bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron transfer reactions of V(IV) with Cl(I), Br(I) and I(I). A kinetic study
Authors: Radhakrishnamurti P. S. , Janardhana C. , Behera G. P. , Mohanty G. K. 
Published: January 2005

AbstractA kinetic study on the oxidation of V(IV) by chloramine‐T (CAT) at pH 6.85 by N‐bromo succinimide (NBS) in aqueous acetic acid–perchloric acid media and by N‐iodo succinimide (NIS) in aqueous perchloric acid medium has been carried out. In all the systems studied the order with respect to the oxidant is unity. NBS and CAT oxidation reactions exhibited Michaelis–Menten type kinetics, and the NIS study indicated unit dependence on [substrate]. Independence on acidity has been observed in the case of CAT and NBS reactions, but NIS reactions exhibited inverse unit dependence on [acid]. Novel solvent influences have been noticed in the case of CAT reactions, but with NIS and NBS reactions retardation in the rate has been observed with an increase in the percentage of acetic acid. Plausible mechanisms consistent with the results have been postulated, and suitable rate laws in consonance with the postulated mechanisms have been derived.
The reaction of methyl p‐nitrophenyl sulfate with hydrogen peroxide anion determination of pKa of hydrogen peroxide in methanol by a kinetic spectrophotometric procedure
Authors: Buncel Erwin , Chuaqui Claudio , Wilson Harold 
Published: January 2005

AbstractA kinetic spectrophotometric investigation of the reaction of the hydrogen peroxide anion with methyl p‐nitrophenyl sulfate in methanol solvent resulted in the evaluation of the pKa of HOOH in methanol at 25°C as 15.8 ± 0.2. Since normal kinetic procedures for the determination of the equilibrium constant K for the process CH3O− + H2O2 ⇄ CH3OH + HO were found to be associated with high uncertainty, another procedure was devised to establish the magnitude of K. This method is based on an analysis of the changing slopes of plots of pseudo‐first‐order rate constants against the total base concentration as the stoichiometric amount of hydrogen peroxide is varied. The method is applicable to any system in which anionic nucleophiles generated in situ compete with solvent anions. Such a corroboration of kinetically determined equilibrium constants is believed essential. The kinetic data allow the specific rate constant kHOO‐for the reaction of methyl p‐nitrophenyl sulfate with hydrogen peroxide anions to be evaluated and yield the rate constant ratio k/k = 8.8 ± 2.2. This confirms the existence of an α effect at saturated carbon in this system.
A reexamination of the pyrolysis of bis trifluoromethyl peroxide
Authors: Batt L. , Walsh R. 
Published: January 2005

AbstractThe literature results for the pyrolysis of bis trifluoromethyl peroxide are reexamined and compared with those for dimethyl peroxide. The thermochemistry yields the result that the π‐bond energy in carbonyl fluoride is 96 ± 10 kcal/mol compared to 74 kcal/mol for that in formaldehyde. Thermodynamic additivity contributions are derived for the C(F)3(O) and O(C)(F) groups. Some conclusions are drawn in relation to the oxidation of halogeno methyl radicals and the chemistry of the atmosphere.
Photolysis of carbon tetrachloride in the presence of alkanes
Authors: Matheson Ian , Tedder John , Sidebottom Howard 
Published: January 2005

AbstractThe photolysis of carbon tetrachloride in the presence of a number of alkanes has been investigated in the gas phase. The products obtained from the photolysis experiments were those expected from a chain reaction in which trichloromethyl radicals abstract hydrogen atoms from the alkane. The data have been used to determine Arrhenius parameters for hydrogen abstraction from the series of alkanes CH4, C2H6, C3H8, and i‐C4H10 by trichloromethyl radicals, magnified image The rate data obtained are used to explain why termination reactions involving alkyl radicals become less significant as the alkane becomes more complex.
Reaction between U(IV) and H2O2 in hydrochloric acid medium
Authors: Bhattacharyya P. K. , Saini R. D. , Ruikar P. B. 
Published: January 2005

AbstractKinetic investigations on the reaction between U(IV) and H2O2 have been carried out at different acidities in chloride medium at an ionic strength of 2M. The observed bimolecular rate constant has been found to be dependant on [H+]−1.3. The activation energy of the overall reaction has been found to vary from 13.4 ± 0.7 to 18.0 ± 0.8 kcal/mol in the range of acidity from 0.3 to 1.5M. The results have been explained on the basis of three parallel rate‐controlling reactions involving unhydrolyzed species of U(IV) and hydrolyzed species UCl(OH)2+ and UO2+. The values of the rate constants for these three reaction paths have been found to be of the order of 3.95, 5.59 × 103, and 1.49 × 105M−1 min−1, respectively.
Kinetics and mechanism of chlorination of toluene and some substituted toluenes by chloramine‐T
Authors: Radhakrishnamurti P. S. , Pati Subas C. , Dev B. R. 
Published: January 2005

AbstractThe kinetics of chlorination of toluene, o‐methyl toluene, p‐methyl toluene, m‐methyl toluene, and m‐chlorotoluene by chloramine‐T(CAT) in aqueous acetic acid in the presence of HClO4 have been studied. The reaction is first order with respect to [CAT] as well as [H+]. The order with respect to the substrate is unity in the case of toluene and m‐chlorotoluene, fractional in the case of o‐methyl toluene and p‐methyl toluene, and zero order in the case of m‐methyl toluene. Nuclear halogenation has been observed with m‐methyl toluene, while nuclear and side‐chain halogenation for p‐methyl toluene and o‐methyl toluene, and sidechain halogenation for toluene and m‐chlorotoluene are the pathways. An increase in the proportion of acetic acid accelerates the rate. Added acetate ions inhibit the reaction, and added p‐toluene sulfonamide causes a pronounced retardation. A mechanism involving AcO+HCl as the important electrophile is discussed.
Thermal reaction of hydrogen–butene‐2‐cis mixtures at 500°C: Hydrogenation, hydrogenolysis, and thermal reaction of the olefin
Authors: Collongues C. , Richard C. , Martin R. 
Published: January 2005

AbstractThe thermal reaction of hydrogen–butene‐2‐cis mixtures has been studied in a static system at low extent of reaction around 500°C. Hydrogen does not affect the thermal reaction itself of the olefin, but gives rise to new stoichiometries of hydrogenolysis and hydrogenation, which are specified:

The reaction is described in terms of a molecular and free‐radical mechanism. It is shown that the key process for the hydrogenolysis–hydrogenation reaction is
equation image
and that the rate constant of this process can be determined from either propylene, or methane, or butene‐1 formations:

with θ = 4.57 × 10−3 T kcal/mol. Other rate constants are estimated and agree with literature data.
Kinetics of the reactions of O3 and OH radicals with furan and thiophene at 298 ± 2 K
Authors: Atkinson Roger , Aschmann Sara M. , Carter William P. L. 
Published: January 2005

AbstractRate constants for the reactions of O3 and OH radicals with furan and thiophene have been determined at 298 ± 2 K. The rate constants obtained for the O3 reactions were (2.42 ± 0.28) × 10−18 cm3/molec·s for furan and <6 ×10−20 cm3/molec·s for thiophene. The rate constants for the OH radical reactions, relative to a rate constant for the reaction of OH radicals with n‐hexane of (5.70 ± 0.09) × 10−12 cm3/molec·s, were determined to be (4.01 ± 0.30) × 10−11 cm3/molec·s for furan and (9.58 ± 0.38) × 10−12 cm3/molec·s for thiophene. There are to date no reported rate constant data for the reactions of OH radicals with furan and thiophene or for the reaction of O3 with furan. The data are compared and discussed with respect to those for other alkenes, dialkenes, and heteroatom containing organics.
Mechanism and thermochemistry of oxidation of HCl and HBr at high temperatures. The heat of formation of HO2
Authors: Shum Lilian G. S. , Benson Sidney W. 
Published: January 2005

AbstractUsing currently available thermochemical and kinetic data and estimation methods to analyze the thermochemistry and the kinetic parameters of the elementary reactions involved in the oxidation of HCl and HBr, reaction mechanisms are proposed which account for the previously reported reaction products, the rate law, and the kinetic data. For oxidation of HCl, two competitive pathways, the radical initiation by hydrogen abstraction and the fourcenter reaction pathway, were invoked to account for the observations. In the oxidation of HBr one must invoke a fast surface reaction of the type

to account for the reaction.
Complex rate law for the cerium(IV) oxidation of glycolic acid in the medium HClO4–Na2SO4–NaClO4
Authors: Calvaruso Giuseppe , Cavasino F. Paolo , Sbriziolo Carmelo , Triolo Roberto 
Published: January 2005

AbstractThe kinetics of the cerium(IV) oxidation of glycolic acid have been studied in the medium HClO4Na2SO4NaClO4 at varying organic substrate (HL), hydrogen, and bisulfate ion concentrations at 25.0°C and ionic strength 2.0M. Under the experimental conditions used (0.03 ⩽ [H+] ⩽ 0.5M; 0.02 ⩽ [HSO4−] ⩽ 0.1M; 0.01 ⩽ [HL] ⩽ 0.1M) the observed pseudo‐first‐order rate constant kobs has been found to follow the complex expression
equation image
where the values of the various constants have been estimated by a nonlinear least‐squares method. According to this expression the oxidation process occurs significantly through three simultaneous pathways. Moreover three equilibria involving cerium(IV) and HSO4− (or SO42−) ions are important from a kinetic point of view, whereas only two equilibria involving the corresponding complexes with the organic substrate are predominant.
A reexamination of the pyrolysis of bis trifluoromethyl peroxide. Addendum: Concerning D(CF3O2‐CF3) and D(CF3‐O2)
Authors: Batt L. , Walsh R. 
Published: January 2005

AbstractEarlier arguments concerning D(CF3O2‐CF3) and D(CF3‐O2) are shown to be probably wrong. New values of 86 and 49 kcal/mol, respectively, are derived. C–O bond strengths are compared between CF3‐ and CH3‐containing compounds.
Kinetic analysis of an extended single‐path sequence of first‐order reactions. The reaction of mesitonitrile in sulfuric acid
Authors: Al‐ka′bi Ja′far , Gore Peter H. , Saad Esmat F. , Waters David N. , Moxon Gerald F. 
Published: January 2005

AbstractThe system of a sequence of five first‐order reactions, A → B → C → D → E → F, has been analyzed kinetically. An actual example is proposed in the reaction of mesitonitrile in 89.8% (w/w) sulfuric acid at 98.3°C. The analysis provides estimates of concentration ratios as functions of time, and the progress of the buildup and decay of the intermediate species can be monitored. The kinetics have been measured for the hydration of mesitonitrile, the hydrolysis of mesitamide, and the sulfonation of mesitylenesulfonic acid in 89.8% sulfuric acid. The calculated values of the concentration ratios of mesitylenedisulfonic acid as a function of time were satisfactorily close to those found in experiment.
Reaction of CF3 radicals with H2O and D2O
Authors: Pasteris Leonor , Oexler Elena V. , Staricco Eduardo H. 
Published: January 2005

AbstractThe reaction of CF3 radicals with H2O (D2O) has been studied over the range of 533–723 K using the photolysis and the pyrolysis of CF3I as the free radical source. Arrhenius parameters for the reactions

where X = H or D, relative to CF3 radical recombination are given by

where k/k is in cm3/2/mol1/2·s1/2 and θ = 2.303RT/cal/mol. The activation energy and the primary kinetic isotope effect have been compared with those derived from the BEBO method.
Studies in nickel(IV) Chemistry. Kinetics of the aquacopper(II)‐catalyzed oxidation of phenylhydrazine by tris(dimethylglyoximato)‐nickelate(IV) in aqueous medium
Authors: Acharya S. , Neogi G. , Panda R. K. 
Published: January 2005

AbstractThe kinetics of electron transfer in the redox system containing phenylhydrazine (S) and tris(dimethylglyoximato)nickelate(IV), in the presence of catalytic amounts of added Cu(II)aq, have been studied in aqueous medium at an ionic strength of 0.25M in the pH range of 6.01–9.06. The kinetics exhibit pseudo‐zero‐order disappearance of Ni(IV) when an excess of [S]0 and small amounts of Cu(II) are present. While the pseudo‐zero‐order rate constants are almost linearly dependent on [S]0 at constant [Cu(II)] and pH tending to become non‐linearly dependent on higher relative [S]0, they are linearly dependent on [Cu(II)] in a 20‐fold range. The pH‐rate profiles with low [S]0 and [Cu(II)] show a monotonic decrease in rates with increasing pH, the rates tending to attain limiting values at higher relative pH. Results are interpreted in terms of a probable mechanism involving the formation of precursor complexes of phenylhydrazine and Cu(II) species in the medium, followed by the rate‐determining breakdown of the precursors with concomitant electron transfer. The hydrolyzed species of Cu(II) reacts more slowly than does the aquacopper(II). Ni(IV) does not appear to have any kinetic role in the redox system and is involved only in rapid product formation steps. The oxidation product of phenylhydrazine is 4‐hydroxyazobenzene.
Formation of nitrous acid and nitric oxide in the heterogeneous dark reaction of nitrogen dioxide and water vapor in a smog chamber
Authors: Sakamaki Fumio , Hatakeyama Shiro , Akimoto Hajime 
Published: January 2005

AbstractThe dark reaction of NOx and H2O vapor in 1 atm of air was studied for the purpose of elucidating the recently discussed unknown radical source in smog chambers. Nitrous acid and nitric oxide were found to be formed by the reaction of NO2 and H2O in an evacuable and bakable smog chamber. No nitric acid was observed in the gas phase. The reaction is not stoichiometric and is thought to be a heterogeneous wall reaction. The reaction rate is first order with respect to NO2 and H2O, and the concentrations of HONO and NO initially increase linearly with time. The same reaction proceeds with a different rate constant in a quartz cell, and the reaction of NO2 and H218O gave H18ONO exclusively. Taking into consideration the heterogeneous reaction of NO2 and H2O, the upper limit of the rate constant of the third‐order reaction NO + NO2 + H2O → 2HONO was deduced to be (3.0 ± 1.4) × 10−10 ppm−2‐min−1, which is one order of magnitude smaller than the previously reported value. Nitrous acid formed by the heterogeneous dark reaction of NO2 and H2O should contribute significantly to both an initially present HONO and a continuous supply of OH radicals by photolysis in smog chamber experiments.
Kinetics and mechanism of the reactions of the superoxide ion in solutions. II. The kinetics of protonation of the superoxide ion by water and ethanol
Authors: Afanas′ev I. B. , Kuprianova N. S. 
Published: January 2005

AbstractThe rate constants for the protonation of “free” (that is, solvated) superoxide ions by water and ethanol are equal to 0.5–3.5 ×10−3M−1·s−1 in DMF and AN at 20º. It has been found that the protonation rates for the ion pairs of \documentclass{article}\pagestyle{empty}\begin{document}${\rm O}_{\rm 2}^{\overline {\rm .} }$\end{document} with the Bu4N+ cation are much slower than those for “free” \documentclass{article}\pagestyle{empty}\begin{document}${\rm O}_{\rm 2}^{\overline {\rm .} }$\end{document}. It is suggested that the effects of aprotic solvents on the protonation rates of \documentclass{article}\pagestyle{empty}\begin{document}${\rm O}_{\rm 2}^{\overline {\rm .} }$\end{document} are mainly due to the fact that the proton donors form solvated complexes of different stability in these solvents.
Methyl thiirane: Kinetic gas‐phase titration of sulfur atoms in SX OY systems
Authors: Martinez Richard I. , Herron John T. 
Published: January 2005

AbstractThe reaction SO + SO →l S + SO2(2) was studied in the gas phase by using methyl thiirane as a titrant for sulfur atoms. By monitoring the C3H6 produced in the reaction \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm S} + {\rm CH}_3\hbox{---} \overline {{\rm CH\hbox{---}CH}_2\hbox{---} {\rm S}} \to {\rm S}_2 + {\rm C}_3 {\rm H}_6 (7) $\end{document}, we determined that k2 ≃ 3.5 × 10−15 cm3/s at 298 K.
The azoethane‐initiated thermal reaction of isobutene. Heat of formation of the 2‐methyl‐2‐pentyl radical
Authors: Seres L. , Görgényi M. , Farkas J. 
Published: January 2005

AbstractThe azoethane‐sensitized thermal reaction of isobutene has been studied at 526–565 K. The initial concentrations of azoethane and isobutene were in the ranges of 1.40–10.5 × 10−4 and 6.78–26.6 × 10−4 mol/dm3, respectively. From the initial rates of formation of ethane and 2‐methylpentane the heat of formation of the 2‐methyl‐2‐pentyl radical was determined. The result obtained is ±H(2‐methyl‐2‐pentyl) = 0.8 ± 2.0 kcal/mol. The entropy of the radical, obtained from statistical mechanical calculations and experimentally, is S0(2‐methyl‐2 pentyl) = 92.8 ± 1.5 cal/mol°K. The results support the high heat of formation of the t‐butyl radical suggested by different authors.
Gas‐phase thermal isomerization of hexachlorocyclopropane
Authors: Cosa Juan José , Hamity Mauricio 
Published: January 2005

AbstractThe gas‐phase thermal isomerization of hexachlorocyclopropane to hexachloropropene at 208–283°C is first order and unaffected by changes in the surface‐to‐volume ratio or by the addition of iodine, tetrachloroethylene, and oxygen. The first‐order rate constants fit the Arrhenius equationThe reaction was interpreted as an unimolecular process taking place with chlorine atom migration. A comparison of the reactivities of several chlorocyclopropanes is made.
Laser‐induced kinetics: Arrhenius parameters for t‐C4H9 + XI → i‐C4H9X + I (X = H,D) and the Heat of Formation of the t‐butyl radical
Authors: Rossi M. J. , Golden D. M. 
Published: January 2005

