Metallorganische Peroxide. VIII. Zum Mechanismus der Zersetzung von Bis-organoantimonyl-peroxiden. Teil II

Organometallic Peroxides. VIII. Mechanism of the Decomposition of Bis-organoantimony-peroxides. Part II Bis-(bromo-triphenylantimony)-peroxide ( 1a ) reacts with bromine or iodine in an analogous way as we suggested concerning the mechanism of decomposition of 1a , yielding singulet oxygen. Moreover, we found that triphenylantimony bisiodide catalyses the decomposition of 1a . Also bis-(chloro-triphenylantimony)-peroxide ( 1b ) easily decomposes in the presence of such additives releasing singulet oxygen.     

Rheology and melt strength of long chain branching polypropylene prepared by reactive extrusion with various peroxides

Long Chain Branching Polypropylenes were prepared in an extruder by a melt grafting reaction in the presence of various peroxides and a polyfunctional monomer of 1,6‐hexanediol diarylate. Fourier Transformed Infrared spectra and the rheological characteristics indicated that the grafting reaction added long branched chains to linear polypropylene (PP). In comparison to the initial PP, the branched samples exhibited higher melt strength, lower melt flow index, and enhancement of crystallization temperature. The branching number of the modified samples agreed well with their melt viscoelasticity and the improved degree of their melt strength. The branching level in modified PPs could be controlled by the property and structure of the peroxide used. Peroxides with lower decomposition temperature and more stable radicals after decomposition promoted the branching reaction, leading to the modified PPs with higher branching level and melt strength. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Über die Autoxydation gesättigter Fettsäuren IV: Sauerstoff-Verbrauch und Bildung von Peroxiden bei der Oxydation von Laurin- und Stearinsäure sowie ihrer Methylester

Autoxidation of Saturated Fatty Acids IV: Oxygen Consumption and the Formation of Peroxides in the Oxidation of Lauric and Stearic Acids and their Methyl Esters The investigation showed a reproducible course of oxygen uptake and peroxide formation. In the oxidation of free acids the oxygen uptake was considerably higher than the corresponding peroxide content. The amounts of peroxides determined are so small that secondary reactions may be assumed to occur at relative ease under the experimental conditions. The higher content of peroxide compounds in the oxidation of methyl esters compared to that in the oxidation of free acids indicated a hindrance of the subsequent reactions which are associated with the decomposition of the peroxides. The experiments showed that initially an unusually large part of the absorbed oxygen is consumed in the formation of peroxides. The formation of split products can therefore occur here only with great difficulty in contrast to the case of free acids.     

Reactions of fatty materials with oxygen. XVIII. Catalytic hydrogenation of autoxidized methyl oleate and oleic acid. Preparation of monohydroxystearic acids

Summary Autoxidation of methyl oleate and oleic acid beyond the peak peroxide values followed by catalytic hydrogenation gave mixed monohydroxystearic acids in high yield. The complicated autoxidation mixture which contains peroxides, hydroxy, carbonyl, and oxirane compounds was simplified considerably in composition by this procedure. For complete reduction of the double bond, and the carbonyl and oxirane groups, hydrogenation was conducted at about 150° and 150 lbs.. Peroxides were reduced at room temperature. Catalysts used were palladium on carbon and Raney nickel. The selective reduction of peroxides in autoxidation mixtures has been studied by chemical and catalytic means. Peroxides were converted largely to carbonyl compounds rather than to the anticipated hydroxy compounds. Palladium-lead on calcium carbonate is an excellent catalyst for reducing peroxides with hydrogen. tert-Butyl hydroperoxide, 12- ketostearic acid, stearone,cis-9,10-epoxystearic acid and methyl oleate peroxide concentrate were employed as model substances in determining hydrogenation conditions. Paper XVII. is reference 5. Presented at the fall meeting of the American Oil Chemists' Society, Minneapolis, Minn., Oct. 11–13, 1954. A laboratory of the Eastern Utilization Research Branch, Agricultural Research Service, U. S. Department of Agriculture.     

Photochemical studies of rancidity: Rate of peroxide development under constant intensity of light

Conclusions (1) Peroxides in oils increase at a uniform rate when the oils are irradiated with light from a constant source, such as CX lamps. (2) An oil which has been protected by a sextant green filter and which has already developed a certain amount of peroxides will, when exposed simultaneously to light of CX lamps with a fresh sample of the same oil, continue to develop peroxides, and at the same rate as that of the fresh oil. (3) The induction period of an oil which has been protected by a sextant green filter is unaffected by the peroxides which were developed during protection and is equal to that of a fresh sample of the same oil. (4) The development of rancidity in oils that have been protected by a sextant green filter proceeds independently of the peroxides that may be already formed. (5) Peroxides which develop under a sextant green filter do not increase the susceptibility of the oil to become rancid. Food Research Division Contribution No. 331.     

