (33) using a phenolic antioxidant such as a-tocopherol (a-T) known to trap two peroxyl radicals (15) so that R , is given by eq. [ 2 ] , where T is the period during which oxidation is suppressed.…”

Section: Introductionmentioning

confidence: 99%

Autoxidation of phosphatidylcholines initiated with dicumylhyponitrite in solution and in bilayers

Barclay¹,

Kong²,

VanKessel³

1986

Can. J. Chem.

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“…UV (27) NHC6H5 NC6H5 IR, UV (28) 2.OYj - products. This successful combination of selective separation and analytical determination processes (Figure 15) permitted the direct identification, for the given example, of the reaction mechanism of inhibition during rubber oxidation through the intervention of the charge-transfer complex.…”

Section: + 2romentioning

confidence: 99%

The development of methods for examining stabilizers in polymers and their conversion products

Schroeder¹

1973

Pure and Applied Chemistry

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In the field of stabilizer analysis today there is a need for the analytical determination of the decomposition or transformation products of the stabilizers in polymer systems including their reaction products with the polymers. For the solution of such a complex analytical task, separation problems are at the centre of modern scientific work. These separation problems are subdivided into two partial processes, namely (a) separation of the low molecular substances from the polymer; (b) separation of the mixture of low molecular substances.Selective stage extractions and gel permeation chromatography are particularly favourable. The well-known method of the precipitation of the polymer from diluted solutions needs a more thorough scientific consideration of the solvent-precipitant effects on the stability of the reaction products of stabilizers or their fragments with the polymer.Thin-layer chromatography (TLC) has brought the greatest success, multistage processes here also offer prospective possibilities for the separation of complex systems. Gas chromatography (GC) is less important. Liquid chromatography (LC) with new high-efficiency carrier materials having particle diameters in the micro range will be most important in the future.Structure examinations of the decomposition products of the stabilizers in principle correspond to the classical organo-analytical concepts after separation processes. The most important of the decomposition products of the stabilizers were those of the tin compounds and those of stabilizers based on urea. All toxic substances were detectable by TLC.Structure examinations of stable transformation products of the nitrogencontaining antioxidants with u.v. and i.r. spectrometry are demonstrated in relation to the most discussed mechanism of the inhibition reaction. An analytical scheme for oxidized vulcanizates in the presence of secondary and tertiary mono-and diamines is given at the end to demonstrate the necessity of combining largely selective separation processes with all analytical detection and determination processes of high sensitivity for a successful overall analytical process.

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“…The induction periods produced by these coinpounds were compared under the same experimental conditions with the induction period produced by 2,6-di-tbutyl-4-inethgrlphenol, an inhibitor which is kno~vn to stop t\vo oxidation chains per molecule (10). Cuinene is an excellent substrate for induction period deterininations because even \veal< inhibitors produce quite sharp breaks in the oxygen absorption curves.…”

Section: Cz~nzenementioning

confidence: 99%

THE INHIBITION OF AUTOXIDATION BY 2,4,6-TRI-tert-BUTYL SUBSTITUTED PHENOL, ANILINE, AND THIOPHENOL

Gardner¹,

Howard²,

Ingold³

1964

Can. J. Chem.

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The reactions of peroxy radicals with 2,4,6-tri-t-butyl substituted phenol, aniline, and thiophenol have been examined by a kinetic method. The primary process involves abstraction of the hydrogen atom attached to the functional group, since all three compounds show fairly large isotope effects when this hydrogen is replaced by deuterium. The phenol and aniline react with about two peroxy radicals per molecule. In contrast, the thiophenol reacts with only a single peroxy radical. ,

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Air Oxidation of Hydrocarbons.¹ II. The Stoichiometry and Fate of Inhibitors in Benzene and Chlorobenzene

Cited by 223 publications

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Autoxidation of phosphatidylcholines initiated with dicumylhyponitrite in solution and in bilayers

Autoxidation of phosphatidylcholines initiated with dicumylhyponitrite in solution and in bilayers

The development of methods for examining stabilizers in polymers and their conversion products

THE INHIBITION OF AUTOXIDATION BY 2,4,6-TRI-tert-BUTYL SUBSTITUTED PHENOL, ANILINE, AND THIOPHENOL

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Air Oxidation of Hydrocarbons.1 II. The Stoichiometry and Fate of Inhibitors in Benzene and Chlorobenzene

Cited by 223 publications

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Autoxidation of phosphatidylcholines initiated with dicumylhyponitrite in solution and in bilayers

Autoxidation of phosphatidylcholines initiated with dicumylhyponitrite in solution and in bilayers

The development of methods for examining stabilizers in polymers and their conversion products

THE INHIBITION OF AUTOXIDATION BY 2,4,6-TRI-tert-BUTYL SUBSTITUTED PHENOL, ANILINE, AND THIOPHENOL

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Air Oxidation of Hydrocarbons.¹ II. The Stoichiometry and Fate of Inhibitors in Benzene and Chlorobenzene