bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of solvent on the reactions of coordination complexes: Part 15: Base hydrolysis ofCis‐(Chloro)(benzimidazole)‐Bis‐(ethylenediamine)cobalt(III) ion in mixed solvent media
Authors: Dash Anadi C. , Dash Neelamadhab 
Published: January 2005

AbstractThe kinetics of base hydrolysis ofthecis‐(chloro)‐(benzimidazole)bis(ethylenediamine) cobalt(III) ion was investigated in Methanol‐water and Ethyleneglycol‐water media of varying compositions and at isodielectric conditions(Ds ≃ 61 at 25°C) in isopropanol‐ and Acetonitrile‐water media at 35°C in the pH range, 7.2–8.9. It is of interesttonote that the aquation rate constant of the conjugate base, cis‐[Co(en)2(bzm)Cl]+ (Bzm = N H deprotonated benzimidazole, en = ethylenediamine) is virtually insensitive to the compositions of the mixed solvents studied, unlike the aquation rate constant of the conjugate acid form of the title complex. This is indicative of a true dissociative mode of activation (Dcb) of the conjugate base.
Kinetics and mechanism of oxidation of indigo carmine by hypohalites
Authors: Puttaswamy  , Mahadevappa D. S. , Gowda N. M. Made 
Published: January 2005

AbstractKinetics of oxidation of indigo carmine (IC) by sodium hypohalites, NaOX (X  Cl or Br), in alkaline buffer of pH 9–11 has been studied spectrophotometrically at λ = 610 nm. The experimental rate law obtained is −d[IC]/dt = k[OX−][IC][OH−]x where x <1. Variation of ionic strength or dielectric constant of the medium had no effect on the reaction rate while the addition of halide ions slightly retarded the rate. A most plausible mechanism proposed on the basis of experimental results involves the formation of isatin sulphonate which undergoes further oxidation to anthranilate. Activation parameters have been evaluated.
Kinetics and mechanism of chloramine‐T oxidation of cinnamaldehyde in two acid media
Authors: Mythily C. K. , Rangappa K. S. , Made Gowda N. M. 
Published: January 2005

AbstractKinetics of oxidation of cinnamaldehyde (Cinn) by chloramine‐T (CAT) has been studied in solutions containing HCl and H2SO4 at 313 K. The respective experimental rate laws obtained in HCl and H2SO4 media are as follows:
equation image
and
equation image
Here the value of x varies from 0.9 to zero while the values of y and z are 0.83 and 0.72, respectively. Effects, on the reaction rate, of ionic strength, reaction product (p‐toluenesulfonamide), dielectric constant of the solvent medium, and the anions, Cl− and SO42−, have been investigated. Activation parameters have been computed, based on the rate constants determined at different temperatures. Mechanisms proposed and the rate laws derived are consistent with the observed kinetic data represented by the experimental rate laws.
Kinetic study of some reactions related to the Mn(II)‐catalyzed bromate‐saccharide oscillating reactions
Authors: Ou Chin‐chou , Jwo Jing‐jer 
Published: January 2005

AbstractIn the stirred batch experiment, the Mn(II)‐catalyzed bromate‐saccharide reaction in aqueous H2SO4 or HClO4 solution exhibits damped oscillations in the concentrations of bromide and Mn(II) ions. Peculiar multiple oscillations are observed in the system with arabinose or ribose. The apparent second‐order rate constants of the Mn(III)‐saccharide reactions at 25°C are (0.659, 1.03, 1.76, 2.32, and 6.95) M−1 s−1 in 1.00 M H2SO4 and (4.69, 7.51, 10.2, 13.5, and 36.2) M−1 s−1 in (2.00–4.00) M HClO4 for (glucose, galactose, xylose, arabinose, and ribose), respectively. At 25°C, the observed pseudo‐first‐order rate constant of the Mn(III)‐Br− reaction is kobs = (0.2 ± 0.1) [Br−] + (130 ± 5)[Br−]2 + (2.6 ± 0.1) × 103[Br−]3 + (1.2 ± 0.2) × 104[Br−]4 s−1 and the rate constant of the Br2Mn(II) reaction is less than 1 × 10−4 M−1 s−1. The second‐order rate constants of the Br2‐saccharide reactions are (3.65 ± 0.15, 11.0 ± 0.5, 4.05, 12.5 ± 0.7, and 2.62) × 10−4 M−1 s−1 at 25°C for glucose, galactose, xylose, arabinose, and ribose, respectively.
Kinetics of the solvolysis of [Co(3Rpy)4Cl2]+ (R = Me or Et) in water + propan‐2‐ol mixtures
Authors: El‐subruiti Gehan M. , Wells Cecil F. , Sidahmed Ibrahim M. 
Published: January 2005

AbstractRates of solvolysis of complex ions [Co(3Rpy)4Cl2]+ with R = Me and Et have been determined in mixtures of water with the hydrophobic co‐solvent propan‐;2‐ol for a range of temperatures. The variations of the enthalpies and entropies of activation with the solvent composition have been correlated with the physical properties of the solvent and it has been shown that the linear plot found for ΔH* against ΔS* in water + propan‐2‐ol is coincident with that found for water + methanol mixtures. A free energy cycle has been applied to the dissociative‐type process of initial state (Cn+) going to the transition state (M(n+1)+…‥ Cl−) using values for the free energy of transfer of the chloride ion from water into the mixture, ΔG(Cl−), derived from the solvent sorting technique or from the TATB/TPTB method. Irrespective of the source of ΔG(Cl−), it is found that ΔG(Co(3Rpy)4Cl2+*) ca. ΔG(Co(3Rpy)4Cl2+) (where * indicates a species in the transition state) for mol fractions of propan‐2‐ol x2 ≳ 0.04–0.05 with ΔG(Co(3Rpy)4Cl2+*) becoming increasingly more negative than ΔG(Co(3Rpy)4Cl2+) as x2 increases above 0.05. These variations are compared with those for the solvolysis of the same ions in water + methanol mixtures and of a range of other ions in water + propan‐2‐ol mixtures. It is concluded that, using values for ΔG(Cl−) from either source, the stabilizing influence of changes in solvent structure is greater on the cation in the transition state than on the cation in the initial state for the solvolyses of complexes [Co(Rpy)4Cl2+] and [Coen2LCl]n+.
A shock tube study of the reactions of NH with NO, O2, and O
Authors: Mertens John D. , Chang Albert Y. , Hanson Ronald K. , Bowman Craig T. 
Published: January 2005

AbstractThe reactions of NH(X3Σ−) with NO, O2, and O have been studied in reflected and incident shock wave experiments. The source of NH in all the experiments was the thermal dissociation of isocyanic acid, HNCO. Time‐histories of the NH(X3Σ) and OH(X2Π) radicals were measured behind the shock waves using cw, narrow‐linewidth laser absorption at 336 nm and 307 nm, respectively. The second‐order rate coefficients of the reactions:
equation image
were determined to be:

and

cm3 mol−1 s−1, where ƒ and F define the lower and upper uncertainty limits, respectively.The branching fraction of channel
equation image
defined as k3b/k3total, was determined to be 0.19 ± 0.10 over the temperature range of 2940 K to 3040 K.
Kinetics and mechanism of oxidation of hydrazinium ion with peroxomonophosphoric acid in acid perchlorate solutions and role of trace iodide ions
Authors: Dhas T. Peter Amala , Mishra D. K. , Mittal R. K. , Gupta Y. K. 
Published: January 2005

AbstractThe reaction of peroxomonophosphoric acid and hydrazinium ion in acid perchlorate solutions occurs as per stoichiometry (i), and the rate law (ii) at large [N2H5 +],
equation image
where K′d is the first acid dissociation constant of H3PO5 and k 1 and k 2 are rate constants found to be 2.6 × 10−4 s−1 and 5.0 × 10−2 M−1 s−1, respectively, at 35°. The reaction is greatly catalyzed by iodide ions. The mechanism involves a redox cycle I−/I2 and the rate is independent of [N2H5 +] in the presence of iodide ions. K′d was found to be 0.55 M−1 and independent of temperature.
Kinetics of the reactions of the IO radical with dimethyl sulfide, methanethiol, ethylene, and propylene
Authors: Maguin F. , Mellouki A. , Laverdet G. , Poulet G. , Bras G. Le 
Published: January 2005

AbstractThe reactions of IO radicals with CH3SCH3, CH3SH, C2H4, and C3H6 have been studied using the discharge flow method with direct detection of IO radicals by mass spectrometry. The absolute rate constants obtained at 298 K are the following: IO + CH3SCH3 → products (1): k1 = (1.5 ± 0.2) × 10−14; IO + CH3SH → products (2): k2 = (6.6 ± 1.3) × 10−16; IO + C2H4 →products (3): k3 < 2 × 10−16; IO + C3H6 → products (4): k4 < 2 × 10−16 (units are cm3 molecule−1 s−1). CH3S(O)CH3 and HOI were found as products of reactions (1) and (2), respectively. The present lower value of k1 compared to our previous determination is discussed.
Kinetic modeling of the reduction of nitric oxide in combustion products by isocyanic acid
Authors: Miller James A. , Bowman Craig T. 
Published: January 2005

AbstractThe RAPRENOx process for NO reduction in combustion products involves reaction of nitric oxide with isocyanic acid. We have developed a mechanism for the gas‐phase reaction of isocyanic acid with nitric oxide in the presence of various amounts of O2, H2O, and CO. Kinetics calculations using the mechanism are compared with the experimental data of Siebers and Caton, and the model reproduces all trends of these data. Sensitivity and rate‐of‐production analyses show that the reactions of HNCO with OH, O, and H play a major role in the NO‐removal process and that NO removal occurs primarily by reaction of NO with NCO to form N2O, which subsequently reacts slowly to form N2. The overall reaction is critically dependent on production of radicals. When O2, H2O, and CO are present, the radicals are supplied by the moist‐CO chain branching sequence. When any of these species is absent, radicals must be supplied by other reactions, principally the N2O decomposition reaction and the reaction of the NH2 radical with NO.
Kinetics and mechanisms of oxidation by metal ions, part XII [1] oxidation of formaldehyde by alkaline osmium(VIII)
Authors: Vishnoi Minakshi , Sharma Kamla , Mehrotra Raj N. 
Published: January 2005

AbstractThe stopped‐flow measurements on the disappearance of alkaline osmium(VIII) at 402 nm indicated a first‐order dependence each in [Os(VIII)] and [HCHO]. The pseudo first‐order rate constant kobs ([HCHO] ≫ [Os(VIII)]) decreased with increasing [OH−]. The ionic strength, however, had no effect on kobs. The rapid scan spectra of the reaction mixture indicated the formation of an inert complex which absorbs at 319 nm. Therefore the rate determining step is considered to involve the bimolecular collision between OsO4(OH) and hydrated formaldehyde. The values of the rate limiting constant k and the equilibrium constant Kha for the formation of the alkoxide ion from the reaction of hydrated formaldehyde with OH− are evaluated. The equilibrium constant Kha, within the experimental limits, is independent of temperature. The pKa value, calculated from Kha, is 13.62 ± 0.05 which is in good agreement with the pKa value 13.27 for formaldehyde. The activation parameters, ΔH‡ = 40 ± 2 kJ mol−1 and ΔS‡ = −51 ± 6 JK−1 mol−1, for the rate limiting constant k are determined.
Are reaction rate coefficients additive? Revised transition state theory calculations for OH + alkane reactions
Authors: Cohen N. 
Published: January 2005