AbstractThe metathesis reaction of DI with t‐C4H9 generated by 351‐nm photolysis of 2,2′‐azoisopropane was studied in a low‐pressure reactor (VLPϕ Knudsen cell) in the temperature range of 302–411 K. The data obeyed the following Arrhenius relation when combined with recent data by Rossi and Golden gathered by the same technique (t‐C4H9 by thermal decomposition of 2,2′‐azoisobutane): log k2D(M−1s−1) = 9.60 – 1.90/θ, where θ = 2.303RT kcal/mol for 302 K < T > 722 K. The metathesis reaction of HI with t‐C4H9 was studied at 301 K and resulted in k2H(M−1·s−1) = (3.20 ± 0.62) × 108. An analogous Arrhenius relation was calculated for the protiated system if the small primary isotope effect k2H/k2D was assumed to be √2 at 700 K. It was of the following form: log k2H(M−1·s−1) = 9.73 – 1.68/θ.Preliminary data of Bracey and Walsh indicate that earlier Arrhenius parameters determined for the reverse reaction are somewhat in error. Their value of log k1(M−1·s−1) = 11.5 – 23.8/θ yields 7delta;Hf,3000(t‐butyl) = 9.2 kcal/mol and S3000(t‐butyl) = 74.2 cal/mol7°K when taken in conjuction with this study.
Kinetics of the reaction of OH with pernitric and nitric acids
Authors: Smith C. A. , Molina L. T. , Lamb J. J. , Molina M. J. 
Published: January 2005

AbstractThe 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:

These results are in very good agreement with recent studies of reaction (2), and also of reaction (1) at 295 K.
Steric influence in the direction of elimination of gas‐phase pyrolyses of several highly branched secondary acetates
Authors: Arcila Carolina , Pino Maria , Lubinkowski Jacek , Hernandez A Jose Adan , Chuchani Gabriel 
Published: January 2005

AbstractThe 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.
Electron transfer from α‐aminoalkyl radicals to methyl viologen
Authors: Kim‐Thuan Nguyen , Scaiano J. C. 
Published: January 2005

AbstractThe reactions of tert‐butoxyl radicals with amines, leading to the formation of α‐aminoalkyl radicals, and the reactions of these with the electron acceptor methyl viologen have been examined using laser flash photolysis techniques. For example, the radicals CH3ĊHNEt2 and HOCH2ĊH N(CH2CH2OH)2 react with methyl viologen with rate constants equal to (1.3 ± 0.1) × 109 and (2.1 ± 0.4) × 109M−1 · s−1, respectively, in wet acetonitrile at 300 K.
Product formation in the association reaction of ClO with NO2 investigated by diode laser kinetic spectroscopy
Authors: Cox R. A. , Burrows J. P. , Coker G. B. 
Published: January 2005

AbstractDiode laser spectroscopy has been employed to monitor the formation of chlorine nitrate (ClONO2) in the association reaction of ClO with NO2. Chlorine nitrate is the only stable end‐product of this reaction at room temperature. Time‐resolved measurements of ClONO2 formation using molecular modulation showed no evidence for any involvement of unstable isomers of ClNO3 in the reaction. These measurements gave a value of k1 = (1.8 ± 0.4) × 10−31 cm6/molecule2 · s for the reaction

at 295 K and an upper limit of 5 ms for the lifetime of any isomeric products at this temperature.
Experimental determination of the energy distribution of activated molecules. Extensive test of hard‐collision approximations
Authors: Becerra R. , Figuera J. M. , Martín M. , Rodríguez J. C. 
Published: January 2005

AbstractThe approximations developed to determine the energy distribution function of molecules activated above energy decomposition threshold, from experimental data, have been tested. The approach involved the theoretical (RRKM) calculations of “pseudoexperimental” data for a variety of activated energy distributions. (Single or double Gaussian representations were used in all cases.) Subsequently the algorithms mentioned were applied in order to recuperate the original (i.e., input) energy distributions from these pseudoexperimental data. The results obtained provide strong evidence in favor of the validity of the algorithms and illustrate the necessary requirements for their applications. A trend toward lower accuracy as the energy distributions move to higher energies has been observed. Evidence of the influence of the distribution width is also reported. The origins of the approximation errors have been studied, and ways for further improvement are suggested.