bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal dehydration kinetics of disaccharides
Authors: Scheer Milton D. 
Published: January 2005

AbstractThe vacuum decomposition of sucrose and cellobiose has been observed in the 150–250°C temperature range. The predominant decomposition product of both sugars is H2O with less than 5% CO, CO2, CH2O, CH3CHO, CH3OH, and C2H5OH formed. The detailed rates and temperature dependences suggest that with the possible exception of C2H5OH, the minor products are formed in secondary reactions of the dehydration products. Further it is shown that the so‐called “melting with decomposition” of a sugar is in reality a high‐temperature dissolution of the disaccharide in the eliminated water.
Relative rate constants for removal of vibrationally excited OH(X2πi)v=9 by some small molecules at room temperature
Authors: Finlayson‐pitts B. J. , Toohey D. W. , Ezell M. J. 
Published: January 2005

AbstractVibrationally excited OH in v = 9 [designated OH†(9)] was generated by the reaction of hydrogen atoms with ozone in a fast‐flow discharge system at 300 ± 3 K and a total pressure of 1.1 ± 0.1 torr, with argon as the carrier gas. The addition of a species X, which can deactivate the OH†(9) or react with it, led to a decrease in the Meinel band chemiluminescent emission intensities at both 626 nm (9 → 3 band) and 519 nm (9 → 2 band), which were monitored as a function of the concentration of X. Application of the kinetic scheme developed previously for this chemical system gave the relative rate constant for the removal of OH†(9) by X. The relative rate constants determined in this study, taking O2 as the reference deactivator (k = 1.0), are as follows: He ≤ 0.02; H2 ≤ 0.05; SF6 0.09 ± 0.01; CF4 0.19 ± 0.01; N2O 3.5 ± 0.4; NO 17.7 ± 1.5; H2O 74.3 ± 2.9; D2O 57.6 ± 2.0; NH3 61.3 ± 1.9; ND3 58.7 ± 1.6; SO2 7.1 ± 1.4; COS 8.4 ± 1.7; H2S 33.7 ± 8.4; CH4 1.56 ± 0.03; CD4 1.06 ± 0.06. Application of these relative rate constants to conditions in the upper atmosphere (60–100 km) suggests that OH†(9) is removed primarily by deactivation by O2, and at altitudes ≳90 km, possibly by O(3P). However, since O2 is unusually efficient for a homonuclear diatomic in deactivating OH†(9), it may not be the primary deactivator for the lower (v ≤ 8) vibrational levels. These results are compared to earlier studies of OH†(9), and possible mechanisms of interaction of OH†(9) with these molecules are discussed.
Reaction of pentafluoroethyl radicals with hydrogen cyanide
Authors: Pasteris Leonor , Oexler Elena V. , Staricco Eduardo H. 
Published: January 2005

AbstractThe reaction of C2F5 radicals with HCN has been studied over the range of 533–673 K using the pyrolysis of pentafluoroethyl iodide as the free‐radical source. Arrhenius parameters for the reaction
equation image
relative to C4F10 recombination are given by

where θ = 2.303RT kJ/mol and kH/k is in cm3/2/mol1/2·s1/2.
Intramolecular hydrogen isotope effect in the pyrolysis of diethyl carbonate‐1,1,1,2,2‐d5
Authors: Farneth William E. , Beck Thomas L. 
Published: January 2005

AbstractThe thermal unimolecular decomposition of diethyl carbonate‐1,1,1,2,2‐d5 has been examined in the high‐pressure‐limiting region. The observed chemistry is consistent with a simple, competitive two‐channel model:
equation image
The intramolecular isotope effect kH/kD has been determined, and the relative Arrhenius parameters for the two channels are given by

over the temperature range of 540–620 K. These Arrhenius parameters predict an isotope effect kH/kD = 5.4 at 300 K.
The kinetics of secondary reactions in the iodination of monogermane. The effect of iodine substitution on the GeH bond dissociation energy
Authors: Noble Paul N. , Walsh Robin 
Published: January 2005

AbstractA study has been made both of secondary reactions occurring during the reaction of I2 with GeH4, and of the direct reaction between I2 and GeH3I. Both these studies show that the abstraction reaction

occurs about 30 times faster than the reaction

in the temperature range of 425–446 K. This information is used to show that iodine substitution weakens Ge–H bonds by 14.4 ± 2.5 kJ/mol and that D(H2IGeH) = 332 ± 10 kJ/mol (79.3 kcal/mol). Possible reasons for the effects of halogen substituents on GeH and SiH bond strengths are discussed.
The gas‐phase reaction of hydrazine and ozone: A nonphotolytic source of OH radicals for measurement of relative OH radical rate constants
Authors: Tuazon Ernesto C. , Carter William P. L. , Atkinson Roger , Pitts James N. 
Published: January 2005

AbstractThe homogeneous gas‐phase reaction of N2H4 with O3 in air atmospheric pressure has been used to generate OH radicals in the dark, allowing the determination of relative OH radical rate constants for compounds which photolyze rapidly. This technique was first validated by determining the OH radical rate constant ratios for n‐butane/cyclohexane and methanol/dimethyl ether, both of which are in excellent agreement with the literature values. The rate constant for the reaction of OH radicals with methyl nitrite at 300 ± 3 K was then determined relative to those for the reaction of OH radicals with n‐hexane and dimethyl ether. The resulting rate constant of 1.8 × 10−13 cm3/molecule·s is about seven times lower than those of previous measurements which employed a different nonphotolytic relative rate method.
Kinetics and mechanism of osmium(VIII)‐catalyzed oxidation of D‐proline and L(–)‐methionine by hexacyanoferrate(III)
Authors: Upadhyay Santosh K. 
Published: January 2005

AbstractThe osmium(VIII)‐catalyzed oxidation of D‐proline and L(–)‐methionine by alkaline hexacyanoferrate(III) has been studied spectrophotometrically. The reactions follow kinetics different from those of the oxidation of many amino acids investigated earlier, being first order in hexacyanoferrate(III) and osmium(VIII). The order in proline or methionine and OH− decreases from unity to zero at higher concentrations of proline or methionine and OH−, respectively. A mechanism consistent with the kinetic data is proposed and discussed.
The kinetics and mechanisms of the gas‐phase pyrolysis of ethyl 4‐bromobutyrate. The ion‐pair mechanism revisited
Authors: Chuchani Gabriel , Dominguez Rosa M. 
Published: January 2005

AbstractThe gas‐phase pyrolysis of ethyl 4‐bromobutyrate has been investigated in a static system over the temperature range of 354.6–374.7°C and the pressure range of 51–126 torr. The elimination reaction in seasoned vessels and in the presence of at least twofold of a chain radical inhibitor is homogeneous, unimolecular, and obeys a first‐order rate law. The rate coefficients are given by the Arrhenius equation log k1(s−1) = (13.31 ± 0.82) – (205.1 ± 8.6)kJ/mol/2.303RT. The partial rates for the parallel eliminations to normal dehydrobromination, lactone formation, and bromobutyric acid product have been estimated and reported. The carboethoxy substituent of the bromoester has been found to assist anchimerically the elimination process, where dihydrobromination and lactone formation arise from an intimate ion‐pair mechanism.
Kinetic and equilibrium study of gas‐phase interconversions of 1,3,6‐cyclooctatriene, 1,3,5‐cyclooctatriene and bicyclo[4.2.0]octa‐2,4‐diene
Authors: Greathead John M. , Orchard S. Walter 
Published: January 2005

AbstractThe gas‐phase equilibrium and rate constants for the isomerizations of 1,3,6‐cyclooctatriene (136COT) to 1,3,5‐cyclooctatriene (135COT) [reaction (1)] and bicyclo[4.2.0]octa‐2,4‐diene (BCO) to 135COT [reaction (‐2)] have been measured between 390 and 490 K and between 330 and 475 K, respectively. The rate constant of reaction (1) obeys the Arrhenius equation

The corresponding equilibrium constant is given by the van′t Hoff equation

The strain energy of the 136COT ring is calculated to be 31.7 kJ/mol, based on the known value of 37.2 kJ/mol for 135COT, and ΔH(298 K) for gaseous 136COT is 196.3 kJ/mol. The rate constant of reaction (‐2) obeys the Arrhenius equation

