bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanistic and kinetic aspects of the reduction of nitryl chloride in aprotic media
Authors: Boughriet A. , Coumare A. , Fischer J. C. , Wartel M. 
Published: January 2005

AbstractIn order to bring more information on the thermodynamic and kinetic behavior of nitryl chloride in aprotic media, we have surveyed exhaustively the first NO2Cl‐reduction step in sulfolane (at the platinum electrode), taking into account our preliminary results about the electrochemical properties of NO2Cl in aprotic solvents. We have excluded the intervention of the weak ionic dissociation of NO2Cl (NO2Cl ⇆ NO + Cl− [I]) and its slow molecular decomposition as: 2NO2Cl ⇄ Cl2 + 2NO (⇄ N2O4) [II] in this process. We have admitted the occurrence of a rapid chemical reaction which controls kinetically the electrochemical system studied: \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm NO} + {\rm NO}_{\rm 2} {\rm Cl}\buildrel {k^*} \over \longrightarrow {\rm NOCl} + {\rm NO}_{\rm 2}^ \cdot {\rm}[{\rm III]} $\end{document}. By analyzing the kinetic currents resulting from the 1 st cathodic wave of NO2Cl at the temperature range 303–323 K, the rate constant, k*, and the activation energy, E*, of reaction [III] have been determined. These results and those previously found in the gas phase are discussed.
Mechanism of oxidations in partially aqueous media: Kinetics of oxidation of thiosemicarbazide and thiosemicarbazone by chloramine‐T and dichloramine‐T in aqueous methanol
Authors: Gowda B. Thimme , Sherigara B. S. 
Published: January 2005

AbstractKinetics of oxidation of thiosemicarbazide (TSC) and its hydrazone (Benzaldehyde thiosemicarbazone) by chloramine‐T (CAT) and dichloramine‐T (DCT) in aqueous methanol medium in the presence of perchloric acid has been studied. Oxidation of TSC by both the oxidants showed first order dependences in [oxidant], fractional order in [TSC] and nearly inverse first order in [H+]. The conversion of TSC into its benzaldehyde hydrazone changed the rate dependence in [CAT] from first to second order, while the dependence in [DCT] remained unchanged. The dependence in [TSC] changes from fractional order to zero order in both CAT and DCT oxidations. The rate followed inverse fractional order kinetics in [H+] in both the cases. Increase in ionic strength of the medium slightly decreased the rate, while the decrease in dielectric constant of the medium increased the rates of oxidations for both the oxidants. But the addition of reaction products, p‐toluenesulphonamide and chloride had no effect on the rate. Oxidation of TSC with both the oxidants has been shown to follow Michaelis‐Menten type mechanism. In hydrazone oxidations oxidants have been shown to disproportionate in slow steps to HOCl, which in turn attacks the substrate in fast steps to give the final products. [TSC] was varied at different temperatures and the constants of rate limiting steps were calculated at each temperature. Using the latter constants the activation parameters have been computed from the Arrhenius plots. The rate constants have been predicted from the rate law for the variation of [H+] at constant [TSC] and [oxidant]. The predicted values are in reasonable agreement with the experimental rate constants, providing additional support to the suggested mechanisms.
Gas phase thermolysis of benzyl t‐butyl sulfide, phenyl t‐butyl sulfide, and phenyl t‐butyl ether
Authors: Martin Gonzalo , Martinez Henry , Ascanio Julian 
Published: January 2005

AbstractThe pyrolysis kinetics of the title compounds has been studied in a stirred‐flow reactor over the temperature range 440–530°C and pressures between 5 and 14 torr. Benzyl t‐butyl sulfide and phenyl t‐butyl ether formed isobutene as product in over 98% yield, together with the corresponding benzyl thiol and phenol. The benzyl thiol decomposes to a large extent into hydrogen sulfide and bibenzyl. In the pyrolysis of phenyl t‐butyl sulfide, the hydrocarbon products consisted of 80 ±5% isobutene plus 20% isobutane, while the sulfur containing products were thiophenol and diphenyl disulfide. Order one kinetics was observed for the consumption of the reactants. The first order rate coefficients, based on isobutene production, followed the Arrhenius equations: Benzyl t‐butyl sulfide:

Phenyl t‐butyl sulfide:

Phenyl t‐butyl ether:

For benzyl t‐butyl sulfide and phenyl t‐butyl ether, the results suggest a unimolecular mechanism involving polar four center cyclic transition states. For phenyl t‐butyl sulfide, the t‐butyl‐sulfur single bond fission mechanism is a parallel, less important process than the complex fission one.
A kinetic and mechanistic study of the formation of alkyl nitrates in the photo‐oxidation of n‐heptane studied under atmospheric conditions
Authors: Harris Stephen J. , Kerr J. Alistair 
Published: January 2005

AbstractThe photo‐oxidation of n‐heptane in synthetic air containing methyl nitrite and nitric oxide has been ivestigated in an atmospheric flow reactor. By measuring the total yields of heptyl nitrate products, relative to the depletion of the n‐heptane, the rate constant ratio, k3b/k3a has been determined for the reactions:
equation image
Over the temperature range 253–325 K and at a total pressure of 730 Torr, the following relative Arrhenius equation has been obtained from the present study together with literature data:

These results confirm that the formation of alkyl nitrates from the photo‐oxidation of n‐alkanes arise from a primary reaction between the alkylperoxy radicals and nitric oxide. Furthermore the present experiments show that the lifetime of the intermediate in this type of reaction, presumed to be an alkyl peroxynitrite, ROONO, must be less than a few seconds.
Reactivity of tert‐butoxy radicals towards thiols, alkyl sulfides, and alkyl disulfides
Authors: Encinas M. V. , Lissi E. A. , Majmud C. , Olea A. F. 
Published: January 2005

AbstractRate constants for the reactions of tert‐butoxy radicals (generated by the thermal decomposition of di‐tert‐butylperoxyoxalate) with several sulfur containing compounds have been measured at 310 K in benzene. Hexanethiol (k = 6.5 × 107M−1s−1) reacts considerably faster than alkyl sulfides and disulfides. For these compounds the reaction rate constants are slightly dependent on the α‐hydrogen type, changing (when it is expressed per hydrogen atom) only a factor 5 for sulfides and 3 for disulfides when the α‐hydrogen is changed from primary (methyl) to tertiary (isopropyl). The data obtained are compared to those found for the deactivation of the benzophenone triplet. Values of ktert‐butoxy/kbenzophenone range from ca 10−3 (di‐tert‐butyl disulfide) to 7.5 (hexanethiol). The results obtained are rationalized in terms of bond strength, steric hindrance, and charge transfer contributions to the critical configuration energies.
The mechanism in the elimination kinetics of 2‐chloropropionic acid in the gas phase
Authors: Chuchani Gabriel , Rotinov Alexandra 
Published: January 2005

AbstractThe elimination kinetics of 2‐chloropropionic acid have been studied over the temperature range of 320–370.2°C and pressure range of 79–218.5 torr. The reaction in seasoned vessel and in the presence of the free radical suppressor cyclohexene, is homogeneous, unimolecular, and obeys a first‐order rate law. The dehydrochlorination products are acetaldehyde and carbon monoxide. The rate coefficient is expressed by the following Arrhenius equation: log k1(s−1) = (12.53 ± 0.43) – (186.9 ± 5.1) kJ mol−1 (2.303RT)−1. The hydrogen atom of the carboxylic COOH appears to assist readily the leaving chloride ion in the transition state, suggesting an intimate ion pair mechanism operating in this reaction.
Kinetics of UV‐laser induced dehydrochlorination of 1‐chloro‐1,1‐difluoroethane
Authors: Dong Z. F. , Schneider M. , Wolfrum J. 
Published: January 2005

