Results 1 - 10 of 1697
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[en] Full text: There have been suggested various hypothesis of phasesous scheme for the mechanism of going the selective hydrogenation ethane-ethylene fraction (EEF) of paralysis gas. According to each hypothesis kinetic models have been elaborated. In order to define the parameters of kinetic models there was used industrial information. It has been found that the model, constructed on the 2-centres mechanism described the industrial processes the most exactly. The adequacy of this model has been proved
[en] A number of prominent Q-branches of the ν7 band of C2H6 have been identified near 3000 cm-1 in aircraft and ground-based infrared solar absorption spectra. The aircraft spectra provide the column amount above 12 km at various altitudes. The column amount is strongly correlated with tropopause height and can be described by a constant mixing ratio of 0.46 ppbv in the upper troposphere and a mixing ratio scale height of 3.9 km above the tropopause. The ground-based spectra yield a column of 9.0 x 1015 molecules cm-2 above 2.1 km; combining these results implies a tropospheric mixing ratio of approximately 0.63 ppbv
[en] A library of N,N-substituted isoindigo derivatives were prepared by reaction of isoindigo with a variety of alkylating agents in the presence of MeONa under mild conditions in yields of 65–80%. A new, more efficient synthesis of (3Z,3′Z)-3,3′-(ethane-1,2-diylidene)bis(indolin-2-one) is described by reaction of oxindole with glyoxal at reflux in methanol—a small library of N,N′-substituted derivatives were also prepared in 60–70% yield. Graphical abstract: .
[en] Using a system of four GEMs operating in tandem and coupled to pad readout, we have demonstrated the detection of single electrons in ethane at 1 bar. The paper presents measurements of single electron pulse height distributions, total gas gain measurement and calculation, pad-to-pad cross-talk, quenching capability, high rate capability, charging effects, etc. We describe the overall operational experience, including addition of a gaseous photocathode, TMAE, and compare it to the SLD CRID single-electron detector , which has been operational during the past decade
[en] The cracking of heptane (HEP) and the cracking of the binary system of triethylamine/heptane (TEA/HEP) in a continuous tubular reactor at 3.5 MPa are studied, to test the effect of triethylamine on the pyrolysis of heptane under a supercritical condition. It is found that triehtylamine can promote the cracking of heptane under the supercritical condition, and more effective in lower temperatures. The selectivity of ethane, ethylene, propylene, and C4 by pyrolysis of TEA/HEP is notably higher than that by HEP in a low temperature, while the difference of the selectivity is weak when in a high temperature. The kinetic character of the cracking of heptane under the supercritical condition is studied, through which the activation energy and the pre-exponential factor are obtained by pseudo-isothermal method with a quick convergence process
[en] The effect on the ethane internal rotation barrier of (1) zero-point vibrational averaging and (2) distortions in equilibrium geometry during internal rotation is determined. We find that the (previously ignored) averaging term is 374+-90 cal/mole which is substantially larger, and opposite in sign, to the distortion correction of -161+-20 cal/mole. The isotope shift, other experimental tests, and some important implications of our results are discussed
[en] The reaction of 1-(2-oxocyclohexyl)ethane-1,1,2,2-tetracarbonitrile with crotonic aldehyde, cinnamic aldehyde, 2-furylacrolein, 3-phenyl-2-propinal, 3-butyl-2-propinal, and R-(−)-myrtenal have been investigated. It has been shown that these reactions proceed through the stage of the formation of 8a-hydroxyhexahydro-2H-chromene-3,3,4,4-tetracarbonitrile, followed by the formation of 10-iminotetrahydro-8a,4-(epoxymethane)chromene-3,3,4(2H,4aH-tricarboritrile. The X-ray diffraction data have suggested that the stereochemical features of the target products are determined by the reaction path.
[en] The geochemistry exploration uses direct methods to determine the presence of accumulations of hydrocarbons. Most of the big discoveries of hydrocarbons in the world were carried out with base in superficial manifestations (springs) and it is considered that with base in this direct evidence has been discovered more oil and gas that with any other prospecting technique. The springs and micro-escapes of oil and gas in the terrestrial surface and marine funds are the result of the vertical migration of hydrocarbons from the ores until the surface. The superficial expressions of the escapes of hydrocarbons appear as halos with the biggest concentrations in the limit of the accumulation. The hydrocarbons are generated starting from the organic material by biogenic and thermo-catalytic processes, it are the light products as the gases those that have the biggest easiness for migration and to arrive to the surface. The geochemistry prospecting non alone uses the information of the contained gases in the floor, it also uses a series of secondary indicators as: the presence of microorganisms that consume hydrocarbons, the magnetic susceptibility of diagenic magnetic minerals, the radiometry with base in the presence of uranium in ambient both reducers and oxidizers, the electromagnetic induction on mineralization anomalies, the laser remote spectrometry of the gas aureoles, the satellite images for detection of anomalies, the thermoluminescence of the flow of gamma rays near to surface and the radar for the detection of superficial propane
[en] SiH_2-(CH_2)_2 and CH_2=CH-SiH_3 were observed in the matrix IR spectra following reactions of laser-ablated Si atoms with ethane on the basis of correlation with computed frequencies. Evidently photon energy is required for the formation of the cyclic Si compound. These Si complexes are similar to the primary products in the previous studies of group 4 metals, in line with the previous results that s"2p"2 and s"2d"2 electronic configurations yield similar products. The relatively long C–C bond in the cyclic Si product reflects the structural strain, and the short C-Si and C-C bonds of CH_3CH=SiH_2 and CH_2=CH-SiH_3 show that they are true double bonds in line with the natural bond orders. Reactions of transition-metal atoms with small alkanes and halomethanes have been studied in a series of recent investigations. High oxidation-state products (methylidenes and methylidynes) along with insertion complexes were identified in the matrix spectra. It is interesting whether or not Si, a group 14 metalloid, undergoes similar reactions with larger hydrocarbons to provide higher oxidation-state compounds