Addition Of T-butyl Hydroperoxide Research Articles

The effect of oxidative stress on retinal pigment epithelial cell migration

This study sought to determine if the migration and adhesion of retinal pigment epithelial (RPE) cell could be modulated by oxidative stress induced by t-butyl hydroperoxide (TBH). Intracellular RPE reactive oxygen species (ROS) was labeled by Carboxy-H(2)DCFDA staining. Cell migration was measured by a modified Boyden Chamber Assay. After RPE cells were treated with different concentrations of TBH (1-200 micromol/L) for one hour, chemotaxis toward PDGF (30 ng/ml) was measured after additional 5 hours incubation. The actin cytoskeleton was evaluated by phalloidin (F-actin) staining. Focal adhesion kinase (FAK) and vinculin expression were evaluated using immunofluorescence staining. The expression of MAP Kinase and FAK were studied by western blot. Cell survival and attachment of treated RPE cells were determined using MTT assay. ROS production was elevated in the RPE cells pretreated with TBH. The PDGF-independent RPE cell migration was enhanced by TBH at low concentration up to 30 micromol/L, and the PDGF-induced RPE cell migration was significantly inhibited by TBH at concentration higher than 50 micromol/L. F-actin was aggregated in the periphery of the RPE cells after treatment with TBH at a dose higher than 100 micromol/L. FAK and vinculin expression in RPE cells decreased and their distribution were changed after the treatment of higher concentrations of TBH. MAP Kinase level was up-regulated in response to 10-200 micromol/L TBH exposure. The cell attachment was declined upon addition of TBH above 50 micromol/L. Oxidant stress induced by TBH can inhibit or promote RPE cell migration.

Elevation of resting mitochondrial membrane potential of neural cells by cyclosporin A, BAPTA-AM, and bcl-2.

This study tested the hypothesis that the activity of the mitochondrial membrane permeability transition pore (PTP) affects the resting mitochondrial membrane potential (DeltaPsi) of normal, healthy cells and that the anti-apoptotic gene product Bcl-2 inhibits the basal activity of the PTP. DeltaPsi was measured by both fluorometric and nonfluorometric methods with SY5Y human neuroblastoma cells and with GT1-7 hypothalamic cells and PC12 pheochromocytoma cells in the absence and presence of Bcl-2 gene overexpression. The resting DeltaPsi of Bcl-2 nonexpressing PC12 and wild-type SY5Y cells was increased significantly by the presence of the PTP inhibitor cyclosporin A (CsA) or by intracellular Ca(2+) chelation through exposure to the acetoxymethyl ester of 1, 2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA-AM). The DeltaPsi of Bcl-2-overexpressing PC12 cells was larger than that of Bcl-2-negative cells and not significantly increased by CsA or by Ca(2+) chelation. CsA did not present a significant effect on the DeltaPsi monitored in unstressed GT1-7 cells but did inhibit the decrease in DeltaPsi elicited by the addition of t-butyl hydroperoxide, an oxidative inducer of the mitochondrial permeability transition. These results support the hypothesis that an endogenous PTP activity can contribute to lowering the basal DeltaPsi of some cells and that Bcl-2 can regulate the endogenous activity of the mitochondrial PTP.

α-Melanocyte-stimulating Hormone Reduces Impact of Proinflammatory Cytokine and Peroxide-generated Oxidative Stress on Keratinocyte and Melanoma Cell Lines

