bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of ring size on the gas phase elimination kinetics of cycloalkyl acetates
Authors: Chuchani Gabriel , Martin Ignacio , Rotinov Alexandra , Dominguez Rosa M. , Morris David G. , Shepherd Alistair G. 
Published: January 2005

AbstractThe rates of elimination of seven cycloalkyl acetates containing between 5 and 15 ring carbons have been determined in a static system over a temperature range 280–370°C and a pressure range 35–234 torr. The unimolecular reactions, carried out in the presence of the inhibitor cyclohexene, are homogeneous in seasoned vessels and follow a first‐order rate law. The rate coefficients are exemplified by that found for cyclopentyl acetate:

The sequence of relative rates is analogous to that found in most solution reactions of these compounds. The contribution of ring strain to energy barriers of these compounds is described.
Further experiments on pyrolysis of 2,2‐dimethylpropane behind shock waves
Authors: Rao V. Subba , Skinner Gordon B. 
Published: January 2005

AbstractPyrolysis of a dilute mixture of neopentane (2,2‐dimethylpropane) has been studied behind incident shock waves at an average pressure of 0.35 atm; the reaction was followed by absorption spectroscopy for H atoms. In the temperature range 1230–1455 K, the rate constant for dissociation of neopentane to t‐butyl and methyl radicals is 1.1 E 13 exp(−62 kcal/RT) s−1. These data and some of the literature results, between 1000 and 1450 K, can be fitted by an RRKM model of the hindered Gorin type, with five active internal rotors in the complex. To match our data with other literature data down to 800 K, a vibrational model was more satisfactory, but this did not fit very low pressure pyrolysis data in the 1000–1100 K range. Apparently, the VLPP data are too high because of heterogeneous processes or chain reactions.
Kinetics and mechanisms of the reaction of OH radicals with dimethyl sulfide
Authors: Barnes I. , Bastian V. , Becker K. H. 
Published: January 2005

AbstractThe rate constant of the reaction of OH with DMS has been measured relative to OH + ethene in a 420 l reaction chamber at 760 torr total pressure and 298 ± 3 K in N2 + O2 buffer gas using the 254 nm photolysis of H2O2 as the OH source. In agreement with a recent absolute rate determination of the reaction the measured effective rate constant was found to increase with increasing partial pressure of O2 in the system, for 760 torr air a rate constant of (8.0 ± 0.5) × 10−12 cm3 s−1 was obtained.Product studies have been performed on the reaction in air using FTIR absorption spectrometry for detection of reactants and products. On a molar basis, SO2 was formed with a yield of 70% and dimethyl sulfone (CH3SO2CH3) with a yield of approximately 20%. These results are considerably different to those obtained in other product studies which were carried out in the presence of NOx. These differences are compared and their relevance for the atmospheric oxidation mechanisms of DMS is discussed.
Ru(III) catalysis in N‐bromoacetamide oxidation of ethylene glycol and glycerol: A kinetic and mechanistic study
Authors: Singh Bharat , Singh Deepika , Singh A. K. 
Published: January 2005

AbstractKinetics of oxidation of ethylene glycol and glycerol by acidic solution of N‐bromoacetamide (NBA) in the presence of ruthenium (III) chloride as a homogeneous catalyst and mercuric acetate as scavenger in the temperature range of 30–50°C have been reported. The reactions follow identical kinetics, being zero‐order in substrate and first‐order in Ru(III). First order dependence of the reaction on NBA at its low concentrations tends to zero order in the higher concentration range. Positive effect of [H−] and [Cl−] has been observed. A negative effect of acetamide and ionic strength of the medium is observed while D2O and mercuric acetate show zero effect on the reaction velocity. Various activation parameters have been computed. The main product of the oxidation is corresponding acid. (H2OBr)+ has been postulated as the oxidizing species. A suitable mechanism in conformity with the kinetic data has been proposed.
Kinetics of the reactions of acenaphthene and acenaphthylene and structurally‐related aromatic compounds with OH and NO3 radicals, N2O5 and O3 at 296 ± 2 K
Authors: Atkinson Roger , Aschmann Sara M. 
Published: January 2005

AbstractThe kinetics of the atmospherically important gas‐phase reactions of acenaphthene and acenaphthylene with OH and NO3 radicals, O3 and N2O5 have been investigated at 296 ± 2 K. In addition, rate constants have been determined for the reactions of OH and NO3 radicals with tetralin and styrene, and for the reactions of NO3 radicals and/or N2O5 with naphthalene, 1‐ and 2‐methylnaphthalene, 2,3‐dimethylnaphthalene, toluene, toluene‐α,α,α‐d3 and toluene‐d8. The rate constants obtained (in cm3 molecule−1 s−1 units) at 296 ± 2 K were: for the reactions of O3; acenaphthene, <5 × 10−19 and acenaphthylene, ca. 5.5 × 10−16; for the OH radical reactions (determined using a relative rate method); acenaphthene, (1.03 ± 0.13) × 10−10; acenaphthylene, (1.10 ± 0.11) × 10−10; tetralin, (3.43 ± 0.06) × 10−11 and styrene, (5.87 ± 0.15) × 10−11; for the reactions of NO3 (also determined using a relative rate method); acenaphthene, (4.6 ± 2.6) × 10−13; acenaphthylene, (5.4 ± 0.8) × 10−12; tetralin, (8.6 ± 1.3) × 10−15; styrene, (1.51 ± 0.20) × 10−13; toluene, (7.8 ± 1.5) × 10−17; toluene‐α,α,α‐d3, (3.8 ± 0.9) × 10−17 and toluene‐d8, (3.4 ± 1.9) × 10−17. The aromatic compounds which were observed to react with N2O5 and the rate constants derived were (in cm3 molecule−1 s−1 units): acenaphthene, 5.5 × 10−17; naphthalene, 1.1 × 10−17; 1‐methylnaphthalene, 2.3 × 10−17; 2‐methylnaphthalene, 3.6 × 10−17 and 2,3‐dimethylnaphthalene, 5.3 × 10−17. These data for naphthylene and the alkylnaphthalenes are in good agreement with our previous absolute and relative N2O5 reaction rate constants, and show that the NO3 radical reactions with aromatic compounds proceed by overall H‐atom abstraction from substituent‐XH bonds (where X = C or O), or by NO3 radical addition to unsaturated substituent groups while the N2O5 reactions only occur for aromatic compounds containing two or more fused six‐membered aromatic rings.
Kinetics and mechanism of autocatalytic oxidation of formaldehyde by nitric acid
Authors: Horváth Monika , Lengyel István , Bazsa György 
Published: January 2005

AbstractThe kinetics of the reaction between nitric acid and formaldehyde have been studied by spectrophotometry. The reaction is autocatalytic. A two‐step mechanism is proposed, which accounts for this behavior and describes the effect of reactant concentrations on the characteristics of the kinetic curves: the length of the induction period, ti, the maximum rate, rmax of nitrous acid production and the final product concentration, cf.
Decomposition of methylamino and aminomethyl radicals. The heats of formation of methyleneimine (CH2NH) and hydrazyl (N2H3) radical
Authors: Grela M. A. , Colussi A. J. 
Published: January 2005

