摘要:

AbstractUsing a relative rate technique, rate constants for the gas phase reactions of the OH radical withn‐butane,n‐hexane, and a series of alkenes and dialkenes, relative to that for propene, have been determined in one atmosphere of air at 295 ± 1 K. The rate constant ratios obtained were (propene = 1.00): ethene, 0.323 ± 0.014; 1‐butene, 1.19 ± 0.06; 1‐pentene, 1.19 ± 0.05; 1‐hexene, 1.40 ± 0.04; 1‐heptene, 1.51 ± 0.06; 3‐methyl‐1‐butene, 1.21 ± 0.04; isobutene, 1.95 ± 0.09;cis‐2‐butene, 2.13 ± 0.05;trans‐2‐butene, 2.43 ± 0.05; 2‐methyl‐2‐butene, 3.30 ± 0.13; 2,3‐dimethyl‐2‐butene, 4.17 ± 0.18; propadiene, 0.367 ± 0.036; 1,3‐butadiene, 2.53 ± 0.08; 2‐methyl‐1,3‐butadiene, 3.81 ± 0.15;n‐butane, 0.101 ± 0.012; andn‐hexane, 0.198 ± 0.017. From a least‐squares fit of these relative rate data to the most reliable literature absolute flash photolysis rate constants, these relative rate constants can be placed on an absolute basis using a rate constant for the reaction of OH radicals with propene of 2.63 × 10−11cm3molecule−1s−1. The resulting rate constant data, together with previous relative rate data from these and other laboratories, lead to a self‐consistent data set for the

ISSN:0538-8066    

DOI:10.1002/kin.550161002

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe effect of pressure on the rate constant of the OH + CO reaction has been measured for Ar, N2, and SF6over the pressure range 200–730 torr. All experiments were at room temperature. The method involved laser‐induced fluorescence to measure steady‐state OH concentrations in the 184.9 nm photolysis of H2O‐CO mixtures in the three carrier gases, combined with supplementary measurements of the CO depletion in these same carrier gases in the presence and absence of competing reference reactants. The effect of O2on the pressure effect was determined. A pressure enhancement of the rate constant was observed for N2and SF6, but not for Ar, within an experimental error of about 10%. The pressure effect for N2was somewhat lower than previous literature reports, being about 40% at 730 torr. For SF6a factor of two enhancement was seen at 730 torr. In each case it was found that O2had no effect on the pressure enhancement. The roles of the radical species HCO and HOCO were ev

ISSN:0538-8066    

DOI:10.1002/kin.550161003

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe kinetics of the oxidation of lactic and atrolactic acids by ceric sulfate have been studied in the medium HClO4‐Na2SO4‐NaClO4at 25.0°C and ionic strength 2.0 mol dm−3over a wide range of organic substrate (HL), hydrogen and bisulfate ion concentrations. The redox reactions proceed significantly through three simultaneous paths involving intermediate complexes between the reactive cerium(IV) species and the organic substrate according to the following expression\documentclass{article}\pagestyle{empty}\begin{document}$$k_{{\rm obs}} = \frac{{(b[{\rm HSO}_4^ -] + c[{\rm HSO}_4^ -]^2 + [{\rm H}^ +]){\rm [HL]}}}{{\{ f_1 [{\rm HSO}_4^ -]^3 + d_1 [{\rm HSO}_4^ -] + e_1 [{\rm HSO}_4^ -]^2){\rm }[{\rm H}^ +]\} + A'[{\rm HL}]}}$$\end{document}wherekobsindicates the observed pseudo‐first‐order rate constant,bandcare rate constants relative to that for the path associated with the term [H+] in the numerator, andA' is a quantity depending on the [H+] and [HSO 4−] concentrations. Moreover, three equilibria involving cerium(IV) and HSO 4−(or SO 42−) ions are important from a kinetic point of view, the cumulative equilibrium constants being in the ratios β1: β2: β3=d1:e1:f1. The present data are compared with those obtained previously for the cerium(IV) oxidation of glycolic acid and the subs

ISSN:0538-8066    

DOI:10.1002/kin.550161004

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractIt 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 constan

ISSN:0538-8066    

DOI:10.1002/kin.550161005

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe reactions of O3with ethylene, allene, 1,3‐butadiene, andtrans‐1,3‐pentadiene have been studied in the presence of excess O2over the temperature range 232 to 298 K. The initial O3pressure 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 O3decay was monitored by ultraviolet absorption. The reactions are first order in both O3and olefin, and the rate coefficients are independent of the O2pressure. 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 (kin cm3s−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 an

ISSN:0538-8066    

DOI:10.1002/kin.550161006

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe extinction coefficients and the decay kinetics of I 2−.and (SCN) 2−⋅have been characterized over the 15–90°C‐temperature range. The extinction coefficients of I 2−⋅at 385 and 725 nm were determined to be 10,000 and 2560M−1cm−1, respectively, based on the extinction coefficient of (SCN) 2−⋅at 475 nm being equal to 7600M−1cm−1. At these three wavelengths, all extinction coefficients were constant over the temperature range studied. The rate of decay of both I 2−⋅and (SCN) 2−⋅was found to be a function of I−and SCN−c

ISSN:0538-8066    

DOI:10.1002/kin.550161007

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe 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 practi

ISSN:0538-8066    

DOI:10.1002/kin.550161008

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe 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, logk1(s−1) = (12.75 ± 0.30) – (201.4 ± 3.8) kJ/mol/2.303RT; for ethyl cyanoacetate, logk1(s−1) = (12.19 ± 0.18) – (191.8 ± 2.1) kJ/mol/2.303RT; for ethyl dichloroacetate, logk1(s−1) = (12.62 ± 0.36) – (193.9 ± 4.3) kJ/mol/2.303RT; for ethyl trichloroacetate, logk1(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 logk/k0vs. 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

ISSN:0538-8066    

DOI:10.1002/kin.550161009

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractMathematical modeling was used for the kinetics of gas‐phase propane oxidation at 586, 613, and 658 K and pressures 172 and 250 torr. The reaction mechanism involving branching by decay of the peracetyl peroxy radical, and oxygen‐containing products formed on decay of the RO4radical is discussed. Fair agreement between calculated and experimental results on the kinetics and accumulation rates of reaction products was obtai

ISSN:0538-8066    

DOI:10.1002/kin.550161010

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractA kinetic study of oxidation of hydroxylamine by bromate ion in acid sulfate solution using spectrophotometric and potentiometric methods is reported. Oxidation of hydroxylamine to nitrate is quantitative and followed competitive, consecutive, and auto catalytics steps characterized by induction periods. In the slow rate limiting step, hydroxylamine on reaction with HOBr (k 1′) forms an intermediateI, which further reacts fast with second molecule of HOBr (k 2′) giving nitrite. Nitrite reacts with HOBr (k 3′) yielding the final product nitrate. Nitric acts as an autocatalyst also and its initial addition decreased the induction periods. In excess of hydrogen ion concentration all the reaction steps follow second‐order kinetics. All the second‐order rate constants are reported and the reaction mechan

ISSN:0538-8066    

DOI:10.1002/kin.550161011

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY