摘要:

AbstractReaction data described by the second‐order growth functionA(t) =A∞(αt) (1 + αt)−1, whereA∞is the ultimate value of the product concentrationA(t), can be linearized by plotting a suitable functionF(t) against the time (t). The slope of the straight line obtained is (2α), where α is the product of the rate constant (k2) and the initial concentration of either reactant, with the result thatk2can be determined without knowledge ofAϰ. Optimal determination of the parameter α requires that data taking be limited to the interval 0 ≤t≤T, where (αT) is approximately 4.0. Numerical data derived from an experiment on the exchange of lead by zinc ions in the enzyme carbonic anhydrase are analyzed to illustrate the method. The effects of small errors in the initial concentrations and of small deviations from second‐order kinetics a

ISSN:0538-8066    

DOI:10.1002/kin.550180302

出版商:John Wiley&Sons, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractUsing a relative rate technique, rate constants for the gas‐phase reactions of the OH radical with a series of monoterpenes have been determined in one atmosphere of air at 294 ± 1 K. Relative to a rate constant for the reaction of OH radicals with 2,3‐dimethyl‐2‐butene of 1.12 × 10−10cm3molecule−1sec−1, the rate constants obtained were (in units of 10−11cm3molecule−1sec−1): α‐Pinene, 5.45 ± 0.32; β‐pinene, 7.95 ± 0.52; Δ3‐carene, 8.70 ± 0.43; d‐limonene, 16.9 ± 0.5; α‐terpinene, 36.0 ± 4.0; γ‐terpinene, 17.6 ± 1.8; α‐phellandrene, 31.0 ± 7.1; myrcene, 21.3 ± 1.6; and ocimene (acis‐,trans‐mixture), 25.0 ± 1.9. These are the first quantitative kinetic data reported for many of these monoterpenes. The rate constants obtained are compared with the available literature data and witha prioriestimates based on the number and configuration of substituents around the double bond(s). The tropospheric lifetimes of these monoterpenes with OH radicals, NO3radicals and O3are estimated and compared. Atmospheric lifetimes with respect to reaction with the OH radical are calculated to ran

ISSN:0538-8066    

DOI:10.1002/kin.550180303

出版商:John Wiley&Sons, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractOn the basis of the thermal decomposition of mixtures of propylene and propane with molar ratios of 0.0–0.33 in the temperature range 779–812K, the influencing functions describing the inhibition by propylene of the decomposition of propane were determined. The rate‐reducing effect is explained mainly by the reactions\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm C}_{\rm 3} {\rm H}_{\rm 6} + {}^.{\rm R} \longrightarrow {}^.{\rm C}_{\rm 3} {\rm H}_{\rm 5} + RH $$\end{document}(in which.R =.H,.CH3and 2‐Ċ3H7) and also by the addition reactions\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm C}_{\rm 3} {\rm H}_{\rm 6} + {}^.{\rm H} \to 1 - {\rm \dot C}_{\rm 3} {\rm H}_{\rm 7} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ \to 2 - {\rm \dot C}_{\rm 3} {\rm H}_{\rm 7}. $$\end{document}It was established that the bulk of the allyl radicals formed\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm C}_{\rm 3} {\rm H}_{\rm 8} + {}^.{\rm C}_{\rm 3} {\rm H}_{\rm 5} \to 1 - {\rm \dot C}_{\rm 3} {\rm H}_{\rm 7} + {\rm C}_{\rm 3} {\rm H}_{\rm 6} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ \to 2 - {\rm \dot C}_{\rm 3} {\rm H}_{\rm 7} + {\rm C}_{\rm 3} {\rm H}_{\rm 6} $$\end{document}participate in the chain step, but, due to their lower reactivity, they restore the decomposition chain more slowly than the original radicals do.From the characteristic change in the ratio υ CH 4/υ H 2, the rate ratios of hydrogenabstraction reaction by radicals from propylene and propane could be determined. In these reactions there was no significant difference between the selectivities of the radicals. For an interpretation of the changes, the decomposition mechanism must be completed with the reaction\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm C}_{\rm 3} {\rm H}_{\rm 6} + 2 - {\rm \dot C}_{\rm 3} {\rm H}_{\rm 7} \to 1 - {\rm \dot C}_{\rm 3} {\rm H}_{\rm 7} + {\rm C}_{\rm 3} {\rm H}_{\rm 6}. $$\end{document}Evaluation of the influencing curves revealed that the initiation reactions\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm C}_{\rm 3} {\rm H}_{\rm 6} + {\rm C}_{\rm 3} {\rm H}_{\rm 6} \to {}^.{\rm C}_{\rm 3} {\rm H}_{\rm 5} + {}^.{\rm C}_{\rm 3} {\rm H}_{\rm 7} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm C}_{\rm 3} {\rm H}_{\rm 8} + {\rm C}_{\rm 3} {\rm H}_{\rm 6} \to {}^.{\rm C}_{\rm 3} {\rm H}_{\rm 7} + {}^.{\rm C}_{\rm 3} {\rm H}_{\rm 7} $$\end{document}must be taken into account.By parameter estimation we have determined the rate ratios characterizing the above initiation reactions, the unimolecular decomposition of propane, hydrogen abstraction by radicals from propane and propylene, intermolecular isomerization of the 2‐propyl radical via propane and propylene, and abstraction of propane hydrogens by the ethyl and methyl radicals; these ar