AbstractA kinetic analysis of the thermal decomposition of methylamino and aminomethyl radicals into methyleneimine, reactions (1) and (2):

equation image

leads to ΔH(CH2NH) = 25.0 ± 3 kcal/mol in excellent agreement with ion cyclotron resonance spectroscopy measurements and to a pi bond energy of Eπ = 55.0 kcal/mol in CH2NH which is comparable but smaller than to the corresponding value in CH2CH2 (63.7 kcal/mol). Assuming that Eπ(CH2NH) = 0.5 [Eπ(CH2CH2) + Eπ(NHNH)] then requires that Eπ(NHNH) = 46.8 kcal/mol in diimine and BDE(N2H3‐H) = 87.5 kcal/mol i.e. about 11.5 kcal/mol larger than current data for hydrazine but otherwise consistent with additional evidence.The entropy and heat capacity of methyleneimine, calculated from recent infrared and microwave spectroscopic data using the rigid rotor harmonic oscillator approximation, are also reported.
Measurement of diffusion coefficients for diffusion‐controlled reactions
Authors: Ayscough Peter B. , Bartle Keith D. , Clifford Anthony A. , Mills Derek 
Published: January 2005

AbstractThe Taylor dispersion technique has been used to measure the diffusion coefficients of nine compounds in dilute solution in isopropanol at 300 K. These compounds correspond, by the difference of a single hydrogen atom, to nine free radicals, for which the rate constants for bimolecular (termination) reactions have been previously measured under the same conditions by e.s.r. Comparison of the two sets of results show the termination reactions to be essentially diffusion‐controlled, and, assuming no activation‐energy effect, interaction parameters for the termination reactions are calculated and discussed.
A kinetic study of the decomposition of HNO3 and its reaction with NO
Authors: Svensson Roger , Ljungström Evert 
Published: January 2005

AbstractThe rate of reaction between NO and HNO3 and the rate of thermal decomposition of HNO3 have been measured by FTIR spectroscopy. The measurements were made in a teflon lined batch reactor having a surface to volume ratio of 14 m−1. During the experiments, with initial HNO3 concentrations between 2 and 12 ppm and NO concentrations between 2 and 30 ppm, a reactant stoichiometry of unity and a first order NO and HNO3 dependence were confirmed. The observed rate constant for the reaction

at 22°C and atmospheric pressure was determined to 1.1 (±0.3) 10−5 ppm−1 min−1. At atmospheric pressure, HNO3 decomposes into NO2 and other products with a first order HNO3 dependence and with a rate constant of 2.0 (±0.2) 10−3 min−1. The apparent activation energy for the decomposition is 13 (±4) kJ mol−1.
Pulse radiolysis study of formation of poly(4‐vinylbiphenyl) anions in 2‐methyltetrahydrofuran solution at 100–120 K
Authors: Kato Noriyuki , Miyazaki Tetsuo , Fueki Kenji , Saito Atsushi 
Published: January 2005

AbstractThe reactions of poly(4‐vinylbiphenyl) (denoted as PVB) polymers and biphenyl molecules with solvated electrons in the 2‐methyltetrahydrofuran (MTHF) solvent have been studied at 100–120 K by electron‐pulse radiolysis. The formation of PVB polymer anions as well as biphenyl anions was observed by the electron‐pulse irradiation of the MTHF‐PVB(or biphenyl) solution. The anions are formed by two processes; a rapid formation during the pulse irradiation (<20 ns) and a slow formation after the pulse irradiation. The slow formation is due to a diffusion‐controlled reaction between solutes, such as PVB and biphenyl, and solvated electrons. It was found that the reaction efficiency, expressed in monomer unit, of PVB polymers is 1/27 of that of biphenyl molecules. The reaction radius for the electron capture reaction of PVB polymers is estimated as 200–370 A, which is much larger than the gyration radius (107 A) of polymer coils in MTHF solution.
Kinetic measurements on the system: 2NO2 = N2O4 at (224 ± 2) K using time‐resolved infrared laser absorption
Authors: Brunning John , Frost Michael J. , Smith Ian W. M. 
Published: January 2005

AbstractDirect kinetic measurements have been made on the reaction: 2NO2 = N2O4. Equilibrium mixtures of NO2 and N2O4 at (224 ± 2) K were perturbed by flash photolysis of a fraction of the N2O4. The rate of relaxation back to equilibrium was monitored by observing the transmittance of the 14P(11) line from a cw CO laser selected to coincide with the v9 band of N2O4. Measurements were made in the presence of 350–750 torr of He, N2, or CF4. Within this limited pressure range, the kinetics were consistent with third‐order behavior with the following rate constants (cm3 molecule−1 s−1): k0 = (2.4 ± 0.5) × 10−34 [He]; (1.0 ± 0.1) × 10−33 [N2]; (1.8 ± 0.3) × 10−33 [CF4].
The kinetics of successive addition of oxirane to alkanethiols in the presence of basic catalysts
Authors: Chlebicki Jan , Cichacz Zbigniew 
Published: January 2005

AbstractRate constants and activation parameters of direct reaction of oxirane with certain alkyl‐2‐hydroxyethyl sulfides and/or successive oxyethylene adducts in the presence of basic catalyst were studied at temperatures 323–353 K. The reactions were found to be of the first order with respect to oxirane, sulfide, and catalyst concentrations. The kinetics are consistent with a termolecular mechanism.
Kinetics and mechanisms of the permanganate oxidation of L‐valine in neutral aqueous solutions
Authors: Pérez‐benito Joaquin F. , Rodriguez Rosa M. , De Andrés Jaime , Brillas Enrique , Garrido José A. 
Published: January 2005

AbstractThe permanganate oxidation of L‐valine has been studied by visible spectrophotometry in neutral aqueous solutions. Under these conditions, both the zwitterionic and anionic forms of the amino acid are oxidized, the reaction being autocatalyzed by soluble colloidal manganese dioxide. Kinetic data for both the uncatalyzed and autocatalytic reaction pathways have been obtained, and reaction sequences consistent with the experimental findings are proposed.
Reaction rate analysis of complex kinetic systems
Authors: Turányi T. , Bérces T. , Vajda S. 
Published: January 2005

AbstractUsing the elementary sensitivity densities, a reaction rate sensitivity gradient is obtained which is the derivative of the rate of species concentration change with respect to the rate coefficient. The dimensionless (log‐normalized) form of the reaction rate sensitivity gradient is the ratio of the rate of concentration change of species i due to elementary reaction j and the net rate of concentration change of species i. This result provides a mathematical basis for the use of various forms of reaction rate analyses in the study of complex reaction mechanisms. The kinetic information inherent in the relative reaction rate matrix is extracted by principal component analysis. The method is used to analyze the mechanism of high‐temperature formaldehyde oxidation and high‐temperature propane pyrolysis. Ranking of the elementary reactions allowed us to reduce significantly the original mechanisms and a detailed study of the results revealed the reaction structures and the major reaction paths of the species.
Canonical statistical adiabatic channel model calculations of the H + CH3 → CH4 recombination reaction on an ab initio potential energy surface. The role of the transitional modes
Authors: Cobos C. J. 
Published: January 2005

AbstractThe canonical formalism of the statistical adiabatic channel model is used to calculate limiting high pressure rate constants for the H + CH3 → CH4 recombination reaction on a recently reported analytic potential energy surface based on ab initio calculations. An effective adiabatic channel potential which incorporates the Gϕϕ matrix element of the twofold degenerate H3CH transitional bending mode, quartic anharmonicity, and state selected mode coupling effects is implemented. The rate constants calculated over the temperature range 200–1000 K are in very good agreement with recent canonical variational transition state theory calculations performed on the same surface. The comparison with experimental results is also discussed.
Kinetics of gas‐phase thermal elimination of (α‐phenylethyl) and (β‐phenylethyl)‐pyrazole
Authors: Perez Jorge Daniel , Phagouape Leonardo Miguel 
Published: January 2005

AbstractFlash Vaccum Pyrolysis of (α‐phenylethyl) and (β‐phenylethyl)‐pyrazole were studied. Pyrazole and Styrene were found as only products of both reactions. The kinetic parameters obtained reinforce the results previously found about the poor influence of the substitutents on the α and β carbons of the ethyl group in the FVP of N‐alkyl pyrazoles and (β‐haloethyl) pyrazoles.
Kinetics of oxidation of some ortho, meta, and para substituted S‐phenylmercaptoacetic Acids by N‐Chloro‐3‐Methyl‐2,6‐Diphenyl piperidin‐4‐one in buffered ethanol‐water
Authors: Ganapathy K. , Kabilan S. 
Published: January 2005

