bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonlinear structure–reactivity correlations. The hydrolysis of 2,4,6‐trinitrophenyl acetate catalyzed by general bases
Authors: De Rossi Rita H. , Nuñez Alberto 
Published: January 2005

AbstractThe hydrolysis of 2,4,6‐trinitrophenyl acetate was studied in the presence of several carboxylic bases and tertiary amines. Carboxylic bases pyridine and imidazole react as nucleophilic catalysts, while 2,4‐dimethyl and 2,4,6‐trimethyl pyridine react as general‐base catalysts. The nonlinear structure–reactivity correlations (log kcat versus log kOH and log kcat versus pK of the leaving group) for the series of aryl acetates are discussed, and it is suggested that there is a change in transition‐state structure along the series.
Third‐order rate constants of atmospheric importance
Authors: Patrick Roger , Golden David M. 
Published: January 2005

AbstractInput data and results are presented for the calculation of a number of third‐order rate constants of atmospheric interest using Troe′s approximate method. A comparison with experimental data indicates that this approach provides a reliable method for predicting unknown rate constants and estimating temperature dependences. These calculations form the basis of the recommendations of the NASA review panel for third‐order rate constants to be used in atmospheric modeling.
The gas‐phase decomposition of methylsilane. Part II. Mechanisms of decomposition under static system conditions
Authors: Sawrey B. A. , O'Neal H. E. , Ring M. A. 
Published: January 2005

AbstractThe static system pyrolysis of methylsilane (T ∼ 700 K, PT ∼ 150 torr), pure and in the presence of ethylene, propylene, and acetylene, has been investigated. It is proposed that in the uninhibited system, the major products (silane and dimethylsilane) are produced by free radical processes, and that the free radicals are formed at the walls from methylsilylenes. In the presence of olefins, the free radicals are trapped to form methylsilane adducts. In acetylene, trapping of methylsilylenes prevents free radical production and eliminates the free radical produced products of the pure and the olefin inhibited systems. Rates of initiation correlate with rates of reactant loss in acetylene inhibited systems, and with rates of hydrogen formation in olefin inhibited systems. Rough estimates of primary dissociation process yields give for the 1,1‐H2 elimination ϕ1,1 ≅ 0.78, for the 1,2‐H elimination ϕ1,2 ≅ 0.16, and for the methane elimination ϕCH4 ≅ 0.06 at 700 K. Deuteration lowers initial step kinetics by about 15%.
Reaction of carbon monoxide with ozone and oxygen atoms
Authors: Toby Sidney , Sheth Shailesh , Toby Frina S. 
Published: January 2005

AbstractThe reaction between ozone and carbon monoxide was reinvestigated in the range of 80–160°C. The previously reported rate law −d[O3]/dt = ka[O3][CO] + kb[O3]2 was confirmed and simulated using a mechanism based on an impurity‐initiated chain reaction. When the CO was sufficiently purified, kb tended to zero and ka reduced to the value expected for the thermal decomposition of O3. Subsequent reactions of O atoms with CO produced chemiluminescence which was used to measure k3 for

as 10−14.0±0.3 exp[−(1630 ± 325)/T] cm3 molecule−1 s−1. The implications of this are discussed.
Updated chemical mechanism for atmospheric photooxidation of toluene
Authors: Leone Joseph A. , Seinfeld John H. 
Published: January 2005

AbstractA new reaction mechanism describing the atmospheric photochemical oxidation of toluene is formulated and tested against environmental chamber data from the University of California, Riverside, Statewide Air Pollution Research Center (SAPRC). On simulations of toluene—NOx and toluene—benzaldehyde—NOx irradiations, the average predicted O3 and PAN maxima are within 3% of the experimental values. Simulations performed with the new mechanism are used to investigate various mechanistic paths, and to gain insight into areas where our understanding is not complete. Specific areas that are investigated include benzaldehyde photolysis, organic nitrate formation, alternate ring fragmentation pathways, and conjugated γ‐dicarbonyl condensation to the aerosol phase.
Kinetics and mechanism of the reaction of aqueous sulfite with N‐chloroalanylalanylalanine
Authors: Stanbro William D. , Lenkevich Michael J. 
Published: January 2005

AbstractThe rate of the reaction of aqueous sulfite with the N‐chloropeptide N‐chloroalanylalanylalanine has been studied as a function of pH, temperature, and ionic strength. The results of this work suggest that the mechanism of the reaction involves the interaction of the neutral chloramine with the three ionic forms of sulfite, SO, HSO, and H2SO3, with the rate of reaction increasing rapidly with increasing protonation. The estimated second‐order rate constants for each ionic species as a function of temperature are

where the activation energies are in units of cal/mol.
Rate constants for the reactions of O3 and OH radicals with a series of alkynes
Authors: Atkinson Roger , Aschmann Sara M. 
Published: January 2005

AbstractRate constants for the reactions of O3 and OH radicals with acetylene, propyne, and 1‐butyne have been determined at room temperature. The rate constants obtained at 294 ± 2 K for the reactions of O3 with acetylene, propyne, and 1‐butyne were (7.8 ± 1.2) × 10−21 cm3/molecule · s, (1.43 ± 0.15) × 10−20 cm3/molecule · s, and (1.97 ± 0.26) × 10−20 cm3/molecule · s, respectively. The rate constants at 298 ± 2 K and atmospheric pressure for the reactions with the OH radical, relative to a rate constant for the reaction of OH radicals with cyclohexane of 7.57 × 10−12 cm3/molecule · s, were determined to be (8.8 ± 1.4) × 10−13 cm3/molecule · s, (6.21 ± 0.31) × 10−12 cm3/molecule · s, and (8.25 ± 0.23) × 10−12 cm3/molecule · s for acetylene, propyne, and 1‐butyne, respectively. These data are discussed and compared with the available literature rate constants.
Mechanism and kinetics of the shock‐tube decomposition of vinylsilane
Authors: Rickborn S. F. , Ring M. A. , O'Neal H. E. , Coffey D. 
Published: January 2005

AbstractThe shock‐induced thermal decompositions of vinylsilane and vinylsilane‐d3 (0.2% on argon) have been studied in the temperature range of 1085–1275 K, and at total pressures of about 3100 torr. In systems without silylene traps, some induced decomposition occurs which is attributed to the silylene chain sequence VSiH → C2H2 + SiH2, S̈iH2 + VSiH3 ⇄ VSiH2SiH3 → VSiH2S̈iH + H2, VSiH2S̈iH → VSiH + S̈iH2. In the presence of silylene traps (butadiene and acetylene), the overall decomposition kinetics are log k(VSiH3, s−1) = 14.95 − 63,268 cal/2.303RT and log k(VSiD3, s−1) = 15.14 − 64,815 cal/2.303RT. Three primary processes contribute to the decomposition: 1,1‐H2 elimination, 1,2‐H2 elimination, and ethylene elimination. Two mechanisms are proposed, one for exclusive primary process formation of C2H4, and the other for both primary and secondary formation routes. Modeling studies are reported which show that both mechanisms can be made compatible with the rate and product yield data within experimental errors.
Reaction of CF3 radicals with H2S
Authors: Arican Haluk , Arthur Neville L. 
Published: January 2005

AbstractHydrogen abstration from H2S by CF3 radicals, generated by the photolysis of both CF3COCF3 and CF3I, has been studied in the temperature range 314–434 K. The rate constant, based on the value of 1013.36 cm3/mol · s for the recombination of CF3 radicals, is given by

with CF3COCF3 as the radical source, and

with CF3I as the radical source, where k2 is in cm3/mol · s and E is in J/mol. These results resolve a previously existing controversy concerning the values of the rate constants for this reaction. They show that CF3 radicals are less reactive than CH3 radicals in attacking H2S, and this behavior indicates that polar effects play a significant role in the hydrogen transfer reactions of CF3 radicals.
Cyanogen pyrolysis and the CN + NO reaction behind incident shock waves
Authors: Colket M. B. 
Published: January 2005

AbstractThe reaction chemistry of C2N2Ar and C2N2NOAr mixtures has been investigated behind incident shock waves. Progress of the reaction was monitored by observing the cyano radical (CN) in absorption at 388.3 nm. A quantitative spectroscopic model was used to determine concentration histories of CN. From initial slopes of CN concentration during cyanogen pyrolysis, the rate constant for C2N2+ M → 2CN + M (1) was determined to bek1= (4.11 ± 1.8) × 1016exp(−47,070 ± 1400/T) cm3/mol · s. A reaction sequence for the C2N2NO system was developed, and CN profiles were computed. By comparison with experimental CN profiles the rate constant for the reaction CN + NO → NCO + N (3) was determined to bek3= 10(14.0 ± 0.3)exp(−21,190 ± 1500/T) cm3/mol · s. In addition, the rate of the four‐centered reaction CN + NO → N2+ CO (2) was estimated to be approximately three orders of magnitude below collision frequency.
The reactions of isotopically labeled N15NO+ with CO, NO, O2, N2, NO2, and N2O
Authors: Kemper Paul R. , Bowers M. T. 
Published: January 2005

AbstractThe reactions of labeled N15NO+ with CO, NO, O2, 18O2, N2, NO2, and N2O have been investigated using a tandem ICR instrument. In each case the total rate coefficient, product distribution, and kinetic energy dependence were measured. The results indicate that very specific reaction mechanisms govern these reactions. This conclusion is suggested by the lack of isotopic scrambling in many cases and by the complete absence of energetically allowed products in almost all of the systems. The kinetic energy studies indicate that most of the reaction channels proceed through an intermediate complex at low energies and via a direct mechanism at higher kinetic energies. Such direct mechanisms include long range charge transfer and atom or ion transfer.
Ebulliometric study of the decomposition of urea in aqueous media
Authors: de Azevedo Francisco G. , de Oliveira Walace A. 
Published: January 2005

AbstractBoiling‐temperature measurements have been used to study the kinetics of the decomposition of urea. Values for the rate constants in neutral, acid, and basic media have been obtained and compared with literature data. The effect of the reverse reaction on the value of the experimental rate constants is discussed. The profile of the ebulliometric curves is different for the three media and is correlated with the number of various species present in solution. It is concluded that ebulliometric measurements can be useful for kinetic studies.
The reactions of S(3PJ) atoms with thiiranes
Authors: Van Roodselaar A. , Safarik I. , Strausz O. P. 
Published: January 2005

AbstractThe reactions of ground‐state S(3PJ) atoms with thiirane, methylthiirane, and trans‐2,3‐dimethylthiirane have been studied by flash photolysis‐VUV kinetic absorption spectroscopy. From the analysis of the S(3PJ) decay plots the following rate constants were determined: (1.4 ± 0.2) × 1013, (2.7 ± 0.3) × 1013 and (4.0 ± 0.2) × 1013 (in cm3 mol−1 s−1 units) for thiirane, methylthiirane and trans‐2,3‐dimethylthiirane, respectively, showing an upward trend with increasing methylation.
Basic hydrolysis of glyceryl nitrate esters. II. 1,2‐glyceryl and 1, 3‐glyceryl dinitrate esters
Authors: Capellos C. , Fisco W. J. , Ribaudo C. , Hogan V. D. , Campisi J. , Murphy F. X. , Castorina T. C. , Rosenblatt D. H. 
Published: January 2005

AbstractKinetics of the basic hydrolysis of 1,2‐glyceryl dinitrate (1,2‐DNG) and 1,3‐glyceryl dinitrate (1,3‐DNG) esters were investigated in CO2‐free aqueous calcium hydroxide solutions. The hydrolysis reactions were carried out in a temperature controlled reactor vessel with provision for continuous N2 sparging of the reaction mixture. Both glyceryl dinitrate esters hydrolyzed via second‐order reaction at 25°C. 1,2‐DNG in basic solutions isomerized to 1,3‐DNG which subsequently hydrolyzed to yield products. The main hydrolysis product of 1,3‐DNG was identified as glycidyl nitrate. Other products formed during the basic hydrolysis of DNGs were nitrites and nitrates.
Thermal decomposition of methyl nitrite in shock waves studied by laser probing
Authors: Hsu D. S. Y. , Burks G. L. , Beebe M. D. , Lin M. C. 
Published: January 2005

AbstractThe unimolecular decomposition of methyl nitrite in the temperature range 680–955 K and pressure range 0.64 to 2.0 atm has been studied in shock‐tube experiments employing real‐time absorption of CW CO laser radiation by the NO product. Computer kinetic modeling using a set of 23 reactions shows that NO product is relatively unreactive. Its initial rate of production can be used to yield directly the unimolecular rate constant, which in the fall‐off region, can be represented by the second‐order rate coefficient in the Arrhenius form:

A RRKM model calculation, assuming a loose CH3ONO≠ complex with two degrees of free internal rotation, gives good agreement with the experimental rate constants.
A pulse radiolysis study of I and (SCN) in aqueous solutions over the temperature range 15–90°C
Authors: Elliot Allen John , Sopchyshyn Frederick Charles 
Published: January 2005

AbstractThe extinction coefficients and the decay kinetics of I and (SCN) have been characterized over the 15–90°C‐temperature range. The extinction coefficients of I at 385 and 725 nm were determined to be 10,000 and 2560M−1 cm−1, respectively, based on the extinction coefficient of (SCN) at 475 nm being equal to 7600M−1 cm−1. At these three wavelengths, all extinction coefficients were constant over the temperature range studied. The rate of decay of both I and (SCN) was found to be a function of I− and SCN− concentration, respectively, as well as temperature.
Mechanism of propane oxidation–mathematical modeling
Authors: Levitsky A. A. , Polyak S. S. , Shtern V. Ya. 
Published: January 2005

AbstractMathematical modeling was used for the kinetics of gas‐phase propane oxidation at 586, 613, and 658 K and pressures 172 and 250 torr. The reaction mechanism involving branching by decay of the peracetyl peroxy radical, and oxygen‐containing products formed on decay of the RO4 radical is discussed. Fair agreement between calculated and experimental results on the kinetics and accumulation rates of reaction products was obtained.
Conversion effect on the reaction CF3 + HCN. Analysis of I2 and I participation with CF3I as radical source
Authors: Lane S. I. , Oexler E. V. , Staricco E. H. 
Published: January 2005

AbstractThe gas‐phase reaction of CF3 with HCN has been examined over a wide conversion range using CF3I as a thermal and photolytic source of radicals. Quantitative and qualitative results show a significant increase of the specific rate constant for the hydrogen abstraction reaction relative to CF3 recombination when reaction is carried out under ultraviolet irradiation. This “extra” formation of the reaction product, CF3H, has been assigned to the participation of iodine in this system through the formation of a (I‐HCN) intermediate. Arrhenius parameters obtained for the addition mechanism of I to HCN do not seem to conform to a single reaction step, on the contrary, they correspond to a more complex reaction scheme.
The kinetics and mechanism of the shock induced gas phase decomposition of ethylsilane
Authors: Rickborn S. F. , Ring M. A. , O'Neal H. E. 
Published: January 2005

AbstractThe decomposition kinetics of ethylsilane under shock tube conditions (PT ca. 3100 torr, T ≃ 1080–1245 K), both in the absence and presence of silylene trapping agents (butadiene and acetylene) are reported. Arrhenius parameters under maximum butadiene inhibition are: log k(C2H5SiH3) = 15.14‐64,769 ± 1433 cal/2.303 RT; log k(C2H5SiD3) = 15.29‐66,206 ± 1414/2.303 RT. The uninhibited reaction is subject to silylene induced decomposition (63% lowest T ‐‐ 24% highest T). Major reaction products are ethylene and hydrogen, consistent with two dominant primary dissociation reactions: C2H5SiD3 → C2H5SiD + D2, ϕ ≃ 0.66; C2H5SiD3 → CH3CH = SiD2 + HD, ϕ ≃ 0.30. Minor products suggest several other less important primary processes: alkane elimination, ϕ ≃0.02, and free‐radical production via simple bond fission, ϕ ≃0.02. An upper limit for the activation energy of the decomposition, C2H5SiH → C2H4 + SiH2, of E < 30 ± 4 kcal is established, and speculations on the mechanism of this decomposition (concerted or stepwise) with conclusions in favor of the stepwise path are made. Computer modeling studies for the reaction both in the absence and presence of butadiene are shown to be in good agreement with the experimental observations.
Products and mechanism for the OH radical initiated oxidation of acrylonitrile, methacrylonitrile, and allylcyanide in the presence of NO
Authors: Hashimoto Satoshi , Bandow Hiroshi , Akimoto Hajime , Weng Jian‐Hua , Tang Xiao‐Yan 
Published: January 2005

AbstractThe photooxidation of acrylonitrile, methacylonitrile, and allylcyanide in the presence of NO was studied in parts per million concentration using the long‐path Fourier transform IR spectroscopic method. The stoichiometry of the OH radical initiated oxidation of methacrylonitrile was established as \documentclass{article}\pagestyle{empty}\begin{document}$ \left( {{\rm OH}} \right) + {\rm CH}_{\rm 2} = {\rm C}\left( {{\rm CH}_{\rm 3} } \right){\rm CN + 2NO + 2O}_{\rm 2} \mathop {\hbox to 20pt{\rightarrowfill}}\limits^{1.0} {\rm HCHO + CH}_{\rm 3} {\rm COCN + 2NO}_{{\rm 2}} + \left( {{\rm OH}} \right) $\end{document}. The yield of HCHO for acrylonitrile and allylcyanide was found to be ca. 100 and 80%, and the stoichiometric reactions were assessed to proceed, \documentclass{article}\pagestyle{empty}\begin{document}$ \left( {{\rm OH}} \right) + {\rm CH}_{\rm 2} = {\rm CHCN + 2NO + 2O}_{\rm 2} \mathop {\hbox to 20pt{\rightarrowfill}}\limits^{1.0} {\rm HCHO + HCOCN + 2NO}_{\rm 2} + \left( {{\rm OH}} \right) $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ \left( {{\rm OH}} \right) + {\rm CH}_{\rm 2} = {\rm CHCH}_{\rm 2} {\rm CN + 2NO + 2O}_{\rm 2} \mathop {\hbox to 20pt{\rightarrowfill}}\limits^{0.8} {\rm HCHO + HCOCH}{\rm 2} {\rm CN + 2NO}_{\rm 2} + \left( {{\rm OH}} \right) $\end{document}, respectively. These results revealed that the reaction mechanism for these unsaturated organic cyanides are analogous to that of olefins.
High‐pressure range of the recombination O + O2 → O3
Authors: De Cobos A. E. Croce , Troe J. 
Published: January 2005

AbstractThe recombination reaction O + O2 → O3 was studied by laser flash photolysis of pure O2 in the pressure range 3–20 atm, and of N2OO2 mixtures in the bath gases Ar, N2, (CO2, and SF6) in the pressure range 3–200 atm. Fall‐off curves of the reaction have been derived. Low‐pressure rate coefficients were found to agree well with literature data. A high‐pressure rate coefficient of k∞ = (2.8 ± 1.0) × 10−12 cm3 molecule−1 s−1 was obtained by extrapolation.
On the temperature dependence of the activation enthalpy for sucrose hydrolysis
Authors: Ward J. Richard 
Published: January 2005

AbstractRecent interest in the measurement and the interpretation of heat capacities of activation has led to more rigorous methods to detect temperature‐varient activation parameters. One such method devised by Blandamer and co‐workers was applied to the sucrose hydrolysis data of Moelwyn‐Hughes and Leininger and Kilpatrick. Both sets of investigators claimed that the energy of activation for sucrose inversion decreased with increasing temperature, while Heidt and Purvis and more recently, Kuhler's group contend that the energy of activation is constant. It was found that neither the data of Moelwyn‐Hughes nor of Leininger and Kilpatrick warrant the inclusion of a temperature‐dependent activation enthalpy.
Kinetics study of the reaction HO + HNO3
Authors: Connell Peter S. , Howard Carleton J. 
Published: January 2005

AbstractThe reaction
equation image
has been studied using a discharge‐flow tube with resonant fluorescence detection of HO. Measurements of k1 have been made at temperatures between 237 and 404 K. Our results and earlier work suggest that the rate constant has a minimum at T ≃ 500 K. Below room temperature our results are given by the expression k = (2.0 ± 0.4) × 10−14 exp[(430 ± 60)/T] cm3 molecule−1 s−1, where the error limits include an estimate of the measurement accuracy. No dependence of k1 on pressure at 300 K is observed in studies between 1‐ and 10‐torr helium. An upper limit of kb < 1% k1 at 300 K is given.
Decomposition of chemically activated dimethylcyclopropane molecules vibrationally excited to various extent
Authors: Bérces T. , Szilágyi I. , Zalotai L. , Márta F. 
Published: January 2005

AbstractThe photolyses of ketene (at 313 and 280 nm) and diazirine at 313 nm in the presence of cis‐butene‐2 were studied. Vibrational relaxation of chemically activated dimethylcyclopropane was shown to occur as a multistep process, and 17 ± 4 kJ mol−1 was obtained for the average energy transferred per collision with butene‐2 collider. Activated cis‐dimethylcyclopropane is formed in the reaction of singlet methylene and cis‐butene‐2 with broad energy distribution which originates from the energy partitioning in the photolytic act. About 30% of the energy released in the photolysis of the methylene source is carried by singlet methylene as vibrational energy at the time of reaction, and this fraction was found to be practically independent of the radical source.
Pyrolysis of 1‐chloro‐1,1‐difluoroethane in the absence and in the presence of CCl4 and mixtures of CCl4 + HCl
Authors: Huybrechts G. , Hubin Y. 
Published: January 2005

AbstractThe thermal dehydrochlorination CF2ClCH3 → CF2  CH2 + HCl has been studied in a static system between 637 and 758 K. It is a homogeneous, molecular first‐order reaction and its rate constant is given by

This reaction has also been studied in the presence of CCl4 and mixtures of CCl4 and HCl between 585 and 662 K. It is then accelerated and the initial rate increase is given by

with log10 (k′, L½ /mol½ · s) = −(41,650 ± 180)/4.576T + (10.84 ± 0.06) and log10 k″ = (7900 ± 180)/4.576T − (0.59 ± 0.06). A radical chain mechanism is shown to be consistent with these latter results.
The kinetic and mechanism of the gas phase pyrolysis of 1,1,1,2‐tetrachloropropane
Authors: Domínguez Rosa M. , Chuchani Gabriel 
Published: January 2005

AbstractThe gas phase pyrolysis of 1,1,1,2‐tetrachloropropane was studied in a static system and seasoned vessel over the temperature range of 393.0–452.8°C and pressure range of 27.5–118.5 torr. The reaction is homogeneous, unimolecular, follows a first‐order rate law, and is not affected by the presence of the free radical inhibitor, toluene, or propene. The main dehydrochlorination products are 1,1,1‐trichloro‐2‐propene and 1,1,2‐trichloro‐1‐propene. The temperature dependence of the rate coefficient is given by the Arrhenius equation

The Arrhenius parameters of this reaction are apparently low. Consequently, in estimating the transition state of A = 1013.5, the following expression is obtained

The partial rates and kinetic parameters for the parallel elimination products have been estimated and reported. The trichloromethyl substituent has been found to affect this elimination process through its electron withdrawing effect.
Pyrolysis of 2‐phenylethylamines heats of formation of aminomethyl radicals R2NCH2 · (R = H, CH3)
Authors: Grela M. A. , Colussi A. J. 
Published: January 2005

AbstractA kinetic study of the very low‐pressure pyrolysis of ethylbenzene (I), 2‐phenylethylamine (II), and N,N‐dimethyl 2‐phenylethylamine (III)
equation image
above 900 K yields the heats of formation of aminomethyl (A) and N,N‐dimethylaminomethyl (B) radicals: ΔHƒ, 300 K(A) = 30.3 and ΔHƒ, 300 K(B) = 27.5 kcal/mol. The difference of stabilization energies Es, (relative to methyl radicals): Δ = Es(B) − Es(A) = (2 ± 1) kcal/mol, conforms to similar effects in methyl substituted alkyl and amino free radicals.