The equilibrium constant for 135COT ⇆ BCO fits the van′t Hoff equation

The strain energy of the BCO skeleton is calculated to be 108.3 kJ/mol, and ΔH(298 K) for gaseous BCO is 183.3 kJ/mol.
Stopped‐flow determination of carbon dioxide–diethanolamine reaction mechanism: Kinetics of carbamate formation
Authors: Barth D. , Tondre C. , Delpuech J. J. 
Published: January 2005

AbstractThe reaction mechanism of carbon dioxide with diethanolamine (DEA) is investigated using the stopped‐flow method with optical detection in the ranges of concentration [DEA] = 0.111–8.4 × 10−2Mand [CO2] = 2.94–5.6 × 10−3M. The comparison of the fast time‐dependent light transmission change of a pH indicator with theoretical simulations of integrated rate equations requires a kinetic model in which a simple carbamate formation takes place simultaneously with hydration reactions, whose contributions are far from being negligible. A first‐order reaction relative to DEA is thus found with a rate constant for carbamate formation smaller than usually predicted (110 ± 15M−1s−1at 25°C). The equilibrium constant for the same reaction is also determined giving pKR= 5.3 at 25°C, in satisfactory agreement with values assumed so far.
Effects of ring strain on gas‐phase rate constants. 2. OH radical reactions with cycloalkenes
Authors: Atkinson Roger , Aschmann Sara M. , Carter William P. L. 
Published: January 2005

AbstractRelative rate constants for the gas‐phase reactions of OH radicals with a series of cycloalkenes have been determined at 298 ± 2 K using methyl nitrite photolysis in air as a source of OH radicals. Using a rate constant for the reaction of OH radicals with isoprene of 9.60 × 10−11 cm3 molecule−1 s−1, the rate constants obtained were (X 1011 cm3 molecule−1 s−1): cyclopentene 6.39 ± 0.23, cyclohexene 6.43 ± 0.17, cycloheptene 7.08 ± 0.22, 1,3‐cyclohexadiene 15.6 ± 0.5, 1,4 cyclohexadiene 9.48 ± 0.39, bicyclo[2.2.1]‐2‐heptene 4.68 ± 0.39, bicyclo[2.2.1] 2,5 heptadiene 11.4 ± 1.0, and bicyclo[2.2.2] 2 octene 3.88 ± 0.19. These data show that the rate constants for the nonconjugated cycloalkenes studied depend on the number of double bonds and the degree of substitution per double bond, and indicate that there are no obvious effects of ring strain energy on these OH radical addition rate constants. A predictive technique for the estimation of OH radical rate constants for alkenes and cycloalkenes is presented and discussed.
Energy of activation and temperature for the hydrolysis of sucrose
Authors: Buchanan Susan , Kubler Donald G. , Meigs Cynthia , Owens Michael , Tallman Alan 
Published: January 2005

AbstractWe have reinvestigated temperature effects on the rates of hydrolysis of 0.0585M sucrose in 0.57M HCl solutions over the range of 10–40°C using polarimetry as a physical method to follow the reaction while simultaneously analyzing the solutions by HPLC for the disappearance of sucrose and by GLC for the appearance of glucose. When the polarimetric data are corrected for the mutarotation lag, the energy of activation values are the same by all three analytical methods and are temperature‐independent.
The kinetics of the reactions of i‐C3F7 radicals with BR2 and HBr
Authors: Weeks Ian , Whittle Eric 
Published: January 2005

AbstractThe reactions

have been studied competitively in the vapor phase over the range of 52–204°C. The i‐C3F7 radicals were generated by means of the reaction

It was found that

where θ = 2.303RT J/mol. Absolute Arrhenius parameters are derived for the reactions

where R = CF3, C2F5, and i‐C3F7.
Effect of solvent polarity on the rate of ozone reaction with unsaturated compounds
Authors: Gomes M. , Razumovskii S. D. , Zaikov G. E. 
Published: January 2005

AbstractThe effect of the polarity of seven solvents (ϵ ≈ 2–60) on the rate of ozone reactions with stilbene and allyl chloride has been studied. The data show that the rate of the reaction is insensitive to the medium polarity. The results of earlier publications are revised and are shown to be in agreement with the present data.
The gas‐phase decomposition of methylsilane. Part III. Kinetics
Authors: Sawrey B. A. , O'Neal H. E. , Ring M. A. , Coffey D. 
Published: January 2005