We have previously shown that alpha-melanocyte-stimulating hormone (alpha-MSH) can oppose tumor necrosis factor alpha activation of NF-kappaB (1-2 h) and intercellular adhesion molecule 1 up-regulation (mRNA by 3 h and protein by 24 h) in melanocytes and melanoma cells. The present study reports on the ability of four MSH peptides to control intracellular peroxide levels and glutathione peroxidase (GPx) activity in pigmentary and nonpigmentary cells. In human HBL melanoma and HaCaT keratinocytes tumor necrosis factor alpha and H(2)O(2) both activated GPx in a time- and concentration-dependent manner (by 30-45 min). alpha-MSH peptides were found to inhibit the stimulated GPx activity and had biphasic dose-response curves. MSH 1-13 and MSH [Nle(4)-d-Phe(7)] achieved maximum inhibition at 10(-10) and 10(-12) m, respectively. Higher concentrations (10-100 fold) of MSH 4-10 and MSH 11-13 were required to produce equivalent levels of inhibition. alpha-MSH was also capable of reducing peroxide accumulation within 15 min, and again this inhibition was biphasic. The data support a role of alpha-MSH in acute protection of cells to oxidative/cytokine action that precedes NF-kappaB and GPx activation. The rapidity and potency of the response to alpha-MSH in pigmentary and nonpigmentary cells suggest this to be a central role of this peptide in cutaneous cells.

Interaction between peroxide ion and phenol group which are coordinated to the same iron(III) ion

We have prepared several new iron(III) complexes with ligands which contain a phenol group; these are tetradentate [(X-phpy)H, X and H(phpy) represent the substituents on the phenol ring and N, N-bis(2-pyridylmethyl)- N-(2-hydroxybenzyl)amine, respectively] and pentadentate ligands [(R-enph-X)H; R=ethyl(Et) or methyl(Me) derivative and H(Me-enph) denotes N, N-bis(2-pyridylmethyl)- N″-methyl- N″-(2″-hydroxyl-benzylamine)ethylenediamine] and have determined the crystal structures of Fe(phpy)Cl 2, Fe(5-NO 2-phpy)Cl 2, and Fe(Me-enph)ClPF 6, which are of a mononuclear six-coordinate iron(III) complex with coordination of one or two chloride ion(s). These compounds are highly colored (dark violet) due to the coordination of phenol group to an iron(III) atom. When hydrogen peroxide was added to the solution of the iron(III) complex, a color change occurs with bleaching of the violet color, indicating that oxidative degradation of the phenol moiety occurred in the ligand system. The bleaching of the violet color was also observed by the addition of t-butylhydroperoxide. The rate of the disappearance of the violet color is highly dependent on the substituent on the phenol ring; introduction of an electron-withdrawing group in the phenol ring decreases the rate of bleaching, suggesting that disappearance of the violet band should be due to a chemical reaction between the phenol group and a peroxide adduct of the iron(III) species with an η 1-coordination mode and that in this reaction the peroxide adduct acts as an electrophile towards phenol ring. The intramolecular interaction between the phenol moiety and an iron(III)-peroxide adduct may induce activation of the peroxide ion, and this was supported by several facts that the solution containing an iron(III) complex and hydrogen peroxide exhibits high activities for degradation of nucleosides and albumin.

Alkane oxidation with mixed addenda heteropoly catalysts containing Ru(III) and Rh(III)

Oxidation of alkanes, mainly of cyclohexane, with t-butyl hydroperoxide (TBHP) catalyzed by alkylammonium salts of mixed addenda heteropoly compounds having Keggin-type polyanions were studied in benzene solutions, with regard to the relative catalytic activity, reaction orders and the stability of catalysts. Tetra- n-hexylammonium salts of SiRu(H 2O)W 11O 5− 39 and SiRh(H 2O)W 11O 5− 39 showed higher catalytic activities than the corresponding Fe- and Co-substituted catalysts for the selective oxidation of cyclohexane to cyclohexanol and cyclohexanone. Although the Ru catalyst was possibly a mixture, it consisted mainly of SiRu(H 2O)W 11O 5− 39 and gave reproducible catalytic performance for repeated preparations. The initial rates were approximately proportional to the concentrations of cyclohexane, TBHP and the catalyst. Although the rate decreased with the consumption of TBHP, the initial rate was resumed by the addition of TBHP, indicating the absence of the deterioration of catalytic activity. Similarly alcohols and ketones were selectively formed from n-decane and ethylbenzene.

Augmented glucose use and pentose cycle activity in hepatic endothelial cells after in vivo endotoxemia.

Glucose use and pentose cycle activity were determined in freshly isolated rat hepatic endothelial cells 3 hr after an intravenous injection of Escherichia coli lipopolysaccharide (0.1 mg/kg body weight), by use of [1-14C]glucose, [6-14C]glucose and [2-3H]glucose. Lipopolysaccharide treatment in vivo increased glucose use fivefold, whereas glucose oxidation in the pentose cycle was elevated from 0.2 to 1.5 nmol/hr/10(7) cells. In vitro incubation of endothelial cells from saline- and lipopolysaccharide-treated animals in the presence of phorbol 12-myristate 13-acetate (10(-6) mol/L) increased pentose cycle activity twofold and eightfold, respectively. Phorbol 12-myristate 13-acetate caused only a 40% to 60% increase in glycolysis in both groups. Addition of t-butyl hydroperoxide (0.5 mmol/L), a substrate for glutathione peroxidase, caused a 24-fold and 16-fold increase in the glucose flux through the pentose cycle in cells from saline- and lipopolysaccharide-treated rats, respectively. Oxidation of glucose through the Krebs cycle was also increased several-fold after t-butyl hydroperoxide administration. Depletion of cellular glutathione by N-ethylmaleimide (0.1 mmol/L) inhibited the phorbol 12-myristate 13-acetate-induced or t-butyl hydroperoxide-induced increase in the pentose cycle activity with no marked effects on glycolysis. Diphenyleneiodonium (0.1 mmol/L), an inhibitor of superoxide and nitric oxide synthesis inhibited the phorbol 12-myristate 13-acetate-induced increased pentose cycle activity with no effects on the t-butyl hydroperoxide-induced response.(ABSTRACT TRUNCATED AT 250 WORDS)

Hydroperoxide metabolism in rat liver

Addition of t-butylhydroperoxide (0.2 mM) to isolated perfused rat liver led to a net K+ release of 7.2 +/- 0.2 mumol/g within 8 min and a net K+ reuptake of 6.6 +/- 0.4 mumol/g following withdrawal of the hydroperoxide, in line with earlier findings by Sies et al. [Sies, H., Gerstenecker, C., Summer, K. H., Menzel, H. & Flohé, R. (1974) in Glutathione (Flohé, L., Benöhr, C., Sies, H., Waller, H. D., eds) pp. 261-276, G. Thieme Publ. Stuttgart]. Net K+ release roughly paralleled the amount of GSSG released from the liver under the influence of the hydroperoxide. The t-butylhydroperoxide-induced K+ efflux was inhibited by approximately 70% in the presence of Ba2+ (1 mM), by 30% in Ca(2+)-free perfusions and was decreased by 50-60% when the intracellular Ca2+ stores were simultaneously depleted by repeated additions of phenylephrine. t-Butylhydroperoxide-induced K+ efflux was accompanied by a decrease of the intracellular water space by 58 +/- 14 microliter/g (n = 4), corresponding to a 10% cell shrinkage. The effect of t-butylhydroperoxide on cell volume was inhibited by 70-80% in the presence of Ba2+. In isolated rat hepatocytes treatment with t-butylhydroperoxide led to a slight hyperpolarization of the membrane at concentrations of 100 nM, but marked hyperpolarization occurred at t-butylhydroperoxide concentrations above 10 microM. t-Butylhydroperoxide (0.2 mM) transiently increased the portal-perfusion pressure by 3.3 +/- 0.6 cm H2O (n = 18), due to a slight stimulation of prostaglandin-D2 release under the influence of the hydroperoxide. In the presence of Ba2+ (1 mM), t-butylhydroperoxide increased the perfusion pressure by 12.7 +/- 1.2 cm H2O (n = 9) and produced an approximately tenfold increase of prostaglandin-D2 and thromboxane-B2 release. Under these conditions, glucose output from the liver rose from 0.9 +/- 0.03 to 2.9 +/- 0.7 mumol.g-1.min-1 (n = 4) with a time course roughly resembling that of portal-pressure increase and prostaglandin-D2 overflow. These effects were largely abolished in the presence of ibuprofen or the thromboxane-receptor-antagonist BM 13.177. The t-butylhydroperoxide effects on perfusion pressure, glucose and eicosanoid output were also enhanced in the presence of insulin or during hypotonic exposure; i.e. conditions known to swell hepatocytes, but not during hyperosmotic exposure. The data suggest that t-butylhydroperoxide induces liver-cell shrinkage and hyperpolarization of the plasma membrane due to activation of Ba(2+)-sensitive K+ channels.(ABSTRACT TRUNCATED AT 400 WORDS)

In situ detection of oxidative stress in rat hepatocytes.

In rat hepatocytes in primary culture incubated with nitro blue tetrazolium, formazan content was increased by addition of t-butyl hydroperoxide, a potent oxidant, in a dose-related manner, but not by addition of valinomycin, which kills hepatocytes through mitochondrial damage. This increment after t-butyl hydroperoxide addition was not seen in hepatocytes preincubated with deferoxamine mesylate, a ferric iron chelator which inhibits radical formation. Liver perfusion with nitro blue tetrazolium and t-butyl hydroperoxide in rats produced formazan deposition faintly on the surface of hepatocytes throughout the liver and prominently in the cytoplasm of some hepatocytes, which was attenuated when performed following deferoxamine mesylate perfusion. When liver perfusion with nitro blue tetrazolium was performed in carbon tetrachloride-intoxicated rats, formazan deposition appeared diffusely in hepatocytes in the centrilobular areas. Similar deposition was also observed on the surface and in the cytoplasm of hepatocytes in the periportal and mid-zonal areas in rats undergoing post-ischaemic reperfusion. Liver perfusion with nitro blue tetrazolium can detect in situ oxidative stress in hepatocytes and may be a useful tool for studying the role of lipid peroxidation in rat liver injury.

Thiobarbituric acid-reactive substances from peroxidized lipids.

The thiobarbituric acid (TBA) reaction was performed on linoleic acid 13-monohydroperoxide, autoxidized fatty esters, edible fats and oils, rat liver microsomal lipids, and on human erythrocyte ghost lipids in order to determine which substances from peroxidized lipids are TBA-reactive. The reaction was carried out in 2% acetic acid containing butylated hydroxytoluene using two different reaction modes: a one-step mode which involves heating at 100°C, and a two-step mode which involves first treatment at 5°C and subsequent heating at 100°C. Yields of the red 1∶2 malonaldehyde/TBA adduct, as estimated by absorbance, fluorescence intensity and high-performance liquid chromatography, were much higher than the malonaldehyde content as determined by direct chemical analysis. Yields of red pigment obtained by the two-step mode were slightly higher than those obtained by the one-step mode. Pigment yields were dramatically increased by addition oft-butyl hydroperoxide. Red pigment formation from alkenals and alkadienals was similarly enhanced by the two-step mode or by addition oft-butyl hydroperoxide, whereas pigment formation from malonaldehyde was not. It appears likely that a component of the total red pigment formed from the peroxidized lipids was due to aldehyde species other than malonaldehyde.

