Disproportionation and combination reactions of simple alkyl radicals: methyl, ethyl, n-propyl, and isopropyl

1967 ◽  
Vol 45 (20) ◽  
pp. 2327-2333 ◽  
Author(s):  
J. O. Terry ◽  
J. H. Futrell
Keyword(s):  
Free Radicals ◽  
High Intensity ◽  
Room Temperature ◽  
Methyl Ethyl ◽  
High Concentration ◽  
Cross Combination ◽  
Alkyl Radicals ◽  
Competing Reactions

Rates of the possible cross-disproportionation reactions of these radicals relative to their rates of cross-combination, have been measured and are compared with auto-disproportionation-to-combination ratios which were also determined for these radicals. Selected asymmetric azo alkanes RNNR′ and mixtures of symmetric azo alkanes RNNR were used as sources of the desired free radicals. Photolysis under relatively high intensity conditions (ca. 1018 quanta/cm2 s) at room temperature generated the radicals in sufficiently high concentration that competing reactions of abstraction and condensation were negligible. Both the alkene and alkane products of disproportionation reactions were measured to ensure the completeness of the mechanism invoked and to increase the accuracy of the results. Δ(Me, Et) = 0.036 ± 0.003, Δ(Me, Prn) = 0.058 ± 0.004, Δ(Me, Prs) = 0.163 ± 0.005, Δ(Et, Prn) = 0.065 ± 0.005, Δ(Et, Prs) = 0.18 ± 0.008, Δ(Prn, Et) = 0.057 ± 0.005, Δ(Prs, Et) = 0.12 ± 0.01, and Δ(Prn, Prs) = 0.41 ± 0.02 were deduced from the data, where Δ(A, B) refers to the ratio of disproportionation producing the alkane product derived from A to the combination of A with B.

scholarly journals PO-133 Effects of different concentrations of hydrogen on oxidative stress in rats with high intensity exercise

2018 ◽  
Vol 1 (4) ◽  
Author(s):  
Xue Geng ◽  
Zhihui Li ◽  
Lin Zhang ◽  
Chenggang Zhang
Keyword(s):  
Oxidative Stress ◽  
Free Radicals ◽  
Oxidative Damage ◽  
High Intensity ◽  
Statistical Difference ◽  
The Body ◽  
High Intensity Exercise ◽  
High Concentration ◽  
Significant Difference ◽  
Exercise Induced

Objective Exercise-induced oxidative stress is due to the massive increase in free radicals caused by strenuous exercise, which exceeds the ability of self-clearing. It is one of the main causes of sports injury and sports fatigue. Eliminating excessive production of free radicals is the key to alleviating exercise induced oxidative damage. Therefore, the purpose of this study is to study the effect of hydrogen on exercise-induced oxidative damage, to explore its possible mechanism and to explore the best dose of hydrogen with different concentrations. Methods 40 male SD rats (200±20g) were randomly divided into five groups(n=8):sedentary, exercise control, low concentration hydrogen with exercise(H1), medium concentration hydrogen with exercise(H2), high concentration hydrogen with exercise(H3). The rats performed high-intensity exercise for 4 weeks, except the sedentary. rats that with Low, medium and high concentration hydrogen were placed in a hydrogen atmosphere with a concentration of 0.5%, 1% and 1.5% for 1 h immediately after each exercise (keeping the concentration of oxygen and nitrogen in the environment the same as those in the air). The rats were weighed weekly during the experiment. The next day after 4 weeks of training, the samples were collected, and the contents of total superoxide dismutase (T-SOD), catalase (CAT), total antioxidant capacity (T- AOC) and malondialdehyde (MDA) were determined respectively. Results The weight of exercise control was significantly lower than sedentary in the third and fourth weeks of exercise (P<0.05). Compared to sedentary rats, there was no significant difference in the weight of rats between H1, H2 and H3 group. The contents of T-AOC, CAT and T-SOD in exercise control were significantly higher than those in sedentary (P<0.05). The content of CAT in H2 group was significantly decreased compared with exercise control (P<0.01). Compared with exercise control, the T-AOC and T-SOD in the H2 group showed a downward trend but no statistical difference (P>0.05), there was no significant difference between the above indexes, compared with sedentary. In addition, there was no difference in T-SOD and CAT content between H1 group and exercise control; Compared with exercise control, there was no significant difference in T-SOD, T-AOC and CAT in H3 group. At the MDA level, each exercise group increased significantly compared with the sedentary (P<0.05), and the MDA levels in the H1, H2, and H3 groups were decreased compared with the exercise control, but there was no statistical difference. Conclusions It can be seen from the above results that different concentrations of hydrogen intervention can improve the weight loss of rats after intensive exercise. More importantly, the dosage and effect of 1% concentration of hydrogen is easier to remove the excessive radicals produced by intense exercise in the body, avoid the aggravation of oxidative stress, and have very good therapeutic effect. It provides a theoretical basis for the further study of the application of hydrogen in exercise oxidative damage. 

