bluuebunny/crossref_metadata_2025_split huggingface dataset:
Does the HO2 radical react with H2S, CH3SH, and CH3SCH3?
Authors: Mellouki A. , Ravishankara A. R. 
Published: January 2005

AbstractThe kinetics of the title reactions were investigated in a discharge flow tube by using laser magnetic resonance detection of HO2. The upper limits for the bimolecular rate constants for the reactions of HO2 with H2S (k1), CH3SH (k2), and CH3SCH3 (k3) are <3 × 10−15, <4 × 10−15, and <5 × 10−15 cm3 molecule−1 s−1, respectively, at 298 K. Our upper limit for k1 is three orders of magnitude lower than the previously reported value.Measurements at higher temperatures also yield similar upper limits. Our results suggest that HO2 is not an important oxidant for these reduced compounds in the atmosphere. © 1994 John Wiley & Sons, Inc.
An analytic hindered rotor model for calculating microcanonical variational unimolecular rate constants from reaction path properties
Authors: Hase William L. , Zhu Ling 
Published: January 2005

AbstractA model is proposed for performing microcanonical variational transition state theory calculations which incorporates ideas from vibrator and flexible variational transition state models. Vibrational frequencies, moments of inertia, and potential energy for the variational transition state are found by reaction path following as for the vibrator model. However, the transitional modes are treated as hindered rotors using an analytic potential and an analytic density of states, which are fit to barriers for hindered rotation determined from reaction path following. The model proposed here differs from the flexible transition state model in that the density of states for the transitional modes is analytic and transitional modes and external rotational angular momenta are uncoupled. For the H + CH3 ⇌ CH4 system, rate constants calculated with this new model are only 6–23% smaller on average from those of the flexible transition state model for values of total angular momentum which correspond to average rotational temperatures of 0–2000 K. Harmonic frequencies calculated for the transitional modes from the hindered rotor Hamiltonian are in good agreement with the exact values found by a reaction path analysis. © 1994 John Wiley & Sons, Inc.
Modeling the thermal DENOx process in flow reactors. Surface effects and Nitrous Oxide formation
Authors: Glarborg Peter , Dam‐Johansen Kim , Miller James A. , Kee Robert J. , Coltrin Michael E. 
Published: January 2005

AbstractWe have investigated the impact of surface reactions such as NH3 decomposition and radical adsorption on quartz flow reactor data for Thermal DeNOx using a model that accounts for surface chemistry as well as molecular transport. Our calculations support experimental observations that surface effects are not important for experiments carried out in low surface to volume quartz reactors. The reaction mechanism for Thermal DeNOx has been revised in order to reflect recent experimental results. Among the important changes are a smaller chain branching ratio for the NH2 + NO reaction and a shorter NNH lifetime than previously used in modeling. The revised mechanism has been tested against a range of experimental flow reactor data for Thermal DeNOx with reasonable results. The formation of N2O in Thermal DeNOx has been modelled and calculations show good agreement with experimental data. The important reactions in formation and destruction of N2O have been identified. Our calculations indicate that N2O is formed primarily from the reaction between NH and NO, even though the NH2 + NO2 reaction possibly contributes at lower temperatures. At higher temperatures N2O concentrations are limited by thermal dissociation of N2O and by reaction with radicals, primarily OH. © 1994 John Wiley & Sons, Inc.
Kinetic study of the oxidation of ethanol by 3,4‐lutidine chromium(VI) peroxide in dichloromethane solution
Authors: Mousavi Mir Fazlollah , Firouzabadi Habib , Shamsipur Mojtaba 
Published: January 2005

AbstractThe oxidation kinetics of ethanol with 3,4‐lutindine chromium(VI) peroxide (LCP) were investigated by monitoring the absorbance change at 565 nm in dichloromethane solution. The reaction had a first‐order dependence on oxidant and a fractional (one half) dependence on reactant. The stoichiometric ratio between LCP and ethanol was 1 : 2. The activation parameters were determined from temperature dependence of the reaction rate. It was found that the cleavage of the peroxide groups of LCP is primarily responsible for the oxidant of ethanol to acetaldehyde. Based on the kinetic results obtained (including deuterium isotope effect) a plausible mechanism is proposed. © 1994 John Wiley & Sons, Inc.
Yield of 16OS18O from the 18OH initiated oxidation of CS2 in 16O2
Authors: Lovejoy Edward R. , Ravishankara A. R. , Howard Carleton J. 
Published: January 2005

AbstractThe yield of 16OS18O from the 18OH initiated oxidation of CS2 in 16O2 was measured by using a discharge flow reactor coupled to a chemical ionization mass spectrometer. 16OS18O is the dominant SO2 isotopomer produced with a yield of 0.90 ± 0.20 relative to 18OH loss. The errors are estimates for the uncertainty at the 95% confidence level. The implications of these results to the understanding of the CS2 oxidation mechanism are discussed. © 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.
Electron transfer. 121. Oxidations by Rhodium‐Bound Superoxide
Authors: Ghosh Sanchita P. , Ghosh Manik C. , Gould E. S. 
Published: January 2005

AbstractThe violet superoxo complex, [(H2O)4(OH)RhIII(O2)RhIII(OH)(H2O)4]3+, formed by treatment of (RhII)24+ with O2 in HClO4, is converted to a le− reduction product, the corresponding μ‐peroxo complex, by the reductants I−, IrCl63−, and the trinuclear aquamolybdenum(III) cation, (MoIII)3. Each reaction is first‐order in both redox partners, and the le− reduction by IrCl63− is followed by a much slower conversion to a peroxide‐free complex. Among the rapid reductions of the superoxo derivative examined here and in a previous study, only that by IrCl63− is accelerated by increases in acidity; the rate law for this reaction features both an acid‐independent and a [H+]‐proportional component, the latter stemming from partial conversion of the oxidant to its conjugate acid (pKA < −1.0). Rate laws for reductions by other metal‐center reagents generally exhibit inverse‐[H+] terms, reflecting deprotonation of the reductant. All reductions thus far observed involving this superoxo species appear to be outer‐sphere. Treatment of acid‐independent rate constants within the framework of the Marcus model, allows estimates of the self‐exchange rate, k11, for the (RhIII)2‐bound superoxo‐peroxo couple. Because values of k11 calculated from the several reductions span a range of 104.5, reductions of the superoxo complex cannot be taken to conform satisfactorily to the Marcus treatment, being in this respect comparable to the systems VO(OH)+/2+, Mn2+/3+, Eu2+/3+, and Ti(OH)2+/3+, each of which exhibits similar divergences. The wide range of calculated self‐exchange rates appears to invalidate an earlier suggestion that reduction of the superoxo complex by Fe2+ proceeds primarily through a bridged path. © 1994 John Wiley & Sons, Inc.
Thermal Decomposition of CF3C(O)O2NO2, CClF2C(O)O2NO2, CCl2FC(O)O2NO2, and CCl3C(O)O2NO2
Authors: Zabel F. , Kirchner F. , Becker K. H. 
Published: January 2005

AbstractHaloacetyl, peroxynitrates are intermediates in the atmospheric degradation of a number of haloethanes. In this work, thermal decomposition rate constants of CF3C(O)O2NO2, CClF2C(O)O2NO2, CCl2FC(O)O2NO2, and CCl3C(O)O2NO2 have been determined in a temperature controlled 420 l reaction chamber. Peroxynitrates (RO2NO2) were prepared in situ by photolysis of RH/Cl2/O2/NO2/N2 mixtures (R = CF3CO, CClF2CO, CCl2FCO, and CCl3CO). Thermal decomposition was initiated by addition of NO, and relative RO2NO2 concentrations were measured as a function of time by long‐path IR absorption using an FTIR spectrometer. First‐order decomposition rate constants were determined at atmospheric pressure (M = N2) as a function of temperature and, in the case of CF3C(O)O2NO2 and CCl3C(O)O2NO2, also as a function of total pressure. Extrapolation of the measured rate constants to the temperatures and pressures of the upper troposphere yields thermal lifetimes of several thousands of years for all of these peroxynitrates. Thus, the chloro(fluoro)acetyl peroxynitrates may play a role as temporary reservoirs of Cl, their lifetimes in the upper troposphere being limited by their (unknown) photolysis rates. Results on the thermal decomposition of CClF2CH2O2NO2 and CCl2FCH2O2NO2 are also reported, showing that the atmospheric lifetimes of these peroxynitrates are very short in the lower troposphere and increase to a maximum of several days close to the tropopause. The ratio of the rate constants for the reactions of CF3C(O)O2 radicals with NO2 and NO was determined to be 0.64 ± 0.13 (2σ) at 315 K and a total pressure of 1000 mbar (M = N2). © 1994 John Wiley & Sons, Inc.
Kinetics and mechanism of the reaction of CH3O with NO
Authors: Dóbé S. , Lendvay G. , Szilágyi I. , Bérces T. 
Published: January 2005

AbstractThe kinetics of the reaction of CH3O with NO and the branching ratio for HCHO product formation, obtained as ΓHCHO = (Rate of HCHO formation) / (Rate of CH3O decay), have been studied using a discharge flow reactor. Laser induced fluorescence has been used to monitor the decay of the CH3O radical and the build‐up of the HCHO product. Overall rate constants and product branching ratios were measured at room temperature over the pressure range of 0.72–8.5 torr He. Three reaction mechanisms were considered which differed in the routes of HCHO formation: (i) direct disproportionation; (ii) via an energized collision complex; or (iii) both reaction routes. It has been shown that data on the pressure dependence of the overall rate constant are not sufficient to distinguish between these mechanisms. In addition, an accurate value of Γ is required. Analysis of the available experimental data provided 0.0 and about 0.1 as the lower and upper limit for Γ, respectively. Since the rate constants derived for CH3ONO formation were not sensitive to the value assumed for Γ, k = (1.69 ± 0.69) × 10−29 cm6 molecule−2 s−1 and k = (2.45 ± 0.31) × 10−11 cm3 molecule−1 s−1 could be derived. The rate constant obtained for formaldehyde formation when extrapolated to zero pressure is k = (3.15 ± 0.92) × 10−12 cm3 molecule−1 s−1. © 1994 John Wiley & Sons, Inc.
Micellar effects upon the reaction of hydroxide ion with 2‐phenoxyquinoxaline
Authors: Cuenca Angela , Bruno Cesidio 
Published: January 2005

AbstractCationic micelles of alkyltrimethylammonium chloride and bromide (alkyl = nC12H25, nC14H29, and nC16H33) catalyze and anionic micelles of sodium dodecyl sulfate inhibit the reaction of hydroxide ion with 2‐phenoxyquinoxaline (1). Inert anions such as chloride, nitrate, mesylate, and n‐butanosulfonate inhibit the reaction in CTABr by competing with OH− at the micellar surface. The overall micellar effects on rate in cationic micelles and dilute electrolyte can be treated quantitatively in terms of the pseudo‐phase ion‐exchange model. The determined second‐order rate constants in the micellar pseudo‐phase are smaller than the second‐order constants in water. © 1994 John Wiley & Sons, Inc.
Bistability in the nitric acid‐hydroxylamine CSTR system
Authors: Horváth Attila , Póta György , Stedman Geoffrey 
Published: January 2005

AbstractExperimental and theoretical investigations of bistability occurring in the nitric acid–hydroxylamine CSTR system are presented. Features of the stationary concentration vs. inlet concentration diagram and some mechanistic implications are discussed. © 1994 John Wiley & Sons, Inc.
UV absorption spectrum of CF3CFClO2 and kinetics of the self reaction of CF3CFCl and CF3CFClO2 and the reactions of CF3CFClO2 with NO and NO2
Authors: Sehested Jens 
Published: January 2005

AbstractThe ultraviolet absorption spectrum of CF3CFClO2 and the kinetics of the self reactions of CF3CFCl and CF3CFClO2 radicals and the reactions of CF3CFClO2 with NO and NO2 have been studied in the gas phase at 295 K by pulse radiolysis/transient UV absorption spectroscopy. The UV absorption cross section of CF3CFCl radicals was measured to be (1.78 ± 0.22) × 10−18 cm2 molecule−1 at 220 nm. The UV spectrum of CF3CFClO2 radicals was quantified from 220 nm to 290 nm. The absorption cross section at 250 nm was determined to be (1.67 ± 0.21) × 10−18 cm2 molecule−1. The rate constants for the self reactions of CF3CFCl and CF3CFClO2 radicals were (2.6 ± 0.4) × 10−12 cm3 molecule−1 s−1 and (2.6 ± 0.5) × 10−12 cm3 molecule−1 s−1, respectively. The reactivity of CF3CFClO2 radicals towards NO and NO2 was determined to (1.5 ± 0.6) × 10−11 cm3 molecule−1 s−1 and (5.9 ± 0.5) × 10−12 cm3 molecule−1 s−1, respectively. Finally, the rate constant for the reaction of F atoms with CF3CFClH was determined to (8 ± 2) × 10−13 cm3 molecule−1 s−1. Results are discussed in the context of the atmospheric chemistry of HCFC‐124, CF3CFClH. © 1994 John Wiley & Sons, Inc.
The study of decomposition reactions through the exchange of thermal energy
Authors: Constantinou C. P. 
Published: January 2005

AbstractIn many decomposition reactions, the reaction velocity can be described as a product of two functions: a temperature dependent partK(T) and the kinetic functionf(1 – α), whereTdesignates the temperature and α the fraction of reactant that has decomposed. The physical interpretation of these functions is discussed for both solid and homogeneous systems. A method is described by whichf(1 – α) andK(T) can be determined from kinetic data. The mechanism of decomposition can subsequently be identified which should be consistent with the derived kinetic parameters. The method has been applied to analyze the kinetics of the thermal decomposition of nitromethane. © 1994 John Wiley & Sons, Inc.
Kinetic and mechanistic aspects of the NO oxidation by O2 in aqueous phase
Authors: Pires Marçlal , Rossi Michel J. , Ross David S. 
Published: January 2005

AbstractThe oxidation kinetics of NO by O2 in aqueous solution was observed using a stopped flow apparatus. The kinetics follows a third order rate law of the form k · [NO]2 · [O2] in analogy to gas‐phase results. The rate constant at 296 K was measured as (6.4 ± 0.8) · 106 M−2 s−1 with an activation energy of 2.3 kcal/mol and a preexponential factor of (4.0 ± 0.5) · 108 M−2 s−1. The rate constant displays a very slight pH dependence corresponding to less than a factor of three over the range 0 to 12. The system NO/O2 in aqueous solution is an efficient nitrosating agent which has been tested using phenol as a substrate over the pH range 0 to 12. The rate limiting step leading to formation of 4‐nitrosophenol is the formation of the reactive intermediate whose competitive hydrolysis yields HONO or NO2−. The absence of NO3− in the autoxidation of NO, the exclusive presence of NO2− as a product of the nitrosation reaction of phenol, and the kinetic results of the N3− trapping experiments point towards N2O3 as the reactive intermediate. © 1994 John Wiley & Sons, Inc.
The nature of the transition state in amides pyrolysis. The rates of pyrolysis of N‐benzoyl and N‐acetylpropanamide, N‐benzoyl and N‐acetyl‐2‐methylpropanamide, and N‐thioacetylpropanamide
Authors: Al‐Awadi Nouria A. , Al‐Omran Fatima A. , Mathew Tommy 
Published: January 2005

AbstractThe rates of gas‐phase elimination reactions of N‐benzoyl and N‐acetyl‐propanamide and N‐benzoyl and N‐acetyl‐2‐methylpropanamide are measured and discussed. They undergo unimolecular first‐order elimination reactions. The reactivities of N‐benzoylamides have been compared with each other and with those of N‐acetylamides. The kinetic data together with the product analysis reveals that, the statistical factor of the availability of β‐hydrogen atoms for elimination as well as steric factor are obscured by polar factor in gas‐phase elimination reactions of N‐benzoylamides while the statistical factor rather than electronic effect operates in each of N‐acetylamides. © 1995 John Wiley & Sons, Inc.
Consecutive reactions of diethoxydimethylsilane and triethoxymethylsilane with methoxide ions in methanol solution
Authors: Jäglid Ulf , Lindqvist Oliver 
Published: January 2005

AbstractThe consecutive reactions of (CH3)2Si(OC2H5)2 and CH3Si(OC2H5)3 with methoxide ions were investigated in methanol solutions. The reverse transesterification reactions with ethoxide ions could be neglected in both cases since the concentration of ethoxide in methanol solution was assumed to be low due to the fast equilibrium reaction C2H5O− + CH3OH ⇌ C2H5OH + CH3O−. The progress of the reactions was followed by monitoring the formation of ethanol with a Fourier‐transform infrared spectrometer. All rate constants were determined at 295 K. The reactions between the dialkoxydimethylsilanes and methoxide ions were assumed to consist of two consecutive steps that can be represented by the net reaction; (CH3)2Si(OC2H5)2 + 2CH3O− → (CH3)2Si(OCH3)2 + 2C2H5O−. The two consecutive rate constants were established as 1.93 ± 0.12M−1s−1 and 1.00 ± 0.12M−1s−1, respectively. The consecutive rate constants for the reactions between the trialkoxymethylsilanes and methoxide ions can be written according to the total reaction; CH3Si(OC2H5)3 + 3CH3O− → CH3Si(OCH3)3 + 3C2H5O−. The three rate constants corresponding to each consecutive step were established as 1.12 ± 0.09 M−1s−1, 0.82 ± 0.10 M−1s−1, and 0.51 ± 0.06 M−1s−1, respectively. © 1995 John Wiley & Sons, Inc.
Atmospheric chemistry of CF3COOH: Kinetics of fluorine and chlorine atom reaction at 295 ± 2 K
Authors: Wallington T. J. , Hurley M. D. 
Published: January 2005

AbstractUsing a relative rate technique the reactions of fluorine and chlorine atoms with CF3COOH have been determined to proceed with rate constants of (5.6 ± 0.7) × 10−11 and <1 × 10−17 cm3 molecule−1 s−1, respectively. Quoted errors for the F atom rate constant reflect statistical uncertainty (two standard deviations). Systematic errors could add an additional 20% uncertainty. Experiments were performed at 295 ± 2 K and 700 torr total pressure of nitrogen diluent. The reactions of Cl and F atoms with CF3COOH are of no atmospheric importance. Rainout is believed to be the dominant mechanism by which CF3COOH is removed from the atmosphere. The results from this study are discussed with respect to the design and interpretation of laboratory studies of the atmospheric chemistry of CFC replacements. © 1995 John Wiley & Sons, Inc.
On the action of organic solvent in the new B‐Z oscillator in aqueous‐organic mixed media
Authors: He Zhanbo 
Published: January 2005

AbstractThe author pointed out that hydrolysis of acetonitrile, trace impurity of someorganic solvents, and insolubility of benzene can make great effects on B‐Z or B‐R oscillators in aqueous‐organic mixed media. And surfactant is better than organic solvent in the design of chemical oscillators with insoluble substance as substrate. © 1995 John Wiley & Sons, Inc.
Temperature dependence of the rate constants of the reactions of oxygen atoms with trans‐2‐butene, cis‐2‐butene, 2‐methylpropene, 2‐methyl‐2‐butene, and 2,3‐dimethyl‐2‐butene
Authors: Biehl H. , Bittner J. , Bohn B. , Geers‐Müller R. , Stuhl F. 
Published: January 2005

AbstractThe kinetics of the reactions of ground state oxygen atoms with trans‐2‐butene, cis‐2‐butene, 2‐methylpropene, 2‐methyl‐2‐butene, and 2,3‐dimethyl‐2‐butene was investigated in the temperature range 200 to 370K. In this range, the rate constants are (in units 10−11 cm3 s−1): (1.1 ± 0.1) exp[+(180 ± 24)K/T]; (0.98 ± 0.09) exp[+(149 ± 23)K/T]; (1.14 ± 0.13) exp[+(128 ± 33)K/T]; (2.34 ± 0.16) exp[+(250 ± 16)K/T]; and (3.31 ± 0.50) exp[+(257 ± 36)K/T], respectively. The atoms were generated by the H2 laser photolysis of NO and detected by the time resolved chemiluminescence in the presence of NO. The concentrations of the O(3P) atoms were kept so low that secondary reactions with products are unimportant. © 1995 John Wiley & Sons, Inc.
Absolute reaction rate of chlorine atoms with neopentane
Authors: Kambanis Kyriakos G. , Lazarou Yannis G. , Papagiannakopoulos Panos 
Published: January 2005

AbstractThe reaction of atomic chlorine with neopentane was studied in the gas phase with the Very Low Pressure Reactor (VLPR) technique over the temperature range 273–333 K. The absolute reaction rate was found to be temperature‐independent, and the average rate constant was k1 = (1.11± 0.13) × 10−10 cm3 molecule−1 s−1 within experimental error. The reaction proceeds via metathesis of a hydrogen atom with no activation energy, and leads to the formation of HCl and neopentyl radical. © 1995 John Wiley & Sons, Inc.
Kinetics, catalysis, and mechanism of isomerization of N‐[(benzotriazol‐1‐yl)methyl]anilines into the benzotriazol‐2‐yl derivatives
Authors: Katritzky Alan R. , Rachwal Stanislaw , Rachwal Bogumila , Frankenfeld John W. 
Published: January 2005

AbstractThe 1H NMR technique was applied for the measurement of the isomerization rates of N‐ethyl‐N‐[(benzotriazol‐1‐yl)methyl]aniline (4) and 4‐butyl‐N‐[(benzotriazol‐1‐yl)methyl]aniline (7) to the corresponding benzotriazol‐2‐yl isomers in dioxane‐d8 at 35°C. The rate constants obtained for pure dioxane‐d8 were 1.62 and 0.28 h−1 for 4 and 7, respectively. For both compounds, addition to acetic acid to the dioxane solutions accelerated the isomerizations whereas addition of triethylamine retarded it strongly. Addition of water slowed the isomerization of 4 but accelerated that of 7: the different effects operating in the two cases are discussed and rationalized. © 1995 John Wiley & Sons, Inc.
Rate constants for some reactions of free radicals with haloacetates in aqueous solution
Authors: Maruthamuthu Pichai , Padmaja S. , Huie Robert E. 
Published: January 2005

AbstractThe kinetics of the acqueous‐phase reactions of the free radicals ·OH, ·Cl, and SO· with the halogenated acetates, CH2FCOO−, CHF2COO−, CF3COO−, and with CH2ClCOO−, CHCl2COO−, CCl3COO− were investigated. Generally, the reactivity decreases with increasing halogen substitution and is in the order k(·OH) > k(SO·) > k(·Cl), but there is no general relation between the effect on reactivity of chlorine and fluorine substitution. © 1995 John Wiley & Sons, Inc.
Comparison of singlet methylene removal rates by group IV hydrides
Authors: Gutsche Greg J. , Lawrance Warren D. , Staker Warren S. , King Keith D. 
Published: January 2005

AbstractThe technique of laser flash photolysis/laser absorption has been used to obtain an absolute removal rate constant of (3.85 ± 0.18) × 10−10 cm3 molecule−1 s−1 for singlet methylene, 1CH2 (ã1A1), with germane (GeH4) at ambient temperature. The removal rate constant is compared with the values for methane (CH4) and silane (SiH4) which have been determined previously. © 1995 John Wiley & Sons, Inc.