摘要:

AbstractThe kinetics of gas‐phase elimination of 3‐methyl‐1‐butyl acetate and 3,3‐dimethyl‐1‐butyl acetate into acetic acid and the corresponding substituted butenes have been measured over the temperature range of 360–420°C and the pressure range of 63–250 Torr. The reactions are homogeneous in both clean and seasoned vessels, obey first‐order law, and are unimolecular. The temperature dependence of the rate constants is given by the Arrhenius equation3‐methyl‐1‐butyl acetate:\documentclass{article}\pagestyle{empty}\begin{document}$$ {log k(sec}^{{ - 1}} {) = (12}{.73 } \pm { 0}{.29) - (202}{.5 } \pm { 3}{.8) kJ/mol/2}{.303}RT $$\end{document}3,3‐dimethyl‐1‐butyl acetate:\documentclass{article}\pagestyle{empty}\begin{document}$$ {log k(sec}^{{ - 1}} {) = (12}{.34 } \pm { 0}{.35) - (194}{.1 } \pm { 4}{.2) kJ/mol/2}{.303}RT $$\end{document}The points in a plot of log (k/k0) of β‐alkyl and several β‐substituted ethyl acetates againstEsvalues appear aligned in an approximate linear relationship. These results may be interpreted as a consequence of steric

ISSN:0538-8066    

DOI:10.1002/kin.550110602

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe reactions of S + OH → SO + H (1) and SO + OH → SO2+ H (2) were studied in a discharge flow reactor coupled to an EPR spectrometer. The rate constants obtained under the pseudo‐first‐order conditions with an excess of S or SO were found to bek1= (6.6 ± 1.4) × 10−11andk2= (8.4 ± 1.5) × 10−11at room temperature. Units are cm3/molec·sec. Besides no reactivity was observed between S and CO2at 298 K and between CIO an

ISSN:0538-8066    

DOI:10.1002/kin.550110603

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe kinetics of the gas‐phase thermal iodination of hydrogen sulfide by I2to yield HSI and HI has been investigated in the temperature range 555–595 K. The reaction was found to proceed through an I atom and radical chain mechanism. Analysis of the kinetic data yields logk(l/mol·sec) = (11.1 ± 0.18) – (20.5 ± 0.44)/θ, where θ = 2.303RT, in kcal/mol. Combining this result with the assumptionE−1= 1 ± 1 kcal/mol and known values for the heat of formation of H2S, I2, and HI, ΔHf,2980(SH) = 33.6 ± 1.1 kcal/mol is obtained. Then one can calculate the dissociation energy of the HSH bond as 90.5 ± 1.1 kcal/mol with the well‐known values for

ISSN:0538-8066    

DOI:10.1002/kin.550110604

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractRate constants determined for the thermal dimerization of chlorotrifluoroethene to dichlorohexafluorocyclobutane at 404–672 K have been correlated with previously published results. For the temperature range of 404–800 K,\documentclass{article}\pagestyle{empty}\begin{document}$$ k{ = 1}{.08} \times { 10}^{{ - 9}} { T }^{{4}{.02}} { exp ( - 86,700/RT) m}^{3} {/mol} \cdot \sec $$\end{document}The dependence of the preexponential factor on temperature corresponds to a value of 17 J/K·mol for the difference in heat capacity (ΔCp±) between the activation complex and the re

ISSN:0538-8066    

DOI:10.1002/kin.550110605

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractUsing the technique of CO2laser photosensitized decomposition, ethane and propane decomposition was investigated in relation to energy transfer from an SF6photosensitizer to the hydrocarbon. The end products appearing in the course of irradiation are similar to those formed during classical thermal pyrolysis. The energy transfer from SF6to the hydrocarbon is closely related to hydrocarbon decomposition. A similar overall kinetic behavior for the two alcanes allows the use of a general diffusional kinetic treatment, provided pressure, intensity, and duration of irradiation are well defined.

ISSN:0538-8066    

DOI:10.1002/kin.550110606

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe absolute quantum yield of O(1D2) in the photolysis of ozone in the Hartley band, between about 230 and 280 nm, has been determined using the isotopic exchange reaction between C16O2and18O(1D2). A value of 1.00 ± 0.05 has been obtained within a 95% confidence limit. A value of unity may therefore be accepted as the average quantum yield of O(1D2) atoms in the 230–280‐nm region within an uncertainty of only several per