ISSN:0538-8066    

DOI:10.1002/kin.550180304

出版商:John Wiley&Sons, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractThe thermal decomposition of butene‐2‐cisat low conversion and its effect on the pyrolysis of propane have been studied in the temperature range 779‐812 K.It was established that 2‐butene decomposes in a long‐chain process, with the chain cycle\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm 2 - C}_{\rm 4} {\rm H}_{\rm 8} + {}^.{\rm CH}_{\rm 3} \to {}^.{\rm C}_{\rm 4} {\rm H}_{\rm 7} + {\rm CH}_{\rm 4} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm 2 - C}_{\rm 4} {\rm H}_{\rm 8} + {}^.{\rm CH}_{\rm 3} \to {}^.{\rm C}_{\rm 4} {\rm H}_{\rm 7} + {\rm CH}_{\rm 4} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm 2 - C}_{\rm 4} {\rm H}_{\rm 8} + {}^.{\rm CH}_{\rm 3} \to {}^.{\rm C}_{\rm 4} {\rm H}_{\rm 7} + {\rm CH}_{\rm 4} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ {}^.{\rm C}_{\rm 4} {\rm H}_{\rm 7} \to {}^.{\rm H} + 1,3 - {\rm C}_{\rm 4} {\rm H}_{\rm 6} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm 2 - C}_{\rm 4} {\rm H}_{\rm 8} + {}^.{\rm H} \to {}^.{\rm C}_{\rm 4} {\rm H}_{\rm 7} + {\rm H}_{\rm 2} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ \to 2 - {\rm \dot C}_{\rm 4} {\rm H}_{\rm 9} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm 2 - C}_{\rm 4} {\rm H}_{\rm 8} \to + 1,3 - {\rm C}_{\rm 3} {\rm H}_{\rm 6} + {\rm H}_{\rm 2} $$\end{document}(Besides the radical path, the molecular reactioncan also play a role in the formation of the products.)The thermal decomposition of propane is considerably inhibited by 2‐butene, which can be explained by the fact that the less reactive radicals formed in the reactions between the olefin and the chain‐carrying radicals regenerate the chain cycle more slowly than the original radicals in the above chain cycle or in the reactions\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm C}_{\rm 3} {\rm H}_{\rm 8} + {}^.{\rm C}_{\rm 4} {\rm H}_{\rm 7} \to 1 - {\rm \dot C}_{\rm 3} {\rm H}_{\rm 7} + {\rm C}_{\rm 4} {\rm H}_{\rm 8} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ \to 2 - {\rm \dot C}_{\rm 4} {\rm H}_{\rm 7} + {\rm C}_{\rm 3} {\rm H}_{\rm 8} $$\end{document}The reactions of the 2‐propyl radical\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm 2 - \dot C}_{\rm 3} {\rm H}_{\rm 7} + 2 - {\rm C}_{\rm 4} {\rm H}_{\rm 8} \to {}^.{\rm C}_{\rm 4} {\rm H}_{\rm 7} + {\rm C}_{\rm 3} {\rm H}_{\rm 8} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ \to 2 - {\rm \dot C}_{\rm 4} {\rm H}_{\rm 9} + {\rm C}_{\rm 3} {\rm H}_{\rm 6} $$\end{document}are further initiation steps. The ratios of the rate coefficients of the elementary steps of the decomposition (Table III) have been determined via the ratios of the products.Estimation of the radical concentrations indicated that only the methyl, 2‐propyl and methylallyl radicals are of importance in the chain termination.On the basis of the inhibition‐influenced curves, the role of the bimolecular initiation steps.\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm 2 - C}_{\rm 4} {\rm H}_{\rm 8} + {\rm C}_{\rm 3} {\rm H}_{\rm 8} \to {\rm \dot C}_{\rm 4} {\rm H}_{\rm 9} + {\rm \dot C}_{\rm 3} {\rm H}_{\rm 7} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm 2 - C}_{\rm 4} {\rm H}_{\rm 8} + 2 - {\rm C}_{\rm 4} {\rm H}_{\rm 8} \to {}^.{\rm C}_{\rm 4} {\rm H}_{\rm 9} + {\rm C}_{\rm 4} {\rm H}_{\rm 7} $$\end{document}could be clarified in the p