scholarly journals Physiological and biochemical responses of two precious Carpinus species to high-concentration NO2 stress and their natural recovery

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Qianqian Sheng ◽  
Min Song ◽  
Zunling Zhu ◽  
Fuliang Cao
Keyword(s):  
Ecosystem Function ◽  
Room Temperature ◽  
Normal Growth ◽  
Urban Greening ◽  
High Concentration ◽  
Scientific Application ◽  
Natural Recovery ◽  
Biochemical Responses ◽  
Damage Response ◽  
Physiological And Biochemical

AbstractCarpinus betulus and Carpinus putoensis are precious species in the world. Studies on the ecosystem function of the two species are rare. This study investigated the physiological and biochemical responses of C. betulus and C. putoensis to NO2 stress and their natural recovery. C. betulus and C. putoensis seedlings underwent fumigation with 12.0 mg/m3 NO2 for 0, 1, 6, 12, 24, 48, and 72 h, respectively. Then, the plants were allowed to recover at room temperature for 30 d. Physiological and biochemical changes in the leaves were compared between the two species. In terms of peroxidase (POD) activity, the damage response of C. betulus under NO2 stress appeared later than that of C. putoensis. The soluble protein content of C. betulus was noticeably higher than that of C. putoensis, and C. betulus exhibited more stable membrane lipoperoxidation. The tendency of the changes in nitrate reductase of C. betulus was less noticeable than that of C. putoensis. The variation amplitudes of N, K, Mg, Zn and Mn in the leaves of C. putoensis were greater than those of C. betulus. C. putoensis showed more sensitive metabolisms in response to NO2 stress compared with C. betulus. High-concentration NO2 caused damage to C. betulus and C. putoensis was reversible, and both species returned to normal growth via their own metabolism after 30-d recovery. The results of this study may provide useful reference data for quantitative assessment of the ecosystem function of C. betulus and C. putoensis and for their scientific application in urban greening.

scholarly journals The Cytoprotective and Cell Recovery Properties of Apple Extracts on H2O2 induced-NIH3T3 Cells: An Anti Aging Candidate

2018 ◽  
Vol 9 (2) ◽  
pp. 78 ◽  
Author(s):  
Nunuk Aries Nurulita ◽  
Anjar Mahardian Kusuma ◽  
Darsini Darsini ◽  
Weny Delvia ◽  
Veby Tri Yulianti
Keyword(s):  
Free Radicals ◽  
Vitamin C ◽  
Protective Effect ◽  
Cell Damage ◽  
Cell Aging ◽  
Fibroblast Cells ◽  
Cell Recovery ◽  
High Concentration ◽  
High Potency ◽  
Nih3t3 Cells

Apple contains high concentration of phenolic compounds that protect cells from oxidative stress. The prolong exposure of free radicals may induce cell damage and premature cell aging. Both local and imported apple contain flavonoid, saponin, tannin, steroid, and terpenoid. The extract of local and imported apples showed low toxicity on NIH3T3 fibroblast cells, with IC50 value of 529 and 463 µg/mL, respectively. Both apple extracts (50 – 250 µg /mL) protected three-day-H2O2 induced-cell damage and cell death. Protective effect was observed as the viability increase of treated cells compared to untreated ones. The protective effect of both extracts were higher than the effect of vitamin C as standard antioxidant at this study. Both apple extracts could reverse cell damage caused by three-hour-high concentration H2O2 exposure, similar with vitamin C. Low concentration of both extracts (50 µg /mL) induced the increase of fibroblast cells’ proliferation kinetics. The extract of imported apple showed higher properties of protective, cell recovery and proliferation of fibroblast cells tha local apple, but not statistically significance. This study concludes that the extract of local and imported apples have high potency in cytoprotective effect and cell recovery of damaged cells caused by free radicals induction. Both apple extracts have high potency to be developed the candidate of antiaging and cells’ regeneration agent.Key words: antiaging, cell recovery, cytoprotective, NIH3T3 cells

Untersuchung konkurrierender Reaktionen in strömenden Kohlenwasserstoff-Gemischen / Investigation of Competing Reactions in Flowing Mixtures of Hydrocarbons

1974 ◽  
Vol 29 (4) ◽  
pp. 642-649 ◽  
Author(s):  
R. Laupert ◽  
G. von Bünau
Keyword(s):  
Rate Constants ◽  
Atomic Hydrogen ◽  
Relative Rate ◽  
Experimental Conditions ◽  
Kinetic Evaluation ◽  
Alkyl Radicals ◽  
Relative Rate Constants ◽  
Flow Apparatus ◽  
Competing Reactions

The reactions of atomic hydrogen with propene, butene-2, and trimethylethylene, and with mixtures of these olefins with ethylene have been studied using flow apparatus. It was found that under the experimental conditions intermediate alkyl radicals reacted practically only with atomic hydrogen. This made possible a kinetic evaluation of the results yielding numerical values of several relative rate constants of competing intermediate reactions.

The detection of free radicals in the high intensity photolysis of hydrogen azide

1956 ◽  
Vol 235 (1200) ◽  
pp. 143-147 ◽  
Keyword(s):  
Free Radicals ◽  
Absorption Spectra ◽  
High Intensity ◽  
Inert Gas ◽  
Hydrogen Azide

The absorption spectra of the radicals NH and NH 2 have been observed in the flash photo­lysis of hydrogen azide in the presence of an excess of inert gas. A new complex, but slightly diffuse, absorption has been detected around 2700 Å. This spectrum shows no shift when DN 3 is substituted for HN 3 , and it is attributed to the N 3 radical. The mechanism of the hydrogen azide photolysis is discussed briefly with reference to these observations.

Radiation damage in polyethylene as studied by electron spin resonance

1961 ◽  
Vol 262 (1309) ◽  
pp. 207-218 ◽  
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Alkyl Radical ◽  
Room Temperature ◽  
Chemical Properties ◽  
Resonance Method ◽  
Alkyl Radicals ◽  
Spin Resonance ◽  
Physical And Chemical ◽  
Kinetics Of

The electron spin resonance method was employed to study the nature, concentration and kinetics of the disappearance under varying conditions of radicals produced in polyethylene by fast electron irradiation at 77°K. The predominant radical species at 77°K is the alkyl radical —CH 2 —ĊH—CH 2 —. On being warmed to room temperature it disappears rapidly, revealing a more stable un­identified radical. The kinetics of the decay at room temperature of both radicals was observed. Their stabilities were found to vary in polyethylene samples of differing physical and chemical properties. G values for these radicals are given. Comparison was made with spectra obtained under similar conditions with two pure paraffins and a pure olefin to evaluate the effect of crystallinity branching, molecular weight and unsaturation. In the olefin there is evidence for a build-up of allyl radicals due to the encounter of an alkyl radical with main chain unsaturation. This supports the view that alkyl radicals are mobile, and cross-linking occurs when two such radicals meet.

Influence of Hydrochloric Acid Concentrations on the Formation of AgCl-Doped Iron Oxide-Silica Coreshell Structures

2012 ◽  
Vol 77 ◽  
pp. 184-189 ◽  
Author(s):  
Norsuria Mahmed ◽  
Oleg Heczko ◽  
Simo Pekka Hannula
Keyword(s):  
Iron Oxide ◽  
Hydrochloric Acid ◽  
Room Temperature ◽  
Silver Chloride ◽  
Ambient Atmosphere ◽  
High Concentration ◽  
Wet Chemistry ◽  
Hcl Concentration ◽  
Average Size ◽  
Very High

Silver chloride (AgCl) nanoparticles with the average size of about 45 nm have successfully been doped onto the iron oxide-silica coreshell surfaces by a simple room temperature wet chemistry method under ambient atmosphere. The Stöber process has been used to make the coreshell structure, followed by adsorption of Ag+ species on silica surface prior to the addition of hydrochloric acid (HCl) and polyvinylpyrrolidone (PVP). The concentration of HCl acid that was used to induce the growth of AgCl particles was varied from 0.12 mM to 12x103 mM of concentrations. Results showed that at a very high concentration of HCl (12x103 mM), large AgCl agglomerates (0.3-0.6 microns) with irregular cubic-like morphology were obtained while at a very low, 12 mM HCl concentration, 30-50nm AgCl particles having a uniform cubic morphology were observed. Concentrations below 12 mM result in irregular and nearly spherical morphology of AgCl particles with a smaller size (28-60 nm). UV-Vis absorption of the composite materials showed absorption in the visible wavelength indicating that Ag nanoclusters might coexist together with AgCl particles.

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