Hydrogenation of oxidized soybean oil

Anderson Clayton Foods, Richardson, TX 75080 Portions of refined and bleached soybean oil were stored at various temperatures for various lengths of time, then hydrogenated to 70 iodine value (IV) to find the effect of peroxides on the rate of hydrogenation and on characteristics of hydrogenated product. Samples were treated up to 3 wk at up to 65°C and provided samples with peroxide values (PV) of up to 358. All samples were analyzed, hydrogenated, and reanalyzed. Peroxides affected the fatty acid composition as determined by gas chromatography, the calculated iodine value based on fatty acid composition, and rate of hydrogenation. Peroxides also affected the selectivity of hydrogenation and slope of the solids curve in hydrogenated products.     

Azoperoxide. VI. Selektive Spaltungen von β-Azo-acylperoxiden

Azoperoxides. VI. Selective Decomposition of β-Azoacylperoxides The selective decomposition of the O O-Groups in the azoperoxides 1 and 2 is possible by reaction with dimethylaniline at 35°C. Rate constants were measured and the decomposition products were analyzed. Intermediates are azoalkyl radicals. The radical yield of the amine induced decomposition of 2 in ethylbenzene is 8.2% at 35°C. UV irradiation of the azoperoxides 1 and 2 at 20°C in ethylbenzene results in a quantitative and selective decomposition of the azo groups. Intermediates are C-radicals with intact peroxide groups. The reaction of 1 and 2 with triethylstannane yields reduction products of the O O-groups and the NN-groups, respectively.     

Zur Polarographie von Peroxiden im Null-Volt-Bereich II: Oszillopolarogramme von Hydroperoxiden,Quecksilbersalzen und Hg-Ionen in Gegenwart von Diacylperoxiden

Polarography of Peroxides in Zero-Volt Range II: Oscillo-Polarogramms of Hydroperoxides, Mercury Salts and Hg-Ions in the Presence of Diacyl Peroxides Further experiments carried out in order to explain the occurrence of each of the two polarographic peak currents and current step-ups, A₁ and A₂ respectively, of peroxides in zero-volt range are reported. Occurrence of both the peak currents is probably due to the reduction of monovalent mercury ions. A part of the Hgions which were formed by the oxidation of the Hg-electrode due to the peroxides, is reduced at A₁, and the other part is chemically oxidized by the peroxides further to Hg²⁺ions. The latter can, in a similar fashion, give rise to Hgions by reaction with the Hg electrode. The Hgions are probably reduced at A₂, the reduction being influenced by the nature of binding of the Hg-ions and the catalytic action of chlorides.     

Lipid peroxide catalyzed chemical carcinogenesis

Peroxides, including lipid peroxides, with heme catalysts cause the binding of C¹⁴-acetylaminofluorene to DNA if microsomes are present. This binding was 96% inhibited by paraoxon, a deacetylase inhibitor. It is concluded that peroxide-peroxidase systems rapidly oxidize acetylated arylamines to proximate carcinogens following deacetylation by microsomal deacetylases. The DNA binding observed was greater than that observed with the liver microsomal mixed function oxidase catalyzed activation to N-OH-acetylaminofluorene, which binds to DNA following deacetylation by microsomal deacetylase. Lipid peroxidation or prostaglandin synthesis should therefore enhance carcinogenesis induced by arylamides.     

The corrosion of zinc by vapours from polyester resins

The corrosion of zinc metal by vapours from cured styrene-based polyester resins has been studied. The production of corrosive vapours has been found to be greatly influenced by the curing system. Peroxides of different types have been examined, some in the presence of accelerators. Resins cured by γ-radiation, and by azodi-isobutyronitrile, showed very low corrosion rates. Zinc formate was present in the corrosion products. It is suggested that the corrosion is due, at least in part, to the production of formic acid through oxidation of styrene monomer by the peroxidic catalysts, and the slow release of this acid by the cured resin.     

Über die Autoxydation gesättigter Fettsäuren V: Angriff des Sauerstoffes und Bildung von Peroxiden bei der Oxydation von Laurin- und Stearinsäure sowie ihrer Methylester

Autoxidation of Saturated Fatty Acids V: The Attack of Oxygen Consumption and the Formation of Peroxides in the Oxidation of Lauric and Stearic Acids and their Methyl Esters No unsaturated compounds were found amongst the products of oxidation. Alkan-2-ones and alkanals containing one C-atom lesser than the fatty acid chain were identified as the primary products of degradation of the acids and esters. From the composition and periodic occurrence of the products of degradation, one can conclude that preferentially a β-oxidation takes place. The formation of alkanals having chain lengths shortened by one C-atom than the starting materials indicate the occurrence of α-oxidation as well, which, however, lags far behind the β-oxidation.     