Increased microsomal interaction with iron and oxygen radical generation after chronic acetone treatment

In vivo administration of acetone influences a variety of reactions catalyzed by rat liver microsomes. The effect of chronic treatment with acetone (1% acetone in the water for 10–12 days) on interaction with iron and subsequent oxygen radical generation by liver microsomes was evaluated. Microsomes from the acetone-treated rats displayed rates of H 2O 2 generation, an increase in iron-dependent lipid peroxidation, and enhanced chemiluminescence upon the addition of t-butylhydroperoxide. The ferric EDTA-catalyzed production of formaldehyde from DMSO or of ethylene from 2-keto-4-thiomethylbutyrate was increased 2-fold after acetone treatment. This increase in hydroxyl radical generation was accompanied by a corresponding increase in NADPH utilization and was sensitive to inhibition by catalase and a competitive scavenger, ethanol, but not to superoxide dismutase. In vitro addition of acetone to microsomes had no effect on oxygen radical generation. Associated with the chronic acetone treatment was a 2-fold increase in the microsomal content of cytochrome P-450 and in the activity of NADPH-cytochrome- P-450 reductase. It appears that increased oxygen radical generation by microsomes after chronic acetone treatment reflects the increase in the major enzyme components which comprise the mixed-function oxidase system.

Chemiluminescent and respiratory responses related to thyroid hormone-induced liver oxidative stress.

Chemiluminescent and respiratory responses were studied in the liver of rats treated with 0.1 mg of triiodothyronine (T3)/kg for 1 to 7 days. Hyperthyroidism resulted in significant increments in the spontaneous chemiluminescence of the in situ liver in animals exhibiting a calorigenic response. Microsomal NADPH-dependent oxygen uptake was enhanced by T3 treatment for 2 days, an effect that was completely abolished by the antioxidant cyanidanol. A similar microsomal antioxidant-sensitive respiratory component was observed in this situation after the addition of t-butyl hydroperoxide (t-BHP). However, basal rates of microsomal oxygen uptake and light emission in liver homogenates and microsomes were decreased by t-BHP, probably related to thyroid hormone-induced diminution in the content of cytochrome P-450 (Fernández et al.) In addition, liver superoxide dismutase and catalase activities as well as the total content of glutathione were depressed by T3. These results indicate that the calorigenic response in the hyperthyroid state is accompanied by the development of an hepatic oxidative stress characterized by enhanced spontaneous chemiluminescence, enhanced NADPH-dependent microsomal respiration and a decreased antioxidant cellular activity.

A comparison of protein S-thiolation (protein mixed-disulfide formation) in heart cells treated with t-butyl hydroperoxide or diamide

Beating neonatal heart cell cultures were treated with diamide or t-butyl hydroperoxide, and changes in glutathione oxidation, cell beating, and protein S-thiolation (protein mixed-disulfide formation) were examined. Both compounds caused extensive oxidation of glutathione. Cells treated with diamide stopped beating within 2 min, and beating returned to normal after 30–45 min. Cells stopped beating 25 min after the addition of t-butyl hydroperoxide, and beating did not resume. t-Butyl hydroperoxide caused S-thiolation of a variety of proteins, but only one protein, of molecular mass 23 kDa, was extensively modified. Diamide caused extensive modification of proteins with molecular masses of 97, 42 and 23 kDa as well as three proteins of about 35 kDa. Though the GSSG content of cell cultures returned to normal by 15 min after diamide treatment. S-thiolation of several proteins persisted. These studies show that S-thiolation of proteins is an important metabolic response in cells exposed to an oxidative challenge by t-butyl hydroperoxide or diamide, and that the specificity of the response depends on the agent used.

Relation between glutathione redox changes and biliary excretion of taurocholate in perfused rat liver.