ISSN:0538-8066    

DOI:10.1002/kin.550110607

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe thermal decomposition of SF5O3SF5has been investigated between 5 and 25°C. In the presence of sufficient high pressures of O2the only products formed are SF5O2SF5and O2:\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm SF}_5 {\rm O}_3 {\rm SF}_5 { } \to { SF}_{5} {O}_{2} {SF}_{5} { + (}{\raise0.5ex\hbox{$\scriptstyle {1}$} \kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle {2}$}}{) O}_{2} {, }\Delta n{ = }{\raise0.5ex\hbox{$\scriptstyle {1}$} \kern-0.1em/\kern-0.15em \lower0.25ex\hbox{$\scriptstyle 2$}} $$\end{document}The reaction is homogeneous. Its rate is strictly first order with respect to the trioxide pressure and independent of the total pressure of the reaction products and of oxygen above a certain limiting pressure:\documentclass{article}\pagestyle{empty}\begin{document}$$ - \frac{{{\rm d}[{\rm SF}_5 {\rm O}_3 {\rm SF}_5 ]}}{{{\rm dt}}}{ = + }\frac{{{\rm d}[{\rm SF}_5 {\rm O}_2 {\rm SF}_5 ]}}{{{\rm dt}}}{ = 2}\frac{{{dp}}}{{{\rm dt}}}{ = k[SF}_{5} {O}_{3} {SF}_{5} {]} $$\end{document}The experimental results can be explained with the following mechanism:In the presence of O2>100 Torr the concentration of SF5is insignificantly small. Therefore reactions (5) and (6) do not have to be considered any more, and steps (2) and (2′) will be of no importance. From reactions (1)–(4) it follows:\documentclass{article}\pagestyle{empty}\begin{document}$$ - \frac{{d[{\rm SF}_{\rm 5} {\rm O}_{\rm 3} {\rm SF}_{\rm 5} ]}}{{dt}} = + \frac{{d[{\rm SF}_{\rm 5} {\rm O}_{\rm 2} {\rm SF}_{\rm 5} ]}}{{dt}} = k_1 \frac{{[{\rm SF}_{\rm 5} {\rm O}_{\rm 3} {\rm SF}_{\rm 5} ]}}{{1 + k'_1 (1/2k_3 k_4 )^{1/2} }}k({\rm sec}^{{\rm - 1}}) = k_1 /\left[ {1 + k'_1 \left({\frac{1}{{2k_3 k_4 }}} \right)^{1/2} } \right] = 10^{16.06 \pm 0.37} {\rm exp( - 26,000} \pm {\rm 500}\,{\rm cal)/1}{\rm .987 }T $$\end{document}The numerical value of the factor [1 + (k′12/2k3k4)1/2] is small. It can be estimated thatE3≃ 2 ± 1 kcal; therefore,E–E1≤ 1 kcal, andD (SF 5OO 2SF 

ISSN:0538-8066    

DOI:10.1002/kin.550110608

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractKinetic and thermodynamic data for reaction (1) of certain C‐centered aromatic radicals (referred to in this paper by the numbers I to X) in chlorobenzene:have been obtained. Thek1values of radicals varied between (1.1 ± 0.2) × 106M−1·sec−1(radical VIII) and (3.6 ± 0.7) × 109M−1sec−1(radical VI) at 20°C. An investigation of the relationship between the recombination rates of radicals I–VIII and X and the solvent viscosity (mixture of toluene and dibutylphthalate, 0.6<η10 cP and are activation reactions in solvents having a viscosity η<10 cP. The recombination of radicals VIII and IX is an activation reaction, while that of radicals V–VII is diffusion‐controlled in the entire viscosity range. The recombination of radical X is limited, in the viscosity range of 18.4 to 2 cP, by intrusion into the first coordination sphere of the partner, the effect of viscosity on the radical X recombination rate in the specified range being the same as its effect on diffusion‐controlled reactions. The possible reasons of the discrepancies between the experimental fast recombination rate constants and the theoretical values calculated by the Debye–Smoluchowski theory are discussed. The equilibrium constant depends strongly on the nature of the substituent in the phenyl fragment: the substituents which increase unpaired electron delocalization in the radical intensify the dissociation of the respective dimer. Long‐wave absorption bands have been recorded for radicals I–X and their extinction coefficients obtained. Dimers I–V ar

ISSN:0538-8066    

DOI:10.1002/kin.550110609

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractRate constants for the reaction HO2+ NO2(+ M) = HO2NO2(+ M) have been obtained from direct observations of the HO2radical using the technique of molecular modulation ultraviolet spectrometry. HO2was generated by periodic photolysis of Cl2in the presence of excess H2and O2, andk1was determined from the measured concentrations and lifetime of HO2with NO2present.k1increased with pressure in the range of 40–600 Torr, and a simple energy transfer model gave the following limiting second‐ and third‐order rate constants at 283 K:k1∞= 1.5 ± 0.5 × 10−12cm3/molec·sec andk1III= 2.5 ± 0.5 × 10−31cm6/molec·sec. The ultraviolet absorption spectrum of peroxynitric acid was also recorded in the range of 195–265 nm; it showed a broad feature with a maximum at 200 nm,

ISSN:0538-8066    

DOI:10.1002/kin.550110610

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe mutual combination reactionis proposed as the rate‐limiting step in the removal of ClO radicals at moderate pressures. The third‐‐order rate constants measured at room temperature werek1(Ar) = 3.51 ± 0.14 × 109l2/mol2·ec;k1(He) ≈ 2.8 × 109l2/mol2·sec, andk1(O2) ≈ 7.9 × 109l2/mol2·sec. There is also an independent second‐order reactionfor whichk3≈ 8 × 106l/mol·sec. A new absorption spectrum has been observed in the ultraviolet and attributed to Cl2O2. The extinction coefficient for Cl2O2has been measured at six wavelengths, and, between 292 and 232 nm, it increases from 0.4 × 103to 2.9 × 103l/mol·cm. In the presence of the chlorine atom scavengers OClO or Cl2O, Cl2O2exists in equilibrium with ClO. The equilibrium constantKe1= 3.1 ± 0.1 × 106l/mol at 298 K, and, with ΔS10estimated to be −133 ± 11 J/K·mol, ΔH10= −69 ± 3 kJ/

ISSN:0538-8066    

DOI:10.1002/kin.550110611

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY