摘要:

AbstractThe kinetics of the oxidation of iodide by hydrogen peroxide catalyzed by acidic molybdate have been studied by a spectrophotometric stopped‐flow method. The results are interpreted in terms of the mechanismand the implied rate law\documentclass{article}\pagestyle{empty}\begin{document}$$ - d[{\rm H}_{\rm 2} {\rm O}]/dt = \frac{{k_4 k_1 k_2 [{\rm H}_2 {\rm O}_2]^2 [{\rm mol}][{\rm I}^ -]}}{{1 + k_1 [{\rm H}_2 {\rm O}_2] + k_1 k_2 [{\rm H}_2 {\rm O}_2]^2 + {\rm K}_{\rm 3} [{\rm I}^{\rm -}]}}$$\end{document}where [mol] is total analytical concentration of molybdate. The values obtained for the rate and equilibrium constants arek4= (3.3 ± 1) × 1021./mole · s,K1= (1.2 ± 0.6) × 1041./mole,K2= (1.3 ± 0.7) × 1031./mole, andK3= (4 ± 3) × 1021./mol

ISSN:0538-8066    

DOI:10.1002/kin.550080102

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe gas‐phase photochlorination (λ = 436 nm) of the 1,1,1,2‐C2H2Cl4has been studied in the absence and the presence of oxygen at temperatures between 360 and 420°K. Activation energies have been estimated for the following reaction steps:\documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{*{20}c} {{\rm CCl}_3 {\rm CHCl}^{\rm .} + {\rm Cl}_2 \to {\rm CCl}_3 {\rm CHCl}_{\rm 2} + {\rm Cl}^{\rm .}} & {E_3 = (4.6 \pm 0.4){\rm kcal/mole}} \\ \end{array}$$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{*{20}c} {{\rm CCl}_3 {\rm CHCl}^{\rm .} \to {\rm CCl}_2 {\rm CHCl} + {\rm Cl}^{\rm .}} & {E_4 = (20.6 \pm 1.4){\rm kcal/mole}} \\ \end{array}$$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{*{20}c} {{\rm CCl}_3 {\rm CHClO}_{\rm 2} {\rm CHClCCl}_3 \to 2{\rm CCl}_3 {\rm CHClO}^{\rm .}} & {E_{15} = (33.5 \pm 3.0){\rm kcal/mole}} \\ \end{array}$$\end{document}The dissociation energyD(CCl3CHClO2) ± (24.8 ± 1.5) kcal/mole has also been estimated from the difference in activation energy of the direct and reverse reactionsThe mechanism is discussed and the rate parameters are compared to those obtained for a series of other chlorinate

ISSN:0538-8066    

DOI:10.1002/kin.550080103

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550080104

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe rate law −d[O3]/dt=k1[A][O3] +k3[A][O3]2/ (k4+k5[O2]) has been found to obtain for the reaction of ozone with allene and with 1,2‐butadiene. We now find that this rate law also applies to the reaction of ozone with ethylene and presumably with all lower alkenes. This generalizes the inhibiting effect of oxygen and accounts for the simplifed rate law found in the presence of excess oxygen. Oxygen itself is a product of the ozone–ethylene reaction, and we find that as [O3]0increases, the (O2formed)/(O3used) ratio approaches 1.5. Values ofk1,k3/k5for ethylene are compared with those for allene, 1,3‐butadiene, and propene. A generalized mechanism is postulated for the reaction of ozone with alkenes involving a chain sequence that produces oxygen and which accounts for the observed rate law. A specific mechanism is postulated for the reaction of O3with ethylene, and the thermochemistry of the chain sequence is examined in

ISSN:0538-8066    

DOI:10.1002/kin.550080105

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractAn analytical and kinetic study of the thermal reaction ofcis‐ ortrans‐2‐butene has been performed in a static system over the temperature range of 480–550°C and at a low extent of reaction and initial pressures of 10–100 torr.The rate constant of the unimolecularcis–transisomerization ofcis‐2‐butene, determined under the conditions\documentclass{article}\pagestyle{empty}\begin{document}$$k_{ct} = 10^{13.6 \pm 0.3 - 62,000 \pm 1000/2.3{\rm RT}} {\rm sec}^{- 1} $$\end{document}(2.3RTin cal/mole) is in good agreement with previous measurements made at lower pressures.A comparison between the formation rates of hydrogen from the thermal reactions ofcis‐ andtrans‐2 butene around 500°C leads to the rate constant value\documentclass{article}\pagestyle{empty}\begin{document}$$k_m = 10^{13 \pm 0.5 - 65,500 \pm 2000/2.3{\rm RT}} {\rm sec}^{- 1} $$\end{document}(2.3RTin cal/mole) for the unimolecular 1,4hydrogen elimi

ISSN:0538-8066    

DOI:10.1002/kin.550080106

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe rate constant fortert‐butyl radical recombination has been measured near 700°K by the very‐low‐pressure pyrolysis (VLPP) technique and was found to be 108.8±0.3M−1·sec−1with neglibible temperature dependence. The thermochemical parameters fortertbutyl radicals were varied within reasonable limits to bring into agreement the data for the decomposition of 2,2,3,3‐tetramethyl butane and the recombination oftert‐butyl radicals. The revised thermochemistry also makes the gas‐phase results and liquid‐ph

ISSN:0538-8066    

DOI:10.1002/kin.550080107

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe rate of decomposition oft‐butyl nitrite (TBN) has been studied in a static system over the temperature range of 120–160°C. For low concentrations of TBN (10−5‐ 10−4M), but with a high total pressure of CF4(∼0.9 atm) and small extents of reaction (∼1%), the first‐order homogeneous rates of acetone (M2K) formation are a direct measure of reaction (1), sincek3»k2(NO): TBN . Addition of large amounts of NO in place of CF4almost completely suppresses M2K formation. This shows that reaction (1) is the only route for this product. The rate of reaction (1) is given byk1= 1016.3–40.3/θ s−1. Since (E1+RT) and ΔH °1are identical, both may be equated withD(RO‐NO) = 40.9 ± 0.8 kcal/mole andE2= O ± 1 kcal/mole. From ΔS °1andA1,k2is calculated to be 1010.4M−1·s−1, implying that combination oftBuO and NO occurs once every ten collisions. From an independent observation thatk2/k2′ = 1.7 ± 0.25 independent of temperature, it is concluded thatk2′ = 1010.2M−1· s−1andk1′ = 1015.9−40.2/θ s−1;. This study shows that MeNO arises solely as a result of the combination of Me and NO. Since NO is such an excellent radical trap fort‐Bu\documentclass{article}\pagestyle{empty}\begin{document}${\rm Me\dot O}$\end{document}, reaction (2) may be used in a competitive study of the decomposition oftBu\documentclass{article}\pagestyle{empty}\begin{document}${\rm Me\dot O}$\end{document}in order to obtain the first absolute value fork3. Preliminary results show thatk3(∞) = 1015.7–17.0/θ s−1. The pressure dependence ofk3is demonstrated over the range of 10−2−1 atm (160°C). The thermochemistry for reaction (3) implies that the Hg 6(3P1) sensitised decomposition oft‐BuOH occurs via reaction (m):In addition to the products accounted for by the TBN radical split, isobutene is formed as a result of the 6‐centre elimination of HONO: TBN\documentclass{article}\pagestyle{empty}\begin{document}$\mathop \to \limits^7 $\end{document}isobutene + HONO. The rate of formation of isobutene is given byk7= 1012.9–33.6/θ s−1.t‐BuOH, formed at a rate comparable to that of isobutene–at least in the initial stages–is thought to arise as a result of secondary reactions between TBN and HONO. The apparent discrepancy between this and previous studies is reconciled

ISSN:0538-8066    

DOI:10.1002/kin.550080108

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractHydroxyl radicals were prepared from the photolysis of N2O at 213.9 nm in the presence of excess H2. The O(1D) produced in the primary photolytic act reacts with H2to produce OH radicals. If CO is also present, then OH can react either with H2or CO:The competition between reactions (1) and (2) was measured by measuring the CO2yield at various values of the ratio [CO]/[H2] at 217–298°K. At 298°K the ratio of the rate coefficientsk1/k2increased with pressure from a low‐pressure limiting value of 14 to a high‐pressure limiting value of 50. The low‐pressure limiting value agrees well with the low‐pressure values found by others. At lower temperatures our high‐pressure values ofk1/k2were larger than deduced from the accepted low‐pressure Arrhenius expression and could be fitted to the expression\documentclass{article}\pagestyle{empty}\begin{document}$$k_1 ^\infty /k_2 = 0.20{\rm exp (} + 3400/RT{\rm)}$$\end{document}The mechanism which seems to fit the results best iswithk1° =k

ISSN:0538-8066    

DOI:10.1002/kin.550080109

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractMixtures of N2O, CO, and NO in excess H2were photolyzed at 213.9 nm and 298°K. The initially formed O(1D) atoms from the photolysis of N2O abstract an H atom from H2permitting a study of the competition:From the CO2yield the relative rate coefficientk1/k2is obtained. It is found to be slightly dependent on pressure for total pressures (mainly H2) of 95.5 to 768 torr. However, the values are near the high‐pressure limiting value which is found by extrapolation to givek1∞= 1.2 × 10−11cm3/sec based onk2∞= 3.55 × 10

ISSN:0538-8066    

DOI:10.1002/kin.550080110

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe reaction of O(1D) with CH4was studied to determine the efficiency of H2production in a direct process, and it was found to be 0.11 ± 0.02. Thus the two channels which account for all of the reaction between O(1D) and CH4in the gas phase ar

ISSN:0538-8066    

DOI:10.1002/kin.550080111

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY