bluuebunny/crossref_metadata_2025_split huggingface dataset:
A shock tube study of the reactions of the hydroxyl radical with several combustion species
Authors: Bott J. F. , Cohen N. 
Published: January 2005

AbstractReactions of the hydroxyl radical, OH, with several organic species of interest in combustion chemistry have been studied near 1200 K and 1 atm in shock tube experiments in which UV absorption was used to monitor the OH concentration. Rate coefficients were measured for the reactions of OH with 2,3‐dimethylbutane, isooctane, neooctane, ethylene, propylene, acetylene, formaldehyde, methanol, and ethanol. The values were found to be (in units of 1012 cm3/mol‐s): 21, 22, 18, 2.6, 9.6, 0.28, 12, 5.2, and 5.3. These measured values are compared with previous experimental results and, where appropriate, transition‐state theory calculations.
The thermal decomposition of peroxyacetic nitric anhydride (PAN) and peroxymethacrylic nitric anhydride (MPAN)
Authors: Roberts James M. , Bertman Steven B. 
Published: January 2005

AbstractThe rate coefficients of thermal decomposition of peroxyacetic nitric anhydride (PAN) and peroxymethacrylic nitric anhydride (MPAN) were measured over the temperature range 302–323 K. The resulting Arrhenius expressions were k = 1017.4±0.4 exp(−28.5 ± 0.5/RT) for PAN, and k = 1016.2±0.7 exp(−26.8 ± 1.0/RT) for MPAN, where the activation energy is in Kcal/mol. These results are in good agreement with previous studies of PAN and other PAN‐type compounds, and imply that energies of RC(O)OONO2 bonds are relatively independent of the nature of R.
A theoretical analysis of the reaction between hydrogen atoms and isocyanic acid
Authors: Miller James A. , Melius Carl F. 
Published: January 2005

AbstractUsing BAC‐MP4 potential‐surface parameters, supplemented by an MP2 normal‐mode analysis at one transition state, and statistical theoretical methods, we have computed thermal rate coefficients for the reactions,

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and

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Over the entire temperature range considered, 300 K < T < 3300 K, reaction (2) is the dominant product channel. The theoretical predictions are in excellent agreement with the experimental results available for k2 and k−1, the rate coefficient for the reverse of reaction (1). Modified Arrhenius expressions are given for k1, k−1, and k2. In addition, we identify and discuss a weakness in utilizing a Hartree‐Fock normal‐mode analysis in the prediction of k2. The present result for k2 is much smaller than that used in the initial modeling of the RAPRENOx process. The implications of this are discussed.
Aromatic nucleophilic substitution reactions of 2‐chloro‐quinoxaline with anilines in ethanol
Authors: Patel R. D. 
Published: January 2005

AbstractThe reactions of 2‐chloroquinoxaline with anilines in ethanol are found to follow second order kinetics, first order in each reactant. The activation parameters determined, from the rate data at five different temperatures are found to be typical of bimolecular aromatic nucleophilic substitutions (SN2Ar). The rate data are also correlated in terms of Hammett as well as Bronsted relationships.
Kinetics of the thermal unimolecular decomposition of hex‐1‐ene‐3‐yne. Heat of formation and resonance stabilization energy of the 3‐ethenylpropargyl radical
Authors: Staker Warren S. , King Keith D. , Nguyen Tam T. 
Published: January 2005

AbstractThe thermal unimolecular decomposition of hex‐1‐ene‐3‐yne (HEY) has been investigated over the temperature range 949–1230 K using the technique of very low‐pressure pyrolysis (VLPP). One reaction pathway is the expected C5C6 bond fission to form the resonance‐stabilized 3‐ethenylpropargyl radical. There is a concurrent process producing molecular hydrogen which probably occurs via the intermediate formation of hexatrienes and cyclohexa‐1,3‐diene. RRKM calculations yield the extrapolated high‐pressure rate parameters at 1100 K given by the expressions 1016.0±0.3 exp(−300.4 ± 12.6 kJ mol−1/RT) s−1 for bond fission and 1013.2+0.4 exp(−247.7 ± 8.4 kJ mol−1/RT) for the overall formation of hydrogen. The A factors were assigned from the results of previous studies of related alkynes, alkenes, and alkadienes. The activation energy for the bond fission reaction leads to ΔH [H2CCHCCĊH2] = 391.9, DH [H2CCHCCCH2H] = 363.3, and a resonance stabilization energy of 56.9 ± 14.0 kJ mol−1 for the 3‐ethenylpropargyl radical, based on a value of 420.2 kJ mol−1 for the primary CH bond dissociation energy in alkanes. Comparison with the revised value of 46.6 kJ mol−1 for the resonance energy of the unsubstituted propargyl radical indicates that the ethenyl substituent (CH2CH) on the terminal carbon atom has only a small effect on the propargyl resonance energy. © John Wiley & Sons, Inc.
Thermal decomposition of vinylacetylene in shock waves
Authors: Hidaka Yoshiaki , Masaoka Hiromitsu , Oshita Hidekazu , Nakamura Takuji , Tanaka Koji , Kawano Hiroyuki 
Published: January 2005

AbstractThe thermal decomposition of vinylacetylene (C4H4) was studied behind reflected shock waves using both a single‐pulse method (reaction time between 0.8 and 3.3 ms) and a time‐resolved UV‐absorption method (230 nm). The studies were done over the temperature range of 1170–1690 K at the total pressure range of 1.3–2.3 atm. The mechanism was used to interpret both the early and late stages of vinylacetylene decomposition at the high temperatures. It was confirmed that C4H4 dissociation proceeded through the following three channels.

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The rate constant expression of reaction (1) was determined as k1 = 6.3 × 1013 exp(−87.1 kcal/RT) s−1. The rate constants of the succeeding reactions (chain reaction, C4H4 + H → i‐C4H3 + H2 and C4H4 + H → C2H2 + C2H3 and decomposition reactions of free radicals, i‐C4H3 + M → C4H2 + H + M) were confirmed or estimated. © John Wiley & Sons, Inc.
Disproportionation kinetics of N  Cl‐n‐propylamine and N  Cl‐isopropylamine
Authors: Antelo Juan M. , Arce Florencio , Parajo Mercedes , Rodriguez Pilar , Varela Angel 
Published: January 2005

AbstractThe kinetics of the disproportionation of N  Cl‐n‐propylamine and N – Cl‐isopropylamine to the corresponding N, N‐dichloramines were found to be a second order with respect to the N‐chloramine. The influence of amine concentration, pH, buffers, ionic strength, and temperature were also studied. The observed influence of pH supports a reaction mechanism which allowed estimation of the protonation constants of the chloramines studied. The influence of buffers, which was studied for both the above chloramines and N  Cl‐3‐aminopropanol, reflects general acid catalysis, for which a mechanism is proposed. Bronsted's equation was fitted to the catalytic constants obtained therefrom so as to estimate the values of the parameter α for these three N‐chloramines. © John Wiley & Sons, Inc.
Kinetics and mechanism of oxidation of some aliphatic esters by sodium N‐bromo‐p‐toluenesulfonamide
Authors: Rangappa K. S. , Mythily C. K. , Mahadevappa D. S. , Gowda N. M. Made 
Published: January 2005

AbstractThe kinetics of oxidation of methyl, ethyl, n‐propyl, isopropyl, and n‐butyl acetates to acetic acid and the corresponding aldehyde by the title oxidant in aqueous HCl medium at 40°C has been studied. The reaction shows first‐order with respect to [oxidant] and fractional orders in [H+] and [ester]. An isokinetic relationship was observed with β = 374 K indicating enthalpy as the rate controlling factor. Attempts have been made to arrive at a linear free energy relationship through the Taft treatment. Electron releasing groups in the ester moiety increase the rate with ρ* = −9.88. A two‐pathway mechanism, consistent with the observed kinetic data, has been proposed. © 1993 John Wiley & Sons, Inc.
Two‐film effects on the kinetics of hydrogen isotope exchange between CHCl3 and D2O in two liquid phase system
Authors: Iwasaki Matae , Sakka Tetsuo , Ohashi Shigeyuki , Miyake Yoshikazu , Matsushita Hiroshi 
Published: January 2005

AbstractA model based on the two film approximation is proposed for the description of the kinetics of the hydrogen isotope exchange between CHCl3 and D2O. In this model, details of mass transfer in interfacial region between the two liquid phases are considered and the kinetics of the exchange reaction is quantitatively described without an adjusting parameter. This model is successful in explaining the experimental results obtained with high alkali concentrations, which has not been sufficiently explained in our previous article [M. Iwasaki et al., J. Phys. Chem., 93, 5139 (1989)]. © 1993 John Wiley & Sons, Inc.
Electron‐transfer kinetics and activation barriers for the reductions of nitrosonium and nitronium ions in aprotic solvents
Authors: Boughriet A. , Wartel M. 
Published: January 2005

AbstractUsing the cyclic voltammetry (CV), the electron‐transfer kinetics for the reductions of NO+ and NO2+ cations have been studied at the Pt electrode in nitromethane, sulfolane, and propylene carbonate. The heterogeneous rate constants have been determined by two independent procedures from the transfer coefficient α, the diffusion coefficient D, from a detailed examination of the CV‐peak separations, and from an inspection of the values of the cathodic peak potentials at different scan rates. The results have been compared to those reported in the literature, and discussed. In the classical model, outer‐sphere electron‐transfer reactions are considered subject to an activation energy arising from solvent reorganization and bond reorganization processes. The solvent and molecular reorganizational barriers for these electroreductions have been assessed in aprotic media. The Marcus‐Hush theory has been applied to the self‐exchange reactions of the NO2+/NO2 and NO+/NO couples in an attempt to predict the rate of electron transfer. The findings indicate some improvement between theory and experiment. However, it should be noted that the experimental values of ks found for the NO2+ reduction in the solvents used are still too high in comparison with those determined theoretically. In view of the fairly strong coordination of the solvent molecule(s) as ligand(s) to NO2+ and NO+ cations, we believe that such discrepancies should stem, to some extent, from the involvement of an inner‐sphere pathway by generation of an activated complex on the surface of the Pt electrode. © 1993 John Wiley & Sons, Inc.
CF3BrH2 reaction in shock waves
Authors: Hidaka Yoshiaki , Nakamura Takuji , Kawano Hiroyuki , Koike Tohru 
Published: January 2005

AbstractCF3BrH2 mixtures highly diluted with Ar were studied by using a time‐resolved IR‐emission of HBr and a gas‐chromatography for reaction products. The temperature range covered was 1000–1600 K and the total pressure behind the reflected shock waves used was 1.2–2.6 atm. CF3H, C2F6, and C2F4 were produced and the yields of these products were determined as a function of temperature. The main product under our experimental conditions was CF3H. The mechanism and the rate constants of CF3BrH2 reaction at high temperatures were discussed. The experimental data was satisfactorily modeled using a 14‐reaction mechanism. Reaction (5) played an important role in the formation of CF3H together with reaction (4).
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The rate constant expression k5 = 2.2 × 1013 exp(−12 kcal/RT) cm3 mol−1 s−1 gave the best agreement between the calculated and observed results. © 1993 John Wiley & Sons, Inc.
CO2 laser‐induced decomposition of propan‐2‐ol, butan‐2‐ol, pentan‐2‐ol, pentan‐3‐ol, and hexan‐2‐ol
Authors: Bishop M. , Holbrook K. A. , Oldershaw G. A. , Dyer P. E. 
Published: January 2005

AbstractThe pulsed CO2 laser‐induced decompositions of propan‐2‐ol, butan‐2‐ol, pentan‐2‐ol, pentan‐3‐ol, and hexan‐2‐ol in the gas phase have been investigated. Like ethanol which we examined previously [1] the absorption cross section of propan‐2‐ol for pulsed 9R14 radiation increases with pressure at low pressures, an effect attributed to rotational hole‐filling. In contrast the absorption cross section of butan‐2‐ol (10R24) has only a small pressure dependence and those of pentan‐2‐ol (9R26), pentan‐3‐ol (10R14), and hexan‐2‐ol (9P20) show little or no variation with pressure in the range 0.1–5.0 torr.Decomposition products have been investigated at low pressure where the excitation of the alkanols was essentially collision free. The observed products for all the alkanols can be rationalized on the basis of primary dehydration and CC fission channels, with minor contributions from other molecular eliminations. © 1994 John Wiley & Sons, Inc.
Photochemistry of formic acid monomer at 222 nm
Authors: Irwin Robert S. , Singleton Donald L. , Paraskevopoulos George , McLaren Robert 
Published: January 2005

AbstractThe yields of CO2 and CO formed from the gas‐phase photolysis at 222 nm of very low pressures of formic acid where the monomer predominates have been determined using FTIR spectroscopy. The observed ratio of CO2/CO approaches unity as the formic acid pressure approaches zero. Previous studies have shown that the quantum yield for HCOOH + hv → OH + HCO (or H + CO) is 0.70 at 298 K. The present experimental results indicate that the ratio of the quantum yields of the possible molecular photolysis channels forming H2 + CO2 (ϕ1b) and H2O + CO (ϕ1c) is ca. 1. Including this result in an analysis of previously reported quantum yields of CO and CO2 determined at higher pressures of formic acid, where both monomer and dimer contribute significantly to the products, indicates that ϕ1b = ϕ1c = 0. © 1994 John Wiley & Sons, Inc.
The CSP method for simplifying kinetics
Authors: Lam S. H. , Goussis D. A. 
Published: January 2005

AbstractThe Computational Singular Perturbation (CSP) method of simplified kinetics modeling is presented with emphasis on its comparative merits versus conventional methodologies. A new “refinement” procedure for the basis vectors spanning the fast reaction subspace is presented. A simple example is first worked through using the conventional partial‐equilibrium and quasi‐steady approximations, and is then treated in some detail using CSP. © 1994 John Wiley & Sons, Inc.
Kinetics of the reactions of Cl atoms with CH3Br and CH2Br2
Authors: Gierczak Tomasz , Goldfarb Leah , Sueper Donna , Ravishankara A. R. 
Published: January 2005

AbstractThe rate coefficients for the reactions of Cl atoms with CH3Br, (k1) and CH2Br2, (k2) were measured as functions of temperature by generating Cl atoms via 308 nm laser photolysis of Cl2 and measuring their temporal profiles via resonance fluorescence detection. The measured rate coefficients were: k1 = (1.55 ± 0.18) × 10−11 exp{(−1070 ± 50)/T} and k2 = (6.37 ± 0.55) × 10−12 exp{(−810 ± 50)/T} cm3 molecule−1 s−1. The possible interference of the reaction of CH2Br product with Cl2 in the measurement of k1 was assessed from the temporal profiles of Cl at high concentrations of Cl2 at 298 K. The rate coefficient at 298 K for the CH2Br + Cl2 reaction was derived to be (5.36 ± 0.56) × 10−13 cm3 molecule−1 s−1. Based on the values of k1 and k2, it is deduced that global atmospheric lifetimes for CH3Br and CH2Br2 are unlikely to be affected by loss via reaction with Cl atoms. In the marine boundary layer, the loss via reaction (1) may be significant if the Cl concentrations are high. If found to be true, the contribution from oceans to the overall CH3Br budget may be less than what is currently assumed. © 1994 John Wiley & Sons, Inc.
Investigation of the correlation between the energy of the highest occupied molecular orbital (HOMO) and the logarithm of the OH rate constant of hydrofluorocarbons and hydrofluoroethers
Authors: Bartolotti L. J. , Edney E. O. 
Published: January 2005

AbstractA regression based model was developed to determine whether highest occupied molecular orbital (HOMO) energies, calculated using Kohn‐Sham orbital density functional theory (DFT), could be used to estimate the OH rate constants of hydrofluorocarbons (HFCs) and hydrofluoroethers (HFEs), proposed substitutes for stratospheric O3 depleting chlorofluorocarbons. The goodness of fit of the DFT model was compared with a second regression model, derived using recently reported HOMO energies obtained from Hartree Fock theory (HFT). Both models were employed to predict OH rate constants for a number of HFCs and HFEs whose OH rate constants have not been measured, thus providing data on the types of chemical structures that may increase the OH reactivity of the substitute and hence decrease its contribution to global warming. The estimated percent standard errors in the OH rate constant HFT and DFT regression models were 72% and 78%, respectively. The goodness of fits were such that the models can differentiate between two rate constants only when their ratio exceeds about a factor of four. Model results suggest that (1) only a limited number of HFEs will have OH rate constants that are more than an order of magnitude greater than the value for their corresponding HFCs and (2) the strategy of introducing an ether linkage into an HFC to dramatically enhance its reactivity will be most effective for the least fluorinated HFCs. © 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.
Kinetics of the reactions of OH with alkanes
Authors: Talukdar R. K. , Mellouki A. , Gierczak T. , Barone S. , Chiang S‐Y. , Ravishankara A. R. 
Published: January 2005

AbstractThe rate coefficients for the reactions of OH with ethane (k1), propane (k2), n‐butane (k3), iso‐butane (k4), and n‐pentane (k5) have been measured over the temperature range 212–380 K using the pulsed photolysis‐laser induced fluorescence (PP‐LIF) technique. The 298 K values are (2.43±0.20) × 10−13, (1.11 ± 0.08) × 10−12, (2.46 ± 0.15) × 10−12, (2.06 ± 0.14) × 10−12, and (4.10 ± 0.26) × 10−12 cm3 molecule−1 s−1 for k1, k2, k3, k4, and k5, respectively. The temperature dependence of k1 and k2 can be expressed in the Arrhenius form: k1 = (1.03 ± 0.07) × 10−11 exp[−(1110 ± 40)/T] and k2 = (1.01 ± 0.08) × 10−11 exp[−(660 ± 50)/T]. The Arrhenius plots for k3 – k5 were clearly curved and they were fit to three parameter expressions: k3 = (2.04 ± 0.05) × 10−17 T2 exp[(85 ± 10)/T] k4 = (9.32 ± 0.26) × 10−18 T2 exp[(275 ± 20)/T]; and k5 = (3.13 ± 0.25) × 10−17 T2 exp[(115 ± 30)/T]. The units of all rate constants are cm3 molecule−1 s−1 and the quoted uncertainties are at the 95% confidence level and include estimated systematic errors. The present measurements are in excellent agreement with previous studies and the best values for atmospheric calculations are recommended. © 1994 John Wiley & Sons, Inc.
The temperature dependence of the OH radical reactions with some aromatic compounds under simulated tropospheric conditions
Authors: Semadeni Marco , Stocker David W. , Kerr J. Alistair 
Published: January 2005

AbstractThe temperature dependence of the rate coefficients for the OH radical reactions with toluene, benzene, o‐cresol, m‐cresol, p‐cresol, phenol, and benzaldehyde were measured by the competitive technique under simulated atmospheric conditions over the temperature range 258–373 K. The relative rate coefficients obtained were placed on an absolute basis using evaluated rate coefficients for the corresponding reference compounds. Based on the rate coefficient k(OH + 2,3‐dimethylbutane) = 6.2 × 10−12 cm3 molecule−1s−1, independent of temperature, the rate coefficient for toluene kOH = 0.79 × 10−12 exp[(614 ± 114)/T] cm3 molecule−1 s−1 over the temperature range 284–363 K was determined. The following rate coefficients in units of cm3 molecule−1 s−1 were determined relative to the rate coefficient k(OH + 1,3‐butadiene) = 1.48 × 10−11 exp(448/T) cm3 molecule−1 s−1: o‐cresol; kOH = 9.8 × 10−13 exp[(1166 ± 248)/T]; 301–373 K; p‐cresol; kOH = 2.21 × 10−12 exp[(943 ± 449)/T]; 301–373 K; and phenol, kOH = 3.7 × 10−13 exp[(1267 ± 233)/T]; 301–373 K. The rate coefficient for benzaldehyde kOH = 5.32 × 10−12 exp[(243 ± 85)/T], 294–343 K was determined relative to the rate coefficient k(OH + diethyl ether) = 7.3 × 10−12 exp(158/T) cm3 molecule−1 s−1. The data have been compared to the available literature data and where possible evaluated rate coefficients have been deduced or updated. Using the evaluated rate coefficient k(OH + toluene) = 1.59 × 10−12 exp[(396 ± 105)/T] cm3 molecule−1 s−1, 213–363 K, the following rate coefficient for benzene has been determined kOH = 2.58 × 10−12 exp[(−231 ± 84)/T] cm3 molecule−1 s−1 over the temperature range 274–363 K and the rate coefficent for m‐cresol, kOH = 5.17 × 10−12 exp[(686 ± 231)/T] cm3 molecule−1 s−1, 299–373 K was determined relative to the evaluated rate coefficient k(OH + o‐cresol) = 2.1 × 10−12 exp[(881 ± 356)/T] cm3 molecule−1 s−1. The tropospheric lifetimes of the aromatic compounds studied were calculated relative to that for 1,1,1‐triclorethane = 6.3 years at 277 K. The lifetimes range from 6 h for m‐cresol to 15.5 days for benzene. © 1995 John Wiley & Sons, Inc.
Thermal isomerization and decomposition of 1,2‐butadiene in shock waves
Authors: Hidaka Yoshiaki , Higashihara Tetsuo , Ninomiya Natsuhiko , Oki Takashi , Kawano Hiroyuki 
Published: January 2005