AbstractThe homogeneous gas‐phase decomposition kinetics of methylsilane and methylsilane‐d3 have been investigated by the comparative‐rate‐single‐pulse shock‐tube technique at total pressures of 4700 torr in the 1125–1250 K temperature range. Three primary processes occur: CH3SiH3 → CH3SiH + H2 (1), CH3SiH3 → CH4 + SiH2 (2), and CH3SiH3 → CH2 = SiH2 + H2 (3). The high‐pressure rate constants for the primary processes in CH3SiH3 obtained by RRKM calculations are log (k1 + k3) (s−1) = 15.2 ‐ 64,780 Cal/θ and log k2 (s−) = 14.50 ‐ 67,600 → 2800 Cal/θ. For CH3SiD3 these same rate constants are log k1 (s−) = 14.99 ‐ 64,700 cal/θ log k2 (s−) = 14.68 – 66,700 → 2000 cal/θ, and log k3 (s−) = 14.3 ‒ 64,700 cal/θ.
Shock tube study of cyanogen oxidation kinetics
Authors: Louge Michel Y. , Hanson Ronald K. 
Published: January 2005

AbstractMixtures of cyanogen and nitrous oxide diluted in argon were shock‐heated to measure the rate constants of
equation image
A broad‐band mercury lamp was used to measure CN in absorption at 388 nm [B2Σ+(v = 0) ← X2Σ+(v = 0)], and the spectral coincidence of a CO infrared absorption line [v(2 ← 1), J(37 ← 38)] with a CO laser line [v(6 → 5), J(15 → 16)] was exploited to monitor CO in absorption. The CO measurement established that reaction (3) produces CO in excited vibrational states. A computer fit of the experiments near 2000 K led to

An additional measurement of NO via infrared absorption led to an estimate of the ratio k5/k6:
equation image
with k5/k6 ≃ 103.36±0.27 at 2150 K. Mixtures of cyanogen and oxygen diluted in argon were shock heated to measure the rate constant of
equation image
and the ratio k5/k6 by monitoring CN in absorption. We found near 2400 K:

and

The combined measurements of k5/k6 lead to k5/k6 ≃ 10−3.07 exp(+31,800/T) (±60%) for 2150 ≤ T ≤ 2400 K.
Cage reactions in the photolysis of 2,2,4,4‐tetramethyl‐3‐pentanone
Authors: Abuin E. B. , Encinas M. V. , Díaz S. , Lissi E. A. 
Published: January 2005

AbstractThe product quantum yields in the photolysis of 2,2,4,4‐tetramethyl‐3‐pentanone have been measured in homogeneous solvents of different viscosities, in micellar solutions of cetyltrimethylammonium chloride and sodium dodecyl sulfate, and in dioctadecyl ammonium chloride vesicles.The product quantum yield in n‐heptane was found to be 1. This value decreases to 0.5 in paraffin oil as a consequence of geminate recombination. In the presence of free radical scavengers, the extent of geminate disproportionation can be evaluated from the yields of isobutene and 2,2‐dimethyl propionaldehyde. From these yields and the geminate recombination yields the total amount of geminate processes and the disproportionation‐to‐combination ratio for caged radicals are estimated. It is found that micelles provide the most efficient cages. In these media only about 10% of the radicals avoid cage processes. The disproportionation‐to‐combination ratio of tert‐butyl and pivaloyl radicals was found to be extremely media dependent. The measured values ranged from about 0.2 in paraffin oil to 0.8 in cetyltrimethylammonium chloride micelles.
Kinetics of the reactions of CCl3 with O and O2 and of CCl3O2 with NO at 295 K
Authors: Ryan K. R. , Plumb I. C. 
Published: January 2005

AbstractThe reactions of CCl3 with O(3P) and O2 and those of CCl3O2 with NO have been studied at 295 K using discharge flow methods with helium as the bath gas. The rate coefficient for the reaction of CCl3 with O was found to be (4.2 ± 0.6) × 10−11 cm3/s and that for CCl3O2 with NO was (18.6 ± 2.8) × 10−12 cm3/s with both coefficients independent of [He]. For reaction between CCl3 and O2 the rate coefficient was found to increase from 1.51 7times; 10−14 cm3/s to 7.88 × 10−14 cm3/s as the [He] increased from 3.5 × 1016 cm−3 to 2.7 × 1017 cm−3. There was no evidence for a direct two‐body reaction, and it is concluded that the only product of this reaction is CCl3O2. Examination of these results for CCl3 + O2 in terms of current simplified falloff treatment suggests that the high‐pressure limit for this reaction is ∼ 2.5 × 10−12 cm3/s, which may be compared with a direct measurement of the high‐pressure limit of 5 × 10−12 cm3/s. A value of (5.8 ± 0.6) × 10−31 cm6/s has been obtained for k0, the coefficient in the low‐pressure region. This value is compared with corresponding values found earlier for the (CH3, O2) and (CF3, O2) systems and with estimates based on unimolecular rate theory.
Gas phase reaction of NO2 with alkenes and dialkenes
Authors: Atkinson Roger , Aschmann Sara M. , Winer Arthur M. , Pitts James N. 
Published: January 2005

AbstractThe kinetics of the gas phase reactions of NO2 with a series of organics have been studied at 295 ± 2 K. It was observed that only 2,3‐dimethyl‐2‐butene and the conjugated dialkenes studied reacted at observable rates, with rate constants which ranged from 1.5 × 10−20 cm3 molecule−1 s−1 for 2,3‐dimethyl‐2‐butene to 1.3 × 10−17 cm3 molecule−1 s−1 for α‐phellandrene. These rate constants are compared with the available literature data and the mechanisms of these reactions are discussed.
The reactions of hydrogen atoms with bis(trifluoromethyl)disulfide
Authors: Ekwenchi M. M. , Safarik I. , Strausz O. P. 
Published: January 2005

AbstractThe reactions of hydrogen atoms produced by the mercury‐photosensitized decomposition of H2 with bis(trifluoromethyl)disulfide has been studied. The rate coefficient for the primary reaction, H + CF3SSCF3 → CF3SH + CF3S, was determined in competition with the reaction H + C2H4S → SH + C2H4 to have the value k = (3.0 ± 0.18) × 1014 exp[‐(4560 ± 140)/RT] cm3 mol−1 S−1. The high A factor can be partially accounted for by assuming free rotation for the two CF3 groups and the SCF3 groups about the S—S bond in the transition state. The relatively high activation energy is attributed to inductive and orbital overlap effects. CH3SH, H2S, and CF3SH all react with CF3SSCF3 to yield solid complexes which were not explored further.
Thermal decomposition of azoethane
Authors: Péter A. , Ács G. , Huhn P. 
Published: January 2005

AbstractThe thermal decomposition of azoethane (AE) was studied by detailed product analysis in the temperature and pressure intervals 508–598 K and 2.7–13.3 kPa. Besides the hydrocarbon products, three characteristic and quantitatively important nitrogen‐containing compounds were also determined: ethyl‐2‐butyldiimide, ethanal‐diethylhydrazone, and tetraethyl‐hydrazine. Apart from the predominant termination reactions of the ethyl radical with itself and with the μ2 radical, the decomposition is characterized by a very short chain reaction. The measurements led to determination of the following rate constants and rate constant ratios:

for the following reactions:magnified image
Thermal decomposition of azoisopropane. I. Primary decomposition processes
Authors: Péter A. , Ács G. , Huhn P. 
Published: January 2005

AbstractThe thermal decomposition of azoisopropane (AIP) was studied by detailed product analysis in the temperature and pressure intervals 498–563 K and 0.67–5.33 kPa. Besides the predominant termination and hydrogen‐abstraction reaction of the 2‐propyl radical, the decomposition is characterized by a very short chain process. The following rate constants were determined from the measurements

for the following reactions:magnified image
Kinetics and equilibria of the reaction between bromine and ethyl ether. The CH bond dissociation energy in ethyl ether
Authors: Kondo Osamu , Benson Sidney W. 
Published: January 2005

AbstractThe kinetics and equilibria of the reaction:

have been studied in the temperature range 298–333 K by using the very low pressure reactor (VLPR) technique. Combining the estimated entropy change of reaction (1), ΔS = 8.1 ± 1.0 eu, with the measured ΔG, we find ΔH = 4.2 ± 0.4 kcal/mol; ΔH(CH3CHOC2H5) = −20.2 kcal/mol, and DH° [Et OCH(Me)‐H] = 91.7 ± 0.4 kcal/mol. We find:

where θ = 2.3 RT in kcal/mol. It has been shown that the reaction proceeds via a loose transition state and the “contact TS” model calculation gives a very good agreement with the observed value.
Kinetics of the reactions of O3 and OH radicals with a series of dialkenes and trialkenes at 294 ± 2 K
Authors: Atkinson Roger , Aschmann Sara M. , Carter William P. L. 
Published: January 2005

AbstractRate constants for the gas phase reactions of O3 and OH radicals with 1,3‐cycloheptadiene, 1,3,5‐cycloheptatriene, and cis‐ and trans‐1,3,5‐hexatriene and also of O3 with cis‐2,trans‐4‐hexadiene and trans ‐2,trans ‐4‐hexadiene have been determined at 294 ± 2 K. The rate constants determined for reaction with O3 were (in cm3 molecule‐1s−1 units): 1,3‐cycloheptadiene, (1.56 ± 0.21) × 10‐16; 1,3,5‐cycloheptatriene, (5.39 ± 0.78) × 10−17; 1,3,5‐hexatriene, (2.62 ± 0.34) × 10−17; cis−2,trans‐4‐hexadiene, (3.14 ± 0.34) × 10−16; and trans −2, trans ‐4‐hexadiene, (3.74 ± 0.61) × 10−16; with the cis‐ and trans‐1,3,5‐hexatriene isomers reacting with essentially identical rate constants. The rate constants determined for reaction with OH radicals were (in cm3 molecule−1 s−1 units): 1,3‐cycloheptadiene, (1.31 ± 0.04) × 10−10; 1,3,5‐cycloheptatriene, (9.12 × 0.23) × 10−11; cis‐1,3,5‐hexatriene, (1.04 ± 0.07) × 10−10; and trans 1,3,5‐hexatriene, (1.04 ± 0.17) × 10−10. These data, which are the first reported values for these di‐ and tri‐alkenes, are discussed in the context of previously determined O3 and OH radical rate constants for alkenes and cycloalkenes.
Determination of the rate constants for the reactions of CFCl2O2radical with NO and NO2by laser photolysis and time resolved mass spectrometry
Authors: Lesclaux R. , Caralp F. 
Published: January 2005

AbstractThe rate constants for reactions (4) and (5)equation imagewere determined at room temperature by pulsed laser photolysis and time resolved mass spectrometry. A description of the experimental setup is given. CFCl2O2radicals were generated by photolysis of CFCl3at 193 nm in the presence of an excess of oxygen, using an excimer laser. The rate constant for reaction (4), determined under different experimental conditions is:The rate constant of reaction (5) was determined in the pressure range of 1–12 torr, using oxygen as the buffer gas. The reaction is in its fall‐off region and the parameters determined by using the semiempirical method of Troe, takingFc= 0.6 are:The value ofk(∞) is obtained from the low‐pressure measurements and therefore the uncertainty on the actual high‐pressure limit is higher than the error limits quoted above. The results are compared with those reported for similar reactions.
Kinetics and mechanism of diethanolamine degradation in aqueous solutions containing carbon dioxide
Authors: Kim C. J. , Sartori G. 
Published: January 2005

AbstractThe problem of diethanolamine (DEA) degradation in gas‐treating processes was quantified through a detailed kinetic study. This reaction was found to be catalyzed by CO2, and degradation occurs in a successive manner to 3‐(2‐hydroxyethyl)oxazolidone‐2, to N,N,N′‐tris(2‐hydroxyethyl)ethylenediamine and then to N,N′‐bis(2‐hydroxyethyl)piperazine. A reaction mechanism consistent with these observations was proposed and tested through kinetic analyses. A satisfactory kinetic model which can be of practical use was derived.