AbstractThe decomposition of 1‐chloro‐1,1‐difluoroethane by a radical chain reaction has been studied in a flow reactor in the temperature range from 503 to 773 K. For the initiation of the chain small amounts of added chlorine were photolyzed with a XeCl laser (λ = 308 nm). The formation of the dehydrochlorination and chlorination products, vinylidene fluoride, and 1,2‐dichloro‐1,1‐difluoroethane respectively, is described by a kinetic model. Arrhenius parameters for the two abstraction reactions

and

were determined by a competition method:

Experimental and modeling results are discussed with respect to former studies on the thermal reaction of 1‐chloro‐1,1‐difluoroethane.
Kinetics and mechanism of formation and decay of 2,2′‐azinobis‐(3‐ethylbenzothiazole‐6‐sulphonate) radical cation in aqueous solution by inorganic peroxides
Authors: Venkatasubramanian Lakshmanan , Maruthamuthu Pichai 
Published: January 2005

AbstractThe kinetics of oxidation of 2,2′‐azinobis‐(3‐ethylbenzothiazole‐6‐sulphonate) (ABTS) by the inorganic peroxides, peroxomonosulphate, peroxodisulphate, peroxodiphosphate, and hydrogen peroxide were investigated in aqueous solution. The kinetics of formation of the radical cation, ABTS.+, on one‐electron abstraction by these peroxides and the further reaction of ABTS.+ with higher concentrations of these peroxides at longer time scale were studied by following the growth and decay of the radical cation, ABTS.+ at 417 nm. The rate of formation of ABTS.+ was found to obey a total second‐order, first‐order each in [ABTS] and [peroxide], except for H2O2, which reacted through Michaelis‐Menten kinetics. All the peroxides investigated were found to react with ABTS.+; however peroxodisulphate alone oxidized ABTS.+ to the dication (ABTS++), the other peroxides reacted via ionic mechanism, probably forming sulphoxide and sulphone as products. The kinetics of decay of the radical cation, ABTS.+, was also found to follow a total second‐order, first‐order each in [ABTS.+] and [peroxide], except peroxodiphosphate the reaction of which obeyed Michaelis‐Menten kinetics. The effect of pH and temperature were also investigated in all the systems and the kinetic and thermodynamic parameters were evaluated and discussed with suitable reaction mechanisms.
Rate constants for hydrogen abstraction reactions of the sulfate radical, SO4−. Alkanes and ethers
Authors: Huie Robert E. , Clifton Carol L. 
Published: January 2005

AbstractRate constants have been determined for the reactions of SO4− with a series of alkanes and ethers. The SO4− radical was produced by the laser‐flash photolysis of persulfate, S2O82−. For methane, only an upper limit of 1 × 106 M−1 s−1 could be determined. For ethane, propane, and 2‐methylpropane, rate constants of 0.44, 4.0, and 10.5 × 107 M−1 s−1 were found. For ethyl and n‐propyl ether, rate constants of 1.3 × 108 and 2.2 × 108 M−1 s−1 were found and for 1,4‐dioxane and tetrahydrofuran, rate constants of 7.2 × 107 and 2.8 × 108 were obtained. The reaction of SO4− with allyl alcohol was also studied and found to have a rate constant of 1.4 × 109 M−1 s−1.
Nitroarene products from the gas‐phase reactions of volatile polycyclic aromatic hydrocarbons with the OH radical and N2O5
Authors: Arey Janet , Zielinska Barbara , Atkinson Roger , Aschmann Sara M. 
Published: January 2005

AbstractThe nitroarene products of the gas‐phase reactions of acenaphthylene, acenaphthene, phenanthrene, and anthracene‐d10 with N2O5 and the OH radical (in the presence of NOx) are reported. The calculated atmospheric lifetimes of these polycyclic aromatic hydrocarbons (PAH), as well as those of naphthalene, 1‐ and 2‐methylnaphthalene, biphenyl, fluoranthene, pyrene, and acephenanthrylene, show that reaction with the OH radical is the dominant loss process for these PAH, with the exception of acenaphthylene, acenaphthene, and acephenanthrylene which contain an external cyclopenta‐fused ring. For these latter PAH, reaction with the NO3 radical, and for acenaphthylene and acephenanthrylene reaction with O3, are also expected to be important atmospheric loss processes.The nitroarenes observed as products of the atmospherically‐important gas‐phase reactions of the PAH in environmental chamber studies are compared with the nitroarenes measured in ambient air samples collected in California. It is concluded that although nitroarenes are formed in low yields (≲5%) from the OH radical‐initiated reactions of the PAH, atmospheric formation of nitroarenes may contribute significantly to ambient nitroarene concentrations.
Decomposition of 1,1,2,2‐tetrafluorocyclopropane. Arrhenius parameters and their influence on the chemical activation results
Authors: Boaglio D. G. , Arbilla G. , Ferrero J. C. , Staricco E. H. 
Published: January 2005