Abstract1,2‐Butadiene diluted with Ar was heated behind reflected shock waves over the temperature and the total density range of 1100–1600 K and 1.36 × 10−5 − 1.75 × 10−5 mol/cm3. The major products were 1,3‐butadiene, 1‐butyne, 2‐butyne, vinylacetylene, diacetylene, allene, propyne, C2H6, C2H4, CH4, and benzene, which were analyzed by gas chromatography. The UV kinetic absorption spectroscopy at 230 nm showed that 1,2‐butadiene rapidly isomerizes to 1,3‐butadiene from the initial stage of the reaction above 1200 K. In order to interpret the formation of 1,3‐butadiene, 1‐butyne, and 2‐butyne, it was necessary to include the parallel isomerizations of 1,2‐butadiene to these isomers. The present data were successfuly modeled with a 82 reaction mechanism. From the modeling, rate constant expressions were derived for the isomerization 1,2‐butadiene = 1,3‐butadiene to be k3 = 2.5 × 1013 exp(−63 kcal/RT) s−1 and for the decomposition 1,2‐butadiene = C3H3 + CH3 to be k6 = 2.0 × 1015 exp(−75 kcal/RT) s−1, where the activation energies, 63 kcal/mol and 75 kcal/mol, were assumed. These rate constants are only applicable under the present experimental conditions, 1100–1600 K and 1.23–2.30 atm. © 1995 John Wiley & Sons, Inc.
Oxidation of L‐aspartic acid and L‐glutamic acid by manganese(III) ions in aqueous sulphuric acid, acetic acid, and pyrophosphate media: A kinetic study
Authors: Sherigara B. S. , Bhat K. Ishwar , Pinto Ivan , Gowda N. M. Made 
Published: January 2005

AbstractKinetics of oxidation of L‐aspartic acid and L‐glutamic acid by manganese(III) ions have been studied in aqueous sulphuric acid, acetic acid, and pyrophosphate media. Manganese(III) solutions were prepared by known electrolytic/chemical methods in the three media. The nature of the oxidizing species present in manganese(III) solutions was determined by spectrophotometric and redox potential measurements. The reaction shows a variable order in [manganese(III)]o: the order changes from two to one as the reactive oxidizing species changes from an aquo ionic form to a complex form. There is a first‐order dependence of the rate on [amino acid]o in all the three media while the other common features include an inverse dependence each on [H+] and on [manganese(II)]. Effects of varying ionic strength and solvent composition were studied. Added anions such as pyrophosphate, fluoride, or chloride alter the reaction rate and mechanism by changing the formal redox potential of Mn(III)‐Mn(II) couple. Activation parameters have been evaluated using the Arrhenius and Eyring plots. Mechanisms consistent with the kinetic data have been proposed and discussed. © 1995 John Wiley & Sons, Inc.