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• 1980-1984  (594)
• Physical Chemistry  (593)
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• 1
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 397-405
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: A vacuum ultraviolet photolysis of C2H5Br at 147 nm was studied over a pressure range of 0.5-50 torr at 298 K. The effects of additives He and NO were also investigated.The principal reaction products were found to be C2H4 and C2H6, with lesser yields of CH4 and C2H2. With increasing pressure the product quantum yields Φi of C2H4, CH4, and CH2H6 remained constant, while that of C2H2 decreased from 0.03 to almost 0. The effect of He as an additive was found to be extremely small on the quantum yields of the major products. Addition of NO completely suppresses the formation of CH4, C2H2, and C2H6, and reduces partially the production of C2H4. The primary processes appear to involve two electronically excited states. One state mainly yields C2H4 by molecular elimination of HBr and is thought to be due to a Rydberg transition. The other state decomposes to C2H5 and Br radicals by C—Br bond fission. These two competitive reaction modes contribute to the photodecomposition in proportions of 50% and 50%. The extinction coefficient for C2H5Br at 147 nm and at 298 K has been determined as ∊ = (1/PL) In(Io/It) = 712 ± 7 atm-1 · cm-1.
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• 2
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 603-620
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The reaction of methyl radicals (Me) with hexafluoroacetone (HFA), generated from ditertiary butyl peroxide (dtBP), was studied over the temperature range of 402-433 K and the pressure range of 38-111 torr. The reaction resulted in the following displacement process taking place: where TFA refers to trifluoroacetone. The trifluoromethyl radicals that were generated abstract a hydrogen atom from the peroxide: such that k6a is given by: \documentclass{article}\pagestyle{empty}\begin{document}$${\rm log}\,\,k_{6{\rm a}} \left( {M^{ - 1} \cdot {\rm s}^{ - 1} } \right)\,\, = \,\,8.2\, \pm \,0.7\, - \,8.9\, \pm \,{{1.3} \mathord{\left/ {\vphantom {{1.3} \theta }} \right. \kern-\nulldelimiterspace} \theta }$$\end{document} where θ = 2.303RT kcal/mol. The interaction of methyl and trifluoromethyl radicals results in the following steps: Product analysis shows that k17/k151/2k161/2 = 2.0 ± 0.2 such that k17 = 1010.4±0.5M-1 · s-1. The rate constant k5 is given by: \documentclass{article}\pagestyle{empty}\begin{document}$${{{\rm log}\,\,k_5 } \mathord{\left/ {\vphantom {{{\rm log}\,\,k_5 } {\left( {M^{ - 1} \cdot {\rm s}^{ - 1} } \right)}}} \right. \kern-\nulldelimiterspace} {\left( {M^{ - 1} \cdot {\rm s}^{ - 1} } \right)}}\,\, = \,\,8.0\, \pm \,1.3\, - \,5.1\, \pm \,{{0.7} \mathord{\left/ {\vphantom {{0.7} \theta }} \right. \kern-\nulldelimiterspace} \theta }$$\end{document} It is concluded that the preexponential factor for the addition of methyl radicals to ketones is lower than that for the addition of methyl radicals to olefins.
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• 3
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 707-724
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The reactions of labeled N15NO+ with CO, NO, O2, 18O2, N2, NO2, and N2O have been investigated using a tandem ICR instrument. In each case the total rate coefficient, product distribution, and kinetic energy dependence were measured. The results indicate that very specific reaction mechanisms govern these reactions. This conclusion is suggested by the lack of isotopic scrambling in many cases and by the complete absence of energetically allowed products in almost all of the systems. The kinetic energy studies indicate that most of the reaction channels proceed through an intermediate complex at low energies and via a direct mechanism at higher kinetic energies. Such direct mechanisms include long range charge transfer and atom or ion transfer.
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• 4
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984)
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Type of Medium: Electronic Resource
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• 5
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 793-799
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: Boiling-temperature measurements have been used to study the kinetics of the decomposition of urea. Values for the rate constants in neutral, acid, and basic media have been obtained and compared with literature data. The effect of the reverse reaction on the value of the experimental rate constants is discussed. The profile of the ebulliometric curves is different for the three media and is correlated with the number of various species present in solution. It is concluded that ebulliometric measurements can be useful for kinetic studies.
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• 6
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 835-847
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: Chlorocyclopropane has been produced by addition of CH2(1A1) and CH2(3B1) to chloroethene. CH2 was generated by the photolysis of ketene at 313 and 366 nm. Chlorocyclopropane was formed in a chemically activated state, had an energy content between 378 and 427 kJ/mol, and reacted in three parallel channels to 3-chloropropene, cis- and trans-1-chloropropene. As secondary reactions elimination of HCl from the chemically activated primary products occurred to form allene and propyne. The apparent rate constants for the isomerization and elimination reactions are reported. The results of RRKM calculations including distribution functions for the activated chlorocyclopropane and a stepladder model for the deactivation support the proposed reaction scheme.
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• 7
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 801-816
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The kinetics and mechanism of the thermal decomposition of n-propylsilane have been studied by the single pulse shock tube-comparative rate technique at pressures around 4700 torr between 1095-1240 K. The primary dissociation processes are 1,1 and 1,2 H2 elimination with ø1,1 ⋍ 0.75 and ø1,2 ⋍ 0.25, respectively. Subsequent decompositions of the primary process product, n-propylsilylene, to propylene and ethylene is complete even in the presence of excess butadiene. Possible mechanistic paths for these decompositions are discussed and an activation energy range of 30 ± 4 kcal is established for both processes. Induced decomposition via silylene chains accounts for 36-46% of the overall reaction in the uninhibited decomposition of n-propylsilane. The silylene chains are quenched in excess butadiene, and studies under maximum inhibition give overall decomposition kinetics of, log k(nPrSiD3, s-1) = 15.26-65,300 ± 1950 cal/2.303. Computer modeling results of the overall reaction both in the absence and presence of butadiene are also presented and shown to be in acceptable agreement with the experimental observations.
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• 8
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 817-834
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: Kinetics of hydrogen oxidation near the lower explosion limit in the kinetic region of chain termination has been studied. Major effects, causing deviations of the reaction kinetics from calculations by the linear theory of branched chain processes, are shown to be (1) the inhibition of the reacting mixture by the products of interaction of active centers with vacuum grease or with impurities contained in it and (2) the heterogeneous negative interaction of reaction active centers. The kinetics of hydrogen oxidation in this region has been calculated with consideration of the heterogeneous negative chain interaction. A set of parameters has been obtained that make it possible to determine by the shape of the kinetic curves the sign and the value of nonlinear interaction of chains near the lower explosion limit. It has been shown that the experimental data are in good agreement with the calculations, provided the heterogeneous negative chain interaction is taken into consideration and the inhibiting effect of impurities is eliminated. The rate of heterogeneous generation of chains on a quartz surface treated with hydrofluoric or boric acid has been determined.
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• 9
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 849-866
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: An efficient process for converting the energy stored in electronically excited NF(a1Δ) into blue-green BiF (A—X) band emissions has been discovered. Bismuth atoms are converted to BiF and then repeatedly pumped to the (AO+) state in two steps via collisions with NF(a1Δ). A model has been formulated that predicts BiF emission intensities that are in excellent agreement with the observed values. Some of the rate coefficients required for this model are estimated by means of charge-transfer theories. The cyclic nature of this system, along with its other basic properties, suggests that it has a strong potential to be an efficient blue-green laser system.