AbstractThe kinetics of the gas‐phase thermal decomposition of 1,1,2,2‐tetrafluorocyclopropane (TFC) to 1,1‐difluoroethylene and CF2 was studied in the temperature range of 507.0‐577.0 K and with a total pressure of 200 to 300 torr of a 1:100 mixture of reactant and C2H4. Also at 557.0 K experiments were made at different total pressures, in the range 2–20 torr with neat TFC and between 20–300 torr with the C2H4/TFC mixture, confirming that the reaction is in the high pressure limit. The reaction is first‐order and the rate constants fit the following Arrhenius relationship:

From this value of the activation energy, the data for the decomposition of chemically activated TFC were revised. The new results yield a minimum energy of the activated molecule of 98 ± 4 kcal/mol and ΔH(TFC) = −155.4 ± 7 kcal/mol, while an analysis of the kinetic data yields ΔH(TFC) = −159 ± 9 kcal/mol.
Rate constants for the reactions of the OH radical with the propyl and butyl nitrates and 1‐nitrobutane at 298 ± 2 k
Authors: Atkinson Roger , Aschmann Sara M. 
Published: January 2005

AbstractUsing a relative rate method, rate constants for the gas‐phase reactions of the OH radical with 1‐ and 2‐propyl nitrate, 1‐ and 2‐butyl nitrate and 1‐nitrobutane have been determined in the presence of one atmosphere of air at 298 ± 2 K. Using rate constants for the reactions of the OH radical with propane and cyclohexane of 1.15 × 10−12 and 7.49 × 10−12 cm3 molecule−1 s−1, respectively, following rate constants (in units of 10−12 cm3 molecule−1 s−1) were obtained: 1‐propyl nitrate, 0.62; 2‐propyl nitrate, 0.41; 1‐butyl nitrate, 1.78; 2‐butyl nitrate, 0.93; and 1‐nitrobutane, 1.35. These rate constants are compared and discussed with the literature data.
Micellar effects upon the basic hydrolysis of 2,7‐bis(diethylamino)phenazoxonium chloride
Authors: Cuenca Angela 
Published: January 2005

AbstractThe effect of cationic and anionic surfactants on the reaction of Basic Blue 3 (2,7‐bis(diethylamino)phenazoxonium chloride, 1) with hydroxide ion has been studied. Cetyltrimethylammonium bromide (CTAB), cetyl and tetradecyltrimethylammonium chloride (CTAC and MTAC) enhance the rate of basic hydrolysis whereas sodium dodecyl sulfate (SDS) has an inhibitory effect. The extent of micellar catalysis is reduced by the addition of organic solvents. The results have been analyzed on the basis of the pseudophase ion‐exchange model [1–3].
Determination of the rates of formation of gaseous products from the pyrolysis of octahydro‐1, 3, 5, 7‐tetranitro‐1, 3, 5, 7‐tetrazocine (hmx) by simultaneous thermogravimetric modulated beam mass spectrometry
Authors: Behrens Richard 
Published: January 2005

AbstractThe method for determining the rates of formation of gaseous pyrolysis products during thermal decompositions by simultaneous thermogravimetric modulated beam mass spectrometry is presented. The analysis procedure that handles both molecular and continuum flow from the reaction cell is described. The technique is illustrated with the isothermal decomposition of HMX. The temporal behaviors of the rates of formation of the pyrolysis products, H2O, HCN, CO, CH2O, NO, N2O, methylformamide, C2H6N2O, and octahydro‐1‐nitroso‐3, 5, 7‐trinitro‐1, 3, 5, 7‐tetrazocene, formed during the isothermal decomposition of HMX at 211°C, are presented. The results show that a complex condensed‐phase reaction mechanism controls the decomposition.
The kinetics of successive addition of methyloxirane or ethyloxirane to alkanethiols in the presence of basic catalysts
Authors: Chlebicki Jan , Cichacz Zbigniew 
Published: January 2005

AbstractRate constants and activation parameters for the direct addition reaction of methyloxirane or ethyloxirane to alkyl‐2‐hydroxyalkyl sulfides or successive oxypropylene and oxybutylene adducts in the presence of basic catalysts were determined at 373–403 K. This reaction was found to be of the first order with respect to alkyloxirane, sulfide, and catalyst.
Excimer laser‐induced temperature jump‐measurements on the recombination kinetics of the gas‐phase FSO3 + FSO3 ⇔ F2S2O6 equilibrium between 415 and 525 K
Authors: Cobos C. J. , Croce A. E. , Castellano E. 
Published: January 2005

AbstractThe kinetics of the recombination reaction corresponding to the FSO3 + FSO3 ⇔ F2S2O6 equilibrium system has been studied. A time‐resolved absorption spectroscopy technique was employed to monitor the appearance of thermally generated FSO3 radicals at 450 nm following a small temperature jump induced after partial laser photodissociation of F2S2O6 at 193 rim. The recombination rate constants have been determined over the temperature range 415–525 K and a N2 pressure range 10–600 torr. The reaction was found to be in its first order regime. The resulting limiting high pressure rate constants were combined with previous values measured in this laboratory at lower temperatures yielding the expression 𝓀rec, x = (4.5 ± 0.2) × 10−14 (T/300)(1.0 ± 0.1) cm3 molecule−1 s−1 between 293 and 525 K. The temperature coefficient of 𝓀rec, x is smaller than the one derived from steady‐state experiments of the thermal dissociation of F2S2O6 and the equilibrium constant of the system. A recently formulated version of the canonical statistical adiabatic channel model was used to interprete the rate constants.
Homogeneous pyrolysis of acetylacetone at high temperatures in shock waves
Authors: Choudhury T. K. , Lin M. C. 
Published: January 2005

AbstractThe kinetics of the thermal decomposition of acetylacetone has been studied in a shock tube in the temperature range of 1120–1660 K. Detailed analyses of CO and H2O formation data indicate that H2O is formed by a four‐center molecular channel, whereas CO is formed by the rapid dissociation of CH3CO produced by the CC bond dissociation of acetylacetone. The Arrhenius equations for H2O and CH3CO formation channels are 𝓀2 = 1014.24±0.21 exp(−60,800 ± 1,220/RT)sec−1 and 𝓀3 = 1017.05±0.28 exp(−74,600 ± 1,680/RT) sec−1, respectively. The results of the study suggest that the six‐center molecular channel for the production of acetone and ketene is not important under the condition used in this investigation.
Ethylene pyrolysis and oxidation: A kinetic modeling study
Authors: Dagaut Philippe , Boettner Jean‐Claude , Cathonnet Michel 
Published: January 2005

AbstractEthylene oxidation and pyrolysis was modeled using a comprehensive kinetic reaction mechanism. This mechanism is an updated version of one developed earlier. It includes the most recent findings concerning the kinetics of the reactions involved in the oxidation of ethylene. The proposed mechanism was tested against ethylene oxidation experimental data (molecular species concentration profiles) obtained in jet stirred reactors (1–10 atm, 880–1253 K), ignition delay times measured in shock tubes (0.2–12 atm, 1058–2200 K) and ethylene pyrolysis data in shock tube (2–6 atm, 1700–2200 K). The general prediction of concentration profiles of minor species formed during ethylene oxidation is improved in the present model by using more accurate kinetic data for several reactions (principally: HO2 + HO2 → H2O2 + O2, C2H4 + OH → C2H3 + H2O, C2H2 + OH → Products, C2H3 → C2H2 + H).
A flash photolysis resonance fluorescence investigation of the reactions of Oxygen O(3P) atoms with aliphatic ethers and diethers in the gas phase
Authors: Liu Renzhang , Dagaut Philippe , Huie Robert E. , Kurylo Michael J. 
Published: January 2005

AbstractRate constants for the gas phase reCedex 2, Franceactions of O(3P) atoms with a series of symmetric aliphatic ethers have been determined using the flash photolysis resonance fluorescence technique over the temperature range 240–400 K. The Arrhenius parameters derived from these data are (in units of cm3 molecule −1 s−1):

The error limits are two standard deviations derived from the least‐squares fit. Rate constants for several other ethers were determined only at 298 K. The values obtained were (in units of 10−14 cm3 molecule−1 s−1): tetrahydrofuran (37.5 ± 1.1); 1,4−dioxane 1(6.81 ± 0.46); diethoxymethane (40.4 ± 1.8); ethyl ‐t‐butyl ether (37.0 ± 1.3); and methyl‐t‐amylether (57.3 ± 2.3).
Determination of the absolute concentration of O atoms and OH radicals in laboratory studies
Authors: Canosa‐Mas Carlos E. , Wayne Richard P. 
Published: January 2005

AbstractThe fast reaction of O atoms with NO2 has been used in measurements of absolute concentrations of O atoms. Similarly, the reaction of H with NO2 can be used to generate OH radicals in known concentrations. Relative concentrations of both O atoms and OH radicals have frequently been measured by resonance fluorescence determinations in the ultra‐violet. It will be shown that the stoichiometry of these reactions is strongly dependent on the initial concentration of reactants and on the contact time (in the case of OH on secondary reactions as well), making it impossible to equate directly the loss of NO2 with the loss of O atoms or the production of OH radicals.In the first part of this work a simple analytical mathematical method for the determination of the concentration of atomic oxygen will be developed. The method is based on the integrated second order kinetic equation, and the effect of the experimental conditions on the results is discussed.In the second part, the production of OH as a function of contact time and of the initial concentrations of H and NO2 is examined using a five reaction mechanism. By careful choice of the initial concentrations of reactants it is possible to reproduce the experimental results using simplified analytical expressions for the concentration of OH and hence to calculate a calibration factor.The importance of carrying out the calibration measurements under the same experimental conditions as those employed in kinetic experiments is highlighted.
Kinetics and mechanism of silver(I) catalyzed oxidation of water with bismuth(V) in HClO4HF mixture
Authors: Inani K. M. , Gupta Y. K. , Sharma P. D. 
Published: January 2005

AbstractThe kinetics of the oxidation of water with bismuth(V) in presence of silver(I) has been investigated in a mixture of HClO4 (1.0 mol dm−3) and HF (1.5 mol dm−3). The reaction is second order, viz., first order with respect to bismuth(V) and silver(I), each, and the second order rate constant is (6.6 ± 0.7) × 10−3 dm3 mol−1 s−1. However, rate is independent of hydrogen ion concentration. A comparative analysis of these results with the results obtained for pdp, pds, and Ce(IV), reactions with silver(I) has also been made to correlate the rate constants and the redox‐potentials of the oxidant couples.
Kinetics of Iron‐catalyzed decomposition of hydrogen peroxide in alkaline solution
Authors: Abbot J. , Brown D. G. 
Published: January 2005

AbstractThe decomposition of alkaline hydrogen peroxide solutions at 20°C has been studied in the presence of both supported iron catalysts and in systems with iron initially in solution. Studies with an iron‐alumina supported catalyst showed the decomposition reaction was first order with respect to total peroxide concentration, while studies with alkaline Fe3+ produced more complex behavior. This has been attributed to the presence of at least two distinct catalytically active iron species. The first species is highly active and gives rise to high initial rates of reaction. A decrease in concentration of this species is observed together with an increase in concentration of a second, less active, iron species. The catalytic behavior of this “aged” iron species was found to be very similar to that of the supported iron catalyst.