bluuebunny/crossref_metadata_2025_split huggingface dataset:
Infrared photochemistry of bis(trifluoromethyl) peroxide
Authors: Francisco J. S. , Findeis M. A. , Steinfeld J. I. 
Published: January 2005

AbstractBis(trifluoromethyl) peroxide is readily dissociated by multiple infrared photon excitation at CO2 laser wavelengths. The primary dissociation product is CF3O; approximately 85% of the nascent radicals are further dissociated in the laser field to form CF2O and F. The F atoms then react with the remaining CF3O to produce CF3OF. The formation of CF3OF is strongly inhibited by addition of HI, which reacts preferentially with the F atoms.
Micellar catalyzed enolization of acetone
Authors: Maruthamuthu Meenakshi , Lakshmikanthan N. 
Published: January 2005

AbstractThe acid‐catalyzed enolization of acetone in the presence of bromine is found to be catalyzed by the anionic micelles of sodium dodecyl sulfate. The rate acceleration expected on the basis of lowering of activation energy is largely nullified by the decrease in the entropy of activation, leading to a very small rate enhancement, i.e., kψ/k0 = 1.2 at 30°C. The binding constant for the micelle–substrate complex is determined. The micellar rate enhancement is the same, irrespective of the halogen used, chlorine, bromine, or iodine.
Reactions of the fluorobromocarbene radical studied by laser‐induced fluorescence
Authors: Purdy J. R. , Thrush B. A. 
Published: January 2005

AbstractCFBr radicals produced by the reaction of atomic oxygen with F2CCFBr were monitored in a discharge flow system by fluorescence excited at 424 nm. The rate coefficients for reactions of the CFBr radicals were measured between 298 and 358 K, and the following values were obtained in units of cm3/molec·s: O2 < 2 × 10−16 at 353 K; NO < 10−14 at 298 K; F2CCFBr < 10−15 at 298 K; Cl2 (1.9 ± 0.6) × 10−12 exp(−762 ± 92/T) Br2 (1.4 ± 0.3) × 10−12 exp(−533 ± 62/T).
Substituent effects on the kinetics of the cerium(IV) oxidation of mandelic acids in sulfate media. Anomalous kinetic behavior of the methoxy derivative
Authors: Calvaruso Giuseppe , Cavasino F. Paolo , Sbriziolo Carmelo 
Published: January 2005

AbstractThe kinetics of the cerium(IV) oxidation of p‐nitro and p‐methoxymandelic acids have been investigated in H2SO4‐MHSO4 (M+ = Li+, Na+, K+) and H2SO4‐MClO4 (M+ = H+, Na+) mixtures at a constant total electrolyte concentration of 2.00 mol/dm3. The oxidation of p+nitromandelic acid proceeds through two [H+]‐independent paths, as was also observed for some substituted mandelic acids studied previously. The kinetic behavior of the p‐methoxy derivative differs from that of the other mandelic acids in that (1) the oxidation occurs via two [H+]‐dependent paths, (2) the reaction rate is anomalously high, (3) the activation enthalpy and entropy of the overall process are markedly lower. It provides strong support to the suggestion that a different mechanism is operative. The substituent effects and the reaction mechanism are discussed.
Addition of hot hydrogen atoms to 1‐butene in the gas phase and dissociation of excited butyl radicals
Authors: Gawłowski Janusz , Niedzielski Jan 
Published: January 2005

AbstractThe reaction of hot hydrogen atoms originating from 253.7‐ and 228.8‐nm photolyses of hydrogen sulfide with 1‐butene was investigated. Of the hydrogen atoms undergoing addition a substantial part undergoes it in a first collision (37 and 48% at 253.7 and 228.8 nm, respectively) yielding highly excited butyl radicals. The ratio of nonterminal to terminal addition is 0.5 and practically does not depend on the energy of the hydrogen atoms over the range of 15–33 kcal/mol. Comparing the results of 229‐ and 254‐nm photolyses of hydrogen sulfide with those of 313‐ and 334‐nm photolyses of hydrogen iodide with the use of the decomposition rate constants of n‐butyl radicals calculated by the RRKM methods, the conclusion is reached that the hydrogen atom from H2S photodissociation has 90–95% of the available energy.
Rate constants for the gas‐phase reactions of O3 with a series of carbonyls at 296 K
Authors: Atkinson Roger , Aschmann Sara M. , Winer Arthur M. , Pitts James N. 
Published: January 2005

AbstractRate constants for the gas‐phase reactions of O3 with the carbonyls acrolein, crotonaldehyde, methacrolein, methylvinylketone, 3‐penten‐2‐one, 2‐cyclohexen‐1‐one, acetaldehyde, and methylglyoxal have been determined at 296 ± 2 K. The rate constants ranged from <6 × 10−21 cm3 molecule−1 s−1 for acetaldehyde to 2.13 × 10−17 cm3 molecule−1 s−1 for 3‐penten‐2‐one. The substituent effects of CHO and CH3CO groups on the rate constants are assessed and discussed, as are implications for the atmospheric chemistry of the natural hydrocarbon isoprene.
H + HOONO2 → products: Temperature‐dependent rate constant
Authors: Trevor Paula L. , Barker John R. 
Published: January 2005

AbstractThe absolute reaction rate constant of the title reaction was measured in a stirred‐flow reactor under H‐atom‐rich conditions at seven temperatures from 226 to 315 K. Carbon monoxide was added to convert any OH radicals produced back to H atom by way of the reaction OH + CO → H + CO2. The reaction rate constants were essentially constant between 248 and 315 K: (k ± 2σ) = (2.46 ± 0.35) × 10−14 cm3/s. At temperatures lower than 248 K, the measured rate constant became larger at lower temperatures, possibly due to heterogeneous effects. An hypothesis is advanced that may explain the surprisingly slow rate constant that is virtually independent of temperature, but more experiments are required to determine the dynamical reaction pathway.
INO thermodynamic properties and ultraviolet spectrum
Authors: Forte E. , Hippler H. , Van Den Bergh H. 
Published: January 2005

AbstractThe equilibrium I2(g) + 2NO(g) = 2INO(g) has been studied at room temperature by ultraviolet absorption spectroscopy. The equilibrium constant has been measured as Kp = (2.7 ± 0.3) × 10−6 atm−1 at 298 K. Third‐law calculations lead to ΔH°f,298 (INO) = 120.0 ± 0.3 kJ/mol. The relative absorption spectrum of INO has been measured between 225 and 300 nm. Quantitative measurements gave ϵ(λmax = 238 nm) = (1.79 ± 0.5) × 104 L/mol·cm and ϵ(410 nm) = 234.7 ± 21 L/mol·cm.
Kinetics and mechanism of reactions between aromatic olefins and hydroxyl radicals
Authors: Bignozzi C. A. , Maldotti A. , Chiorboli C. , Bartocci C. , Carassiti V. 
Published: January 2005

AbstractThe rates of the reactions of hydroxyl radicals (OH) with styrene, α‐methylstyrene, and β‐methylstyrene have been measured by irradiating mixtures of these aromatic olefins and NO in an environmental chamber at 298 K. Experimental conditions were used whereby the competition of ozone with OH in oxidizing the hydrocarbons could be considered negligible. The rate constant values, obtained by a relative method using isooctane as reference hydrocarbon, are: styrene (5.3 ± 0.5) × 10−11 cm3/molec·s, α‐methylstyrene (5.3 ± 0.6) × 10−11 cm3/molec·s, and β‐methylstyrene (6.0 ± 0.6) × 10−11 cm3/molec·s. A simplified kinetic treatment of the experimental data shows that styrene and β‐methylstyrene are stoichiometrically converted to benzaldehyde, suggesting that OH attack occurs only on the aliphatic moiety of the aromatic olefins. Benzaldehyde was observed to undergo consecutive oxidation by OH, and its maximum formation yield was about 60%. A reaction mechanism is proposed where the primary rate‐determining OH attack leads to the formation of 1‐hydroxy‐2‐phenyl‐2‐ethenyl radicals, from which benzaldehyde is formed through fast intermediate reactions.
Kinetics of the sulfodeacylation of 2,4,6,2′,6′‐pentamethylbenzophenone, a process comprising successive first‐order reactions occurring by two alternative routes
Authors: Gore Peter H. , Saad Esmat F. , Waters David N. , Moxon Gerald F. 
Published: January 2005

AbstractMesityl 2,6‐xylyl ketone in 89.8% (w/w) sulfuric acid undergoes cleavage to give mesitylenesulfonic acid, xylenesulfonic acid, and carbon dioxide as final products. The reaction has been analyzed in terms of a series of first‐order reactions. Of the two possible reaction paths available it was shown that fission at the mesityl group is responsible for about 98.5% of the overall initial reaction at 25°C.
Kinetics and mechanism of the amine exchange reactions of 2‐aminopyridine derived Schiff‐base ligands and their copper(II) complexes
Authors: Ranganathan Hemalatha , Ramasami T. , Ranganathan C. K. , Ramaswamy D. , Santappa M. 
Published: January 2005

AbstractThe kinetics and product analyses of the amine exchange reactions of two 2‐aminopyridine derived Schiff‐base ligands and their monomeric bischelate and dimeric copper(II) complexes have been studied. The Schiff‐base ligands investigated underwent amine exchange reactions with n‐butyl, cyclohexyl, t‐butyl amines. The coordination of the Schiff‐base ligands to copper(II) rendered the amine exchange reactions slower. With n‐butyl and cyclohexyl amines, parallel first‐ and second‐order terms on their concentrations are observed for the amine exchange reactions of copper(II) bischelates and dimer. The kinetic data favor a mechanism involving a rate‐limiting elimination of 2‐aminopyridine from a diaminoacetal intermediate in preference to a scheme in which a dissociation of the complexes into free ligands and Cu(II) may precede the amine exchange. The steric factors influence the amine exchange reactions of Cu(II) bischelates with the bulkier amines reacting slower as given by the order t‐butylamine (3.3 ± 0.3 × 10−3 dm3/mol·s) < cyclohexylamine (0.2 ± 0.03 dm3/mol·s) < n‐butylamine (2.2 ± 0.2 dm3/mol·s). The bulkiness of the t‐butyl group and the constraints imposed by the changes in the coordination geometry of Cu(II) on amine exchange not only render the reactions of Cu(II) bischelates slower but also make the formation of the mixed adduct ([N‐(5‐methyl)‐2‐pyridyl salicylaldimine][N‐t‐butyl salicylaldimine] Cu(II)) more favored.
Kinetics of the reaction of C2H5O2 with NO at 295 K
Authors: Plumb I. C. , Ryan K. R. , Steven J. R. , Mulcahy M. F. R. 
Published: January 2005

AbstractThe reaction of C2H5O2 with NO in helium carrier gas at 295 K with [He] = 1.6 × 1017 cm−3 has been studied using a gas flow reactor sampled by a mass spectrometer. Because no parent molecular ion or suitable fragment ion produced by C2H5O2 could be detected, the reaction was followed by measuring the formation of NO2. In so doing, account had to be taken of the small amount of HO2 known to be present in the reaction mixture, which also leads to NO2 on reaction with NO. The rate coefficient for the total reaction of C2H5O2 with NO was found to be (8.9 ± 3.0) × 10−12 cm3/s, and the path which produces NO2 was found to account for at least 80% of all C2H5O2.
Kinetics of the thermal reactions of bicyclo[4.2.2]deca‐3,7‐diene and endo‐and exo‐5‐vinylbicyclo[2.2.2]oct‐2‐ene in the gas phase
Authors: Huybrechts G. , Hubin Y. , Narmon M. , Van Mele B. 
Published: January 2005

AbstractThe kinetics of the thermal reactions of bicyclo[4.2.2]deca‐3,7‐diene (BDD) and endo‐ and exo‐5‐vinylbicyclo[2.2.2]oct‐2‐ene (endo‐ and exo‐VBO) have been studied in the gas phase. The temperature range was 459–526 K for BDD, 476–563 K for endo‐VBO, and 513–578 K for exo‐VBO. The initial pressures were varied from 2 to about 40 torr. These compounds isomerize to cis‐1,2,4a,5,8,8a‐hexahydronaphtalene (HHN) and into each other, and decompose to 1,3‐butadiene (BD) + cyclohexa‐1,3‐diene (CHD). The reactions are homogeneous and first order. Their rate constants (in s−1) are given by:
equation image

where the superscripts represent the reagents and the subscripts the products. The heats of formation and the entropies of endo‐VBO, exo‐VBO, and BDD are estimated.
Rate constants for the reaction of ground‐state oxygen atoms with methanol from 297 to 544 K
Authors: Failes R. L. , Singleton D. L. , Paraskevopoulos G. , Irwin R. S. 
Published: January 2005

AbstractThe rate constant for the reaction of ground‐state oxygen atoms with methanol has been determined between 297 and 544 K by a phase‐shift technique using mercury photosensitized decomposition of N2O to generate oxygen atoms. The relative oxygen atom concentration was monitored by the chemiluminescence from the reaction of oxygen atoms with nitric oxide. The results are accommodated by the Arrhenius expression k1 = (9.79 ± 2.71) × 1012 exp[(−2267 ± 111)/T]cm3/mol·s, where the indicated uncertainties are 95% confidence limits for 10 degrees of freedom. As an incidental part of this work, the third‐body efficiency of CH3OH relative to N2O for the reaction O + NO + M → NO2 + M (M = CH3OH) was determined to be 3.1 at 298 K.
The kinetics and mechanisms of the gas‐phase unimolecular eliminations of halogeno esters. Participation of the carbomethoxy group
Authors: Chuchani Gabriel , Rotinov Alexandra , Dominguez Rosa M. 
Published: January 2005

AbstractThe kinetics of the gas‐phase elimination of several chloroesters were determined in a static system over the temperature range of 410–490°C and the pressure range of 47–236 torr. The reactions in seasoned vessels, and in the presence of a free‐radical inhibitor, are homogeneous, unimolecular, and follow a first‐order law. The temperature dependence of the rate coefficients is given by the following Arrhenius equations: for methyl 3‐chloropropionate, log k1(s−1) = (13.22 ± 0.07) ‐ (231.5 ± 1.0) kJ/mol/2.303RT; for methyl 4‐chlorobutyrate, log k1(s−1) = (13.31 ± 0.25) ‐ (221.5 ± 3.4) kJ/mol/2.303RT; and for methyl 5‐chlorovalerate, log k1(s−1) = (13.12 ± 0.25) ‐ (221.7 ± 3.2) kJ/mol/2.303RT. Rate enhancements and lactone formation reveal the participation of carbonyl oxygen of the carbomethoxy group. The order COOCH3‐5 > COOCH3‐6 > COOCH3‐4 in assistance is similar to the sequence of group participation in solvolysis reactions. The partial rates for the parallel eliminations to normal dehydrohalogenation products and lactones have been estimated and reported. The present results lead us to consider that an intimate ion‐pair mechanism through participation of the carbomethoxy group may well be operating in some of these reactions.
Kinetics and mechanism of the oxidation of n‐acetyl l‐cysteine by 2,6‐dichloroindophenol in methanol–water medium
Authors: Shrivastava Manjul , Mishra K. K. , Sinha B. P. 
Published: January 2005

AbstractThe principal reactants interact in a molar ratio of 2:1 forming dihydroindophenol and the corresponding disulfide. The order of reaction is unity with respect to each reactant, namely, N‐acetyl L‐cysteine and indophenol. The rate shows an inverse linear relation with hydroxyl ions. It is not influenced by the variation in the initial concentration of indophenol. The rate increases on adding the salts possessing a cholinergic effect and the neutral electrolytes, as well as on increasing the dielectric constant of the medium. The products, namely, N‐acetyl L‐cystine (disulfide) and the leuco dye, do not influence the rate. A low energy and a highly negative entropy of activation (4.11 kcal/mol and ‐60.49 e.u., respectively) suggest the formation of an outer sphere complex as the rate‐determining step.
The reaction of O(3P) with H2O2
Authors: Roscoe John M. 
Published: January 2005

AbstractThe rate constant for the reaction of O(3P) with H2O2 was measured as a function of temperature and the [H2O2]0/[O]0 ratio. The numerical solution of the appropriate rate equations was used to arrive at a mechanism which adequately describes our results and the rather divergent data in the literature. A recommended expression for the temperature dependence of the absolute rate constant is presented from consideration of the available experimental data.
Gas‐phase thermolysis of sulfur compounds. Part IV. n‐propyl allyl sulfide
Authors: Martin Gonzalo , Ropero Marcos 
Published: January 2005

AbstractThe pyrolysis of n‐propyl allyl sulfide has been studied in static and stirred‐flow systems at temperatures between 270 and 400°C. Propene and 2,4,6‐triethyl‐1,3,5‐trithiane were the only reaction products. The order of the reaction was 0.99 ± 0.05 at 377°C. The first‐order rate coefficients followed the Arrhenius equation

The rate coefficients and the product distribution remained unchanged when cyclohexene was used as carrier gas. A molecular mechanism involving a six‐centered cyclic transition state is proposed to explain the present results. This mechanism is further supported by the pyrolysis of 4‐thia‐5‐dideutero‐1‐heptene at 377°C, where only 3‐deuteropropene is formed. The kinetic deuterium isotope effect had a value of 2.6 ± 0.3 at this temperature. The results are compared with those obtained in the pyrolysis of n‐butyl allyl sulfide previously reported.
The kinetics of the gas‐phase reaction between iodine and phenylsilane and the bond dissociation energy D(C6H5SiH2H)
Authors: Barber M. , Doncaster A. M. , Walsh R. 
Published: January 2005

AbstractThe title reaction has been investigated in the temperature range of 490‐573 K. Initial reactant pressures were varied in the range of 0.2‐5.2 torr (I2) and 2‐20 torr (C6H5SiH3). The rate of iodine consumption, monitored spectrophotometrically, was found to obey

both by initial rate and integrated equation fitting procedures. The effect of added initial HI conformed to this expression. The data are consistent with a conventional I‐atom propagated chain reaction, and for the step

the rate constant is given by

From this is derived the bond dissociation energy value C6H5SiH2H = 374 kJ/mol(88 kcal/mol). A comparison with other SiH dissociation energy values indicates that the “silabenzyl” stabilization energy is small, ≈7 kJ/mol.
The thermal decomposition of fluorinated esters. III. Esters without β hydrogen atoms
Authors: Blake P. G. , Shraydeh B. F. 
Published: January 2005

AbstractThe kinetics of the gas‐phase decomposition of methyl trifluoroacetate and 2,2,2‐trifluoroethyl trifluoroacetate, two esters without β hydrogen atoms, have been investigated, and a comparative study was carried out on methyl acetate. All these compounds are thermally much more stable than fluorinated esters with β hydrogens, decomposing at temperatures some 150°C above the latter by a completely different mechanism involving partly heterogeneous radical chains. The marked difference in behavior between the two types of fluorinated ester confirms that none of them decomposes by hydrogen fluoride elimination, but that those with β hydrogen atoms follow the normal ester decomposition route. The fluorinated esters examined here decompose in a manner generally similar to methyl acetate, but the presence of fluorine in the molecule brings about an extreme sensitivity to surface conditions.
Kinetics of the reactions of CH3 with O(3P) and O2 at 295 K
Authors: Plumb I. C. , Ryan K. R. 
Published: January 2005

AbstractThe reactions of CH3 radicals with O(3P) and O2 have been studied at 295 K in a gas flow reactor sampled by a mass spectrometer. For the reaction between CH3 and O, conditions were such that [O] » [CH3] and the methyl radicals decayed under pseudo‐first‐order conditions giving a rate coefficient of (1.14 ± 0.29) × 10−10 cm3/s. The reaction between CH3 and O2 was studied in separate experiments in which CH3 decayed under pseudo‐first‐order conditions. In this case, the rate coefficient obtained increased with increasing concentration of the helium carrier gas. This was varied over the range of 2.5–25 × 1016 cm−3, resulting in values for the apparent two‐body rate coefficient ranging from 1 × 10−14 to 5.2 × 10−14 cm3/s. No evidence was found for the production of HCHO by a direct two‐body process involving CH3 + O2, and an upper limit of 3 × 10−16 cm3/s was placed on the rate coefficient for this reaction. The experimental results for the apparent two‐body rate coefficient exhibit the curvature one would expect for an association reaction in the fall‐off region. Calculations used to extrapolate these measurements to the low‐pressure limit yield a value for k0 of (3.4 ± 1.1) × 10−31 cm6/s, which is more than a factor of 2 higher than previous estimates.
Kinetics of the isomerization reaction of cholest‐5‐en‐3‐one catalyzed by trichloroacetic acid in aprotic solvents of low dielectric constant
Authors: Salvador Francisco , Gonzalez José Luis , Herræz Miguel A. 
Published: January 2005

AbstractThe isomerization reaction of cholest‐5‐en‐3‐one has been studied in a solution of cyclohexane using trichloroacetic acid as catalyst. At the same time a general reaction scheme is proposed to be valid for all the cases assayed in which the monomer form of the acid is considered as the only effective catalyst. The experimental results agree with these hypotheses and with the calculation of the individual rate constant together with the reaction order with respect to the catalyst. Semiquantitative studies have been carried out with other catalysts and solvents, confirming the validity of the reaction scheme. The thermodynamic activation parameters have also been calculated, and a comparative study was made with the results of the evaluation of the reaction when it takes place in amphiprotic solvents. A reaction mechanism is proposed based on all the kinetic information obtained.
Mechanism of the hydroxyiodination of 2‐butenoic acid
Authors: Furrow Stanley D. 
Published: January 2005

AbstractAqueous iodination of trans‐2‐butenoic acid proceeds via hydrolysis of I2 to form HOI and I−, then rapid addition of HOI across the double bond to form the iodohydrin product. In the presence of iodate to keep iodide concentration low, the reaction proceeds at a conveniently measurable rate. The rate for the addition reaction

is −d[C4H6O2]/dt = 5900 [H+][C4H6O2][HOI]M/s at 25.0°C when [IO] = 0.025M and ionic strength = 0.3. The overall rate law in the presence of iodate is

where [H+] and [IO] are total concentrations used to prepare the solution.
Kinetics and mechanism of the thermal decomposition of methyl isocyanate
Authors: Blake P. G. , Ijadi‐Maghsoodi S. 
Published: January 2005

AbstractThe kinetics of gas‐phase decomposition of methyl isocyanate have been investigated in the range of 427–548°C. Two decomposition routes are followed; the predominant one is a radical‐chain process giving CO, H2, and HCN as major products, which has an order of 1.5 and an Arrhenius equation given by log k(L1/2/mol1/2·s) = (13.12 ± 0.06) − (56,450 ± 1670) cal/mol/2.303 RT. The minor route is the bimolecular formation of N,N′‐dimethylcarbodiimide and CO2, which from the low activation parameters Ea = 31.6 kcal, A = 105.30 L1/2/mol1/2·s, and the reaction order of 1.57 appears to be heterogeneous.
Kinetics and mechanisms of the reaction of acetylene with cyclohexa‐1,3‐diene and the decomposition of bicyclo[2.2.2]‐octa‐2,5‐diene in the gas phase
Authors: Huybrechts G. , Leemans W. , Van Mele B. 
Published: January 2005

AbstractThe reaction of acetylene (A) with cyclohexa‐1,3‐diene (CHD) has been studied between 450 and 592 K. The pressures of A ranged from 25 to 112 torr and those of CHD from 8 to 62 torr. The reaction yields only ethene (E) and benzene (B) instead of bicyclo[2.2.2]octa‐2,5‐diene (BOD), the product that is expected for a 1,4,1′,2′ addition of the Diels–Alder type. It is first order with respect to each reagent. The rate constant (in L/mol·s) is given by

The thermal decomposition of BOD has also been studied. In the ranges of 354–435 K and 0.5–6 torr, the reaction is first order and results in the formation of equal amounts of B and E as the reaction of A with CHD does. Its rate constant (in s−1) is given by

The following consecutive reactions are proposed for the reaction between A and CHD: magnified image where BOD is the primary product that is too unstable to be detected. This implies that the rate constant k is equal to ka. The reaction mechanisms and the strain energy in BOD are discussed.