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• 10
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 867-878
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The kinetics of OH reactions with furan (k1), thiophene (k2), and tetrahydrothiophene (k3), have been investigated over the temperature range 254-425 K. OH radicals were produced by flash photolysis of water vapor at λ 〉 165 nm and detected by timeresolved resonance fluorescence spectroscopy. The following Arrhenius expressions adequately describe the measured rate constants as a function of temperature (units are cm3 molecule-1 S-1): k1 = (1.33 ± 0.29) × 10-11 exp[(333 ± 67)/T], k2 = (3.20 ± 0.70) × 10-12 exp[(325 ± 71)/T], k3 = (1.13 ± 0.35) × 10-11 exp[(166 ± 97)/T]. The results are compared with previous investigations and their implications regarding reaction mechanisms and atmospheric residence times are discussed.
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• 11
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 879-886
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: Relative rate constants for the reactions of hydroxyl radicals with a series of alkyl substituted olefins were measured by competitive reactions between pairs of olefins at 298 ± 2 K and 1 atmospheric pressure. Hydroxyl radicals were produced by the photolysis of H2O2 with 254-nm irradiation. The obtained rate constants were (× 10-11 cm3 molecule-1 s-1): 2.53 ± 0.06, propylene; 5.49 ± 0.17, cis-2-butene; 5.47 ± 0.1, isobutene; 6.46 ± 0.13, 2-methyl-1-butene; 6.37 ± 0.16, cis-2-pentene; 6.23 ± 0.1, 2-methyl-1-pentene; 8.76 ± 0.14, 2-methyl-2-pentene; 6.24 ± 0.08, trans-4-methyl-2-pentene; 10.3 ± 0.1, 2,3-dimethyl-2-butene; 9.94 ± 0.1, 2,3-dimethyl-2-pentene; 5.59 ± 0.07, trans-4,4-dimethyl-2-pentene. A trend in alkyl substituent effect on the rate constant was found, which is useful to predict kOH on the basis of the number of alkyl substituents on the double bond.
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• 12
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New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 899-907
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The reactions of ground-state S(3PJ) atoms with thiirane, methylthiirane, and trans-2,3-dimethylthiirane have been studied by flash photolysis-VUV kinetic absorption spectroscopy. From the analysis of the S(3PJ) decay plots the following rate constants were determined: (1.4 ± 0.2) × 1013, (2.7 ± 0.3) × 1013 and (4.0 ± 0.2) × 1013 (in cm3 mol-1 s-1 units) for thiirane, methylthiirane and trans-2,3-dimethylthiirane, respectively, showing an upward trend with increasing methylation.
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• 13
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 887-898
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: Rate constants have been determined at 296 ± 2 K for the gas phase reaction of NO3 radicals with a series of aromatics using a relative rate technique. The rate constants obtained (in cm3 molecule-1 s-1 units) were: benzene, 〈2.3 × 10-17; toluene, (1.8 ± 1.0) × 10-17; o—xylene, (1.1 ± 0.5) × 10-16; m—xylene, (7.1 ± 3.4) × 10-17; p—xylene, (1.4 ± 0.6) × 10-16; 1,2,3-trimethylbenzene, (5,6 ± 2.6) × 10-16; 1,2,4-trimethylbenzene (5.4 - 2.5) × 10-16; 1,3,5-trimethylbenzene, (2.4 ± 1.1) × 10-16; phenol, (2.1 ± 0.5) × 10-12; methoxybenzene, (5.0 ± 2.8) × 10-17; o-cresol, (1.20 ± 0.34) × 10-11; m-cresol, (9.2 ± 2.4) × 10-12; p-cresol, (1.27 ± 0.36) × 10-11; and benzaldehyde, (1.13 ± 0.25) × 10-15. These kinetic data, together with, in the case of phenol, product data, suggest that these reactions proceed via H-atom abstraction from the substituent groups. The magnitude of the rate constants for the hydroxy-substituted aromatics indicates that the nighttime reaction of NO3 radicals with these aromatics can be an important loss process for both NO3 radicals and these organics, as well as being a possible source of nitric acid, a key component of acid deposition.
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• 14
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 909-918
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The absolute rate constants for reversible addition of the substituted phenylthio radicals to vinylpyridines in solution at 23°C have been determined by flash photolysis method. For each phenylthio radical, the reactivities of vinylpyridines is 3-5 times lower than that of styrene. The relative equilibrium constants estimated with flash photolysis indicate that the stabilities of the adduct carbon-centered radicals generated from vinylpyridines are similar to that from styrene. The Hammett plots suggest that the difference in the reactivities originates in the polar transition state; the nitrogen atom in 4-vinylpyridine withdraws the electrons of vinylic double bond.
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• 15
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 941-945
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: NO Abstract.
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• 16
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984)
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
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• 17
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 919-939
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The formation of nitrous acid (HONO) in the dark from initial concentrations of NO2 of 0.1-20 ppm in air, and the concurrent disappearance of NO2, were monitored quantitatively by UV differential optical absorption spectroscopy in two different environmental chambers of ca.4300- and 5800-L volume (both with surface/volume ratios of 3.4 m-1). In these environmental chambers the initial HONO formation rate was first order in the NO2 concentration and increased with the water vapor concentration. However, the HONO formation rate was independent of the NO concentration and relatively insensitive to temperature. The initial pseudo-first-order consumption rate of NO2 was (2.8 ± 1.2) × 10-4 min-1 in the 5800-L Teflon-coated evacuable chamber and (1.6 ± 0.5) × 10-4 min-1 in a 4300-L all-Teflon reaction chamber at ca.300 K and ca.50% RH. The initial HONO yields were ca.40-50% of the NO2 reacted in the evacuable chamber and ca.10-30% in the all-Teflon chamber. Nitric oxide formation was observed during the later stages of the reaction in the evacuable chamber, but ca.50% of the nitrogen could not be accounted for, and gas phase HNO3 was not detected. The implications of these data concerning radical sources in environmental chamber irradiations of NOx- organic-air mixtures, and of HONO formation in polluted atmospheres, are discussed.
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• 18
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1103-1110
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: Results obtained from the photolysis of ketene with acetylene strongly support the formation of C3H3 radicals 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 (109.8 s-1) which is compared to RRKM predictions. In pulsed laser induced decomposition experiments, recombination products involving C3H3 have been detected (some for the first time) and their formation modeled using step (3) with the same rate constant.
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• 19
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1111-1115
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: Rate 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 constraints by solvation.
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• 20
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1151-1160
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The 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 chemistry.
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• 21
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1139-1150
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The 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 rate constants.
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• 22
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1161-1166
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The 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 find k1 = 2.1 × 1012 cm3/mol s in excellent agreement with independent measurements from photolysis studies. Combining this value with known thermodynamic data gives k-1 = 1 × 1010 cm3/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 and k2 is estimated at 1012.6 cm3/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 of A1 and is probably closer to the lower limit. Reaction -1 is negligible under conditions used.
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• 23
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984)
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
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• 24
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New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1167-1173
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: Potassium persulfate oxidizes triphenylphosphine to triphenylphosphine oxide in 60% aqueous acetonitrile. It has been suggested that the oxygen of the product, triphenylphosphine oxide, might originate from solvent water, following nucleophilic attack on an intermediate phosphonium ion. We have investigated the origin of the oxygen in the oxidation of triphenylphosphine by potassium persulfate in 60% aqueous acetonitrile containing 20% [18O]water. The product was analyzed by using the 18O isotope effect in 31P NMR spectroscopy. The magnitude of the 18O isotope-induced shift was determined by synthesizing triphenylphosphine [18O]oxide and was found to be 0.038 ppm upfield. The product of the oxidation reaction in 20% [18O]water displayed no 18O isotope effect. The origin of the oxygen in the oxidation reaction is the persulfate ion, consistent with an alternative mechanism involving nucleophilic attack by water at the sulfur atom of a phosphonium peroxysulfate intermediate.
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• 25
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New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1213-1226
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: It is shown how kinetic electron spin resonance spectroscopy with intermittent radical generation can be used to obtain rate constants of various simultaneous reactions in systems containing more than one kind of transient radicals. The technique is applied to reactions of tert-butyl [(CH3)3Ċ] and isopropylol [(CH3)2ĊOH] radicals generated by photolysis of di-tert-butyl ketone and acetone in 2-propanol/acetone mixtures. It yields the rates of generation of the two radicals, the rate constants for their self- and crossterminations and for the reaction of tert-butyl with 2-propanol. The extent of diffusion control of the termination constants is discussed.
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• 26
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1247-1256
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The extinction coefficients and the decay kinetics of I2-. and (SCN)2-⋅ have been characterized over the 15-90°C-temperature range. The extinction coefficients of I2-⋅ at 385 and 725 nm were determined to be 10,000 and 2560M-1 cm-1, respectively, based on the extinction coefficient of (SCN)2-⋅ at 475 nm being equal to 7600M-1 cm-1. At these three wavelengths, all extinction coefficients were constant over the temperature range studied. The rate of decay of both I2-⋅ and (SCN)2-⋅ was found to be a function of I- and SCN- concentration, respectively, as well as temperature.
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• 27
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New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1227-1246
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The reactions of O3 with ethylene, allene, 1,3-butadiene, and trans-1,3-pentadiene have been studied in the presence of excess O2 over the temperature range 232 to 298 K. The initial O3 pressure was varied from 4-18 mtorr, and the olefin pressure was varied from 0.1 to 4.5 torr (ethylene), 2.8 to 39.6 torr (allene), 52.7 to 600 mtorr (1,3-butadiene) or 26.2 to 106 mtorr (trans-1,3-pentadiene). The O3 decay was monitored by ultraviolet absorption. The reactions are first order in both O3 and olefin, and the rate coefficients are independent of the O2 pressure. For the O3-ethylene system, various diluent gases (O2, N2, air) were used and the rate coefficients were found to be independent of the nature of the diluent gas. The various rate coefficients fit the Arrhenius expressions (k in cm3 s-1): \documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{l}{\rm For C}_{\rm 2} {\rm H}_4 :k\{ 232 - 298{\rm K}\} {\rm } = {\rm }(7.72 \pm 0.89){\rm } \times {\rm 10}^{ - 15} \exp [- 5080{\rm } \pm {\rm }60)/RT] \\ {\rm For C}_{\rm 3} {\rm H}_4 :k\{ 252 - 298{\rm K}\} {\rm } = {\rm }(1.54 \pm 0.25){\rm } \times {\rm 10}^{ - 15} \exp [- 5343{\rm } \pm {\rm }87)/RT] \\ {\rm For 1,3 - C}_{\rm 4} {\rm H}_{\rm 6} :k\{ 254 - 299{\rm K}\} {\rm } = {\rm }(2.20 \pm 0.44){\rm } \times {\rm 10}^{ - 14} \exp [- 4828{\rm } \pm {\rm }109)/RT] \\ {\rm For trans - 1,3 - C}_{\rm 5} {\rm H}_{\rm 8} :k\{ 238 - 298{\rm K}\} {\rm } = {\rm }(1.07 \pm 0.25){\rm } \times {\rm 10}^{ - 13} \exp [- 4608{\rm } \pm {\rm }122)/RT] \\ \end{array}$$\end{document} where the reported uncertainties are one standard deviation and R is in cal/mol K.
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• 28
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1257-1266
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The problem of diethanolamine (DEA) degradation in gas-treating processes was quantified through a detailed kinetic study. This reaction was found to be catalyzed by CO2, and degradation occurs in a successive manner to 3-(2-hydroxyethyl)oxazolidone-2, to N,N,N′-tris(2-hydroxyethyl)ethylenediamine and then to N,N′-bis(2-hydroxyethyl)piperazine. A reaction mechanism consistent with these observations was proposed and tested through kinetic analyses. A satisfactory kinetic model which can be of practical use was derived.
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• 29
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1267-1273
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The pyrolysis kinetics of several ethyl esters with polar substituents at the acyl carbon have been studied in the temperature range of 319.8-400.0°C and pressure range of 50.5-178.0 torr. These eliminations are homogeneous, unimolecular, and follow a first-order rate law. The rate coefficients are given by the Arrhenius equations: for ethyl glycolate, log k1 (s-1) = (12.75 ± 0.30) - (201.4 ± 3.8) kJ/mol/2.303RT; for ethyl cyanoacetate, log k1 (s-1) = (12.19 ± 0.18) - (191.8 ± 2.1) kJ/mol/2.303RT; for ethyl dichloroacetate, log k1 (s-1) = (12.62 ± 0.36) - (193.9 ± 4.3) kJ/mol/2.303RT; for ethyl trichloroacetate, log k1 (s-1) = (12.27 ± 0.09) - (185.1 ± 1.0) kJ/mol/2.303RT. The results of the present work together with those reported recently in the literature give an approximate linear correlation when plotting log k/k0 vs. σ* values (ρ* = 0.315 ± 0.004, r = 0.976, and intercept = 0.032 ± 0.006 at 400°C). This linear relationship indicates that the polar substituents affect the rate of elimination by electronic factors. The greater the electronegative nature of the polar substituent, the faster is the pyrolysis rate. The alkyl substituents yield, within experimental error, similar values in rates which makes difficult an adequate assessment of their real influence.
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• 30
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1327-1335
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: By photolyzing azomethane over the temperature range 331-491 K in the presence of trifluoroacetone the kinetics of the addition reaction (1), ĊH3 + CF3COCH3 → CF3C(Ȯ)(CH3)2 have been studied. Detailed analyses have shown that the principal product of the adduct radical, CF3C(Ȯ)(CH3)2, is CH3COCH3 from reaction (-2), CF3C(Ȯ)(CH3)2 → CH3COCH3 + ĊF3. The rate constant of the addition reaction has been determined to be k1(dm3/mol s) = (4.5 ± 1.4) × 107 exp(-(3370 ± 120)/T) over the temperature range 331-491 K, based on the value k3 = 2.2 × 1010 dm3/mol s for the reaction (3), 2ĊH3 → C2H6. The results are discussed in relation to existing data for radical additions to groups.
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• 31
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1351-1356
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The reactions of some perfluoroalkyl radicals with carbon tetrachloride have been studied using the photolysis of the corresponding perfluoroalkyl iodide as the free radical source. The Arrhenius parameters, based on the value of 2.3 × 1013 cm3 mol-1 s-1 for the self-combination rate constant of all radicals are: TextReactionlog(A/cm3 mol-1 s-1)E/kcal mol-1CF3 + CCl412.811.3C2F5 + CCl412.811.6n-C3F7 + CCl412.912.0
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• 32
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1337-1350
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The photolysis of trans-3,4-dimethylcyclopentanone has been studied in the gas phase, principally at 313 nm. However, a few experiments have also been performed using laser sources at 308 and 325 nm. Additionally, experiments were also carried out using the cis isomer. The major products produced by all three wavelengths and in the temperature range 100 to 150°C were propene, 1,2-dimethylcyclobutane, carbon monoxide, and 3,4-dimethylpent-4-en-al. The formation of the cyclobutane was stereospecific and the effects of temperature, pressure, and wavelength on the relative product yields could be rationalized in terms of a mechanism involving the formation of a vibrationally excited triplet state which could yield both hydrocarbons and the aldehyde and a nonexcited triplet yielding only the aldehyde. Some high intensity experiments with an exciplex laser at 308 nm gave results which could be due to the occurrence of some two photon absorption by the cyclopentanone or absorption by an excited intermediate. The results are compared with those previously reported for other substituted cyclopentanones.
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• 33
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1357-1370
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The gas-phase reaction of CF3 with HCN has been examined over a wide conversion range using CF3I as a thermal and photolytic source of radicals. Quantitative and qualitative results show a significant increase of the specific rate constant for the hydrogen abstraction reaction relative to CF3 recombination when reaction is carried out under ultraviolet irradiation. This “extra” formation of the reaction product, CF3H, has been assigned to the participation of iodine in this system through the formation of a (I-HCN) intermediate. Arrhenius parameters obtained for the addition mechanism of I to HCN do not seem to conform to a single reaction step, on the contrary, they correspond to a more complex reaction scheme.
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• 34
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1371-1383
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The decomposition kinetics of ethylsilane under shock tube conditions (PT ca. 3100 torr, T ≃ 1080-1245 K), both in the absence and presence of silylene trapping agents (butadiene and acetylene) are reported. Arrhenius parameters under maximum butadiene inhibition are: log k(C2H5SiH3) = 15.14-64,769 ± 1433 cal/2.303 RT; log k(C2H5SiD3) = 15.29-66,206 ± 1414/2.303 RT. The uninhibited reaction is subject to silylene induced decomposition (63% lowest T -- 24% highest T). Major reaction products are ethylene and hydrogen, consistent with two dominant primary dissociation reactions: C2H5SiD3 → C2H5SiD + D2, φ ≃ 0.66; C2H5SiD3 → CH3CH = SiD2 + HD, φ ≃ 0.30. Minor products suggest several other less important primary processes: alkane elimination, φ ≃0.02, and free-radical production via simple bond fission, φ ≃0.02. An upper limit for the activation energy of the decomposition, C2H5SiH → C2H4 + SiH2, of E 〈 30 ± 4 kcal is established, and speculations on the mechanism of this decomposition (concerted or stepwise) with conclusions in favor of the stepwise path are made. Computer modeling studies for the reaction both in the absence and presence of butadiene are shown to be in good agreement with the experimental observations.
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• 35
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1401-1426
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: Small low residence time flow tube reactors made of alumina and used as molecular beam sources are described. In these reactors, gas mixtures are rapidly heated and brought to reaction. The composition of the gas leaving the reactor is analyzed by molecular beam mass spectroscopy. For quantitative simulation of the reacting gas flow, the theory of one-dimensional compressible flow with friction, heat transfer, and chemical reaction is brought into a form suitable for practical computation. The system has been applied to study the thermal decompositions of O3 and N2O. The experimental results on both reactions can be well modeled by homogeneous reaction mechanisms with accepted rate constants. Heterogeneous reaction steps are shown to be unimportant.
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• 36
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1427-1454
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The use of the KMS method for the evaluation of the exponent by the experimentalist requires that a lag or retardation be chosen. The best choice of lag is discussed quantitatively. Its dependence upon the decade range of the data, the relative magnitude of the background, the level and character of the noise, the number and distribution of the data, and the weighted least-squares method of analysis are all detailed. A table of lags and error factors is given, for various ranges, backgrounds, and kinds of noise. Bias in the extracted rate (k), due to noise and treatment of the data, is also discussed.
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• 37
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1385-1399
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The photooxidation of acrylonitrile, methacylonitrile, and allylcyanide in the presence of NO was studied in parts per million concentration using the long-path Fourier transform IR spectroscopic method. The stoichiometry of the OH radical initiated oxidation of methacrylonitrile was established as \documentclass{article}\pagestyle{empty}\begin{document}$\left( {{\rm OH}} \right) + {\rm CH}_{\rm 2} = {\rm C}\left( {{\rm CH}_{\rm 3} } \right){\rm CN + 2NO + 2O}_{\rm 2} \mathop {\hbox to 20pt{\rightarrowfill}}\limits^{1.0} {\rm HCHO + CH}_{\rm 3} {\rm COCN + 2NO}_{{\rm 2}} + \left( {{\rm OH}} \right)$\end{document}. The yield of HCHO for acrylonitrile and allylcyanide was found to be ca. 100 and 80%, and the stoichiometric reactions were assessed to proceed, \documentclass{article}\pagestyle{empty}\begin{document}$\left( {{\rm OH}} \right) + {\rm CH}_{\rm 2} = {\rm CHCN + 2NO + 2O}_{\rm 2} \mathop {\hbox to 20pt{\rightarrowfill}}\limits^{1.0} {\rm HCHO + HCOCN + 2NO}_{\rm 2} + \left( {{\rm OH}} \right)$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$\left( {{\rm OH}} \right) + {\rm CH}_{\rm 2} = {\rm CHCH}_{\rm 2} {\rm CN + 2NO + 2O}_{\rm 2} \mathop {\hbox to 20pt{\rightarrowfill}}\limits^{0.8} {\rm HCHO + HCOCH}{\rm 2} {\rm CN + 2NO}_{\rm 2} + \left( {{\rm OH}} \right)$\end{document}, respectively. These results revealed that the reaction mechanism for these unsaturated organic cyanides are analogous to that of olefins.
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• 38
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984)
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
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• 39
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. i
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
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• 40
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New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 1-5
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The effect of the polarity of seven solvents (∊ ≈ 2-60) on the rate of ozone reactions with stilbene and allyl chloride has been studied. The data show that the rate of the reaction is insensitive to the medium polarity. The results of earlier publications are revised and are shown to be in agreement with the present data.
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• 41
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 7-21
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The gas-phase decompositions of methylsilane and methylsilane-d3 have been investigated in a single-pulse shock tube at 4700 torr total pressure in the temperature range of 1125-1250 K. For CH3SiD3 at 1200 K three primary steps occur in the homogeneous decomposition with efficiencies in parentheses: \documentclass{article}\pagestyle{empty}\begin{document}$${\rm CH}_{\rm 3} {\rm SiD}_{\rm 3} \mathop {\longrightarrow} \limits^1 {\rm CH}_{\rm 3} {\rm SiD} + {\rm D}_{\rm 2} \left( {0.71} \right)$$\end{document}, \documentclass{article}\pagestyle{empty}\begin{document}$${\rm CH}_{\rm 3} {\rm SiD}_{\rm 3} \mathop {\longrightarrow} \limits^2 {\rm CH}_{\rm 4} + {\rm SiD}_{\rm 2} \left( {0.15} \right)$$\end{document}, and \documentclass{article}\pagestyle{empty}\begin{document}$${\rm CH}_{\rm 3} {\rm SiD}_{\rm 3} \mathop {\longrightarrow} \limits^3 {\rm CH}_{\rm 2} \raise1pt\hbox{=\kern-3.45 pt=} {\rm SiD}_{\rm 2} \left( {0.14} \right)$$\end{document}. For CH3SiH3 at 1200 K the primary CH4 elimination efficiency is 0.09 while the total primary H2 elimination efficiency is 0.91. Minor product formations of C2H4, acetylene, dimethylsilane, and SiH4 are discussed.