The influence of the intracellular glutathione status on bile acid excretion was studied in the perfused rat liver. Perturbation of the thiol redox state by short term additions of diamide (100 microM) or hydrogen peroxide (250 microM) or t-butyl hydroperoxide (250 microM) led to a reversible inhibition of biliary taurocholate release without affecting hepatic uptake; inhibition amounted to 45% for diamide and 90% for the hydroperoxides. Concomitantly, the bile acid accumulated intracellularly. Bile flow increased from 1.3 to 2.0 microliters X min-1 X g liver-1 upon infusion of taurocholate (10 microM); the latter value was suppressed to 1.2 microliters X min-1 X g liver-1 by the addition of t-butyl hydroperoxide (250 microM). Similarly, the hepatic disposition of another bile constituent, bilirubin, was suppressed by 70% upon addition of hydrogen peroxide. While the addition of hydrogen peroxide inhibited also the endogenous release of bile acids almost completely, endogenous bile flow was much less affected, decreasing from 1.3 to 1.0 microliters X min-1 X g liver-1. Measurement of [14C]erythritol clearance showed bile/perfusate ratios of about unity both in the absence and presence of hydrogen peroxide, suggesting canalicular origin of the bile under both conditions. In livers from Se-deficient rats low in Se-GSH peroxidase (less than 5% of controls), hydrogen peroxide inhibited taurocholate transport substantially less, providing evidence for the involvement of glutathione in mediating the inhibition observed in normal livers. The percentage inhibition of taurocholate release and intracellular glutathione disulfide (GSSG) content were closely correlated. The addition of t-butyl hydroperoxide caused a several-fold increase of biliary GSSG release, whereas biliary GSH release was even decreased. The results establish a role of glutathione in canalicular taurocholate disposition.

The relationship of biliary glutathione disulfide efflux and intracellular glutathione disulfide content in perfused rat liver.

The intracellular glutathione redox state was estimated using newly adapted methods for tissue analysis. Under standard perfusion conditions of rat liver perfused in situ, intracellular GSH content was 5.5 mumol X g of liver-1, and intracellular GSSG content was 18 nmol X g of liver-1, resulting in a GSH/GSSG ratio of 300. GSSG was transported from the cells into bile. The control rate of release amounts to 0.4 nmol X min-1 X g of liver-1 and corresponds to the rate of release previously observed in anesthetized animals (Sies, H., Koch, O., Martino, E., and Boveris, A. (1979) FEBS Lett. 103, 287-290). No GSSG was released into the caval perfusate. In contrast, GSH release occurs both into bile and into the sinusoidal space, the rates of release being 1 and 14 nmol X min-1 X g of liver-1, respectively. Biliary GSH release in very low in isolated perfused liver. The relationship between intracellular GSSG levels and the rate of biliary GSSG transport was studied. This was achieved in experiments in which internal hydrogen peroxide formation was stimulated with substrates for monoamine oxidase (pargyline-sensitive), or by addition of t-butyl hydroperoxide, or of nitrofurantoin. The apparent concentration ratio, GSSG in bile/GSSG intracellular, was about 50 over the range of intracellular GSSG examined.

Donor-Acceptor Complexes in Copolymerization. XLVII. Alternating Diene-Dienophile Copolymers. 8. Preparation of Equimolar Cyclopentadiene-Maleic Anhydride Copolymers through Copolymerization and Retrograde Isomerization of Diels-Alder Adducts

Abstract An equimolar cyclopentadiene-maleic anhydride copolymer was formed by the addition of t-butyl hydroperoxide to the molten Diels-Alder adducts at 175 to 285[ddot] C. The same copolymer was formed by the high temperature copolymerization of maleic anhydride, in the presence of the hydroperoxide, with cyclopentadiene per se or as generated in situ from dicyclopentadiene. The copolymer resulted from the homopolymerization of the comonomer complex which underwent excitation under the influence of the catalyst. The copolymer, softening point 290 to 320[ddot] C, was saturated and had a proposed norbornane-2, 3-dicarboxylic anhydride repeating unit with 5, 7 linkage.

