Isomerization of methyl isocyanide sensitized by vibrationally excited ethane

1969 ◽  
Vol 47 (4) ◽  
pp. 669-671
Author(s):  
D. H. Shaw ◽  
B. K. Dunning ◽  
H. O. Pritchard
Keyword(s):  
Free Radical ◽  
Total Pressure ◽  
The Other ◽  
Direct Transfer ◽  
Displacement Reaction ◽  
Methyl Radicals ◽  
Vibrationally Excited ◽  
Methyl Isocyanide

The isomerization of methyl isocyanide in the presence of methyl radicals takes place by two mechanisms. One is the simple free-radical displacement reaction which has been described previously. The other is through a direct transfer of energy from vibrationally excited ethane molecules. The vibrationally sensitized component can be quenched by increasing the total pressure.

The reaction of methylene radicals with methyl isocyanide

1979 ◽  
Vol 57 (10) ◽  
pp. 1229-1232 ◽  
Author(s):  
Marsha T. J. Glionna ◽  
Huw O. Pritchard
Keyword(s):  
Gas Phase ◽  
Exploratory Study ◽  
Total Pressure ◽  
Reaction Pathway ◽  
Gas Phase Reactions ◽  
Vibrationally Excited ◽  
Methyl Cyanide ◽  
Isotopic Studies ◽  
Methyl Isocyanide ◽  
Approximate Rate

An exploratory study has been made of the gas-phase reactions of methylene radicals, generated by the photolysis of ketene near 3000 Å, with methyl, ethyl, and allyl isocyanides at room temperature.With methyl isocyanide, the principal product at low pressure is ethyl cyanide, together with a few percent of methyl cyanide; ethyl isocyanide is also formed, increasingly so as the total pressure is increased. Reaction appears to take place through a vibrationally excited ethyl isocyanide intermediate, and approximate rate constants for each reaction pathway are derived. Isotopic studies suggest that the methylene radicals insert in the H3C—NC bond of the methyl isocyanide.

Free-radical-catalyzed isomerization of isocyanides

1967 ◽  
Vol 45 (22) ◽  
pp. 2749-2754 ◽  
Author(s):  
D. H. Shaw ◽  
H. O. Pritchard
Keyword(s):  
Thermal Decomposition ◽  
Free Radical ◽  
Carbon Atom ◽  
Gas Phase ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
Arrhenius Parameters ◽  
Reaction Proceeds ◽  
Methyl Isocyanide ◽  
Butyl Peroxide

The isomerization of methyl isocyanide and of ethyl isocyanide, catalyzed by methyl radicals produced in the thermal decomposition of di-tert-butyl peroxide, has been studied in the gas phase at temperatures near 100 °C. The Arrhenius parameters for the reaction CH3NC + CH3 → CH3 + CH3CN are E = 7.8 ± 0.3 kcal/mole and A = 1012.25 mole−1 cc s−1. It is proposed that the reaction proceeds by addition of the incoming radical to the divalent carbon atom of the isocyanide group, followed by expulsion of the radical originally attached to the N atom. The thermochemistry of addition to the divalent carbon atom is discussed in an Appendix.

Aromatic substitution. XV. The homolytic methylation of pyridine and 3- and 4-picoline

1967 ◽  
Vol 45 (5) ◽  
pp. 509-513 ◽  
Author(s):  
R. A. Abramovitch ◽  
K. Kenaschuk
Keyword(s):  
Free Radical ◽  
Methyl Radicals ◽  
Aromatic Substitution ◽  
Phenyl Radicals

The ratios of isomers formed in the free-radical methylation of pyridine and 3- and 4-picoline have been determined and the results compared with the corresponding phenylations. The results support the concept that methyl radicals are more nucleophilic than phenyl radicals.

scholarly journals Preparation and Thermal and Anti-UV Properties of Chitosan/Mica Copolymer

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Yih-Sheng Huang ◽  
Sheng-Haur Yu ◽  
Yea-Ru Sheu ◽  
Kuo-Shien Huang
Keyword(s):  
Experimental Data ◽  
Thermal Stability ◽  
Free Radical ◽  
Physical Properties ◽  
Ammonium Persulfate ◽  
Sodium Bisulfite ◽  
The Other ◽  
Other Hand

This experiment aims to produce a free radical while annoying the oxidizing-reducing reagent of the ammonium persulfate and the sodium bisulfite under nitrogen, then trigger copolymerization between modified-mica and chitosan to prepare a variety of copolymers. This experiment also aims to study the related properties of these copolymer materials. The experimental data shows that the copolymer has more thermal stability and better absorption of UV than chitosan. But the above physical properties will be less if the mica ratio in copolymer is more than 8%. On the other hand, the SEM photo of the microstructure also shows that the modified mica distributes homogeneously on the surface of the film of the copolymer.

The homogeneous conversion of methane to higher hydrocarbons in the presence of ethylene in the temperature range 925–1023 K

1991 ◽  
Vol 69 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Alain R. Bossard ◽  
Margaret H. Back
Keyword(s):  
Hydrogen Abstraction ◽  
Homogeneous System ◽  
Catalytic Reactions ◽  
The Other ◽  
Methyl Radicals ◽  
Temperature Range ◽  
Vinyl Radicals ◽  
Conversion Of Methane ◽  
Radical Distribution ◽  
Higher Hydrocarbons

Mixtures of ethylene and methane have been pyrolyzed in the temperature range 925–1023 K for the purpose of converting methane to higher hydrocarbons. Addition of methane to thermally-reacting ethylene increases the rate of formation of propylene but decreases the rates of formation of the other major products, ethane, acetylene, and butadiene. Hydrogen abstraction from methane is a major propagation reaction and causes a shift in the radical distribution from ethyl and vinyl radicals, the main radicals in the pyrolysis reactions of ethylene alone, to methyl radicals, which lead to the formation of propylene. At 1023 K with a pressure of ethylene of 6.5 Torr and of methane of 356 Torr, 1.5 mol of methane is converted to higher molecular weight products for every mole of ethylene reacted. The rate of conversion of methane in the homogeneous system is lower than in catalytic reactions but the product is entirely hydrocarbon and no methane is lost to carbon monoxide or carbon dioxide. Key words: methane, ethylene, kinetics, pyrolysis, fuels.

Glutathione Peroxidase-Like Activity of Simple Selenium Compounds. Peroxides and the Heterocyclic N-Oxide Resazurin Acting as O-Atom Donors

1995 ◽  
Vol 50 (3-4) ◽  
pp. 209-219 ◽  
Author(s):  
Walter A. Prtitz
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Glutathione Peroxidase ◽  
Crystal Violet ◽  
The Other ◽  
Atom Transfer ◽  
Selenium Compounds ◽  
Radical Intermediates ◽  
Leuco Crystal Violet ◽  
Acid Pathway

Selenite and selenocystamine [(CyaSe)2] efficiently activate the decomposition of H2O2 y GSH and by other thiols, as demonstrated using a leuco crystal violet POD-based H2O2 assay which is applicable (unlike other assays) also in presence of thiols. The GPx-like activities were estimated to be 3.6 and 2.7 μmol H2O2/min per μmol SeO32- and (CyaSe)2, respectively. Both selenium compounds also activate reduction of the heterocyclic N-oxide resazurin (RN→O) to resorufin (RN) by GSH; H2O2 competes with reduction of this dye. GSSeH and CyaSeH, formed by interaction of GSH with SeO32- and (CyaSe)2, respectively, are likely to be the active reductants. CyaSeH, generated γ-radiolytically from (CyaSe)2, exhibits an absorption peak at 243 nm and is removed by H2O2 with a rate constant of 9.7x102 ᴍ-1 s-1, and slightly slower by hydroperoxides. We have no evidence for one-electron interactions between GSSeH or CyaSeH and H2O2, with formation of free radical intermediates, as previously proposed in the case of selenium-activated reduction of cytochrome c by GSH (Levander et al., Biochemistry 23, 4591-4595 (1973)). Our results can be explained by O-atom transfer from the substrate to the active selenol group. RSeH + H2O2 (RN→O)→RSeOH + H2O (RN), and recycling of RSeOH to RSeH (+ H2O) by GSH, analogous to the selenenic acid pathway of GPx. The substrate specificity appears to be different, however, in that GPx is unable to catalyse RN→O reduction, and GSSeH hardly catalyses the decomposition of cumene- or t-butyl-hydroperoxide; CyaSeH, on the other hand, is active also with the hydroperoxides. RN→O is reduced to RN also by certain oxidizing free radicals, e.g. by the thiyl CyaS·; O -atom transfer may in this case lead to the generation of reactive oxyl radicals.

Selective Surface Modification of Fluorocarbon Resin Using Excimer Laser

1989 ◽  
Vol 158 ◽  
Author(s):  
M. Okoshi ◽  
M. Murahara ◽  
K. Toyoda
Keyword(s):  
Excimer Laser ◽  
Chemical Resistance ◽  
Raw Materials ◽  
The Other ◽  
Methyl Radicals ◽  
Selective Area ◽  
Arf Excimer Laser ◽  
Arf Laser ◽  
Selective Surface Modification ◽  
Stable Material

ABSTRACTThe fluorocarbon resin (Teflon) which is a very stable material chemically, has chemical resistance. Because of this property, it has no affinity for oil or water. Therefore, we have tried selective area modification of the resin surface b-y using an excimer laser.Fluorocarbon resin is a polymer of C-F bonds. In our experiment, the resin surface was irradiated by an ArF excimer laser, of which the photon energy is higher than that of the C-F bond, to excite the strong C-F bonds. B radicals, the best combination for F atoms, were formed simultaneously. Consequently, F atoms of C-F bonds were pulled out by B radicals. B(CH3 )3 with absorption in agreement with the wavelength of the ArF laser were used as raw materials of the B radicals. By irradiating the gas by the ArF laser beam, the photodecomposed B radicals functioned by pulling out F atoms, and the other methyl radicals ( -CH3 ) substituted for F atoms. As the result, this resin surface turned out to be oleophilic exclusively on the areas exposed to the light.

scholarly journals Radial Vaneless Diffusers: A Re-Examination of the Theories of Dean and Senoo and of Johnston and Dean

1978 ◽  
Author(s):  
M. Inoue
Keyword(s):  
Total Pressure ◽  
Shear Force ◽  
Significant Contribution ◽  
The Other ◽  
Wall Friction ◽  
Mixing Process ◽  
Vaneless Diffuser ◽  
Large Loss ◽  
Pressure Losses ◽  
Reversible Work

There are two different, but well-known, theories for calculating the mixing process of the distributed flow discharged from the impeller into the vaneless diffuser. One is by Dean and Senoo, the other by Johnston and Dean. It is intended in this paper to make clear the reason for these two theories predicting similar total pressure losses. The mixing process in the vaneless diffuser, based on the Dean and Senoo theory, is re-examined. It is found that the mixing of the flow is greatly accelerated by wall friction and shear force acting between wake and jet, and it causes the large loss at the diffuser inlet. Nevertheless, the reversible work exchange makes a significant contribution to the mixing out of the flow compared with the stationary jet and wake pattern.

The thermal decomposition of RDX at temperatures below the melting point. III. Towards the elucidation of the mechanism

1971 ◽  
Vol 24 (5) ◽  
pp. 945 ◽  
Author(s):  
JJ Batten
Keyword(s):  
Thermal Decomposition ◽  
Free Radical ◽  
Melting Point ◽  
Nitrogen Dioxide ◽  
The Other ◽  
Decomposition Products ◽  
Radical Traps

The rate of thermal decomposition of RDX has been investigated in the presence of its decomposition products and free radical traps. From the measurements, it is concluded that formaldehyde and nitrogen dioxide, presumably ?encaged? in the sample, catalyse the decomposition of RDX positively and negatively respectively. The non-volatile residue also acts as a positive catalyst. The other products have little or no effect on the rate, and the free radical traps did not reduce the rate.

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