bluuebunny/crossref_metadata_2025 huggingface dataset:
The oxidation of 3,3′‐dimethoxy benzidine with potassium bromate in acidic solutions
Authors: Jonnalagadda S. B. , Munkombwe N. M. , Hensman P. , Mushinga T.
Published: January 2005

The kinetics and mechanism of the oxidation of 3,3′‐dimethoxybenzidine (oda, o‐dianisidine) by potassium bromate in aqueous acidic medium were studied by monitoring the formation rate of the reaction product, 3,3′‐dimethoxy 4,4′‐diphenoquinone at 447 nm. The reaction is, first order with respect to both the substrate and oxidant, and second order with respect to H+. The oda: bromate stoichiometric ratio is 1:1. Plausible mechanism and rate laws are proposed accounting the experimental findings. Computer simulations were done using the proposed mechanism.
Rate of the retro‐Diels‐Alder dissociation of 1,2,3,6‐tetrahydropyridine over a wide temperature range
Authors: Sidhu S. S. , Kiefer J. H. , Lifshitz A. , Tamburu C. , Walker J. A. , Tsang W.
Published: January 2005

Rate constants for the retro‐Diels‐Alder dissociation of 1,2,3,6‐tetrahydropyridine, to 1,3‐butadiene and methanimine, have been measured over 650–1450 K. To cover this range, three separate techniques were used at three laboratories: laser schlieren and single pulse shock tube methods, and a comparative rate flow system technique. The derived rate constants are extrapolated to the high‐pressure limit with an RRKM model parameterized to fit the falloff observed in the laser‐schlieren measurements. The resulting high‐pressure rate constants show a reduction in activation energy of about 10 kcal/mol, comparing the isoelectronic cyclohexene, but little change in A‐factor. There is an apparent increase in activation energy of 4 kcal/mol over the temperature range of these experiments, which is just outside probable error. Such a rise in activation energy is in marked contrast to the drop usually seen in simple bond fission, and may reflect a change from a concerted to a stepwise, biradical mechanism at high temperatures.
Kinetics of ethane oxidation
Authors: Dagaut Philippe , Cathonnet Michel , Boettner Jean‐claude
Published: January 2005

Ethane oxidation in jet‐stirred reactor has recently been investigated at high temperature (800–1200 K) in the pressure range 1–10 atm and molecular species (H2, CO, CO2, CH4, C2H2, C2H4, C2H6) concentration profiles were obtained by probe sampling and GC analysis. Ethane oxidation was modeled using a comprehensive kinetic reaction mechanism including the most recent findings concerning the kinetics of the reactions involved in the oxidation of C1C4 hydrocarbons. The proposed mechanism is able to reproduce experimental data obtained in our high‐pressure jet stirred reactor and ignition delay times measured in shock tube in the pressure range 1–13 atm, for temperatures extending from 800 to 2000 K and equivalence ratios of 0.1 to 2. It is also able to reproduce atoms concentrations (H,O) measured in shock tube at ≈2 atm. The same detailed kinetic mechanism can also be used to model the oxidation of methane, ethylene, propyne, and allene in similar conditions.
Temperature dependence of the rate constants for reactions of the carbonate radical with organic and inorganic reductants
Authors: Huie R. E. , Shoute L. C. T. , Neta P.
Published: January 2005

Rate constants have been measured by pulse radiolysis for the reactions of the carbonate radical, CO3·−, with a number of organic and inorganic reactants as a function of temperature, generally over the range 5 to 80°C. The reactants include the substitution‐inert cyano complexes of FeII, MoIV, and WIV, the simple inorganic anions SO32−, ClO2−, NO2−, I−, and SCN−, several phenolates, ascorbate, tryptophan, cysteine, cystine, methionine, triethylamine, and allyl alcohol. The measured rate constants ranged from less than 105 to 3 × 109 M−1 s−1, the activation energies ranged from −11.4 to 18.8 kJ mol−1, and the pre‐exponential factors ranged from log A = 6.4 to 10.7. The activation energies for the metal complexes and inorganic anions generally decrease with increasing driving force for the reaction, as expected for an outer sphere electron transfer. For highly exothermic reactions, however, the activation energy appears to increase, probably reflecting the temperature dependence of diffusion. For many of the organic reactants, the activation energies were low and independent of driving force, suggesting that the oxidation is via an inner sphere mechanism.
Salt effects in the aqueous alkaline hydrolysis of N‐hydroxyphthalimide. Kinetic evidence for the ion‐pair formation
Authors: Khan M. Niyaz
Published: January 2005

The effects of the concentrations of LiCl, NaCl, KCl, CsCl, Na2CO3, BaCl2, and Me4NCl on the rates of reactions of hydroxide ion with ionized N‐hydroxyphthalimide (NHP) at 30°C and in a H2O–MeCN solvent containing 98%, v/v, H2O reveal a nonlinear increase in observed rate constants with increase in salt concentrations. The observed rate constants are highly sensitive to the valence state of cations and almost insensitive to the valence state of anions of the salts. These observations are explained in terms of ion‐pair formation between cations and NHP−.
The photooxidation of methyl tertiary butyl ether
Authors: Smith D. F. , Kleindienst T. E. , Hudgens E. E. , McIver C. D. , Bufalini J. J.
Published: January 2005

Methyl tertiary butyl ether (MTBE) has been proposed and is being used as an additive to increase the octane of gasoline without the use of tetraethyl lead and alkylbenzenes. The present experiments have been performed to examine the kinetics and mechanisms of the atmospheric removal of MTBE. The kinetics of the reaction of OH with MTBE was examined by using a relative rate technique in which photolysis of methyl nitrite was used as the source of OH. With n‐butane as the reference compound a value of (2.99 ± 0.12) × 10−12 cm3 molecule−1 s−1 at a temperature of 298 K was obtained for the rate constant. The products (and product yields) for the OH reaction with MTBE in the presence of NOx were also determined and found to be t‐butyl formate (0.68 ± 0.05), methyl acetate (0.14 ± 0.02), acetone (0.026 ± 0.003), t‐butanol (0.062 ± 0.009), and formaldehyde (0.48 ± 0.05) in mols/mol MTBE converted. The OH rate constant for the major product formed, t‐butyl formate was also measured and found to be (7.37 ± 0.05) × 10−13 cm3 molecule−1 s−1. Mechanisms to rationalize the formation of the products are presented.
Oxidative pyrolysis of CH2Cl2, CHCl3, and CCl4‐I: Incineration implications
Authors: Taylor Philip H. , Dellinger Barry , Tirey Debra A.
Published: January 2005

The oxidative pyrolysis of methylene chloride, chloroform, and carbon tetrachloride has been investigated using a micro‐bore, fused silica, tubular flow reactor operating under laminar flow conditions coupled to in‐line GC‐MS detection. Data were obtained over the temperature range 573–1273 K for the following conditions: chlorocarbon/oxygen equivalence ratios of 3.0, chlorocarbon concentrations of 2.7 ± 0.1 × 10−5 mols/L, gas‐phase residence times of 2.0 s, and reactor pressures of 1.15 ± 0.05 atm. The parent stability (defined by the temperature required for 99% destruction) was evaluated as:

Chemically activated recombination of chlorinated C1 radicals are proposed as important pathways to chlorinated ethane and olefin products. The most significant finding from analysis of product distributions containing ≥2 carbon atoms was the observation of ca. 1 mol% yields of higher‐molecular‐weight perchlorinated aromatic species from the decomposition of chloroform and carbon tetrachloride. Implications with respect to the controlled high‐temperature incineration of these chlorinated methanes are briefly discussed.
A kinetic approach for the mechanism of malachite green‐peroxydisulphate reaction in aqueous solution
Authors: Mushinga T. , Jonnalagadda S. B.
Published: January 2005

The oxidation kinetics of malachite green (MG) with peroxydisulphate ion (PDS) were investigated by monitoring the absorbance change at 618 nm, in aqueous solutions under buffered and unbuffered conditions. Under both conditions, the reaction had first order dependence on reductant and a fractional order (one half) dependence on the oxidant. The stoichiometric ratio between MG and PDS was 1:2. The reaction had a negative salt effect. Reaction rates were enhanced under both high or low pH relative to neutral conditions. A plausible mechanism is proposed.
Permanganate oxidation of glycine: Influence of amino acid on colloidal manganese dioxide
Authors: Insausti M. J. , Mata‐perez F. , Alvarez‐Macho P.
Published: January 2005

Permanganate ion oxidizes glycine in phosphate buffered solutions, and the product obtained was identified as a soluble form of colloidal manganese dioxide. The influence of glycine on the colloidal product shows glycine concentration changes extinction coefficients of the colloidal product, and only when the influence of glycine has been eliminated, the theoretical and experimental reaction rates coincide. The dependence of the rate of flocculation on several experimental variables was also considered.
Theoretical interpretation of the kinetics and mechanisms of the HNO + HNO and HNO + 2NO reactions with a unified model
Authors: Lin M. C. , He Yisheng , Melius C. F.
Published: January 2005

Previously measured decay rates of HNO in the presence of NO have been kinetically modeled on the basis of thermochemical data calculated with the BAC‐MP4 technique. The results of this modeling, aided by TST‐RRKM calculations for the association of HNO and the isomerization, decomposition, and stabilization of the many dimers of HNO, reveal that the decay of HNO under NO‐lean conditions occurs primarily by association forming cis‐ and trans‐(HNO)2 at temperatures below 420 K. N2O, which is a relatively minor product, is believed to be formed by H2O elimination from cis‐HON  NOH, a product of succesive isomerization reactions: trans‐(HNO)2† → HN(OH)NO† → HN(O)NOH† → cis‐HON NOH†. The calculated rate constants, which fit experimental data quantitatively, can be represented by k = 1016.2 × T−2.40e−590/T cm3/mol sec for the HNO recombination reaction and k = 10−2.44T3.98e−600/T cm3/mol sec for N2O formation in the temperature range 80–420 K, at a total pressure of 710 torr H2 or He.

Under NO‐rich conditions, HNO reacts predominantly by the exothermic termolecular reaction, HNO + 2NO → HN(NO)ONO → HN NO + NO2, with a rate contant of (6 ± 1) × 109 cm6/mol2 sec at room temperature, based on both HNO decay and NO2 production. All existing thermal kinetic data on HNO + HNO and HNO + 2NO processes can be satisfactorily rationalized with a unified model based on the thermochemical data obtained by BAC‐MP4 calculations.
Hydrolysis of schiff bases 2: Intramolecular catalysis of an ortho‐hydroxy group in nonionic surfactant systems
Authors: Mishra Pramila , Mishra Bijay K. , Behera Gopa B.
Published: January 2005

The rates of hydrolysis of N‐(2&4‐hydroxybenzylidene)‐2‐aminobenzothiazoles has been studied in the pH range 4–13 in a 10% dioxane‐water system and in various nonionic surfactant systems. The reaction is found to be due to water mediated intramolecular general base catalysis within the pH range 4.0 to 12.0 and due to nucleophilic catalysis beyond pH 12.0. A ten membered intermediate facilitating transannular attack of a water molecule on the methine carbon forming a naphthalene type transition state has been proposed. The reactivity difference in water and nonionic surfactants has been explained by a suitable entrapment model.
Rate constants for the gas‐phase reactions of Cl atoms with a series of hydrofluorocarbons and hydrochlorofluorocarbons at 298 ± 2 K
Authors: Tuazon Ernesto C. , Atkinson Roger , Corchnoy Stephanie B.
Published: January 2005

A relative rate method has been used to determine rate constants for the gas‐phase reactions of a series of hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) at 298 ± 2 K and atmospheric pressure of air. Based on a rate constant for the reaction of the Cl atom with CH4 of (1.0 ± 0.2) − 10−13 cm3 molecule−1 s−1 at 298 K, the following Cl atom reaction rate constants (in units of 10−15 cm3 molecule−1 s−1) were obtained: CH3F, 340 ± 70; CH3CHF2, 240 ± 50; CH2FCl, 110 ± 25; CHFCl2, 21 ± 4; CHCl2CF3, 14 ± 3; CHFClCF3, 2.7 ± 0.6; CH3CFCl2, 2.4 ± 0.5; CHF2Cl, 2.0 ± 0.4; CH2FCF3, 1.6 ± 0.3; CH3CF2Cl, 0.37 ± 0.08; and CHF2CF3, 0.24 ± 0.05. These Cl atom reaction rate constants are compared with literature data and with the corresponding OH radical reaction rate constants. © John Wiley & Sons, Inc.
Pyrolysis of CH2ClCH3: Considerations about its molecular nature
Authors: Huybrechts G. , Hubin Y. , Van Mele B.
Published: January 2005

Numerical integrations of a hypothetical radical chain reaction model have been performed for the pyrolysis of CH2ClCH3 which is known to be molecular. Analyses of the modelling results have led to a better understanding of the participation (or nonparticipation) of “dead” radicals in the self‐inhibition of the radical chain reaction. Attention is focused on the fact that apparently slow elementary reactions still may have to be taken into account in a pyrolysis mechanism when they produce “dead” radicals which can accumulate. © John Wiley & Sons, Inc.
Substrate structural effects in micellar catalysis with perfluorooctanoic acid
Authors: Berndt D. C. , He Z. , Ayoub M. E.
Published: January 2005

Rates of hydrolysis of a series of hydroxamic acids in aqueous acetonitrile, with perfluorooctanoic acid serving as a reactive counterion surfactant, have been determined. The pseudophase ion exchange model satisfactorily explains the surfactant effects. Variation in the structure of the hydrophobic moiety of the hydroxamic acid substrates was obtained by the incorporation of different chain lengths and differently substituted aryl groups into the substrate. The major influence of the change in substrate structure is on the binding constant for binding of the substrate to the surfactant aggregate. The number of substitutions on the aryl ring appears to be more important than the total number of carbon atoms in the substrate. © John Wiley & Sons, Inc.
Relative rate constant measurements for the gas‐phase reactions of hydroxyl radicals with 4‐methyl‐2‐pentanone, trans‐4‐octene, and trans‐2‐heptene
Authors: O'rji Lawrence N. , Stone Daniel A.
Published: January 2005

The relative OH reaction rates from the simulated atmospheric oxidation of 4‐methyl‐2‐pentanone, trans‐4‐octene, and trans‐2‐heptene have been measured. Reactions were carried out at 297 ± 2 K in 100‐liter FEP Teflon®‐film bags. The OH radicals were produced from the photolysis of methyl nitrite. The measured rate constants (×1011 cm3 molecule−1 s−1) were as follows: 6.77 ± 0.50 for trans‐4‐octene, 1.40 ± 0.07 for 4‐methyl‐2‐pentanone, and 6.70 ± 0.23 for trans‐2‐heptene using an absolute rate constant of 2.63 × 1011 cm3 molecule−1 s−1 for the reaction of OH with propene; the principal reference organic. © John Wiley & Sons, Inc.
Effects of nitric oxide on the thermal decomposition of methyl nitrite: Overall kinetics and rate constants for the HNO + HNO and HNO + 2NO reactions
Authors: He Y. , Lin M. C.
Published: January 2005

The effects of NO on the decomposition of CH3ONO have been investigated in the temperature range 450–520 K at a constant pressure of 710 torr using He as buffer gas. The measured time‐dependent concentration profiles of CH3ONO, NO, N2O, and CH2O can be quantitatively accounted for with a general mechanism consisting of various reactions of CH3O, HNO, and (HNO)2. The results of kinetic modeling with sensitivity analyses indicate that the disappearance rate of CH3ONO is weakly affected by NO addition, whereas that of the HNO intermediate strongly altered by the added NO. In the presence of low NO concentrations, the modeling of N2O yields leads to the rate constant for the bimolecular reaction, HNO + HNO → N2O + H2O (25):

In the presence of high NO concentrations (PNO > 50 torr), the modeling of CH2O yields gives the rate constant for the termolecular radical formation channel, HNO + 2NO → HN2O + NO2 (35):

Discussion on the mechanisms for reactions (25) and (35), and the alkyl homolog of (35), RNO + 2NO, is presented herein. © John Wiley & Sons, Inc.
Rate constants for the elementary reactions between CN radicals and CH4, C2H6, C2H4, C3H6, and C2H2 in the range: 295 ⩽ T/K ⩽ 700
Authors: Herbert Lee , Smith Ian W. M. , Spencer‐smith Rowland D.
Published: January 2005

Pulsed laser photolysis, time‐resolved laser‐induced fluorescence experiments have been carried out on the reactions of CN radicals with CH4, C2H6, C2H4, C3H6, and C2H2. They have yielded rate constants for these five reactions at temperatures between 295 and 700 K. The data for the reactions with methane and ethane have been combined with other recent results and fitted to modified Arrhenius expressions, k(T) = A′(298) (T/298)n exp(−θ/T), yielding: for CH4, A′(298) = 7.0 × 10−13 cm3 molecule−1 s−1, n = 2.3, and θ = −16 K; and for C2H6, A′(298) = 5.6 × 10−12 cm3 molecule−1 s−1, n = 1.8, and θ = −500 K. The rate constants for the reactions with C2H4, C3H6, and C2H2 all decrease monotonically with temperature and have been fitted to expressions of the form, k(T) = k(298) (T/298)n with k(298) = 2.5 × 10−10 cm3 molecule−1 s−1, n = −0.24 for CN + C2H4; k(298) = 3.4 × 10−10 cm3 molecule−1 s−1, n = −0.19 for CN + C3H6; and k(298) = 2.9 × 10−10 cm3 molecule−1 s−1, n = −0.53 for CN + C2H2. These reactions almost certainly proceed via addition‐elimination yielding an unsaturated cyanide and an H‐atom. Our kinetic results for reactions of CN are compared with those for reactions of the same hydrocarbons with other simple free radical species. © John Wiley & Sons, Inc.
Kinetic modeling of propane oxidation and pyrolysis
Authors: Dagaut Philippe , Cathonnet Michel , Boettner Jean‐Claude
Published: January 2005

Propane oxidation in jet‐stirred reactor was modeled using a comprehensive kinetic reaction mechanism including the most recent findings concerning the kinetics of the reactions involved in the oxidation of C1C4 hydrocarbons. The present detailed mechanism is able to reproduce experimental species concentration profiles obtained in our high‐pressure jet‐stirred reactor (900 ⩽ T/K ⩽ 1200; 1 ⩽ P/atm ⩽ 10; 0.15 ⩽ ϕ ⩽ 4) and in a turbulent flow reactor at 1 atm; ignition delay times measured in shock tube (1200 ⩽ T/K ⩽ 1700; 2 ⩽ P/atm ⩽ 15; 0.125 ⩽ ϕ ⩽ 2); H‐atoms concentrations measured in shock tube during the pyrolysis of propane and burning velocities of freely propagating premixed propane‐air laminar flames. The computed results are discussed in terms of pressure and equivalence ratio (ϕ) effects on propane oxidation. The same detailed kinetic reaction mechanism can also be used to model the oxidation of methane, ethylene, ethane, and propene in similar conditions. © John Wiley & Sons, Inc.
Approach to equilibrium after dilution of a monomer/dimer mixture. Measurement of the rate constant for dissociation of trityl dimer by stopped‐flow methods
Authors: Sóley kristjánsdóttir S. , Moody Anne E. , Norton Jack R.
Published: January 2005

A general expression is derived for the approach to a new equilibrium when a monomer/dimer solution is diluted by a factor of n. The error introduced by a simple exponential treatment is analyzed. The response of a trityl monomer/dimer equilibrium to dilution by a factor of two in a stopped‐flow apparatus has been used to measure the rate constant k11. The results fall on the same Eyring plot with those obtained at lower temperatures, by another method, in the early 1930's by Ziegler and co‐workers. © John Wiley & Sons, Inc.
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Kinetics and mechanism of oxidation of tetrahydrofurfuryl alcohol by dihydroxydiperiodatonickelate (IV) complex in aqueous alkaline medium
Authors: Li Zhi‐Ting , Wang Feng‐Li , Wang An‐Zhou
Published: January 2005

The kinetics of oxidation of tetrahydrofurfuryl alcohol by dihydroxydiperiodatonickelate (IV) complex in the temperature range of 20–35°C has been studied by spectrophotometry in aqueous alkaline medium. The reaction order in [Ni(IV)] was found to be unity and that in [alcohol] to be 1.64–1.69. The rate of oxidation increases with increase in [OH−] and decreases with increase in [IO4−], indicating that dihydroxymonoperiodatonickelate (IV) complex is the reactive species of oxidant. Salt effect studies indicated that the reaction is of ion‐dipole type. Under the protection of nitrogen the reaction system does not induce polymerization of acrylonitrile or acrylamide, which indicates that a one‐step two‐electron transfer mechanism without free radical intermediate may be in operation. A mechanism involving a preequilibrium of an adduct formation between Ni(IV) and alcohol has been proposed. All the experimental phenomena can be explained by the equation derived from the mechanism. The activation parameters of the rate‐determining step have been calculated. © John Wiley & Sons, Inc.
The yield of CH3S from the reaction of OH with CH3SSCH3
Authors: Dominé Florent , Ravishankara A. R.
Published: January 2005

The products of the reaction of OH with CH3SSCH3 (DMDS) were investigated at 298 K using a flow tube reactor coupled to a photoionization mass spectrometer and a pulsed photolysis‐pulsed laser induced fluorescence apparatus. The results from the former apparatus were semi‐quantitative and showed that CH3S and CH3SOH are produced in the title reaction. The latter apparatus was used to quantify the yield of CH3S in the title reaction. The measured yield was 0.28 ± 0.20, independent of pressure and buffer gas, suggesting that products other than CH3S and CH3SOH are also important in this reaction. The quoted uncertainty is at the 95% confidence level and includes estimated systematic errors. © John Wiley & Sons, Inc.
A kinetic study of the reduction of toluidine blue with thiourea in acidic solution
Authors: Jonnalagadda S. B. , Tshabalala D.
Published: January 2005

A detailed kinetic study of the reaction of toluidine blue (tolonium chloride) (TB+ Cl−) with thiourea (TU) in aqueous hydrochloric acid solution is reported. The reaction was first order with respect to toluidine blue and the reductant and second order with respect to [H+]. Thiourea had a 2:1 stoichiometric ratio with TB+. Toluidine blue was reduced to a colorless base in two one‐electron reduction steps and TU was oxidized to thioformamidinium ion, which dimerized rapidly to give stable dithioformamidinium ion. The energy parameters obtained for TB+‐TU reaction were mean energy of activation (Ea′) = 26.7 ± 2.4 kJ M−1; enthalpy of activation (ΔH#) = 24.2 kJ M−1; frequency factor (A) = 1.04 × 104 M−3 s−1; and entropy of activation (ΔS#) = −176.35 J M−1 s−1. © John Wiley & Sons, Inc.
Nitrenium ions in N‐chloro‐α‐amino acids decomposition?
Authors: Armesto X. L. , Canle L. M. , Losada M. , Santaballa J. A.
Published: January 2005

This article deals with the kinetics of decomposition of four isomers: NCl‐(L)‐2‐Aminohexanoic acid, NCl‐(L)‐Leucine, NCl‐(L)‐Isoleucine, and NCl‐(L)‐tert‐Leucine, in mild acid and basic aqueous solution. An alternative mechanism for this process which takes place through a nitrenium‐like ion transition state is proposed. This mechanism is in consonance with the experimental data and with those available from the literature. © 1993 John Wiley & Sons, Inc.
An operational approach to N‐Cl‐α‐amino acids decomposition
Authors: Armesto X. L. , Canle M. L. , Losada M. , Santaballa J. A.
Published: January 2005

It has been usually thought that the rate of N‐Cl‐α‐amino acids decomposition changes and that their coefficient of molar absorptivity falls when pH < 5, which has been explained on the basis of a hypothetical process of protonation at the N‐Cl‐amino group.

We have proved: (i) the absence of protonation at the N‐Cl‐amino group, at least when pH > 2−; (ii) the effect of the method of mixing on the reaction rate; (iii) the absolute necessity of a very careful choice of buffers and solvents; and (iv) the need to check the accuracy of the mathematical model to describe the chemical processes. © 1993 John Wiley & Sons, Inc.
Kinetics and thermochemistry of the reaction of benzyl radical with O2: Investigations by discharge flow/laser induced fluorescence between 393 and 433 K
Authors: Elmaimouni L. , Minetti R. , Sawerysyn J. P. , Devolder P.
Published: January 2005

The kinetics of the reaction of the benzyl radical with molecular oxygen has been studied between 393 and 433 K. The Discharge Flow technique with detection of benzyl radicals by Laser Induced Fluorescence in their visible absorption band has been used. All experiments have been performed at ≈1 torr in helium as the buffer gas. The radical benzyl decay plots are characteristic of the approach to equilibrium between benzyl and benzylperoxy: benzyl + O2 \documentclass{article}\pagestyle{empty}\begin{document}$ \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\longrightarrow\over {\smash{\longleftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} $\end{document} benzylperoxy (k3, k−3). Thanks to a reasonable assumption concerning the standard entropy of the reaction (3) (ΔS298°=−29 cal mol−1 K−1), based on the additivity rules of Benson, the following reaction enthalpy is derived for reaction (3): ΔH298°=(−20 ± 1 kcal mol−1). This latter value is compared with a few enthalpies of other related reactions available in the literature. © 1993 John Wiley & Sons, Inc.
Rate constants for some reactions of inorganic radicals with inorganic ions. Temperature and solvent dependence
Authors: Padmaja S. , Neta P. , Huie R. E.
Published: January 2005

Rate constants for several reactions of inorganic radicals with inorganic anions in aqueous and aqueous/acetonitrile solutions have been measured as a function of temperature by laser flash photolysis. The reactions studied were (1) Cl2− + N3−, (2) Br2− + N3−, (3) Cl2− + SCN−, (4) Br2− + SCN−, (5) SO4− + Cl−, (6) SO4− + CO32−, and (7) N3− + I−. The rate constants were corrected for ionic strength and ranged from 106 to 109 L mol−1 s−1. The Arrhenius activation energies varied from 2 to 12 kJ mol−1 for the first 4 reactions, were higher for reaction 6, and negative for reaction 5. The pre‐exponential factors also varied considerably with log A ranging from 5 to 14. The values of k298 decreased in most cases by more than an order of magnitude upon increasing the acetonitrile (ACN) fraction from 0 to 70%. For most reactions, this decrease in k298 was due to changes in log A with little regularity in the small changes observed in Ea. For reaction 7, k298 was practically unchanged due to compensating effects of the changes in Ea and log A with ACN mol fraction, giving an isokinetic relationship. An isokinetic relationship was also observed in the case of reaction 6; Ea and log A change in parallel while changing ACN mol fraction. Reaction 3 (Cl2− + SCN−) was also studied in water/t‐butanol and water/acetic acid mixtures. Linear correlation was found between log k and the dielectric constant of the medium for water/ACN and water/t‐BuOH but the lines for the two solvent mixtures had different slopes, suggesting specific solvation effects in addition to the primary solvent polarity effects. With water/acetic acid, k decreased and then increased upon addition of acetic acid. © 1993 John Wiley & Sons, Inc.
Kinetics of O(1D) reactions with bromocarbons
Authors: Thompson John E. , Ravishankara A. R.
Published: January 2005

The rate coefficients for the removal of O(1D) by reaction with the following seven bromocarbons were measured using time‐resolved vacuum UV atomic resonance fluorescence detection of O(3P): CH3Br, CH2Br2, CHBr3, CF3Br (Halon‐1301), CF2Br2 (Halon‐1202), CF2ClBr (Halon‐1211), and CF2BrCF2Br (Halon‐2402). The branching ratios for the quenching of O(1D) to O(3P) by the above molecules were also determined. From these measurements, the rate coefficients for reactive and nonreactive loss of O(1D) were calculated. These results are discussed in terms of their atmospheric relevance and trends in reactivity of O(1D) with hydrocarbons upon halogen substitution. © 1993 John Wiley & Sons, Inc.
Kinetics of the reactions of OH radicals with selected acetates and other esters under simulated atmospheric conditions
Authors: Williams Dale C. , O'Rji Lawrence N. , Stone Daniel A.
Published: January 2005

The relative hydroxyl radical reaction rate constants from the simulated atmospheric oxidation of selected acetates and other esters have been measured. Reactions were carried out at 297 ± 2 K in 100‐liter FEP Teflon®‐film bags. The OH radicals were generated from the photolysis of methyl nitrite in pure air. Using a rate constant of 2.63 × 10−11 cm3 molecule−1 s−1 for the reaction of OH radicals with propene, the principal reference organic compound, the rate constants (×1012 cm3 molecule−1 s−1) obtained for the acetates and esters used in this study are:

n–propyl acetate
3.42 ± 0.87

n–butyl acetate
5.71 ± 0.94

n–pentyl acetate
7.53 ± 0.48

2–ethoxyethyl acetate
10.56 ± 1.31

2–ethoxyethyl isobutyrate
13.56 ± 2.32

2–ethoxyethyl methacrylate
27.22 ± 2.06

4–pentene‐1‐yl acetate
43.40 ± 3.85

3–Ethoxyacrylic acid ethyl ester
33.30 ± 1.22

Error limits represent 2σ from linear least‐squares analysis of data.

A linear correlation was observed for a plot of the measured relative rate constants vs. the number of CH2 groups per molecule of the following acetates: methyl acetate, ethyl acetate, n‐propyl acetate, butyl acetate, and pentyl acetate. © 1993 John Wiley & Sons, Inc.
Effect of Cetylpyridinium chloride on the electron transfer reactions of acetophenones with Ce(IV)
Authors: Panigrahi Ganesh P. , Sahu Bimal P.
Published: January 2005

The kinetics of electron transfer reactions between acetophenones with Ce(IV) have been studied in aqueous acetic acid medium in the presence of cationic micelle Cetylpyridinium chloride (CPyCl) at different temperatures. Kinetic data reveal first‐order dependence with respect to each of Ce(IV) and acetophenones. The cationic micelle, Cetylpyridinium chloride enhances the oxidation reactions. The catalysis fits to a model developed by Menger and Portnoy as well as Berezin's phase separation model. The binding and partition constants and the transfer free energy from water to micelle have been estimated and discussed, suggesting that the solubilization of both the reactants in the micellar phase, facilitates the oxidation. © 1993 John Wiley & Sons, Inc.
Ruthenium(III) catalyzed kinetics of chloroacetic acids oxidation by sodium N‐bromobenzenesulfonamide in hydrochloric acid medium
Authors: Ananda S. , Venkatesha B. M. , Mahadevappa D. S. , Gowda N. M. Made
Published: January 2005

Kinetics of uncatalyzed and Ru(III)‐catalyzed oxidations of mono‐, di‐, and tri‐chloroacetic acids by the title compound (bromamine‐B or BAB) in HCl medium has been studied at 40°C. The uncatalyzed reaction shows a first‐order dependence of the rate on [BAB], and fractional and zero orders in [acid] at low and high [HCl] ranges, respectively. The Ru(III)‐catalyzed reaction, on the other hand, shows a first‐order behavior on each of [BAB] and [substrate], second‐order dependence on [Ru(III)], and inverse fractional and inverse first orders in [acid] at low and high [HCl] ranges. Addition of halide ions and the reduction product of BAB, benzenesulfonamide, has no effect on the reaction rate. Variation of ionic strength of the medium has no influence on the reaction. Solvent isotope effect was studied using D2O. Activation parameters have been evaluated from the Arrhenius plots. Mechanisms consistent with the above kinetic data have been proposed. The protonation constant of monobromamine‐B evaluated from the uncatalyzed reaction is 12.4 while that evaluated from Ru(III) catalyzed reaction is 12.7. A Taft linear free‐energy relationship is noted for the catalyzed reaction with ρ* = 1.2 and 0.07 indicating that electron withdrawing groups enhance the rate. An isokinetic relation is observed with β = 338 K indicating that enthalpy factors control the reaction rate. © 1993 John Wiley & Sons, Inc.
Optical detection of NO3 and NO2 in “pure” HNO3 vapor, the liquid‐phase decomposition of HNO3
Authors: Crowley J. N. , Burrows J. P. , Moortgat G. K. , Poulet G. , Le Bras G.
Published: January 2005

Flowing and static gas‐phase samples of HNO3 in O2 and N2 were analyzed by long‐path ultraviolet/visible (UV/VIS) spectroscopy to reveal the presence of both NO2 and NO3, the concentrations of which were calculated using differential absorption cross sections. NO2 is produced predominantly by the heterogeneous decomposition of HNO3, whereas NO3 is generated in the gas phase by the thermal decomposition of N2O5, a product of the self‐disproportionation of liquid HNO3. © 1993 John Wiley & Sons, Inc.
Reactions of azolium cations. I. Kinetics and mechanism of alkylation of 5‐phenyltetrazole with isopropyl alcohol in aqueous sulfuric acid media
Authors: Koren A. O. , Gaponik P. N. , Ostrovskii V. A.
Published: January 2005

Alkylation of 5‐phenyltetrazole with isopropyl alcohol in 84–99% sulfuric acid medium occurs regioselectively at N2 position of the heterocycle to produce 2‐isopropyl‐5‐phenyltetrazole. The regioselectivity is conditioned by 1H, 4H‐5‐phenyltetrazolium cation being the alkylation substratum. The reaction mechanism is proved to be two‐stage one. Its first and rate‐limiting stage is an interaction between the azolium cation and isopropyl cation generated from protonated isopropyl alcohol. The reaction rate constant was estimated as 0.47 L mol−1s−1at 25°C. Water activity scale was used for quantitative description of equilibrium of isopropyl cation formation from the protonated alcohol, and the equilibrium constant pKR+= −5.3 was evaluated from the data of the alkylation kinetics. © 1993 John Wiley & Sons, Inc.
Isotope effect in Ni + C2H4 (C2D4) association reaction
Authors: Mitchell S. A.
Published: January 2005

The association reactions of atomic nickel with ethene and fully deuterated ethene in carbon dioxide buffer gas at 295 K have been investigated in the pressure range 5–100 torr, using a laser photolysis‐laser fluorescence technique. By comparison with results of ab initio quantum chemistry calculations for the complex Ni[C2H4], the data are shown to be consistent with reaction on both ground and excited state potential energy surfaces. A simple rate equations treatment is described which shows the form of the pressure dependence of the second‐order recombination rate coefficient in this case. Under conditions which are expected to hold for the Ni + C2H4 (C2D4) reaction, the pressure dependence has the standard Lindemann‐Hinshelwood form, with the limiting high pressure rate constant given by an apparent value which reflects the degree to which the participating electronic states are coupled by nonadiabatic transitions. The limiting high pressure behavior of the recombination rate coefficient for Ni + C2H4 is not strongly affected by deuterium isotope substitution. However, the effect on the low pressure rate constant is large and consistent with RRKM unimolecular reaction theory. This validates the use of RRKM calculations for estimating the binding energy of the complex from kinetic data. The binding energy of Ni[C2H4] is estimated to be 35.2 ± 4.2 kcal mol−1. © 1994 John Wiley & Sons, Inc.
Hetero‐homogeneous pyrolysis of isobutane and platinum wall‐effects in conditioned or unconditioned reactors
Authors: Zils R. , Perrin D. , Martin R.
Published: January 2005

The pyrolysis of isobutane has been studied at 500°C in a “Pyrex” static reactor packed with platinum. It is shown that both dehydrogenation and demethanat on rates are strongly depressed by the metal packing. The reaction rates are very sensitive to the amount of cabonaceous coating which is deposited on the walls. As this amount increases, both rates first increase, go through a maximum and decrease. These observations are compared with those previously made on propane pyrolysis in a “Pyrex” reactor packed with stainless steel. The present results are interpreted on the basis of a hetero‐homogeneous chain mechanism in which the selectivity of the free‐radical reaction is not altered referring to the unpacked reactor. © 1994 John Wiley & Sons, Inc.
Study of the kinetics and equilibrium of the benzyl‐radical association reaction with molecular oxygen
Authors: Fenter Frederick F. , Nozière Barbara , Caralp Francoise , Lesclaux Robert
Published: January 2005

The forward rate constant, k1, and the equilibrium constant, Kp, for the association reaction of the benzyl radical with oxygen have been determined. The rate constant k1 was measured as a function of temperature (between 298 and 398 K) and pressure (at 20 and 760 torr of N2) by two different techniques, argon‐lamp flash photolysis and excimer‐laser flash photolysis, both of which employed UV absorption spectroscopy (at 253 nm and 305 nm, respectively) to monitor the benzyl radical concentration. Over the range of conditions studied, we find that the reaction is independent of pressure and is almost independent of temperature, which is in accord with two early studies of the reaction but in apparent disagreement with more recent work. For our results in 760 torr of N2 and for 298 < T/K < 398, a linear least‐squares fitting of the data yield the expression: k1 = (7.6 ± 2.4) × 10−13 exp[(190 ± 160)K/T] cm3 molecule−1 s−1. With the flash‐photolysis technique, we determined Kp over the temperature range 398–525 K. Experimental values were analyzed alone and combined with theoretically determined entropy values of the benzyl and benzylperoxy radicals to determine the enthalpy of reaction: ΔH = (−91.4 ± 4) kJ mol−1. Previous work on the benzyl radical enthalpy of formation allows us to calculate ΔH°f 298 (Benzylperoxy) = (117 ± 6) kJ mol−1. In addition, we carried out an RRKM calculation of k1 using as constraints the thermodynamic information gained by the study of Kp. We find that all the studies of the association reaction are in good agreement once a fall‐off effect is taken into account for the most recent work conducted at pressures near 1 torr of helium. © 1994 John Wiley & Sons, Inc.
Relationship between bond dissociation energies and activation energies for bond scission reactions
Authors: Smith G. P. , Manion J. A. , Rossi M. J. , Rodgers A. S. , Golden D. M.
Published: January 2005

Bond dissociation energies are frequently derived from values of the high pressure activation energy for bond scission reactions. The value derived depends on the transition state structure chosen for the reaction. We consider several models of the transition state and show that the variation in derived BDE values can be quite substantial, 3 to 6 kcal/mol at the high temperatures of pyrolysis kinetics. Application of the restricted Gorin model of the transition state results in BDE values in good agreement with current thermochemistry, while the other models tested result in lower to much lower values. © 1994 John Wiley & Sons, Inc.
Improved method for fitting falloff data
Authors: Poole James S. , Gilbert Robert G.
Published: January 2005

An extension of the dimensionless treatment of Troe is developed for fitting falloff data from unimolecular and recombination reactions. This method using dimensionless parametrizations derived from accurate numerical solutions of the master equation for system with any type of activated complex and energy transfer probability distribution, is as easily implemented as Troe's method, and allows global fitting of an entire set of pressure‐ and temperature‐dependent rate coefficients. © 1994 John Wiley & Sons, Inc.
0(3P) attack on Boranes. III. B10H14
Authors: Cheng H‐Z. , Bauer S. H.
Published: January 2005

As in our previous studies, 0(3P), generated by titration with NO of microwave discharged N2 (He carrier), was mixed with B10H14 vapor (Ar carrier) in a flow‐tube reactor. Levels of product OH were determined via LIF on an absolute basis, for dwell times 4 to 18 ms. The system was calibrated with C2H6, run under identical conditions. The reactants comprised approximately 1% of the flowing mixture. OH production is ≈62 greater from B10H14 than from B5H9 (under similar conditions but at somewhat lower temperature). FTIR analyses of a solid product that condensed downstream on cold surfaces showed the presence of BOH ⃜OB hydrogen bonds and matched (but not perfectly) the calculated frequencies of HB(OH)2. © 1994 John Wiley & Sons, Inc.
Study of the pseudo‐steady‐state kinetics of CO2 hydrate formation and stability
Authors: Lund P. C. , Shindo Y. , Fujioka Y. , Komiyama H.
Published: January 2005

This article describes a dynamic model for formation and stability of CO2‐hydrate on the interface of liquid CO2(LCO2) and ocean water at large depths. Experimental results indicate that a thin film of hydrate naturally forms on the interfaces between LCO2 and water, and inhibits diffusion between the two phases. Experiments further shows that the flux of CO2 through the hydrate film is dependent of the CO2‐concentration in the ambient sea water. The model proposed here explains these phenomena by introducing four major mechanisms; diffusion of water to the LCO2‐phase, formation of hydrate in the LCO2‐hydrate interface, decay of hydrate in the water‐hydrate interface, and diffusion of CO2 through the water phase. The model explains the CO2 flux not by diffusion through the hydrate film, but suggest a mechanism of continuous hydrate formation and decay. The overall effect is a “moving,” pseudo‐steady‐state hydrate film due to transport of CO2 through the film. The film velocity is dependent of liquid‐liquid diffusivity parameters and reaction constant, and lacking experimental values of these parameters, an order–of‐magnitude analysis is done by fitting the model to experimentally obtained data for the overall film velocity. The motivation for this work is to elucidate options for CO2 depositions in deep oceans, of which liquid CO2 sequestration is believed to be one of the most feasible. Spreading of CO2 from a liquid CO2‐lake and associated lowering of pH in the ecosystem surrounding the lake is of large concern. The work presented here concludes that diffusion of CO2 in the ocean is largely reduced by the hydrate film and suggests that hydrate formation may alleviate some of the environmental concerns regarding deep ocean sequestration of liquid CO2. © 1994 John Wiley & Sons, Inc.
Rates of reaction between the nitrate radical and some aliphatic ethers
Authors: Langer Sarka , Ljungström Evert
Published: January 2005