AbstractThe kinetics of oxidation of a number of ortho, meta, and para substituted S‐phenylmercaptoacetic acids by N‐Chloro‐3‐Metyl‐2,6‐Diphenylpiperidin‐4‐one (NCP) has been studied in buffered ethanol‐water (75:25 v/v) of pH 5.46. The reaction is of first order each in [oxidant] and [substrate]. The rate constant decreases with increase in pH from 5.22 to 5.70. The reaction is accelerated by electron releasing and retarded by electron withdrawing substitutents. The ρ value obtained for this reaction is −1.88 at 10°C with a good correlation coefficient of 0.99 showing an electron deficient transition state. The effect of ortho substitutents also is discussed in detail.
CH bond dissociation energies, isolated stretching frequencies, and radical stabilization energy
Authors: McKean D. C. 
Published: January 2005

AbstractAn earlier correlation between isolated CH stretching frequencies, v, and experimental CH bond dissociation energies, in hydrocarbons, fluorocarbons, and CHO compounds, is updated. A stabilization energy, E, which reflects only the properties of the radical, is defined by the deviation of a point from the above correlation. E values for a variety of radicals are listed and discussed. In HCN and HCO compounds E is low or negligible, due to the low v found in these compounds. The conventional definition of ES then represents a serious misnomer, which distracts attention from the probable source of discrepancies between experimental and ab initio values of DH°(CH), namely, the parent molecules. Stereo electronic effects concerned with the breaking of CH bonds are predicted in a variety of situations.Some experimental determinations of DH°(CH), viz., in C2H4, HCOOH, CH3CHO, CH3NH2, are considered to be probably in error.Schemes for partitioning energies of atomization into ‘standard’ or ‘intrinsic’ bond energies are criticized.
Rate constants for the reactions of Br atoms with a series of alkanes, alkenes, and alkynes in the presence of O2
Authors: Barnes I. , Bastian V. , Becker K. H. , Overath R. , Tong Zhu 
Published: January 2005

AbstractRate constants of Br atom reactions have been determined using a relative kinetic method in a 20 l reaction chamber at total pressures between 25 and 760 torr in N2 + O2 diluent over the temperature range 293–355 K. The measured rate constants for the reactions with alkynes and alkenes showed dependence upon temperature, total pressure, and the concentration of O2 present in the reaction system.Values of (6.8 ± 1.4) × 10−15, (3.6 ± 0.7) × 10−14, (1.5 ± 0.3) × 10−12, (1.6 ± 0.3) × 10−13, (2.7 ± 0.5) × 10−12, (3.4 ± 0.7) × 10−12, and (7.5 ± 1.5) × 10−12 (units: cm3 s−1) have been obtained as rate constants for the reactions of Br with 2,2,4‐trimethylpentane, acetylene, propyne, ethene, propene, 1‐butene, and trans‐2‐butene, respectively, in 760 torr of synthetic air at 298 K with respect to acetaldehyde as reference, k = 3.6 × 10−12 cm3 s−1.Formyl bromide and glyoxal were observed as primary products in the reaction of Br with acetylene in air which further react to form CO, HBr, HOBr, and H2O2. Bromoacetaldehyde was observed as an primary product in the reaction of Br with ethene. Other observed products included CO, CO2, HBr, HOBr, BrCHO, bromoethanol, and probably bromoacetic acid.
Rate constants for hydrogen abstraction reactions of the sulfate radical, SO4−. Alcohols
Authors: Clifton Carol L. , Huie Robert E. 
Published: January 2005