ISSN:0538-8066    

DOI:10.1002/kin.550180305

出版商:John Wiley&Sons, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractThe rate of decomposition of 2‐pentoxy radical to acetaldehyde andn‐propyl radical has been studied in the presence of NO in competition with nitrite formation at and above 200 kPa pressure over the temperature range of 363‐413 K. The rate coefficient for the decomposition is given as log(kla/s−1) = (14.2 ± 0.4) ‐ (13.8 ± 0.8) kcal mol−1/RTln 10. Isomerization of 2‐pentoxy radical by 1,5‐hydrogen shift has been investigated in the range 279–385 K in competition with the decomposition in a static system, with methyl radicals present in high concentration to ensure trapping of the isomerized free radicals. The rate coefficient for isomerization is given as log(k3/s−1) = (11.1 ± 0.7) ‐ (9.5 ± 1.1) kcal mol−1/RTln 10. The implications of the results for atmosphe

ISSN:0538-8066    

DOI:10.1002/kin.550180306

出版商:John Wiley&Sons, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractThe kinetics of the oxidation of S2O32−by ClO2−have been studied in aqueous alkaline solution at 900C using classical titrimetric methods to follow the course of the reaction. The reaction takes place according to the stoichiometry S2O32−+ 2ClO2−+ 2OH−= 2SO42−+ 2Cl−+ H2O even in large S2O32−excess. There is some indication of a complex reaction pattern, but 70% of the ClO2−disappearance can be best described by the autocatalytic rate equation ‐d[ClO2−]/dt= k[S2O32−] [ClO2−] [H+] with k = (1.3 ± 0.2) ×108M−2sec−1. The mechanism is explained by postulating nucleophilic attack of S2O32−on HClO2to form a