Rate coefficients for the reaction of NO3 with dimethyl ether, diethyl ether, di‐n‐propyl ether, and methyl t‐butyl ether (MTBE) have been determined. Absolute rates were measured at temperatures between 258 and 373 K using the fast flow‐discharge technique. Relative rate experiments were also made at 295 K in a reactor equipped with White optics and using FTIR spectroscopy to follow the reactions. The measured rate coefficients (in units of 10−15 cm3 molecule−1 s−1) at 295 K are: 0.26 ± 0.11, 2.80 ± 0.23, 6.49 ± 0.65, and 0.64 ± 0.06 for dimethyl ether, diethyl ether, di‐n‐propyl ether, and methyl t‐butyl ether, respectively. The corresponding activation energies are 21.0 ± 5.0, 17.2 ± 4.0, 15.5 ± 2.1, and 20.1 ± 1.7 kJ mole−1. The error limits correspond to the 95%‐confidence interval. © 1994 John Wiley & Sons, Inc.
Rate constant of the α‐pinene + atomic hydrogen reaction at 295 K
Authors: Vinckier C. , Van Hoof N.
Published: January 2005

The rate constant of the reaction of α‐pinene with atomic hydrogen was determined at 295 K using the fast‐flow reactor technique directly coupled to a mass spectrometric detection technique. The value was found to be equal to (9.8 ± 3.3) × 10−13 cm3 molecules−1 s−1 and independent of the helium pressure between 1 and 2 torr. The major reaction product formed is pinane showing that the stabilization of the adduct radical C10H, followed by a subsequent hydrogen atom addition step, is the important reaction route. © 1994 John Wiley & Sons, Inc.
The determination of kinetic data for the reactions of chromium(VI) with glutathione and other thiols
Authors: Perez‐Benito Joaquin F. , Arias Conchita , Lamrhari Driss , Anhari Abdellah
Published: January 2005

The equations necessary for the determination of the rate constants corresponding to the opposite elementary steps for formation of the oxidant‐reductant ester intermediate, as well as that corresponding to its redox decomposition, in the reduction of chromium(VI) by glutathione and other thiols at physiological pH have been deduced. It is shown that those three rate constants can be obtained with a good reproducibility. © 1994 John Wiley & Sons, Inc.
Spectrokinetic study of SF5 and SF5O2 radicals and the reaction of SF5O2 with NO
Authors: Sehested Jens , Ellermann Thomas , Nielsen Ole John , Wallington Timothy J.
Published: January 2005

UV spectra of SF5 and SF5O2 radicals in the gas phase at 295 K have been quantified using a pulse radiolysis UV absorption technique. The absorption spectrum of SF5 was quantified from 220 to 240 nm. The absorption cross section at 220 nm was (5.5 ± 1.7) × 10−19 cm2. When SF5 was produced in the presence of O2 an equilibrium between SF5, O2, and SF5O2 was established. The rate constant for the reaction of SF5 radicals with O2 was (8 ± 2) × 10−13 cm3 molecule−1 s−1. The decomposition rate constant for SF5O2 was (1.0 ± 0.5) × 105 s−1, giving an equilibrium constant of Keq = [SF5O2]/[SF5][O2] = (8.0 ± 4.5) × 10−18 cm3 molecule−1. The SF5O2 bond strength is (13.7 ± 2.0) kcal mol−1. The SF5O2 spectrum was broad with no fine structure and similar to the UV spectra of alkyl peroxy radicals. The absorption cross section at 230 nm was found to (3.7 ± 0.9) × 10−18 cm2. The rate constant of the reaction of SF5O2 with NO was measured to (1.1 ± 0.3) × 10−11 cm3 molecule−1 s−1 by monitoring the kinetics of NO2 formation at 400 nm. The rate constant for the reaction of F atoms with SF4 was measured by two relative methods to be (1.3 ± 0.3) × 10−11 cm3 molecule−1 s−1. © 1994 John Wiley & Sons, Inc.
Dissolution kinetics of copper(II) oxide in water saturated by sulphur dioxide
Authors: Çakici Avni , Çolak Sabri , Eki̇nci̇ Zafer , Bayrakçeken Samih
Published: January 2005

The dissolution and the kinetics of dissolution of cooper(II) oxide in water saturated by sulphur dioxide has been studied. In the experiments, the particle size, the flow rate of the gas, the solid to liquid ratio, and the reaction temperature have been chosen as parameters, while the stirring rate was held constant. As a result of present experiments, it was observed that the decrease of the particle size, the solid to liquid ratio, and an increase of the reaction temperature increased the dissolution rate. It was also observed that the flow rate of sulphur dioxide in the range of its flow rate values did not affect the dissolution rate.

The reaction kinetics of copper(II) oxide according to the heterogeneous reaction models was examined and it was found that the dissolution rate was controlled by chemical reaction. The calculated activation energy is 66.50 kJmol−1. © 1994 John Wiley & Sons, Inc.
A novel correlative relationship among rates of complexation of 1:1 copper(II) diketonates and basicity of the ligand
Authors: Verdú Jesus , Blanco Carlos A.
Published: January 2005

An exceptional kinetic behavior on the reactivity of β‐diketones against copper(II) have been found. Some relationship between ligand basicity and unexpected enhancement on the rates of complex formation, which may be useful for predicting rate constants of similar monochelated copper(II) complexes, are established. © 1994 John Wiley & Sons, Inc.