AbstractRate constants have been determined for the reactions of SO4− with a series of alcohols, including hydrated formaldehyde. The SO4− radical was produced by the laser‐flash photolysis of persulfate, S2O82−. Rate constants for the reactions of SO4− with alcohols range from 1.0 × 107 for methanol to 3.4 × 108 M−1 s−1 for 1‐octanol. Rate constants for the reactions of SO4− with deuterated methanol and ethanol are lower by about a factor of 2.5. For methanol, ethanol, and 2‐propanol, the temperature dependence of the rate constant was determined over the range 10–45°C.
Thermal decomposition of propane in shock waves
Authors: Hidaka Yoshiaki , Oki Takashi , Kawano Hiroyuki 
Published: January 2005

AbstractThe thermal decomposition of propane was studied behind reflected shock waves over the temperature range 1100–1450 K and the pressure range 1.5–2.6 atm, by both monitoring the time variations of absorption at 3.39 μm and analyzing the concentrations of the reacted gas mixtures. The rate constants of the elementary reactions were discussed from the results. The rate constant expressions, k1 = 1.1 × 1016 exp (−84 kcal/RT) s−1 and k4 = 9.3 × 1013 exp(−8 kcal/RT) cm3 mol−1 s−1, of reactions C3H8 → CH3 + C2H5 and C3H8 + H → n‐C3H7 + H2 were evaluated, respectively.
Kinetic study of the iodine monobromide‐or iodine monochloride‐catalyzed alcoholysis of butoxytriethylsilane: n‐butoxy group — s‐butoxy group exchange reaction
Authors: Ito Katsuko , Ibaraki Takeshi 
Published: January 2005

AbstractThe catalytic activity of iodine monobromide and iodine monochloride were investigated in the reaction, Et3SiOBun + BusOH ⇌ Et3SiOBus + BunOH. Pseudo first‐order rate constants were measured by gas chromatography, at 10°, 20°, 30°, and 40°C for iodine monobromide and at 10°, 20°, and 30°C for iodine monochloride, on reaction mixtures containing both butanols in excess.
The catalytic coefficients of both catalysts were evaluated from the observed rate constants as follows:

The activation paramaters were estimated from these data, and were compared with the values for iodine catalysis. These results are consistent with the mechanism previously proposed.
Formation of ring‐retaining products from the OH radical‐initiated reactions of benzene and toluene
Authors: Atkinson Roger , Aschmann Sara M. , Arey Janet , Carter William P. L. 
Published: January 2005

AbstractThe aromatic ring‐retaining products formed from the gas–phase reactions of the OH radical with benzene and toluene, in the presence of NOx, have been identified and their formation yields determined. These products, and their formation yields, are as follows: from benzene – phenol, 0.236 ± 0.044; nitrobenzene, {(0.0336 ± 0.0078) + (3.07 ± 0.92) × 10−16[NO2]}; from toluene – benzaldehyde, 0.0645 ± 0.0080; benzyl nitrate, 0.0084 ± 0.0017; o−cresol, 0.204 ± 0.027; m− + p−cresol, 0.048 ± 0.009; m‐nitrotoluene, {(0.0135 ± 0.0029) + (1.90 ± 0.25) × 10−16[NO2]}, where the NO2 concentration is in molecule cm−3 units. The formation yields of o‐ and p‐nitrotoluene from toluene were ca. 0.07 and 0.35 that of m‐nitrotoluene, respectively. The observations that the nitro‐aromatic yields do not extrapolate to zero as the NO2 concentration approaches zero are not consistent with current chemical mechanisms for these OH radical‐initiated reactions, and suggest that under the experimental conditions employed in this study the hydroxycyclohexadienyl radicals formed from OH radical addition to the aromatic ring react with NO2 rather than with O2. However, these data concerning the nitroaromatic yields are consistent with our previous conclusions that many of the nitrated polycyclic aromatic hydrocarbons present in ambient air are formed, at least in part, in the atmosphere from OH radical reactions.