Accelerated Oxidations of Polyisoprene. II. Effects of Hydrazines, Sulfur Compounds, and Phenyl-β-Napthylamine in Solution

Abstract At concentrations of 0.1 to 1 mM, phenylhydrazine causes marked decrease in viscosity of polyisoprene solutions in a few minutes at 50° C (see section II). This effect requires the presence of oxygen but no preoxidation of the rubber. Two molecules of oxygen are absorbed and about one fifth to one tenth of a chain is cleaved per molecule of phenylhydrazine added. The reaction is essentially complete within 20 min. This fast reaction is not much affected by the presence of antioxidants but results in the formation of some material (possibly phenolic) which reduces the effectiveness of other prooxidants. 1,1 -Dimethylhydrazine and 1,2-diphenylhydrazine, unlike phenylhydrazine, have slow but sustained effects. Hydrazine monohydrate is intermediate in its action. Investigation of the effects of several sulfur compounds on polyisoprene solutions brought out some striking effects and a need for further work. p-Thiocresol is a strong prooxidant for our polyisoprene solutions at concentrations below 0.2 mM. At higher concentrations, induction periods occurred with some, but not all, samples and could be shortened by the addition of t-butyl hydroperoxide. Di-p-tolyl disulfide was somewhat less active, but its effect increased regularly with its concentration. Other aryl thiols and disulfides had similar activity but benzyl derivatives did not. At low concentrations, benzene sulfinic acid and p-toluene sulfinic acid are as strong prooxidants as the aryl thiols; at high concentrations they are more active but short lived. A few other sulfur compounds or combinations had no interesting prooxidant properties. In contrast to results on polyisoprene, aryl thiols and sulfinic acids had little effect in preliminary tests in promoting the oxidation of cyclopentene and methyl-cyclohexene. The effects of a common rubber antioxidant, phenyl-β-naphthylamine, alone and in combination with various prooxidants, were followed by oxygen absorption and viscosity changes. The effects are complex; there are indications of both catalytic and anticatalytic effects, and of both scission and crosslinking. The results are most useful in showing the potential of the method for future work on understanding and comparing effects of antioxidants.

Mechanism of the Gas-phase Oxidation of Propylene in a Propylene-excess Atmosphere under Pressure

Abstract The mechanism of the oxidation of propylene is studied through the addition of t-butyl hydroperoxide, acetaldehyde, or propionaldehyde to the reactant (propylene and oxygen), and also through the direct addition of the products of the (C3H5Br+O2 or CH3CHO+O2) reaction to propylene. The following conclusions are reached: acetaldehyde and not propionaldehyde is responsible for chain-branching, acetaldehyde is formed from the allyl peroxy radical alone, propylene oxide is formed mainly by the reaction of the acetyl peroxy radical with propylene, the allyl peroxy radical probably contributes to the formation of propylene oxide, propionaldehyde, and acrolein in an equal extent, and the recombination of radicals is highly retarded in this propylene-excess system. On the basis of the data obtained, a plausible reaction scheme is proposed.

Vinyl Polymerization Initiated by Sulfur Dioxide

Abstract A number of monomers have been polymerized in the presence of catalytic and higher concentrations of SO2. The addition of t-butyl hydroperoxide greatly accelerates the rate of polymerization. The use of 35SO2 indicates that at catalytic concentrations of SO2 (10−2 mole/liter), only one or two molecules of SO2 are incorporated in the chain, but, at high SO2 concentrations, copolymerization of SO2 with vinyl monomers occurs.

Notes: Organic Peroxides. XXVIII. Addition of t-Butylhydroperoxide and Hydrogen Peroxide to Bicyclo[2.2.1]hepta-2,5-diene

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNotes: Organic Peroxides. XXVIII. Addition of t-Butylhydroperoxide and Hydrogen Peroxide to Bicyclo[2.2.1]hepta-2,5-dieneNicholas Milas and Petrus OttoCite this: J. Org. Chem. 1960, 25, 12, 2225–2226Publication Date (Print):December 1, 1960Publication History Published online1 April 2003Published inissue 1 December 1960https://doi.org/10.1021/jo01082a607RIGHTS & PERMISSIONSArticle Views42Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (286 KB) Get e-Alerts Get e-Alerts