摘要:

AbstractFrom the results of order of magnitude analyses, it is concluded that during the oxidation of toluene, radical‐atom and radical‐radical reactions (1) and (3) play an unusually important and approximately equal role in the formation of benzaldehyde, an intermediate that leads eventually to the complete removal of the side chain.An additional radical‐radical system, reaction (2), is shown to be the most likely source of benzyl alcohol observed during toluene oxid

ISSN:0538-8066    

DOI:10.1002/kin.550160902

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractKinetics of the incorporation of mercury(II) ion in tetra (p‐trimethylammoniumphenyl)porphine have been investigated in aqueous solution at 30.0°C and 0.2 M (NaNO3) ionic strength. The reaction was found to be first order each in mercury(II) and the porphyrin. The forward (formation) and the reverse (dissociation) rate constants were found to be 1.9 ± 0.2 × 103M−1s−1and 7 ± 2 × 106M−1s−1, respectively. Kinetics of zinc(II) incorporation in tetra(p‐trimethylammoniumphenyl)porphine catalyzed by mercury(II) were also investigated. This catalysis is explained in terms of steady‐state formation of mono mercury(II) porphyrin followed by zinc(II) displacement of mercury(II) ion from the porphyrin. Such a mechanism also illustrates the importance of porphyrin core deformation to m

ISSN:0538-8066    

DOI:10.1002/kin.550160903

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe yields of C5and C6alkyl nitrates from neopentane, 2‐methylbutane, 2‐methylpentane, 3‐methylpentane, and cyclohexane have been measured in irradiated CH3ONONO‐alkane‐air mixtures at 298 ± 2 K and 735‐torr total pressure. Additionally, OH radical rate constants for neopentyl nitrate, 3‐nitro‐2‐methylbutane, 2‐nitro‐2‐methylpentane, 2‐nitro‐3‐methylpentane, and cyclohexyl nitrate, relative to that forn‐butane, have been determined at 298 ± 2 K. Using a rate constant for the reaction of OH radicals withn‐butane of 2.58 × 10−12cm3molecule−1s−1, these OH radical rate constants are (in units of 10−12cm3molecule−1s−1): neopentyl nitrate, 0.87 ± 0.21; cyclohexyl nitrate, 3.35 ± 0.36; 3‐nitro‐2‐methylbutane, 1.75 ± 0.06; 2‐nitro‐2‐methylpentane, 1.75 ± 0.22; and 2‐nitro‐3‐methylpentane, 3.07 ± 0.08. After accounting for consumption of the alkyl nitrates by OH radical reaction and for the yields of the individual alkyl peroxy radicals formed in the reaction of OH radicals with the alkanes studied, the alkyl nitrate yields (which reflect the fraction of the individual RO2radicals reacting with NO to form RONO2) determined were: neopentyl nitrate, 0.0513 ± 0.0053; cyclohexyl nitrate, 0.160 ± 0.015; 3‐nitro‐2‐methylbutane, 0.109 ± 0.003; 2‐nitro‐2methylbutane, 0.0533 ± 0.0022; 2‐nitro‐2‐methylpentane, 0.0350 ± 0.0096; 3‐ + 4‐nitro‐2‐methylpentane, 0.165 ± 0.016; and 2‐nitro‐3‐methylpentane, 0.140 ± 0.014. These results are discussed and compared with previous literature values for th

ISSN:0538-8066    

DOI:10.1002/kin.550160904

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractResults obtained from the photolysis of ketene with acetylene strongly support the formation of C3H3radicals in the title reaction. Stationary state studies are interpreted in terms of the reaction\documentclass{article}\pagestyle{empty}\begin{document}$${\rm C}_3 {\rm H}_{\rm 4}^{\rm *} \buildrel3\over\rightarrow{\rm C}_3 {\rm H}_3^ \cdot + {\rm H}^ \cdot$$\end{document}with a rate constant (109.8s−1) which is compared to RRKM predictions. In pulsed laser induced decomposition experiments, recombination products involving C3H3have been detected (some for the first time) and their formation modeled using step (3) with the same rate constan

ISSN:0538-8066    

DOI:10.1002/kin.550160905

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractRate constants for the self‐ and cross‐termination of the isopropylol radical [(CH3)2ĊOH] and its anion [(CH3)2ĊO−] in aqueous solution are determined by kinetic electron spin resonance. Whereas the self‐termination of the neutral radical occurs close to the diffusion‐controlled limit, the cross‐ and self‐terminations involving the anion are slower and reflect effects of charge repulsion and steric constrain

ISSN:0538-8066    

DOI:10.1002/kin.550160906

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe rate constants for reactions (4) and (5)were determined at room temperature by pulsed laser photolysis and time resolved mass spectrometry. A description of the experimental setup is given. CFCl2O2radicals were generated by photolysis of CFCl3at 193 nm in the presence of an excess of oxygen, using an excimer laser. The rate constant for reaction (4), determined under different experimental conditions is:\documentclass{article}\pagestyle{empty}\begin{document}$$k_4 = 1.6{\rm }(\pm 0.2) \times 10^{ - 11} {\rm cm}^{\rm 3} \cdot {\rm molecule}^{ - 1} \cdot {\rm s}^{ - 1}$$\end{document}The rate constant of reaction (5) was determined in the pressure range of 1–12 torr, using oxygen as the buffer gas. The reaction is in its fall‐off region and the parameters determined by using the semiempirical method of Troe, takingFc= 0.6 are:\documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{l} k(0) = 3.5{\rm }(\pm 0.5) \times 10^{ - 29} {\rm cm}^{\rm 6} \cdot {\rm molecule}^{ - 2} \cdot {\rm s}^{ - 1} \\ k(\infty) = 6.0{\rm }(\pm 1.0) \times 10^{ - 12} {\rm cm}^{\rm 3} \cdot {\rm molecule}^{ - 1} \cdot {\rm s}^{ - 1} \\ \end{array}$$\end{document}The value ofk(∞) is obtained from the low‐pressure measurements and therefore the uncertainty on the actual high‐pressure limit is higher than the error limits quoted above. The results are compared with those reported for similar

ISSN:0538-8066    

DOI:10.1002/kin.550160907

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractA readily applicable empirical formula is obtained for the collisional efficiency for energy transfer between a highly vibrationally excited reactant and a seasoned (usually quartz) wall, in terms of the molecular weight, potential well depth and dipole moment of the reactant. This expression is used to examine corrections due to nonunit wall collision efficiency in the high‐pressure rate parameters obtained from very low‐pressure pyrolysis experiments. It is found that these corrections are up to ca. ±5 kJ/mol in the high‐pressure activation energy and a factor of ca. 2 in the high‐pressure frequency factor, for molecules with molecular weight less than ca. 100 and where experiments are carried out at temperatures exceedin

ISSN:0538-8066    

DOI:10.1002/kin.550160908

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe unimolecular decomposition of methyl nitrite in the temperature range 680–955 K and pressure range 0.64 to 2.0 atm has been studied in shock‐tube experiments employing real‐time absorption of CW CO laser radiation by the NO product. Computer kinetic modeling using a set of 23 reactions shows that NO product is relatively unreactive. Its initial rate of production can be used to yield directly the unimolecular rate constant, which in the fall‐off region, can be represented by the second‐order rate coefficient in the Arrhenius form:\documentclass{article}\pagestyle{empty}\begin{document}$$k_1 = 10^{17.90 \pm 0.21} \exp (- 17200 \pm 400/T){\rm cm}^{\rm 3} {\rm mol}^{ - 1} {\rm s}^{ - 1}$$\end{document}A RRKM model calculation, assuming a loose CH3ONO≠complex with two degrees of free internal rotation, gives good agreement with the experimental rat

ISSN:0538-8066    

DOI:10.1002/kin.550160909

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe absolute rate constant for the OH + HCl reaction has been measured from 240 to 295 K utilizing the techniques of laser/flash photolysis‐resonance fluorescence. The HCl concentrations were monitored continuously by ultraviloet and infrared spectrophotometry. The results can be fit to the following Arrhenius expression:\documentclass{article}\pagestyle{empty}\begin{document}$$k_1 = (4.6{\rm } \pm {\rm }0.3){\rm } \times {\rm }10^{ - 12} \exp [- (500{\rm } \pm {\rm }60)/T{\rm cm}^3 /{\rm molecule} \cdot {\rm s}$$\end{document}The rate constant values obtained in this study are 20–30% larger than those recommended previously for modeling of stratospheric chemis

ISSN:0538-8066    

DOI:10.1002/kin.550160910

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe reaction\documentclass{article}\pagestyle{empty}\begin{document}${\rm Br} + {\rm CH}_3 {\rm CHO}\buildrel1\over\rightarrow{\rm HBr} + {\rm CH}_3 {\rm CO}$\end{document}has been studied by VLPR at 300 K. We findk1= 2.1 × 1012cm3/mol s in excellent agreement with independent measurements from photolysis studies. Combining this value with known thermodynamic data givesk‐1= 1 × 1010cm3/mol s. Observations of mass 42 expected from ketene suggest a rapid secondary reaction:\documentclass{article}\pagestyle{empty}\begin{document}$${\rm Br} + {\rm CH}_3 {\rm CO}\buildrel2\over\rightarrow[{\rm CH}_3 {\rm COBr}]^* \buildrel3\over\rightarrow{\rm HBr} + {\rm CH}_2 {\rm CO}$$\end{document}in which step 2 is shown to be rate limiting under VLPR conditions andk2is estimated at 1012.6cm3/mol s from recent theoretical models for radical recombination. It is also shown that 0 ⩽E1⩽ 1.4 kcal/mol using theoretical models for calculation ofA1and is probably closer to the lower limit. Reaction −1 is negligible under condit

ISSN:0538-8066    

DOI:10.1002/kin.550160911

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY