bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas‐phase reactions of azulene with OH and NO3 radicals and O3 at 298 ± 2 K
Authors: Atkinson Roger , Arey Janet , Aschmann Sara M. 
Published: January 2005

AbstractAzulene, which is isomeric with naphthalene, was studied to determine whether it behaves like a polycyclic aromatic hydrocarbon or an alkene in its gas‐phase reactions with OH and NO3 radicals and O3. Using relative rate methods, rate constants for the reactions of azulene with OH and NO3 radicals and O3 of (2.73 ± 0.56) × 10−10 cm3 molecule−1 s−1, (3.9) × 10−10 cm3 molecule−1 s−1, and <7 × 10−17 cm3 molecule−1 s−1, respectively, were obtained at 298 ± 2 K. The observation that the NO3 radical reaction did not involve NO2 in the rate determining step indicates that azulene behaves more like an alkene than a polycyclic aromatic hydrocarbon in this reaction. No conclusive evidence for the formation of nitroazulene(s) from either the OH or NO3 radical‐initiated reaction of azulene (in the presence of NOx) was obtained.
The mechanism of O(3P) atom reaction with ethylene and other simple olefins
Authors: Knyazev V. D. , Arutyunov V. S. , Vedeneev V. I. 
Published: January 2005

AbstractReactions of oxygen atoms with ethylene, propene, and 2‐butene were studied at room temperature under discharge flow conditions by resonance fluorescence spectroscopy of O and H atoms at pressures of 0.08 to 12 torr. The measured total rate constants of these reactions are K = (7.8 ± 0.6)·10−13cm3s−1,K = (4.3 ± 0.4) ± 10−12 cm3 s−1, K = (1.4 ± 0.4) · 10−11 cm3 s−1. The branching ratios of H atom elimination channels were measured for reactions of O atoms with ethylene and propene. No H‐atom elimination was found for the reaction of O‐atoms with 2‐butene. A redistribution of reaction O + C2 channels with pressure was found. A mechanism of the O + C2 reaction was proposed and the possibility of its application to other olefins is discussed. On the basis of mechanism the pressure dependence of the total rate constant for reaction O + C2 was predicted and experimentally confirmed in the pressure range 0.08–1.46 torr.
Investigation of the reaction order for nucleophilic substitution of dialkyl methylphosphonates by alkoxides
Authors: Leslie D. R. , Long G. J. , Pantelidis S. 
Published: January 2005

AbstractThe rate of nucleophilic substitution at the phosphorus centre of dialkyl methylphosphonates by methoxide and ethoxide has been studied to investigate the possible involvement of hexacoordinated phosphorus species in this reaction. For alkoxide concentrations less than ca. 1.5 M the rate increases with the square of alkoxide concentration. However, consideration of the activity of the alkoxides, represented by an appropriate acidity function, reveals that only one equivalent of alkoxide is involved in the rate‐determining step. Thus, there is no requirement to invoke the intermediacy of a hexacoordinated species in the reaction pathway. © John Wiley & Sons, Inc.
The retro‐aldol mechanism in the pyrolysis kinetics of primary, secondary, and tertiary β‐hydroxy ketones in the gas phase
Authors: Rotinov Alexandra , Chuchani Gabriel , Machado Ruben A. , Rivas Carlos , Quijano Jairo , Yepes Maria Del Socorro , Restrepo Iliana 
Published: January 2005

AbstractThe pyrolysis kinetics of primary, secondary, and tertiary β‐hydroxy ketones have been studied in static seasoned vessels over the pressure range of 21–152 torr and the temperature range of 190°–260°C. These eliminations are homogeneous, unimolecular, and follow a first‐order rate law. The rate coefficients are expressed by the following equations: for 1‐hydroxy‐3‐butanone, log k1(s−1) = (12.18 ± 0.39) − (150.0 ± 3.9) kJ mol−1 (2.303RT)−1; for 4‐hydroxy‐2‐pentanone, log k1(s−1) = (11.64 ± 0.28) − (142.1 ± 2.7) kJ mol−1 (2.303RT)−1; and for 4‐hydroxy‐4‐methyl‐2‐pentanone, log k1(s−1) = (11.36 ± 0.52) − (133.4 ± 4.9) kJ mol−1 (2.303RT)−1. The acid nature of the hydroxyl hydrogen is not determinant in rate enhancement, but important in assistance during elimination. However, methyl substitution at the hydroxyl carbon causes a small but significant increase in rates and, thus, appears to be the limiting factor in a retroaldol type of mechanism in these decompositions. © John Wiley & Sons, Inc.
Kinetics of dissociation of tris‐2,2′‐bipyridyl‐iron(II) cation in aqueous acetic acid solutions
Authors: Sriramam K. , Sreelakshmi J. , Ramadevi L. , Ramakrishna Ch. 
Published: January 2005

AbstractThe kinetics of dissociation of tris‐2,2′‐bipyridyl‐iron(II) complex ion have been examined in aqueous acetic acid solutions. The reaction is first order in the complex ion; the dependence of rate on H+ is somewhat like that observed in aqueous solutions approaching a limiting value at higher H+ concentrations. The influence of solvent composition on the reaction rate under acid‐dependent and acid‐independent conditions shows an initial retardation by acetic acid. The argument of ion‐pair formation based on decrease of dielectric constant proposed to explain the kinetics in other aqueous solvent media was found useless to explain the behavior in acetic acid solutions. Other solvent parameters also did not provide satisfactory correlation with the kinetic results, thus, indicating the operation of more complex microscopic solute‐solvent and solvent‐solvent interactions. While solvent effects play some part in the rate process, the rate of reaction would tend to zero in the absence of H2O and H+. This interesting observation proved useful in proposing a reaction mechanism that is consistent with the rate behavior over the entire range of solvent composition. The activity of water in the reaction medium is controlled by the content of acetic acid which can effect the structure of water through operation of hydrophobic forces and formation of hydrates. While acetic acid cannot possibly fulfill the role of water in occupying the vacated coordination position, the anomalous rise in rate even under some water deficient conditions seems to be related to the coordinating ability of HSO4− derived from H2SO4 present in the solution.
Kinetics and mechanism of oxidation of some para‐, meta‐, and ortho‐substituted ethyl S‐phenylmercaptoacetates by chloramine‐B(CAB)
Authors: Gurumurthy R. , Sathiyanarayanan K. , Gopalakrishnan M. 
Published: January 2005

AbstractThe kinetics of oxidation of ethyl S‐phenylmercapto acetate and several para‐, meta‐, and ortho‐substituted ethyl S‐phenylmercaptoacetates by chloramine‐B have been studied in 50% (V/V) aqueous ethanol medium containing phosphate buffer. This oxidation is of first order with respect to substrate and zero order with respect to oxidant. A catalytic effect of mercury is observed and the order with respect to mercury is fractional (0.74). The increase in pH decreases the rate of oxidation and the order with respect to H+ is 0.05. In general electron‐releasing substituents accelerate the rate while electron‐attracting groups retard the rate. A good correlation is found to exist between log k
1 and Hammett constants. Susceptibility of the reaction to the steric effect of ortho‐substituents has been analyzed in the light of application of Taft's steric energy parameters. © John Wiley & Sons, Inc.
Kinetics and mechanism of oxidation of aspartic acid by bismuth(V) in HClO4‐HF medium
Authors: Rao Indu , Jain Seema , Sharma P. D. 
Published: January 2005

AbstractThe kinetics of oxidation of Aspartic acid by bismuth(V) studied in HClO4‐HF mixture iodometrically exhibit complex dependence with respect to aspartic acid (AA). The rate law (i) accounts for all the experimental observations.

equation image

where [Bi(V)] and [AA] are the gross analytical concentration of all fluorobismuth(V) species and the equilibrium concentration of aspartic acid, respectively. The oxidation product of the amino acid was identified to be an aldehyde. HF and F− do not affect the rate of the reaction. © John Wiley & Sons, Inc.
Implications of the HCN → HNC process to high‐temperature nitrogen‐containing fuel chemistry
Authors: Lin M. C. , He Yisheng , Melius C. F. 
Published: January 2005

AbstractWe have found in our recent kinetic study of the oxidation of HCN by NO2 in the temperature range 623–773 K that HNCO and CO2 are very important early products. The measured kinetic data cannot be accounted for by a “conventional” mechanism involving HCN reactions with NO2, O, and OH. However, the introduction of the isomerization reaction HCN → HNC, followed by the rapid oxidation of HNC by NO2, O, and OH, can quantitatively simulate all measured kinetic data. A similar study of the NO2 + HCN reaction in shock waves at temperatures between 1500 and 2400 K also required the inclusion of HNC reactions in order to quantitatively account for measured product distributions. The effects of the HNC molecule on the high temperature HCN chemistry are discussed in terms of the predicted rate constants for HNC reactions with O and OH employing the BAC‐MP4 method. © John Wiley & Sons, Inc.
In situ separation of heterogeneous and homogeneous reaction components in flow experiment
Authors: Orkin V. L. , Khamaganov V. G. , Larin I. K. 
Published: January 2005

AbstractA method is suggested for the determination of the character (homogeneous or heterogeneous) of the material transformation in the investigation of gas‐phase reactions under tubular flow conditions. The method provides the estimation of the error in the rate constant of a gas‐phase reaction due to the possible parallel occurrence of a heterogeneous process. © 1993 John Wiley & Sons, Inc.
Temperature dependence of the self‐decay rate constants of some phenoxyl radicals in aqueous solution
Authors: Alfassi Z. B. , Shoute L. C. T. 
Published: January 2005

AbstractThe Arrhenius parameters of the bimolecular rate constants for the decay of several phenoxyl radicals in aqueous solution were measured. The p‐halophenoxyl radicals (F, Cl, and Br) decay in a diffusion controlled reaction as the activation energies are the same as that of diffusion of water (16 ± 1.5 kJ · mol−1). The A factors are 1012.2 ± 0.2. For alkyl and alkoxy substituted phenoxyl, slightly higher activation energies were found (19.5 − 21.9 kJ · mol−1). © 1993 John Wiley & Sons, Inc.
Kinetic study of the electrophilic reaction of trialkyltin chlorides and iodine monochloride
Authors: Verbiest P. , Verdonck L. , Van Der Kelen G. P. 
Published: January 2005

AbstractThe kinetics of the electrophilic substitution of several trialkyltin chlorides by iodine monochloride are presented. Rate constants have been determined at four different temperatures and the activation parameters A, Ea, and ΔS°= are calculated. A mechanism is proposed involving charge‐transfer as the driving force for the substitution. © 1993 John Wiley & Sons, Inc.
“Surprising kinetics” or the major role of trace quantities in radical chain mechanisms
Authors: Olbregts Jean 
Published: January 2005

AbstractAlthough hydrogen abstraction from 1,1,1,2‐tetrachloroethane should produce only one kind of radical, CCl3CHCl, the presence of small amounts of trichloroethene, as impurity as well as product of reaction, induces the formation of the a priori unexpected CHCl2CCl2 radicals. The importance of this radical in the reaction pathways of the chlorination and the chlorine induced dehydrochlorination of CCl3CH2Cl, under different experimental conditions, is computed and discussed. For example, at 380 K, and for small partial pressures of chlorine (2 torr), the CHCl2CCl2 radicals account for more than 70% of the formation of the reaction products after only 2% reaction. The major role of trace quantities in long chain radical reactions is emphasized. © 1993 John Wiley & Sons, Inc.
Solvent effects on the rate of reaction of Cl2˙− and SO4˙− radicals with unsaturated alcohols
Authors: Alfassi Z. B. , Padmaja S. , Neta P. , Huie R. E. 
Published: January 2005

AbstractRate constants have been measured in several aqueous/organic solvent mixtures for the addition reaction of Cl2˙− radicals with 2‐propen‐1‐o1 and 2‐buten‐1‐o1 as a function of temperature and with 2, 3‐dimethyl‐2‐butene at room temperature. The rate constants were in the range of 106–109 L mol−1 s−1, the activation energies were relatively low (1–10 kJ mol−1), and the pre‐exponential factors varied over the range log A = 7.9 to 9.4. The rate constants (k) decreased (by up to a factor of 30) upon increasing the fraction of organic solvent and log k correlated linearly with the dielectric constant for a given water/organic solvent system, but the lines for the different solvent systems had different slopes. A better correlation of log k was found with a combination of the solvatochromic factor, ET(30), and the hydrogen‐bond donor acidity factor, α. This suggests that the rate of reaction is influenced by the solvent polarity and also by specific solvation of the ionic reactant and product. Solvent effect on the reaction of SO4˙− with 2‐propen‐1‐o1 was studied for comparison. © 1993 John Wiley & Sons, Inc.
Rate constants for some hydrogen abstraction reactions of the carbonate radical
Authors: Clifton Carol L. , Huie Robert E. 
Published: January 2005

AbstractRate constants have been measured in aqueous solutions for the reactions of the carbonate radical, CO3˙−, with several saturated alcohols and one cyclic ether as a function of temperature. Arrhenius pre‐exponential factors ranged from 2×108 to 1×109 𝓁 mol−1 s−1 and activation energies ranged from 16 to 29 kJ mol−1. The results suggest that the reactions are not pure hydrogen abstraction, but involve an additional interaction of the radical with the OH or O linkage. © 1993 John Wiley & Sons, Inc.
Rate constants for the addition of the 2‐cyano‐2‐propyl radical to alkenes in solution
Authors: Hėberger K. , Fischer H. 
Published: January 2005

AbstractAbsolute rate constants for the addition of the 2‐cyano‐2‐propyl radical to 26 alkenes CH2=CXY at 315 K were determined in solution by time‐resolved electron‐spin‐resonance spectroscopy. They vary with the alkene substituents from 30 M−1 s−1 to 7′010 M−1 s−1. For styrene the temperature dependence is given by log k/M−1 s−1 = 7.7 − 26.1/Θ where Θ = 2.303 RT in kJ/mol. An analysis of the substituent effects in terms of polar and enthalpic factors reveals a dominant influence of the overall reaction enthalpy. © 1993 John Wiley & Sons, Inc.
On the kinetics and mechanism of Nb(V) hydrolysis
Authors: Bottecchia Otávio L. , Boodts Julien F. C. 
Published: January 2005

AbstractKinetics of Nb(V) hydrolysis in MgCl2, Mg(ClO4)2 mixtures has been investigated by electroanalytical methods and the rate constants determined. A hydrolysis model based on species postulated in the literature is proposed. Resolution of the corresponding differential equations led to results consistent with experimental data obtained from polarographic current vs. time curves. © 1993 John Wiley & Sons, Inc.
New substrates in the ferroin‐catalyzed bromate system in aqueous‐organic mixed media
Authors: Lalitha P. V. , Ramaswamy R. 
Published: January 2005

AbstractA large number of substrates have hitherto been employed in the Belousov‐Zhabotinsky (B‐Z) oscillatory system in pure aqueous medium. A systematic study of aromatic bromate oscillators is limited by solubility problem relating to the compounds and the brominated derivatives. The use of aqueous‐organic mixed media for the oscillatory study is found to be highly useful for the study of water insoluble substances. A comparative study of the oscillatory behavior of gallic acid as substrate in pure aqueous as well as in a number of mixed media have been made in order to ascertain the suitability of mixed media in oscillatory systems. The alteration of oscillatory characteristics in the presence of organic solvent can be understood in terms of the Field‐Koros‐Noyes (FKN) mechanism. The oscillatory behavior of seventeen new substrates in the ferroin‐catalyzed bromate system in 20% (v) acetonitrile is also presented and discussed in this communication. The reactivity of structurally related substrates has been correlated to the structure in terms of the relevant oscillatory parameters. The use of aqueous‐organic mixed media in oscillatory systems would enable the investigation of new classes of substrates since getting them into the solution phase would no longer be a limitation. © 1993 John Wiley & Sons, Inc.
A kinetic study of the reaction of fluorine atoms with CH3F, CH3Cl, CH3Br, CF2H2, CO, CF3H, CF3CHCl2, CF3CH2F, CHF2CHF2, CF2ClCH3, CHF2CH3, and CF3CF2H at 295 ± 2 K
Authors: Wallington Timothy J. , Hurley Michael D. , Shi Jichun , Maricq M. Matti , Sehested Jens , Nielsen Ole J. , Ellermann Thomas 
Published: January 2005

AbstractA variety of relative and absolute techniques have been used to measure the reactivity of fluorine atoms with a series of halogenated organic compounds and CO. The following rate constants were derived, in units of cm3 molecule−1 s−1: CH3F, (3.7 ± 0.8) × 10−11, CH3Cl, (3.3 ± 0.7) × 10−11; CH3Br, (3.0 ± 0.7) × 10−11; CF2H2, (4.3 ± 0.9) × 10−12; CO, (5.5 ± 1.0) × 10−13 (in 700 torr total pressure of N2 diluent); CF3H, (1.4 ± 0.4) × 10−13; CF3CCl2H (HCFC‐123), (1.2 ± 0.4) × 10−12; CF3CFH2 (HFC‐134a), (1.3 ± 0.3) × 10−12, CHF2CHF2 (HFC‐134), (1.0 ± 0.3) × 10−12; CF2ClCH3 (HCFC‐42b), (3.9 ± 0.9) × 10−12, CF2HCH3 (HFC‐152a), (1.7 ± 0.4) × 10−11; and CF3CF2H (HFC‐125), (3.5 ± 0.8) × 10−13. Quoted errors are statistical uncertainties (2σ). For rate constants derived using relative rate techniques, an additional uncertainty has been added to account for potential systematic errors in the reference rate constants used. Experiments were performed at 295 ± 2 K. Results are discussed with respect to the previous literature data and to the interpretation of laboratory studies of the atmospheric chemistry of HCFCs and HFCs. © 1993 John Wiley & Sons, Inc.
Kinetics and mechanism of the formation of CO2 hydrate
Authors: Shindo Yuji , Lund Per Christer , Fujioka Yuichi , Komiyama Hiroshi 
Published: January 2005

AbstractThis article proposes a mechanism of CO2 hydrate formation taking into account both diffusion and reaction, and gives an analysis of its kinetics. The most important assumptions on the model are that water dissolves into liquid CO2 and reacts to form CO2 hydrate, and that the hydrate blocks the dissolution and diffusion of water. Computational simulations were conducted, and the model proposed explains well the many observations on the CO2 hydrate formation in previous articles. It is concluded that liquid CO2 disposed in a deep ocean will form a very thin film of CO2 hydrate, and this will greatly control the CO2 diffusion in the ocean. © 1993 John Wiley & Sons, Inc.
The flash photolysis of aqueous solutions of rhodizonic and croconic acids
Authors: Zhao B. , Back M. H. 
Published: January 2005

AbstractThe flash photolysis of aqueous solutions of rhodizonic and croconic acids has been studied in the presence and absence of electron acceptors. No transient absorption which could be identified with an excited state was observed with either anion. The rate of recovery of the ground state in the absence of additives was a first‐order process with both acids and gave rate constants for deactivation of the excited state, kD, of 2.4 × 105 s−1 for rhodizonate and 2.8 × 105 s−1 for croconate. With croconate dianion in the presence of three acceptors, 4‐nitrobenzylbromide, methylviologen, and biacetyl, a transient absorption was detected, with a maximum absorbance at 500 nm, and was tentatively identified with the monoanion radical, formed following electron transfer to the acceptor. From the rate of growth of the transient, rate constants for the rate of electron transfer to the acceptor were measured as follows: 4‐nitrobenzylbromide: 2.8 × 109 M−1 s−1; methyl viologen: 3.7 × 1010 M−1 s−1; and biacetyl: 2.0 × 108 M−1 s−1. The significance of the measurements is discussed in relation to the mechanism proposed for the photochemical reactions of these dianions. © 1994 John Wiley & Sons, Inc.
Structure–reactivity correlations for gas‐phase thermal Diels‐Alder reactions of cyclohexa‐1,3‐diene with substituted ethenes and reverse reactions
Authors: Huybrechts G. , Van Mele B. 
Published: January 2005

AbstractStructure–reactivity correlations are developed and used to test a biradical mechanism for gas‐phase thermal Diels‐Alder reactions of cyclohexa‐1,3‐diene with substituted ethenes and reverse reactions. © 1994 John Wiley & Sons, Inc.
Complex dynamical behavior in the oxidation of hydroxylamine by bromate
Authors: Adamˇíková Lubica , Vranová Tamara , Valent Ivan 
Published: January 2005

AbstractComplex dynamical behavior has been observed in the oxidation of hydroxylamine by bromate in acidic sulfate medium. The reaction shows clock type kinetics in closed conditions and an aperiodic oscillations if gaseous products are removed from the system with a constant flow‐rate. The reduction kinetics of bromate ions with excess hydroxylamine has been studied in the presence of allyl alcohol. The observed pseudo‐first‐order rate constant kobs has been found to follow the expression

where [hydroxylamine] is total initial hydroxylamine concentration, K1 = 0.5 M−1, K2 = 106 M−1, and k = 2.57 × 103 M−1 s−1 at 298.15 K and I = 2.0 M.The rate constant for the bromine oxidation of hydroxylamine in sulfuric aqueous solution has been determined. © 1994 John Wiley & Sons, Inc.
Hydrolysis of 2‐aminoethanethiolsulfate ions
Authors: Zheng Z. B. , Littlejohn D. , Chang S. G. , Zhuang Y. H. 
Published: January 2005

AbstractThe kinetics of the acid catalyzed hydrolysis of 2‐aminoethanethiolsulfate (AETS) ions were investigated. The dependence of the hydrolysis rate constant on acidity and temperature was determined. The hydrolysis rate equation can be expressed as

where Ho is the Hammett acidity function. The rate constant, k, can be expressed as
equation image
The pKa's for the compound were measured and literature value of pKa was found to be in error. The values determined in this study are pKa1 < −0.5 and pKa2 = 9.1 ± 0.1. General acid catalysis of the hydrolysis reaction was found not to proceed to a significant degree. © 1994 John Wiley & Sons, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
Vacuum ultraviolet photolysis of CClF2CH2Cl
Authors: Minamikawa Tadahiro , Ogura Seido , Sakka Tetsuo , Ogata Yukio , Iwasaki Matae 
Published: January 2005

AbstractPhotolysis of CClF2CH2Cl was studied by 147 nm vacuum ultraviolet irradiation. In the presence of NO; CF2CH2, CF2CHCl, and CClF2CN were produced. These products represent three different reaction paths; the molecular dechlorination, molecular dehydrochlorination, and chlorine radical elimination reactions. The reactant pressure and the addition gas (He or NO) pressure effects upon the product yield were studied. © 1994 John Wiley & Sons, Inc.
Kinetics and mechanism of oxidation of glycine, alanine, and threonine by fluoride coordinated bismuth(V) in aqueous HClO4–HF medium
Authors: Devra Vijai , Jain Seema , Sharma P. D. 
Published: January 2005

AbstractThe kinetics of oxidation of amino acids viz. glycine, alanine, and threonine with bismuth(V) in HClO4–HF medium have been studied. The kinetics of the oxidation of all these amino acids exhibit similar rate laws. The second‐order rate constants were calculated to be 2.04 × 10−2 dm3 mol−1 and 2.72 × 10−2 dm3 mol−1 s−1 for glycine and alanine, respectively, at 35°C and 5.9 × 10−2 dm3 mol−1 s−1 for threonine at 25°C. All the possible reactive species of both bismuth(V) and amino acids have been discussed and a most probable kinetic model in each reaction has been envisaged. © 1994 John Wiley & Sons, Inc.