ISSN:0538-8066    

DOI:10.1002/kin.550180307

出版商:John Wiley&Sons, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractThe pyrolyses of four alkyl allyl sulfides with substituents on the αC atom of the alkyl moiety have been studied in a stirred‐flow system over the temperature range 340‐400°C and pressures between 2 and 12 torr. The only products formed are propene and thioaldehydes. The reactions showed first‐order kinetics with the rate coefficients following the Arrhenius equations: Chloromethyl allyl sulfide:\documentclass{article}\pagestyle{empty}\begin{document}$$ k({\rm s}^{{\rm - 1}}) = 10^{10.74 \pm 0.23} \exp ( - 144 \pm 3){\rm kJ/mol}RT $$\end{document}Cyanomethyl allyl sulfide:\documentclass{article}\pagestyle{empty}\begin{document}$$ k({\rm s}^{{\rm - 1}}) = 10^{10.20 \pm 0.19} \exp ( - 129 \pm 2){\rm kJ/mol}RT $$\end{document}1‐cyanoethyl allyl sulfide:\documentclass{article}\pagestyle{empty}\begin{document}$$ k({\rm s}^{{\rm - 1}}) = 10^{11.09 \pm 0.18} \exp ( - 141.5 \pm 2.2){\rm kJ/mol}RT $$\end{document}Neopentyl allyl sulfide:\documentclass{article}\pagestyle{empty}\begin{document}$$ k({\rm s}^{{\rm - 1}}) = 10^{10.54 \pm 0.24} \exp ( - 144 \pm 3){\rm kJ/mol}RT $$\end{document}The effects of these and other substituents on the reactivity is discussed in relation with the stabilization of a polar six‐centered transition state. The results support a non‐concerted mechanism where the 1–5 αH atom shift is assisted by

ISSN:0538-8066    

DOI:10.1002/kin.550180308

出版商:John Wiley&Sons, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractThe pyrolysis of ethylbenzene has been investigated in shock waves with the laser schlieren technique. Mixtures of 1 and 2% ethylbenzene in krypton were studied for reaction conditions of 1300‐1800 K, 70‐550 torr. At high temperatures, the initial rapid endothermic dissociation is followed by a region of net exothermic reaction, which is readily understood as arising mainly from methyl radical recombination after dissociation to methyl and benzyl radicals. The initial unimolecular dissociation rates show no detectable dependence on pressure; with ΔH0298= 75.7 kcal mol−1these rates are\documentclass{article}\pagestyle{empty}\begin{document}$$ \log k({\rm s}^{{\rm - 1}}) = 13.49 - 60.0/\theta $$\end{document}An RRKM extrapolation suggests\documentclass{article}\pagestyle{empty}\begin{document}$$ \log k_\infty ({\rm s}^{{\rm - 1}}) = (15.95 \pm 0.3) - (74.7 \pm 2)/\theta $$\end{document}in excellent agreement with previous lower temperatur

ISSN:0538-8066    

DOI:10.1002/kin.550180309

出版商:John Wiley&Sons, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractInfrared multiple photon decompositions (IRMPD) with more than one reactive pathway can provide significantly more kinetic information than can single‐channel photolyses. The rates of the competing unimolecular reactions and the rate of photon absorption are interrelated, so that knowledge of one yields information about the others. The goals and pitfalls of IRMPD experiments on several well‐studied classes of reactants are revie

ISSN:0538-8066    

DOI:10.1002/kin.550180310

出版商:John Wiley&Sons, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractThe rate of the gas phase reaction of hydroxyl radical with methyl nitrate has been measured to be (3.4 ± 0.4) × 10−14cm3molecule−1s−1at 298 K using flow discharge/ resonance fluorescence techniques. By means of correlation methods, this rate determination is used to predict a vertical ionization potential of 12.6 eV, a bond dissociation energy for HCH2ONO2of 101 kcal mol−1, and a rate for O(3P) reaction with methyl nitrate of ca. 9 × 10−17cm3molecule−1s−1. In conjunction with previously derived relative data for reaction of alkyl nitrates with OH radical in the gas phase,a prioriestimated reactivities for 1‐, 2‐, and 3‐positionally substituted straight chain alkyl nitrates have been reexamined. Revised reactivities for OH abstraction of specific hydrogens substituted on straight chain alkyl nitrates are presented and discussed, and an atmospheric lifetime of ca. 2 yrs is estimated for methyl n

ISSN:0538-8066    

DOI:10.1002/kin.550180311

出版商:John Wiley&Sons, Inc.    

年代:1986

数据来源: WILEY