THE PHOTOLYSIS OF DIMETHYL MERCURY IN HEXANE SOLUTION AT LOW TEMPERATURES

1954 ◽  
Vol 32 (5) ◽  
pp. 457-464 ◽  
Author(s):  
D. H. Derbyshire ◽  
E. W. R. Steacie
Keyword(s):  
Low Temperatures ◽  
Methyl Radicals ◽  
Temperature Range ◽  
Abstraction Reaction ◽  
Hexane Solution ◽  
Mechanism Of The Reaction

The photolysis of dimethyl mercury in solution in n-hexane has been studied over the temperature range +25 °C. to −80 °C. The results indicate that methane is produced by an abstraction reaction involving the solvent, and ethane is produced by dimerization of methyl radicals. The mechanism of the reaction is discussed, and it is concluded that the abstraction reaction involves radicals possessing considerable energy carried over from the photodissociation.

THE REACTION OF METHYL RADICALS WITH FORMALDEHYDE

1959 ◽  
Vol 37 (4) ◽  
pp. 672-678 ◽  
Author(s):  
S. Toby ◽  
K. O. Kutschke
Keyword(s):  
Activation Energy ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
Formyl Radical ◽  
Temperature Range ◽  
Abstraction Reaction

Azomethane was photolyzed in the presence of up to 30 mole per cent formaldehyde and formaldehyde-d2 at temperatures from 80 °C to 180 °C. The value of the activation energy for the abstraction reaction with methyl radicals was found to be 6.2 kcal mole−1 for CH2O and 7.9 kcal mole−1 for CD2O. The results indicated that the formyl radical was stable over the temperature range studied.

Features of radiothermoluminescence of polypropylene and ethylene propylenediene elastomer SKEPT-4044 compositions with nanoscale metal-containing fillers

2020 ◽  
pp. 66-73
Author(s):  
A.M. Magerramov ◽  
◽  
N.I. Kurbanova ◽  
M.N. Bayramov ◽  
N.A. Alimirzoyeva ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Molecular Mobility ◽  
Fe3o4 Nanoparticles ◽  
Low Temperatures ◽  
Frost Resistance ◽  
Relaxation Processes ◽  
Ethylene Propylene ◽  
Temperature Range ◽  
Β Relaxation

Using radiothermoluminescence (RTL), the molecular mobility features in the temperature range of 77-300 K were studied for the polypropylene (PP)/ethylene propylene diene elastomer SKEPT-4044 with NiO, Cu2O and Fe3O4 nanoparticles (NPs) based on ABS-acrylonitrile butadiene or SCS-divinyl styrene matrices. It has been shown that the introduction of nanofillers in PP significantly affects the nature and temperature of γ- and β-relaxation processes, while the region of manifestation of the β-process noticeably shifts to the region of low temperatures. Composites with Cu2O NPs have a higher β-transition temperature Tβ than composites with other NPs. It was found that PP/SKEPT-4044 composites with Cu2O NPs with a dispersion of 11-15 nm and acrylonitrile butadiene thermoplastics have optimal frost resistance compared to other compositions.

Dynamic Viscosity of Compressed Water to 10 Kilobar and Steam to 1500°C

1969 ◽  
Vol 11 (2) ◽  
pp. 189-205 ◽  
Author(s):  
E. A. Bruges ◽  
M. R. Gibson
Keyword(s):  
Gaseous Phase ◽  
Dynamic Viscosity ◽  
Low Temperatures ◽  
Pressure Range ◽  
Low Pressure ◽  
Temperature Range ◽  
Inversion Temperature ◽  
Pressure Steam ◽  
Correlating Equations ◽  
First Time

Equations specifying the dynamic viscosity of compressed water and steam are presented. In the temperature range 0-100cC the location of the inversion locus (mu) is defined for the first time with some precision. The low pressure steam results are re-correlated and a higher inversion temperature is indicated than that previously accepted. From 100 to 600°C values of viscosity are derived up to 3·5 kilobar and between 600 and 1500°C up to 1 kilobar. All the original observations in the gaseous phase have been corrected to a consistent set of densities and deviation plots for all the new correlations are given. Although the equations give values within the tolerances of the International Skeleton Table it is clear that the range and tolerances of the latter could with some advantage be revised to give twice the existing temperature range and over 10 times the existing pressure range at low temperatures. A list of the observations used and their deviations from the correlating equations is available as a separate publication.

Optimization of Sample Holder Materials for Sensitive Magnetometry Measurements at Low Temperatures

2004 ◽  
Vol 825 ◽  
Author(s):  
I. Bossi ◽  
N.R. Dilley ◽  
J. R. O'Brien ◽  
S. Spagna
Keyword(s):  
Magnetic Field ◽  
Low Temperatures ◽  
Magnetic Response ◽  
Sample Holder ◽  
Magnetization Measurements ◽  
Temperature Range ◽  
Paramagnetic Impurities ◽  
Fused Quartz

AbstractMagnetization measurements were performed as a function of magnetic field H and temperature T on samples of nine different materials including clear fused quartz, cartridge brass, G-10 glass-reinforced epoxy, acetal homopolymer, glass-filled acetal, phenolic, and other plastics. A small yet distinct amount of ferromagnetic or paramagnetic impurities is observed in all the materials investigated in this study except quartz. In contrast, the magnetic response of quartz is typical of a diamagnet over the temperature range 5 K to 300 K. The volume susceptibility is equal to −4.4×10−7 (cgs) over the whole temperature range.

THE REACTION OF METHYL RADICALS WITH FORMALDEHYDE

1959 ◽  
Vol 37 (9) ◽  
pp. 1462-1468 ◽  
Author(s):  
A. R. Blake ◽  
K. O. Kutschke
Keyword(s):  
Activation Energy ◽  
Kinetic Analysis ◽  
Addition Reactions ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
A Value ◽  
Abstraction Reaction ◽  
Butyl Peroxide

The pyrolysis of di-t-butyl peroxide has been reinvestigated and used as a source of methyl radicals to study the abstraction reaction between methyl radicals and formaldehyde. At low [HCHO]/[peroxide] ratios the system was simple enough for kinetic analysis, and a value of 6.6 kcal/mole was obtained for the activation energy. At higher [HCHO]/[peroxide] ratios the system became very complicated, possibly due to the increased importance of addition reactions.

MECHANISM AND KINETICS OF THE CH3CH2C(O)OCH2CH3 + OH REACTION: A THEORETICAL STUDY

2011 ◽  
Vol 10 (05) ◽  
pp. 691-709 ◽  
Author(s):  
CONG HOU ◽  
CHENG-GANG CI ◽  
TONG-YIN JIN ◽  
YONG-XIA WANG ◽  
JING-YAO LIUM
Keyword(s):  
Rate Constants ◽  
Hydrogen Abstraction ◽  
Negative Temperature ◽  
State Theory ◽  
Measured Temperature ◽  
Temperature Range ◽  
Global Rate ◽  
Abstraction Reaction ◽  
Lower Temperature ◽  
Kinetic Calculations

The hydrogen abstraction reaction of CH 3 CH 2 C(O)OCH 2 CH 3 + OH has been studied theoretically by dual-level direct dynamics method. Six H-abstraction channels were found for this reaction. The required potential energy surface information for the kinetic calculations was obtained at the MCG3-MPWB//M06-2X/aug-cc-pVDZ level. The rate constants were calculated by the improved canonical variational transition-state theory with small-curvature tunneling correction (ICVT/SCT) approach in the temperature range of 200–2000 K. It is shown that the "methylene H-abstraction" from the alkoxy end of the ester CH 3 CH 2 C(O)OCH 2 CH 3 is the dominant channel at lower temperature (< 400 K), while the other channels from the acetyl end should be taken into account as the temperature increases and become the competitive ones at higher temperature. The calculated global rate constants are in good agreement with the experimental ones in the measured temperature range and exhibit a negative temperature dependence below 500 K. A four-parameter rate constant expression was fitted from the calculated kinetic data between 200–2000 K.

Heat capacities of O2, N2, CO, and NO at low temperatures

1969 ◽  
Vol 47 (1) ◽  
pp. 23-29 ◽  
Author(s):  
J. C. Burford ◽  
G. M. Graham
Keyword(s):  
Low Temperatures ◽  
Degrees Of Freedom ◽  
Anomalous Behavior ◽  
Heat Capacities ◽  
Temperature Range

The heat capacities of O2, N2, CO, and NO have been measured in the temperature range from 4.2 °K to about 0.8 °K. No anomalous behavior was found. The results were fitted to the Debye expression (assuming 3 degrees of freedom per molecule) to yield the following values for Θ0: O2, 104.5 ± 1.0 °K; N2, 83.5 ± 1.0 °K; CO, 103.0 ± 1.0 °K; NO, 122 ± 2 °K. The results are discussed in terms of the residual entropies of CO and NO.

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.

Notizen: Various Donors in n-ZnSb and the Influence of Sample Treatment

1975 ◽  
Vol 30 (3) ◽  
pp. 381-382 ◽  
Author(s):  
A. Abou- Zeid ◽  
G. Schneider
Keyword(s):  
Low Temperatures ◽  
Room Temperature ◽  
Surface Effects ◽  
Sample Treatment ◽  
Temperature Range ◽  
Donor Doping ◽  
P Type

Various donor doping of ZnSb is investigated. Te-doping yields the most stable n-type crystals at room temperature; the samples show p-type behaviour at low temperatures. The influence of surface effects is demonstrated. It was possible to prepare n-type ZnSb for the whole temperature range.

THE REACTION OF HYDROGEN AND DEUTERIUM ATOMS WITH PROPANE

1939 ◽  
Vol 17b (12) ◽  
pp. 371-384 ◽  
Author(s):  
E. W. R. Steacie ◽  
N. A. D. Parlee
Keyword(s):  
Activation Energy ◽  
High Temperatures ◽  
Low Temperatures ◽  
Hydrogen Atoms ◽  
Temperature Range ◽  
Secondary Reactions

The reaction of hydrogen atoms with propane has been investigated over the temperature range 30° to 250 °C. by the Wood-Bonhoeffer method. The products are solely methane at low temperatures, and methane, ethane, and ethylene at higher temperatures.It is concluded that the results can be explained only by the assumption that the reaction[Formula: see text]is of importance. The bearing of this on the Rice-Herzfeld mechanisms is discussed. The activation energy of the reaction is 10 ± 2 Kcal.The main steps in the postulated mechanism are:Primary Reaction[Formula: see text]Secondary Reactions at Low Temperatures[Formula: see text]Additional Secondary Reactions at High Temperatures[Formula: see text]The reaction of deuterium atoms with propane was also investigated. It was found that the methane and ethane produced were highly deuterized, while the propane was not appreciably exchanged.

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