Effects of ionizing radiations on fats. II. Accumulation of peroxides and other chemical changes

The accumulation of peroxides, carbonyl com-pounds and reducing substances during irradia-tion and post-irradiation storage of pure fatty acid methyl esters has been studied. Irradiation and storage of irradiated methyl myristate under vacuum results in formation of small quantities of these compounds. Irradiation under oxygen gives peroxides and carbonyl com-pounds in yields indicating that every ionization results in the formation of one molecule of each group, and antioxidants have no effect on the formation of these compounds during irradiation. Irradiation of methyl linoleate under vacuum results in destruction of pre-formed hydroperox-ides. During irradiation in oxygen, approximately one-eighth of the peroxides formed arises from the direct reaction of irradiation-induced free radi-cals with oxygen, while the rest is formed through a chain mechanism with an average chain length of 7. Peroxides continue to accumulate in irradiated methyl linoleate stored under oxygen at a rate increasing with initial irradiation dose. Antioxidants have some effect in retarding the formation of peroxides during irradiation of methyl linoleate and during post-irradiation stor-age, but the effect is small compared to their antioxygenic activity toward simple autoxidation. The effect varies with the nature of the antioxi-dant and with irradiation dose. Propyl gallate is much less effective than butylated hydroxy-anisole and appears to be easily destroyed during irradiation. For paper I of this series, see Ind. Eng. Chem.49. 1713 (1957). Presented at the AOCS Meeting in Minneapolis, 1963.     

Azoperoxide. VII. Thermolyse von α-Alkylazo-alkylhydroperoxiden

Azoperoxides. VII. Thermolysis of α-Alkylazoalkylhydroperoxides The thermal decomposition of 1-methylazo-1-hydroperoxycyclohexane 1 and 1-tert.-butylazo-1-hydroperoxycyclohexane 2 was studied in ethylbenzene and in the case of 2 also in other solvents. Decomposition products and decomposition rates of the azo and the peroxy groups were selectively estimated. The title compounds decompose faster than the analogous azo compounds and alkylhydroperoxides. A induced homolysis of both initiator groups is proposed; the compounds are not „bifunctional initiators”︁.     

Pyrolysis–molecular weight chromatography–vapor-phase infrared spectrophotometry: An on-line system for analysis of polymers. III. Thermal decomposition of polysulfones and polystyrene

The thermal decomposition of poly(butene-1 sulfone), poly(pentene-1 sulfone), poly(hexene-1 sulfone), poly(styrene sulfone), and polystyrene was investigated in helium at a heating rate of 20°C/min using an experimental system which consists of a programmable pyrolyzer, a thermal conductivity detector, a mass chromatograph, and a vapor-phase infrared spectrophotometer. Poly(butene-1 sulfone), poly(penetene-1 sulfone), and poly(hexene-1 sulfone) displayed two-step decomposition; the primary products of decomposition at both steps were the comonomers (olefin and SO₂). For poly(styrene sulfone), in addition to styrene and SO₂, products with molecular weights corresponding to dimers of styrene were observed. Decomposition of this polymer was compared with that of polystyrene, which formed mostly monomer.     

Grafting of acrylic acid onto corona-treated polyethylene surfaces

Peroxides formed on the surface by corona treatment of low-density polyethylene film can be used to initiate grafting of polar vinyl monomers such as acrylic acid. Different types of peroxides are probably formed on the surface, but at least hydroperoxides could be detected by XPS analysis. The grafting reaction was carried out directly after corona treatment, by placing the corona-treated film above a solution of acrylic acid heated to 100°C. The grafting reaction takes place in a vapor phase of the monomer. After extracting the reacted films with hot methanol and drying, surface analysis by XPS, IR, and contact angle measurements were carried out. Effect of degree of corona treatment and reaction time have been studied. The conclusion from this work is that acrylic acid in vapor phase can successfully be grafted onto corona-treated polyethylene film by this method. © 1992 John Wiley & Sons, Inc.     

New coordination polymers. IV. Oxidation of poly(vinyl alcohol) by permanganate ion in alkaline solutions. kinetics and mechanism of decomposition of intermediate complex

The kinetics of decomposition of [PVA. Mn^VIO-] intermediate complex have been studied spectrophotometrically. A first-order dependence on the intermediate concentration was observed. The decomposition rate was found to be base-catalysed. The kinetic parameters have been evaluated and a mechanism consistent with the results obtained is discussed.     

Zur Polarographie von Peroxiden im Null-Volt-Bereich I: Oszillopolarogramme von Diacylperoxiden

Polarography of Peroxides in Zero Volt Range I: Oscillopolarograms of Diacylperoxides The peak currents A₁ and A₂ which are formed by diacyl peroxides at a starting potential of ±0.0V were investigated in details. The peak current A₁ appears only in LiCi conductivity salt solutions at a starting potential of 0.0V (against Hg in the base). The current is linearly proportional to the concentration of the peroxides and mercury salts, but it shows strong fluctuations. A₁ is the reduced form of a peak current (A₁), which is polarographically measurable only at positive starting potentials in the presence of small amounts of chlorides in LiNO₃ basic electrolytes. It originates by the reduction of mercury ions, which are formed in the presence of chlorides, their formation being only promoted by peroxides. As a result of salt formation, the chlorides interfere with the redox equilibrium of mercury, whereas the peroxides oxidize chemically. Similarly, the peak current A₂ is not specific for diacyl peroxides. The peak current increases linearly with the diacyl peroxide concentration. Also in this process occuring at the electrode, the chlorides are extensively involved.     

Color tests for the detection of alpha-dicarbon compounds formed in the autoxidation of fats

Summary Tests have been devised for detectingα-dicarbonyl compounds in autoxidized fats. The tests are based upon the conversion of theα-dicarbonyl compounds to their dioximes, formation of the nickelous, cupric and bis-pyridine-ferrous derivatives of the dioximes, and extraction of these colored metallic dioxime derivatives into organic solvent phases. The presence ofα-dicarbonyl compounds in a number of autoxidized fatty materials has been demonstrated by these tests. Peroxides in autoxidized fatty materials could be destroyed by treatment with ferrous chloride without destruction ofα-dicarbonyl compounds. This investigation was aided by the Jonathan Bowman Fund for Cancer Research.     

Plastisol foaming process. Decomposition of the foaming agent,polymer behavior in the corresponding temperature range and resulting foam properties

The decomposition of azodicarbonamide, used as foaming agent in PVC—plasticizer (1/1) plastisols was studied by DSC. Nineteen different plasticizers, all belonging to the ester family, two being polymeric (polyadipates), were compared. The temperature of maximum decomposition rate (in anisothermal regime at 5 K min^?1 scanning rate), ranges between 434 and 452 K. The heat of decomposition ranges between 8.7 and 12.5 J g^?1. Some trends of variation of these parameters appear significant and are discussed in terms of solvent (matrix) and viscosity effects on the decomposition reactions. The shear modulus at 1 Hz frequency was determined at the temperature of maximum rate of foaming agent decomposition, and differs significantly from a sample to another. The foam density was determined at ambient temperature and the volume fraction of bubbles was used as criterion to judge the efficiency of the foaming process. The results reveal the existence of an optimal shear modulus of the order of 2 kPa that corresponds roughly to plasticizer molar masses of the order of 450 ± 50 g mol^?1. Heavier plasticizers, especially polymeric ones are too difficult to deform. Lighter plasticizers such as diethyl phthalate (DEP) deform too easily and presumably facilitate bubble collapse. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Photochemische Reaktionen von Pyrazolidon-(3)-betainen. IV. Photooxydation von Pyrazolidon-(3)-azomethiniminen

Photochemical Reactions of 3-Pyrazolidone Betains. IV. Photooxidation of 3-Pyrazolidone Azomethinimines Azomethinimines 1 , easily obtainable from 3-pyrazolidone and aldehydes, on dyesensitized photooxidation in methanol as a solvent undergo decomposition to nitrogen, methyl β-methoxypropionate 3 , methyl acrylate 4 and the corresponding aldehyde 2 . The formation of these products is interpreted by formation and decomposition of a cyclic peroxide 5 , produced by a 1,3-dipolar cycloaddition reaction between 1 and singlet oxygen. The photooxidation of 1 in acetonitrile produces: nitrogen, carbon dioxide, ethylene, β-propiolactone 9 , and the corresponding aldehyde 2 . The dye-sensitized photooxidation in methanol of the azomethinimines 16 , prepared from 3-pyrazolidone and ketones, gives the following products: nitrogen, methyl β-methoxypropionate 3 , methyl acrylate 4 , and the corresponding ketone, besides hydrazine and the corresponding α-methoxy-alkylhydroperoxides 17 and 21 . Key intermediate of the peroxide formation is the Criegee ozonization zwitterion which was trapped with acetaldehyde as an ozonide.