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• 42
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New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 23-30
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The static system pyrolysis of methylsilane (T ∼ 700 K, PT ∼ 150 torr), pure and in the presence of ethylene, propylene, and acetylene, has been investigated. It is proposed that in the uninhibited system, the major products (silane and dimethylsilane) are produced by free radical processes, and that the free radicals are formed at the walls from methylsilylenes. In the presence of olefins, the free radicals are trapped to form methylsilane adducts. In acetylene, trapping of methylsilylenes prevents free radical production and eliminates the free radical produced products of the pure and the olefin inhibited systems. Rates of initiation correlate with rates of reactant loss in acetylene inhibited systems, and with rates of hydrogen formation in olefin inhibited systems. Rough estimates of primary dissociation process yields give for the 1,1-H2 elimination φ1,1 ≅ 0.78, for the 1,2-H elimination φ1,2 ≅ 0.16, and for the methane elimination φCH4 ≅ 0.06 at 700 K. Deuteration lowers initial step kinetics by about 15%.
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• 43
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 31-39
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The homogeneous gas-phase decomposition kinetics of methylsilane and methylsilane-d3 have been investigated by the comparative-rate-single-pulse shock-tube technique at total pressures of 4700 torr in the 1125-1250 K temperature range. Three primary processes occur: CH3SiH3 → CH3SiH + H2 (1), CH3SiH3 → CH4 + SiH2 (2), and CH3SiH3 → CH2 = SiH2 + H2 (3). The high-pressure rate constants for the primary processes in CH3SiH3 obtained by RRKM calculations are log (k1 + k3) (s-1) = 15.2 - 64,780 Cal/θ and log k2 (s-) = 14.50 - 67,600 → 2800 Cal/θ. For CH3SiD3 these same rate constants are log k1 (s-) = 14.99 - 64,700 cal/θ log k2 (s-) = 14.68 - 66,700 → 2000 cal/θ, and log k3 (s-) = 14.3 - 64,700 cal/θ.
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• 44
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984)
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
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• 45
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 69-89
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: Cross-disproportionation/combination ratios for CFH2 and CF3 with C2H5 radicals have been determined to be Δ = 0.032 ± 0.012 and δ = 0.098 ± 0.020, respectively, over the temperature range 25-75°C. For the pathway that yields CFH and C2H6, δ = 0.020 ± 0.005 at 25°C.
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• 46
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 41-55
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The absolute rate constants for the reactions of OH + HO2NO2 (1) and OH + HNO3 (2) have been measured with the technique of flash photolysis resonance fluorescence over the temperature ranges of 240-330 K at 760 torr He for reaction (1) and of 240-370 K at 50 and 760 torr He for reaction (2). Reactant concentrations were monitored continuously by ultraviolet and infrared spectrophotometry. The data can be fitted to the following Arrhenius expressions: \documentclass{article}\pagestyle{empty}\begin{document}$$k_1 = \left( {5.9 \pm 0.4} \right) \times 10^{ - 13} \exp \left[ {{{\left( {650 \pm 30} \right)} \mathord{\left/ {\vphantom {{\left( {650 \pm 30} \right)} T}} \right. \kern-\nulldelimiterspace} T}} \right]{{{\rm cm}^{\rm 3} } \mathord{\left/ {\vphantom {{{\rm cm}^{\rm 3} } {{\rm molecule} \cdot {\rm s}}}} \right. \kern-\nulldelimiterspace} {{\rm molecule} \cdot {\rm s}}}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$${\rm CH}_{\rm 3} {\rm SiD}_{\rm 3} \mathop {\longrightarrow} \limits^3 {\rm CH}_{\rm 2} \raise1pt\hbox{=\kern-3.45 pt=} {\rm SiD}_{\rm 2} \left( {0.14} \right)$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$k_2 = \left( {8.3 \pm 0.9} \right) \times 10^{ - 15} \exp \left[ {{{\left( {850 \pm 40} \right)} \mathord{\left/ {\vphantom {{\left( {850 \pm 40} \right)} T}} \right. \kern-\nulldelimiterspace} T}} \right]{{{\rm cm}^{\rm 3} } \mathord{\left/ {\vphantom {{{\rm cm}^{\rm 3} } {{\rm molecule} \cdot {\rm s}}}} \right. \kern-\nulldelimiterspace} {{\rm molecule} \cdot {\rm s}}}$$\end{document} These results are in very good agreement with recent studies of reaction (2), and also of reaction (1) at 295 K.
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• 47
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 57-67
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The rate coefficients for the gas-phase pyrolyses of a series of structurally related secondary acetates have been measured in a static system over the temperature range of 289.1-359.5°C and the pressure range 50.0-203.0 torr. The temperature dependence of the rate coefficients is given by the following Arrhenius equations: for 3-hexyl acetate, log k1 (s-) = (12.12 ± 0.33) - (176.1 ± 3.9)kJ/mol/2.203RT; for 5-methyl-3-hexyl acetate, log k1 (s-) = (13.17 ± 0.20) - (186.2 ± 2.3)kJ/mol/2.303RT; and for 5,5-dimethyl-3-hexyl acetate, log k1 (s-) = (12.70 ± 0.19) - (177.4 ± 2.2)kJ/mol/2.303RT. The direction of elimination of these esters has shown from the invariability of olefin distributions at different temperatures and percentages of decomposition that steric hindrance is a determining factor in the eclipsed cis conformation. Moreover, a more detailed analysis indicates that the greater the alkyl-alkyl interaction, the less favored the elimination tends to be. Otherwise, an increase of alkyl-hydrogen interaction caused steric acceleration to be the determining factor.
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• 48
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 125-148
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: Vinylacetylene was pyrolyzed at 300-450°C in a packed and an unpacked static reactor with a pinhole bleed to a quadrupole mass spectrometer. The reactant and C8H8 products were monitored continuously during a reaction by mass spectrometry. In some runs, the products were also analyzed by gas chromatography after the run. In these runs CH4, C2H6, C3H6, and C2H4 were also detected.The reaction for vinylacetylene removal and C8H8 formation is homogeneous, second order in reactant, and independent of the presence of a large excess of N2 or He. However, C8H8 formation is about half-suppressed by the addition of the free-radical scavengers NO or O2. The rate coefficient for total vinylacetylene removal is 1.7 × 106 exp(-79 ± 13 kJ/mol RT) L/mol · s. The major reaction for C4H4 removal is polymerization. In addition four C8H8 isomers, carbon, and small hydrocarbons are formed. The three major C8H8 isomers are styrene, cyclooctatetraene (COT), and 1,5—dihydropentalene (DHP).The C8H8 compounds are formed by both molecular and free-radical processes in a second-order process with an overall k ≃ 3 × 108 exp(-122 kJ/mol RT) L/mol · s (average of packed and unpacked cell results). The molecular process occurs with an overall k = 8.5 × 107 exp (-118 kJ/mol RT) L/mol · s. The COT, DHP, and an unidentified isomer (d), are formed exclusively in molecular processes with respective rate coefficients of 4.4 × 104 exp(-77 kJ/mol RT), 1.7 × 105 exp(-89 kJ/mol RT), and 3.1 × 109 exp(- 148 kJ/mol RT) L/mol · s. The styrene is formed both by a direct free-radical process and by isomerization of COT.
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• 49
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 117-124
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The static vessel pyrolysis of bicyclo[2.2.2]octa-2,5,7-triene (barrelene) has been studied between 483 and 523 K. The products were acetylene and benzene (in equal quantities) with no other detectable C8H8 isomer (down to less than 1% of total). The time dependence fitted first-order kinetics, and the data are consistent with a homogeneous unimolecular reaction close to, if not at, its high-pressure limit at 0.25 torr. The rate constant was fitted to the Arrhenius equation \documentclass{article}\pagestyle{empty}\begin{document}$$\log \left( {{k \mathord{\left/ {\vphantom {k {s^{ - 1} }}} \right. \kern-\nulldelimiterspace} {s^{ - 1} }}} \right)\, = \,\left( {14.27\, \pm \,0.18} \right)\, - \,{{\left( {41.71\, \pm \,0.41\,{{{\rm kcal}} \mathord{\left/ {\vphantom {{{\rm kcal}} {{\rm mol}}}} \right. \kern-\nulldelimiterspace} {{\rm mol}}}} \right)} \mathord{\left/ {\vphantom {{\left( {41.71\, \pm \,0.41\,{{{\rm kcal}} \mathord{\left/ {\vphantom {{{\rm kcal}} {{\rm mol}}}} \right. \kern-\nulldelimiterspace} {{\rm mol}}}} \right)} {RT}}} \right. \kern-\nulldelimiterspace} {RT}}\,\ln \,10$$\end{document} These Arrhenius parameters are shown to imply a concerted single-step process. Alternative mechanisms are discussed and a comparison is made with the retro-Diels - Alder reactions of other bicyclo[2.2.2]octa-olefin systems.
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• 50
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New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 103-115
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The kinetics of the thermal reaction between CF3OF and C3F6 have been investigated between 20 and 75°C. It is a homogeneous chain reaction of moderate length where the main product is a mixture of the two isomers 1-C3F7OCF3 (68%) and 2-C3F7OCF3 (32%). Equimolecular amounts of CF3OOF3 and C6F14 are formed in much smaller quantities. Inert gases and the reaction products have no influence on the reaction, whereas only small amounts of oxygen change the course of reaction and larger amounts produce explosions.The rate of reaction can be represented by eq. (I): The following mechanism explains the experimental results: Reaction (5) can be replaced by reactions (5a) and (5b), without changing the result: Reaction (4) is possibly a two-step reaction: \documentclass{article}\pagestyle{empty}\begin{document}$$E_1 = 15.90 \pm 0.45{\rm kcal}\,{\rm mol}^{ - 1}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$k_1 = \left( {7.60 \pm 0.68} \right)10^8 {\rm exp}\left( { - 15,900\,\, \pm \,\,450\,\,{{{\rm cal}} \mathord{\left/ {\vphantom {{{\rm cal}} {RT}}} \right. \kern-\nulldelimiterspace} {RT}}} \right)M^{ - 1} \cdot s^{ - 1}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$E^ * \, = \,12.30\, \pm \,0.25\,{\rm kcal}\,{\rm mol}^{ - 1}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$k^ * \, = \,\left( {6.11\, \pm \,0342} \right)10^7 \,{\rm exp}\left( { - 12,300\, \pm \,250\,{{{\rm cal}} \mathord{\left/ {\vphantom {{{\rm cal}} {RT}}} \right. \kern-\nulldelimiterspace} {RT}}} \right)M^{ - 1} \, \cdot \,{\rm s}^{ - 1}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{*{20}c} {E^ * \, - \frac{1}{2}E_1 \, = \,4.35\,{\rm kcal}\, = \,E_3 \, - \,\frac{1}{2}E_4 ;} & {E_3 \,} \\ \end{array} 〉 \,4.35\,{\rm kcal}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$\nu \,\left( {{\rm chain}\,{\rm length}} \right)\, = \,1 + \,\frac{{k_3 }}{{k_1 ^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} \left( {2k_4 } \right)^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} }}\left( {\frac{{\left| {{\rm CR}_{\rm 3} {\rm OF}} \right|}}{{\left| {{\rm C}_{\rm 3} {\rm F}_{\rm 6} } \right|}}} \right)^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}}$$\end{document} For ∣CF3 = ∣C3F6∣, ν20°C = 36.8, ν50°C = 24.0, and ν70°C = 14.2.
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• 51
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 93-102
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The reactions where Y = CH3 (M), C2H5 (E), i—C3H7 (I), and t—C4H9 (T) have been studied between 488 and 606 K. The pressures of CHD ranged from 16 to 124 torr and those of YE from 57 to 625 torr. These reactions are homogeneous and first order with respect to each reagent. The rate constants (in L/mol·s) are given by \documentclass{article}\pagestyle{empty}\begin{document}$${\rm log}_{{\rm 10}} k_{{\rm NMBO}} = - {{\left( {26530 \pm 80} \right)} \mathord{\left/ {\vphantom {{\left( {26530 \pm 80} \right)} {4.576T + \left( {6.05 \pm 0.03} \right)}}} \right. \kern-\nulldelimiterspace} {4.576T + \left( {6.05 \pm 0.03} \right)}}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$${\rm log}_{{\rm 10}} k_{{\rm XMBO}} = - {{\left( {28910 \pm 130} \right)} \mathord{\left/ {\vphantom {{\left( {28910 \pm 130} \right)} {4.576T + \left( {6.32 \pm 0.05} \right)}}} \right. \kern-\nulldelimiterspace} {4.576T + \left( {6.32 \pm 0.05} \right)}}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$${\rm log}_{{\rm 10}} k_{{\rm NEBO}} = - {{\left( {26150 \pm 120} \right)} \mathord{\left/ {\vphantom {{\left( {26150 \pm 120} \right)} {4.576T + \left( {5.85 \pm 0.05} \right)}}} \right. \kern-\nulldelimiterspace} {4.576T + \left( {5.85 \pm 0.05} \right)}}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$${\rm log}_{{\rm 10}} k_{{\rm XEBO}} = - {{\left( {28560 \pm 120} \right)} \mathord{\left/ {\vphantom {{\left( {28560 \pm 120} \right)} {4.576T + \left( {6.07 \pm 0.05} \right)}}} \right. \kern-\nulldelimiterspace} {4.576T + \left( {6.07 \pm 0.05} \right)}}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$${\rm log}_{{\rm 10}} k_{{\rm NIBO}} = - {{\left( {26560 \pm 80} \right)} \mathord{\left/ {\vphantom {{\left( {26560 \pm 80} \right)} {4.576T + \left( {5.57 \pm 0.03} \right)}}} \right. \kern-\nulldelimiterspace} {4.576T + \left( {5.57 \pm 0.03} \right)}}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$${\rm log}_{{\rm 10}} k_{{\rm XIBO}} = - {{\left( {28350 \pm 100} \right)} \mathord{\left/ {\vphantom {{\left( {28350 \pm 100} \right)} {4.576T + \left( {5.47 \pm 0.04} \right)}}} \right. \kern-\nulldelimiterspace} {4.576T + \left( {5.47 \pm 0.04} \right)}}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$${\rm log}_{{\rm 10}} k_{{\rm NTBO}} = - {{\left( {28920 \pm 50} \right)} \mathord{\left/ {\vphantom {{\left( {28920 \pm 50} \right)} {4.576T + \left( {5.86 \pm 0.02} \right)}}} \right. \kern-\nulldelimiterspace} {4.576T + \left( {5.86 \pm 0.02} \right)}}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$${\rm log}_{{\rm 10}} k_{{\rm XTBO}} = - {{\left( {32890 \pm 120} \right)} \mathord{\left/ {\vphantom {{\left( {32890 \pm 120} \right)} {4.576T + \left( {6.19 \pm 0.05} \right)}}} \right. \kern-\nulldelimiterspace} {4.576T + \left( {6.19 \pm 0.05} \right)}}$$\end{document} The Arrhenius parameters are used as a test for a biradical mechanism and to discuss the endo selectivity of the reactions.
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• 52
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984)
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
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• 53
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 149-157
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The reaction between ozone and carbon monoxide was reinvestigated in the range of 80-160°C. The previously reported rate law -d[O3]/dt = ka[O3][CO] + kb[O3]2 was confirmed and simulated using a mechanism based on an impurity-initiated chain reaction. When the CO was sufficiently purified, kb tended to zero and ka reduced to the value expected for the thermal decomposition of O3. Subsequent reactions of O atoms with CO produced chemiluminescence which was used to measure k3 for \documentclass{article}\pagestyle{empty}\begin{document}$${\rm O}\,\, + \,\,{\rm CO}\,\,\mathop {\longrightarrow}\limits^{\rm 3} \,\,{\rm CO}_{\rm 2} \left( {^3 B_2 } \right)$$\end{document} as 10-14.0±0.3 exp[-(1630 ± 325)/T] cm3 molecule-1 s-1. The implications of this are discussed.
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• 54
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 159-193
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: A new reaction mechanism describing the atmospheric photochemical oxidation of toluene is formulated and tested against environmental chamber data from the University of California, Riverside, Statewide Air Pollution Research Center (SAPRC). On simulations of toluene - NOx and toluene - benzaldehyde - NOx irradiations, the average predicted O3 and PAN maxima are within 3% of the experimental values. Simulations performed with the new mechanism are used to investigate various mechanistic paths, and to gain insight into areas where our understanding is not complete. Specific areas that are investigated include benzaldehyde photolysis, organic nitrate formation, alternate ring fragmentation pathways, and conjugated γ-dicarbonyl condensation to the aerosol phase.
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• 55
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 195-204
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The kinetics of the oxidation of cyclopentanol, cyclohexanol, 2—methylcyclohexanol, and cycloheptanol by hexacyanoferrate(III) ions in mild alkaline medium has been studied in the presence of traces of ruthenium(VI) ≈ 10-7M at constant ionic strength (0.26M). The results suggest that the oxidation of the studied cyclic alcohols proceeds via the formation of a complex between Ru(VI) and the substrate which slowly decomposes, giving the reduced form of ruthenium which was reoxidized to Ru(VI) in a fast step by alkaline hexacyanoferrate(III) ions. The product study shows the production of the corresponding ketone.
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• 56
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 205-211
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The rate constants for the quenching of O2(1Δg) with carbon disulfide, dimethyl sulfide, dimethyl disulfide, diallyl disulfide, ethyl mercaptan, and thiophene have been determined in a discharge flow system in the absence of oxygen atoms. The rate constants are found to be (6.5 ± 0.6) × 104, (1.8 ± 0.2) × 104, and (3.5 ± 0.6) × 103 L/mol · s for dimethyl sulfide, ethyl mercaptan, and thiophene, respectively. The other compounds have rate constants 〈9.9 × 102 L/mol · s. In the case of dimethyl sulfide, even when NO2 concentration is more than what is required to remove oxygen atoms completely, the rate constants are found to vary with different amounts of NO2. No correlation is found to exist between the logarithm of the rate constants and the ionization potentials of the compounds.
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• 57
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 213-220
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: Energetic H atoms produced by photolysis of gaseous HI react with CD3Br by D abstraction (1) and Br abstraction (2) and possibly also by the substitution reactions (4) and (5). Yields of HD and CD3H have been determined for several defined initial translational energies of H*. The phenomenological threshold energy of reaction (1) is 53 ± 5 kJ/mol. Over the range of initial energies of 76-109 kJ mol the integral probability of reaction (1) increases substantially, but the sum of the integral probabilities of reactions (2) and (5) shows little change. The ratio of the sum of the integral yields of reactions (2) and (5) to the integral yield of reaction (1), when normalized to equal numbers of Br and D atoms, is 69 ± 33 at an initial energy of 76 kJ/mol and 31 ± 6 at 109 kJ/mol.
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• 58
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 221-230
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The kinetics of the reactions of iron(III) with diglycolic, tartaric, and citric acids have been studied in aqueous acid solutions by the temperature-jump method at 25.0°C and at ionic strengths 1.0 (for tartaric and citric acids) and 0.50 mol/dm3 (for diglycolic acid). The experimental data indicate that iron(III) monochelate formation occurs by the same reaction mechanism for all three ligands examined and that only pathways involving the FeOH2+ ion contribute to the chelation process. The reacting species for citric acid is the undissociated ligand. For tartaric and diglycolic acids both the neutral ligands and the corresponding monoanions react significantly under the experimental conditions used. Kinetic evidence for the contribution of intermediate steps to the limiting rate in the overall chelate-formation process has been obtained and discussed.
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• 59
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 231-250
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: Mixtures of cyanogen and nitrous oxide diluted in argon were shock-heated to measure the rate constants of A broad-band mercury lamp was used to measure CN in absorption at 388 nm [B2Σ+(v = 0) ← X2Σ+(v = 0)], and the spectral coincidence of a CO infrared absorption line [v(2 ← 1), J(37 ← 38)] with a CO laser line [v(6 → 5), J(15 → 16)] was exploited to monitor CO in absorption. The CO measurement established that reaction (3) produces CO in excited vibrational states. A computer fit of the experiments near 2000 K led to \documentclass{article}\pagestyle{empty}\begin{document}$$k_2 \, = \,10^{11.70\left( { + 0.25, - 0.19} \right)} \,{{{\rm cm}^3 } \mathord{\left/ {\vphantom {{{\rm cm}^3 } {{\rm mol}}}} \right. \kern-\nulldelimiterspace} {{\rm mol}}}\, \cdot \,{\rm s}$$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$k_3 \, = \,10^{13.26 \pm 0.26} \,{{{\rm cm}^3 } \mathord{\left/ {\vphantom {{{\rm cm}^3 } {{\rm mol}}}} \right. \kern-\nulldelimiterspace} {{\rm mol}}}\, \cdot \,{\rm s}$$\end{document} An additional measurement of NO via infrared absorption led to an estimate of the ratio k5/k6: with k5/k6 ≃ 103.36±0.27 at 2150 K. Mixtures of cyanogen and oxygen diluted in argon were shock heated to measure the rate constant of and the ratio k5/k6 by monitoring CN in absorption. We found near 2400 K: \documentclass{article}\pagestyle{empty}\begin{document}$$k_4 \, = \,10^{12.68\left( { + 0.27, - 0.19} \right)} \,{{{\rm cm}^3 } \mathord{\left/ {\vphantom {{{\rm cm}^3 } {{\rm mol}}}} \right. \kern-\nulldelimiterspace} {{\rm mol}}}\, \cdot \,{\rm s}$$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$${{k_5 } \mathord{\left/ {\vphantom {{k_5 } {k_6 }}} \right. \kern-\nulldelimiterspace} {k_6 }}\, = \,10^{2.68 \pm 0.28}$$\end{document} The combined measurements of k5/k6 lead to k5/k6 ≃ 10-3.07 exp(+31,800/T) (±60%) for 2150 ≤ T ≤ 2400 K.
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• 60
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New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 251-258
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The rate of the reaction of aqueous sulfite with the N-chloropeptide N-chloroalanylalanylalanine has been studied as a function of pH, temperature, and ionic strength. The results of this work suggest that the mechanism of the reaction involves the interaction of the neutral chloramine with the three ionic forms of sulfite, SO3-2, HSO3-, and H2SO3, with the rate of reaction increasing rapidly with increasing protonation. The estimated second-order rate constants for each ionic species as a function of temperature are \documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{*{20}c} {{\rm H}_{\rm 2} {\rm SO}_{\rm 3} } \hfill & {k_1 \, = \,2.00\, \times \,10^8 \,{\rm exp}\left( {{{ - 1544} \mathord{\left/ {\vphantom {{ - 1544} {RT}}} \right. \kern-\nulldelimiterspace} {RT}}} \right){\rm min}^{ - 1} } \hfill \\ {{\rm HSO}_{\rm 3}^ - } \hfill & {k_2 \, = \,4.35\, \times \,10^4 \,{\rm exp}\left( {{{ - 1170} \mathord{\left/ {\vphantom {{ - 1170} {RT}}} \right. \kern-\nulldelimiterspace} {RT}}} \right){\rm min}^{ - 1} } \hfill \\ {\,\,{\rm SO}_{\rm 3}^{ - 2} } \hfill & {k_3 \, = 1.58\, \times \,10^{12} \,{\rm exp}\left( {{{ - 12,660} \mathord{\left/ {\vphantom {{ - 12,660} {RT}}} \right. \kern-\nulldelimiterspace} {RT}}} \right){\rm min}^{ - 1} } \hfill \\ \end{array}$$\end{document} where the activation energies are in units of cal/mol.
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• 61
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 259-268
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: Rate constants for the reactions of O3 and OH radicals with acetylene, propyne, and 1-butyne have been determined at room temperature. The rate constants obtained at 294 ± 2 K for the reactions of O3 with acetylene, propyne, and 1-butyne were (7.8 ± 1.2) × 10-21 cm3/molecule · s, (1.43 ± 0.15) × 10-20 cm3/molecule · s, and (1.97 ± 0.26) × 10-20 cm3/molecule · s, respectively. The rate constants at 298 ± 2 K and atmospheric pressure for the reactions with the OH radical, relative to a rate constant for the reaction of OH radicals with cyclohexane of 7.57 × 10-12 cm3/molecule · s, were determined to be (8.8 ± 1.4) × 10-13 cm3/molecule · s, (6.21 ± 0.31) × 10-12 cm3/molecule · s, and (8.25 ± 0.23) × 10-12 cm3/molecule · s for acetylene, propyne, and 1-butyne, respectively. These data are discussed and compared with the available literature rate constants.
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• 62
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 269-276
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The rate of the perchloric acid hydrolysis of aqueous ethyl and butyl vinyl ethers at 25.0°C, in the presence of micellar aggregates [anionic, sodium dodecyl sulfate (SDS); cationic, cetyl trymethyl ammonium bromide (CTAB); and nonionic, polyoxyethylen—23—dodecanol, (Brij 35)], has been studied. Negligible effects were observed in the cases of cationic and nonionic micelles. Anionic micelles produce an enhancement in the reaction velocity, and the rate constants go through maxima with increasing SDS concentration. These maxima disappear in the presence of excess sodium perchlorate. All these facts are interpreted quantitatively by means of the pseudo-phase ion-exchange model.
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• 63
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984)
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
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• 64
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 277-287
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The recent experiments on the chloride-assisted dealkylation of alkylcobalamins by a variety of oxidants (IrCl62-, AuCl4-, Fe(H2O)5Cl2+, and PtCl62-), which are scattered in several previous publications, and their general kinetic characteristics are summarized. The kinetic studies are also extended to include the dealkylations of (methylaquo)-3,5,6-trimethylbenzimidazolylcobamide and protonated base-off ethylcobalamin by IrCl62- (1.0M Cl-) and by Fe(III) ions at 0.1M Cl-, and the demethylation of (methylaquo)-3,5,6-trimethylbenzimidazolylcobamide by AuCl4- (1.0M Cl-). This extension is in an effort to substantiate the general mechanism which has been previously proposed for these oxidative dealkylations. The general kinetic characteristics are described in terms of a preassociation of the reactants, followed by a rate-determining electron-transfer process to yield the R-B12+ radical, which then undergoes further reactions to produce the products observed. The overall reactions are discussed within the framework of chlorine-bridging inner sphere electron-transfer reactions.
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• 65
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 289-305
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The shock-induced thermal decompositions of vinylsilane and vinylsilane-d3 (0.2% on argon) have been studied in the temperature range of 1085-1275 K, and at total pressures of about 3100 torr. In systems without silylene traps, some induced decomposition occurs which is attributed to the silylene chain sequence VSiH → C2H2 + SiH2, S̈iH2 + VSiH3 ⇄ VSiH2SiH3 → VSiH2S̈iH + H2, VSiH2S̈iH → VSiH + S̈iH2. In the presence of silylene traps (butadiene and acetylene), the overall decomposition kinetics are log k(VSiH3, s-1) = 14.95 - 63,268 cal/2.303RT and log k(VSiD3, s-1) = 15.14 - 64,815 cal/2.303RT. Three primary processes contribute to the decomposition: 1,1-H2 elimination, 1,2-H2 elimination, and ethylene elimination. Two mechanisms are proposed, one for exclusive primary process formation of C2H4, and the other for both primary and secondary formation routes. Modeling studies are reported which show that both mechanisms can be made compatible with the rate and product yield data within experimental errors.
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• 66
Electronic Resource
New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 345-352
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: Photochlorination of tetrachloroethylene has been studied in a homogeneous liquid system. Kinetic parameters such as reaction orders for chlorine, tetracholoroethylene and light intensity, preexponential factor, and activation energy were evaluated from experimental data. The following kinetic equation was obtained by parameter estimation following the Marquardt procedure: \documentclass{article}\pagestyle{empty}\begin{document}$$r = \left( {4.02 \pm 0.46} \right)10^{ - 5} \exp \left( { - \frac{{54,700 \pm 200}}{{RT}}} \right)I^{0.489 \pm 0.003} C_{Cl_2 }^{0.889 \pm 0.160} C_{C_2 Cl_4 }^{1.040 \pm 0.042}$$\end{document}
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• 67
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New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 335-344
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: Hydrogen abstration from H2S by CF3 radicals, generated by the photolysis of both CF3COCF3 and CF3I, has been studied in the temperature range 314-434 K. The rate constant, based on the value of 1013.36 cm3/mol · s for the recombination of CF3 radicals, is given by \documentclass{article}\pagestyle{empty}\begin{document}$${\rm log }\,k_2 \, = \,\left( {12.20\, \pm \,0.05} \right)\, - \,{{\left( {19,220\, \pm \,360} \right)} \mathord{\left/ {\vphantom {{\left( {19,220\, \pm \,360} \right)} {19.145T}}} \right. \kern-\nulldelimiterspace} {19.145T}}$$\end{document} with CF3COCF3 as the radical source, and \documentclass{article}\pagestyle{empty}\begin{document}$${\rm log }\,k_2 \, = \,\left( {12.00\, \pm \,0.07} \right)\, - \,{{\left( {18,270\, \pm \,470} \right)} \mathord{\left/ {\vphantom {{\left( {18,270\, \pm \,470} \right)} {19.145T}}} \right. \kern-\nulldelimiterspace} {19.145T}}$$\end{document} with CF3I as the radical source, where k2 is in cm3/mol · s and E is in J/mol. These results resolve a previously existing controversy concerning the values of the rate constants for this reaction. They show that CF3 radicals are less reactive than CH3 radicals in attacking H2S, and this behavior indicates that polar effects play a significant role in the hydrogen transfer reactions of CF3 radicals.
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• 68
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New York, NY : Wiley-Blackwell
International Journal of Chemical Kinetics 16 (1984), S. 353-369
ISSN: 0538-8066
Keywords: Chemistry ; Physical Chemistry
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The re