摘要:

AbstractThe ion–molecule reactions of CH3NH2+, (CH3)2NH+, and (CH3)3N+with the respective amines have been investigated at thermal kinetic energies in a high‐pressure photoionization mass spectrometer at several wavelengths (energies) in the vacuum ultraviolet. The absolute rate coefficient for proton transfer from (CH3)3N+to (CH3)3N decreases from 8.2 × 10−10cm3/molecule · sec at 147.0 nm (8.4 eV) to 4.9 × 10−10cm3/molecule. sec at 106.7‐104.8 nm (11.7 eV). In dimethylamine, the rate coefficient decreases from 11.6 × 10−10cm3/molecular. sec at 8 4 eV to 10.2 × 10−10cm3/molecule osec at 11.7 eV, while no significant effect of energy was detected in methylamine. The reactions of several fragment ions are also reported. Experiments were also carried out at pressures up to 0.5 torr in order to investigate the further solvation of CH3NH2+, (CH3)2NH2+, and (CH3)3NH+. It was found that the maximum proton solvation numbers in methyl‐, dimethyl‐, and trimethyl‐amine are 4, 3, and 2, respectively

ISSN:0538-8066    

DOI:10.1002/kin.550050202

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractThe thermal decomposition of hexachloroethane in the presence of chlorine has been studied over the temperature range 340‐400°C and a pressure range of 0.5°2.5 atm. The rate of the unimolecular CC bond spliting reaction can be described by the Arrhenius equation\documentclass{article}\pagestyle{empty}\begin{document}$$\log k_1 = 1707 - \frac{{68,300}}{{2.3RT}}$$\end{document}Comparison of these rate data with thermodynamic data suggests a combination rate for CCl3radicals which is consistent with earlier measure

ISSN:0538-8066    

DOI:10.1002/kin.550050203

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractThe reactions of singlet molecular oxygen (O21Δg) with a series of organic compounds have been studied in the gas phase at 298°K. The concentration of singlet molecular oxygen was determined by titration with 2,5‐dimethylfuran. The titration technique was checked using a photoionization technique. Absolute rate constants were measured on the basis of the loss of organic reactant and, in some cases, of singlet molecular oxygen. It was found that the usual method of producing singlet molecular oxygen in the gas phase can also, under some conditions, allow reactive species other than singlet molecular oxygen to enter the reactor, leading to serious errors in the determination of rate constants. This problem was eliminated by carrying out the rate measurements in the presence of a small amount of nitrogen dioxide a radical scaven

ISSN:0538-8066    

DOI:10.1002/kin.550050204

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractA description of the current range of activities being pursued in the compilation and evaluation of chemical kinetic data is given. The roles of individual scientists, professional groups, and national and international programs are detailed. The special problems attending on kinetic parameters are enumerated and discussed. An appendix is included which gives a comprehensive list of compilations and evaluations extant in the field of chemical kinetics.

ISSN:0538-8066    

DOI:10.1002/kin.550050205

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractN2O was photolyzed at 2139 Å to produce O(1D) atoms in the presence of H2O and CO. The O(1D) atoms react with H2O to produce HO radicals, as measured by CO2production from the reaction of OH with CO. The relative importance of the various possible O(1D)–H2O reactions isThe relative rate constant for O(1D) removal by H2O compared to that by N2O is 2.1, in good agreement with that found earlier in our laboratory. In the presence Of C3H6, the OH can be removed by reaction with either CO or C3H6:From the CO2yield,k3/k2= 75,0 at 100°C and 55.0 at 200°C to within ± 10%. When these values are combined with the value ofk2= 7.0 × 10−13exp (–1100/RT) cm3/sec,k3= 1.36 × 10−11exp (–100/RT) cm3/sec. At 25°C,k3extrapolates to 1.

ISSN:0538-8066    

DOI:10.1002/kin.550050206

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractThe quantum yields of sensitized biacetyl phosphorescence emission have been determined for SO2–biacetyl–CO2, SO2–biacetyl–N2, and SO2–biacetyl–CO mixtures irradiated at 2875 Å. Series of experiments were made at various SO2, biacetyl, and added‐gas concentrations (up to 4 × 10‐2M). The kinetic data show an “excess” biacetyl emission which requires the participation of some undefined excited state or isomer of SO2in addition to the emitting singlet (1SO2) and triplet (3SO2) states of SO2. These results confirm the experimental observations of Cehelnik et al. [12] and Wampler et al. [9]who reported that an “excess” quantum yield of CO2occurred in 3130 Å‐irradiated SO2‐CO mixtures at high CO pressures. The kinetic analysis of the data is most consistent with the hypothesis of Wampler et al.; the nonreactive, undefined excited state or high‐energy isomer of SO2, designated here as X, is formed in part as1SO2is quenched:1SO2+ M → (SO2M) (1);1SO2+ M →3SO2+ M (2);1SO2+ M → X + M (3). X itself does not transfer energy to biacetyl. It decays largely by a nonradiative first‐order process at low pressures, X → SO2(5), but it generates3SO2by collisional perturbation at high pressures, X + M →1SO2+ M (4). In terms of this mechanism, the following rate constant ratios are derived from the present study:k2/(k1+k2+k3) = 0.020 ± 0.010 (M = CO2), 0.021 ± 0.010 (N2), 0.019 ± 0.010 (CO);k3/(k1+k2+k3) = 0.14 ± 0.02 (M = CO2), 0.085 ± 0.012 (CO), 0.11 ± 0.02 (N2); andk5/k4(mole/l) = 0.020 ± 0.

ISSN:0538-8066    

DOI:10.1002/kin.550050207

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractHeats of formation of solid, liquid, and gaseous nitroalkanes have been shown mostly to obey group additivity. Group values have been obtained for carbon atoms attached to one, two, and three nitro groups. The heat of formation of 1,1,1,3,5,5,5,‐heptanitropentane, either solid or liquid, cannot be fitted to the scheme, even allowing for gauche effects. The differences between observed and estimated values for 1,1,1‐fluorodinitroalkanes and 1,2‐dinitroethane are larger than expected and should be further investigated. Activation energies have been calculated for decomposition by five‐center elimination of HONO from mononitro‐ and dinitroalkanes using thermochemistry and estimated activation energies for the reverse reactions. The key data for these estimates were previously reported activation energies for the decomposition of nitroethane and 1,2‐dinitropropane. The calculations also gave values for the heats of formation (in kcal/mole) of nitroethylene 12.4, and 1‐nitropropylene 5.6, and 2‐nitropropylene 1.6. Activation energies were calculated for the competing unimolecular reaction, CN bond fission, from thermochemistry and previously reported activation energies for the decomposition of 1,1‐ and 2,2‐dinitropropane. Comparison of Arrhenius parameters for the two competing processes, namely, HONO and CN bond fission, shows that, for the geminate dinitroethanes and dinitropropanes, CN bond fission is faster about 370°K and, for the mononitroalkanes and for all the mononitroalkanes and dinitroalkanes, CN bond f

ISSN:0538-8066    

DOI:10.1002/kin.550050208

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractThe thermal decomposition of biacetyl has been studied at small percentage conversion over the temperature range 375‐417°C. For these conditions, an almost quantitative mass balance was obtained by gas‐chromatographic analysis. The following equation was obtained for the overall reactionBetween 240° and 277°C, the decomposition of biacetyl initiated by methyl radicals has also been studied. As source of radicals, the thermolysis of azomethane was used. Moreover, the Arrhenius parameters of the following reactions were determined:whereAis in sec−1for reaction (1) and in cm3mole−1sec−1for reactions (3) and (4);Eis in kcal/mole. Evidence is provided that the displacement reaction (4) proceeds by a two st

ISSN:0538-8066    

DOI:10.1002/kin.550050209

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractThe gas‐phase thermal decomposition of 7,7‐dimethylbicyclo[3.2.0]hept‐2‐en‐6‐one (DBH) to yield cyclopentadiene and 1,1‐dimethylketene as primary products was studied in the temperature range of 470‐550 °K using a static reaction system. First‐order rate constants for the depletion of DBH based on the internal standard technique and gaschromatographic analyses were independent of the initial starting pressure (7‐68 torr) and of the conversion, ranging between 5% and 89%. (Throughout this paper, 1 torr = (101.325/760) kNm−2, and 1 cal = 4.184J). The reaction is essentially homogeneous, as the nature of the reaction vessel surface (Teflon or glass) had no effect on the observed rate constants which fit the Arrhenius relationship\documentclass{article}\pagestyle{empty}\begin{document}$$ \log k/s^{ - 1} = 12.90 \pm 0.22 - (37071 + 0.52{\rm kcal/mole})/\theta $$\end{document}where θ = 2.303RT. These activation parameters, when compared with those for similar reactions involving the molecules bicyclo[3.2.0]hept‐2‐en‐6‐one, bicyclo[3.2.0]heptan6‐one, and cyclobutanone, demonstrate a very small effect of the alkyl substituents bonded to the carbon atom adjacent to the carbonyl carbon. Accepting the previously discussed concerted and pronounced polar nature of the mechanism for these retro‐ketene addition reactions, the present data suggest that considerable changes in charge densities between the ground and transition state are only occurring on the two opposite centers of the molecule, with the negative charge residing essentially on the oxygen atom and the positive charge on the opposing bridgehead carbon atom. It then appears that the charge separation in the transition state is more appropriately described as being pseudo‐zwitterio

ISSN:0538-8066    

DOI:10.1002/kin.550050210

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY

摘要:

AbstractThe reaction of iodine with allyl alcohol has been studied in a static system, following the absorption of visible light by iodine, in the temperature range 150‐190°C and in the pressure range 10‐200 torr. The rate‐determining step has been found to beandk3is consistent with the equationFrom the activation energy and the assumptionE‐3= 1 ± 1 kcal mol−1, it has been calculated thatkcal mol−1. The stabilization energy of the hydroxyallyl radical has been found to be 11.4 ±

ISSN:0538-8066    

DOI:10.1002/kin.550050211

出版商:John Wiley&Sons, Inc.    

年代:1973

数据来源: WILEY