AbstractRecent shock tube measurements [1,2] of the reactions of OH radicals with various hydrocarbons provide the incentive for revising an earlier model [3] used to carry out thermochemical transition state theory calculations for the reaction rate coefficients of OH radicals with alkanes. In this article, details of the revised model are presented and calculations are described and compared with experiments. Of particular interest is the question of the reliability of an additive formulation for H atom abstraction rate coefficients; i.e., can we evaluate the total rate coefficient as the sum of site‐specific rate coefficients, ktotal = Σinki, where we sum either over primary, secondary, and tertiary H atoms or over some larger number of classes of atoms? It is argued that there are two major reasons for expecting different primary, secondary, or tertiary H atoms to have different rate parameters: (1) activation energies may depend on next‐nearest neighbors and (2) activation entropies can be mass‐dependent. In principle the first factor invalidates the common procedure of treating the total rate coefficient for OH + RH H abstraction processes as the sum of invariant primary, secondary, and tertiary rates multiplied by the respective number of such H atoms in the molecule. The second factor places limits on the accuracy of any additive formulation. A separate question is whether there is sufficient experimental evidence to justify these distinctions, or whether, given experimental and theoretical uncertainties, it is adequate to treat them all as equivalent. It is concluded that (1) mass‐dependent variations are just barely discernible; and (2) there are measurable differences among various primary H atom abstractions, and possibly among secondary atoms, but the data base does not justify distinguishing among tertiary H atoms.
Catalytic effect of anionic micelles on alkaline hydrolysis of N‐hydroxyphthalimide. Evidence for the probable occurrence of the reaction in between Gouy‐Chapman and exterior boundary of Stern layers of the micelles
Authors: Khan M. Niyaz 
Published: January 2005

AbstractThe nucleophilic second‐order rate constant (kOH) for the reaction of ŌH with ionized N‐hydroxyphthalimide (S−) appears to follow a reaction mechanism similar to that for reactions of ŌH with neutral phthalimide and its N‐substituted derivatives. Kinetically indistinguishable terms, k′w[H2O][S−] and kŌH[ŌH][SH] (SH represents nonionized N‐hydroxyphthalimide), which constitute the pH‐independent rate region of the pH‐rate profile, are resolved qualitatively. It is shown that the term kŌH[ŌH][SH], rather than k′w[H2O][S−], is important in these reactions. The rates of ŌH‐catalyzed cleavage of S− were studied at 32° in the presence of micelles of sodium dodecyl sulphate (SDS). At a constant [ŌH], the observed pseudo first‐order rate constants (kobs) increase linearly with [SDS]T (total SDS concentration). These data are explained in terms of the pseudophase model of micellar effects on reactivity. The linear dependence of kobs with [SDS]T (within [SDS]T range of 0.0–0.2 or 0.3 M) is attributed to the occurrence of the reaction between the exterior boundary of Stern layer and Gouy‐Chapman layer.
The use of transition‐state theory to extrapolate rate coefficients for reactions of H atoms with alkanes
Authors: Cohen N. 
Published: January 2005

AbstractThe thermochemical kinetics formulation of conventional transition state theory has been applied to metathesis reactions of H atoms with a series of alkanes in order to provide a sound framework for the intercomparison of experimental data, and also to extrapolate rate coefficients to temperature regimes that may lie beyond the range of experiments. The calculations require a value for the rate coefficient at some temperature, necessitating a discussion of the extant experimental data and their reliability. The procedures are described, the results of the calculations are presented, and their agreement with experimental data (for methane, ethane, propane, butane, pentane, isobutane, cyclopropane, cyclohexane, neopentane, neooctane, and 2,2,3‐trimethylbutane) is discussed. A general expression for reactions of H with large (more than 4 carbons) alkanes is proposed:

where np, ns, and nt are the numbers of primary, secondary, and tertiary H atoms available for abstraction.
THERM: Thermodynamic property estimation for gas phase radicals and molecules
Authors: Ritter Edward R. , Bozzelli Joseph W. 
Published: January 2005

AbstractWe have developed a computer code for an IBM PC/XT/AT or compatible which can be used to estimate, edit, or enter thermodynamic property data for gas phase radicals and molecules using Benson's group additivity method. The computer code is called THERM (THermo Estimation for Radicals and Molecules). All group contributions considered for a species are recorded and thermodynamic properties are generated in old NASA polynomial format for compatibility with the CHEMKIN reaction modeling code. In addition, listings are created in a format more convenient for thermodynamic, kinetic, and equilibrium calculations. Polynomial coefficients are valid from 300–5000 K using extrapolation methods based upon the harmonic oscillator model, an exponential function, or the Wilhoit polynomials. Properties for radical and biradical species are calculated by applying bond dissociation increments to a stable parent molecule to reflect loss of H atom. THERM contains a chemical reaction interpreter to calculate thermodynamic property changes for chemical reactions as functions of temperature. These include equilibrium constant, heat release (required heat, ΔHr), entropy change (ΔSr), Gibbs free energy change (ΔGr), and the ratio of forward to reverse Arrhenius A‐factors (for elementary reactions). This interpreter can also process CHEMKIN input files. A recalculation procedure is incorporated for rapid updating of a database of chemical species to reflect changes in estimated bond dissociation energies, heats of formation, or other group values. All input and output files are in ASCII so that they can be easily edited, expanded, or updated.
Thermal unimolecular decomposition of 1,3,5‐trioxane: Comparison of theory and experiment
Authors: Aldridge H. K. , Liu X. , Lin M. C. , Melius C. F. 
Published: January 2005

AbstractThe unimolecular decomposition of 1,3,5‐trioxane into three formaldehyde molecules has been studied thermally at eight temperatures between 523 and 603 K using mixtures highly diluted with Ar. Under these conditions, the only decomposition product detected by means of FTIR analysis was formaldehyde. At 588 K, the effect of total pressure was examined between 25 and 800 torr; a noticeable decline in the first‐order rate constant was observed only at pressures below 500 torr. A least‐squares analysis of the measured high‐pressure, first‐order rate constants leads to

This result differs significantly from earlier data on the reaction, but it compares closely with the theoretical value:

computed with the transition‐state theory using the molecular and TST parameters predicted by the BAC–MP4 method.
Products of the gas‐phase reaction of methyl tert‐butyl ether with the OH radical in the presence of NOx
Authors: Tuazon Ernesto C. , Carter William P. L. , Aschmann Sara M. , Atkinson Roger 
Published: January 2005

AbstractThe products of the reaction of the hydroxyl (OH) radical with methyl tert‐butyl ether (MTBE) in NOx‐air systems were identified and measured by Fourier transform infrared absorption spectroscopy and gas chromatography. The products observed, and their yields, were as follows: t‐butyl formate, 76 ± 7%; formaldehyde, 37%; methyl acetate, 17 ± 2%, and acetone, 2.1 ± 0.9%, where the stated error limits represent both random (two standard deviations) and estimated systematic uncertainties. These products account for ca. 95% of the MTBE carbon reacted. Infrared absorption bands which may be due to small amounts of organic nitrate formation were observed, but organic nitrate yields could not be quantified. These data allow a chemical mechanism for the reaction of MTBE with the OH radical in the presence of NOx to be formulated.
Rate constants for the gas‐phase reactions of OH radicals and Cl atoms with n‐alkyl nitrites at atmospheric pressure and 298 K
Authors: Nielsen Ole J. , Sidebottom Howard W. , Donlon Michael , Treacy Jack 
Published: January 2005

AbstractRate constants for the reactions of OH radicals and Cl atoms with CH3ONO, C2H5ONO, n‐C3H7ONO, n‐C4H9ONO, and n‐C5H11ONO have been determined at 298 ± 2 K and a total pressure of approximately 1 atm. The OH rate data were obtained using both the absolute rate technique of pulse radiolysis combined with kinetic spectroscopy and a relative rate method involving simultaneous measurement of the loss of the nitrite and the reference compound. The Cl rate constants were measured using the relative rate method. Values of the rate constants in units of 10−13 cm3 molecule−1 s−1 are:

Relative Cl
Relative OH
Absolute OH

CH3ONO
94.4 ± 7.4
3.0 ± 1.0
2.6 ± 0.5

C2H5ONO
295 ± 13
7.0 ± 1.5
7.0 −1.1

n‐C3H7ONO
646 ± 58
11.0 ± 1.5
12.0 ± 0.5

n‐C4H9ONO
1370 ± 58
22.7 ± 0.8
27.2 ± 6.0

n‐C5H11ONO
2464 ± 444
37.4 ± 5.0
42.5 ± 8.0

When compared to rate data for the corresponding alkanes the results show that the ‐ONO group decreases the rate constant for H atom abstraction by the OH radical from groups bonded to the ‐ONO group and also decreases that for groups in the β position. Similar results were found for the reaction of Cl atoms with these compounds. The results are discussed in terms of reactivity trends.
Surface chemkin: A general formalism and software for analyzing heterogeneous chemical kinetics at a gas‐surface interface
Authors: Coltrin Michael E. , Kee Robert J. , Rupley Fran M. 
Published: January 2005

AbstractThis article describes a general kinetic formalism for treating the details of heterogeneous reactions at a gas‐solid interface. We develop a nomenclature for treating reactions between the gas phase and surface species residing on any number of surface site types and bulk‐phase species residing in bulk‐phase mixtures or in pure bulk phases. The rate of progress of surface reactions follows the law of mass‐action. We discuss the relationship between macroscopic conservation laws for mass and energy and the microscopic surface reaction rates as they might appear in boundary conditions for a chemically reacting flow. The formalism developed has been implemented in a general package of Fortran computer codes for the evaluation of complex surface‐reaction kinetics called Surface Chemkin.
Schiff bases between pyridoxal 5′‐phosphate and dodecylamine. Kinetic study
Authors: Vázquez M. A. , Muñoz F. , Donoso J. , Blanco F. García 
Published: January 2005

AbstractWe studied the formation and hydrolysis of the Schiff base of pyridoxal‐5′ ‐phosphate (PLP) and n‐dodecylamine (DOD) by kinetic methods and found the formation rate constants to be much larger than those reported for related systems. This can be ascribed to the occurrence of local concentration of charges in the vicinity of the carbinolamine, which stabilizes the corresponding transition state of the dehydration reaction. On the other hand, the hydrolysis rate constants of our system were considerably smaller as a result of the 12‐atom hydrocarbon chain acting as a bulky hydrophobic rest protecting the imine bond from attack by water.
Radical processes in the pyrolysis of acetylene
Authors: Benson Sidney W. 
Published: January 2005

AbstractThe literature on the pyrolysis of acetylene below 1000 K is reviewed and it is shown that the reaction is a radical chain polymerization initiated by H atoms. The induction period is examined and shown to arise from a rapid autocatalysis produced by the very first product, vinyl acetylene. Data from studies of acetylene polymerization induced by vinyl acetylene and styrene are examined and shown to be in good qualitative agreement with the radical chain process presented. Measured and where needed, estimated rate constants are given to produce numerical estimates of chain length, rates of polymerization, induction period, and rates of initiation. It is further shown that all the products of the polymerization are capable of efficiently initiating chains in the system. An examination of the possible kinetics of vinylidene shows that it does not play any role in acetylene chemistry.
A shock tube study of reactions of atomic oxygen with isocyanic acid
Authors: Mertens John D. , Chang Albert Y. , Hanson Ronald K. , Bowman Craig T. 
Published: January 2005

AbstractReactions of atomic oxygen with isocyanic acid (HNCO) have been studied in incident and reflected shock wave experiments using HNCO/N2O/Ar mixtures. Quantitative time‐histories of the NH(X3Σ−) and OH(X2Πi) radicals were measured behind the shock waves using cw, narrow‐linewidth laser absorption at 336 nm and 307 nm, respectively. The second‐order rate coefficients of the reactions:

equation image

and

equation image

were determined from early‐time NH and OH formation rates, with least‐squares two‐parameter fits of the results given by:

and

cm3 mol−1 s−1. The minimum and maximum rate constant factors (ƒ,F) define the lower and upper uncertainty limits, respectively.An upper limit on the rate coefficient of

equation image

was determined to be:

.