bluuebunny/crossref_metadata_2025_split huggingface dataset:
The kinetics of the reactions of O(3P) atoms with dimethyl ether and methanol
Authors: Lefevre Henry F. , Meagher James F. , Timmons Richard B. 
Published: January 2005

AbstractThe kinetics of the reaction of O + CH3OCH3 were investigated using fast‐flow apparatus equipped with ESR and mass‐spectrometric detection. The concentration of O(3P) atoms to CH3OCH3 was varied over an unusually large range. The rate constant for reaction

was found to be k = (5.0 ± 1.0) × 1012 exp [(−2850 ± 200/RT)] cm3 mole−1 sec−1. The reaction O + CH3OH was studied using ESR detection. Based on an assumed stoichiometry of two oxygen atoms consumed per molecule of CH3OH which reacts, we obtain a value of k = (1.70 ± 0.66) × 1012 exp [(−2,280 ± 200/RT)] cm3 mole−1 sec−1 for the reaction

The results obtained in this study are compared with the results from other workers on these reactions. The observation of essentially equal activation energies in these two reactions is indicative of approximately equal CH bond strengths in CH3OCH3 and CH3OH. This is in agreement with recent measurements of these bond energies.
Rate constants for alkyl radical recombination. II. The isopropyl radical
Authors: Hiatt R. , Benson S. W. 
Published: January 2005

AbstractProducts of radical combination from the free‐radical buffer system \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$${{\rm R}^{\rm .} + {\rm R}^{\rm '} {\rm I}\mathop {\leftrightharpoons}\limits^{{\rm K}_{{\rm RR}}}{\rm RI} + {\rm R}^{'}}$$\end{document}. have been analyzed for the two cases, R = Me, R′ = iPr and R = Et, R′ = iPr. Results are consistent with the previously examined system where R = Me, R′ = Et, and give a value of kP for iPr· combination of 108.6±1.1 M−1 sec−1.
The Gas‐phase thermal unimolecular isomerization of n‐propylidenecyclopropylamine to 5‐ethyl‐1‐pyrroline
Authors: Cocks Alan T. , Egger Kurt W. 
Published: January 2005

AbstractThe gas‐phase thermal isomerization of N‐propylidenecyclopropylamine has been studied in the temerature range of 573° to 635°K. The reaction is homogeneous and kinetically first order and yields 5‐ethyl‐1‐pyrroline as the sole product. The rate constants are independent of pressure in the range of 2.5 to 55 torr and fit the Arrhenius relationship log k(sec−1) = (14.05 ± 0.06) ‐ (47.77 ± 0.16)/θ where θ = 2.303 RT in units of kcal/mole, or log k(sec−1) = (14.05 ± 0.06) ‐ (199.9 ± 0.7)/θ, where θ = 2.303RT in kJ/mole. From considerations of a biradical pathway it is concluded that the resonance stabilization energy of the substituted 2‐aza‐allyl radical is very similar to that of the methallyl radical.
Thermal decomposition of 3‐chloro‐3‐trichloromethyldiazirine in solution
Authors: Liu Michael T. H. , Toriyama K. 
Published: January 2005

AbstractThe thermal decomposition of 3‐chloro‐3‐trichloromethyldizairine in carbon tetrachloride and iso‐octane has been investigated over the temperature range 75–115°C. The products, tetrachloroethylene and nitrogen, are formed quantitatively by a first‐order reaction which is probably unimolecular:
magnified image
The results yielded the following Arrhenius equations:

.
The reaction of O(1D) with CH4
Authors: Greenberg Raymond I. , Heicklen Julian 
Published: January 2005

AbstractThe room‐temperature photolysis of N2O (10–100 torr) at 2139 Å to produce O(1D) has been studied in the presence of CH4 (10–891 torr). The reactions of O(1D) with CH4 were found to be

The method of chemical difference was used to measure the rate constant ratio k4/(k2 + k3), where reactions (2) and (3) are

The CH3 radicals produced in reaction (4) react with the O2 and NO produced in reactions (2) and (3). Thus, near the endpoint of the internal titration, ϕ{C2H6} gives an accurate measure of k4/(k2 + k3). For the translationally energetic O(1D) atoms produced in the photolysis, k4/(k2 + k3) = 2.28 ± 0.20. However, if He is added to remove the excess translational energy, then k4/(k2 + k3) drops to 1.35 ± 0.3.
Kinetics of the “a” and “b” band emissions of mercury excimers with added gases
Authors: Penzes S. , Sandhu H. S. , Strausz O. P. 
Published: January 2005

AbstractThe kinetics of the “a” and “b” band emissions arising from the 1Σ ← 3Ou and 1Σ ← 3lu transitions of the diatomic mercury molecule at λmax ∼ 4850 Å and 3350 Å, respectively, have been studied at low concentrations of mercury in the presence of N2, C2H6, C3H8, and N2O. Rate constant values have been obtained for the following reactions of the excimer molecule: Hg2(3lu) + N2 → Hg2(3Ou) + N2 and Hg2(3Ou) + RH → Hg2(1Σ) + RH, where RH = C2H6 or C3H8. From a consideration of the detailed kinetics of band emissions, it was also possible to derive rate constants for the quenching reactions of Hg(3P0) atoms. These values are in reasonable agreement with those obtained previously from monitoring atom concentrations directly by 4047 Å absorbiometry.
Pyrolysis of 4,4‐bisperfluoromethylbutene‐1,4 01 in the gas phase
Authors: Gordon Alvin S. 
Published: January 2005

AbstractPyrolysis of (CF3)2C(OH)CH2CH=CH2, the reverse of the reaction between perfluoroacetone and propene, has been studied in the gas phase between 475° and 598°K. Even at 573°K, the unimolecular reaction rate constant appears to be in its pressure‐independent region at 20.0 torr pressure. In a quartz vessel, the decomposition is homogeneous. The specific unimolecular rate constant is

where the limits are for one standard deviation. Combining these results with the previously reported results on the reverse reaction, the equilibrium constant for the reaction

is

It is noteworthy that in the temperature range of the study of the forward reaction (448° to 573°K), the percentage of back reaction in the times of the experiments varies from less than 0.1 to 1.5. Using group additivities and the above ΔH0, ΔH of (CF3)2CO is calculated to be −325.2 kcal/mole at 600°K and the average CC bond is 42.0 kcal/mole.
A Kinetic study of the reaction of nitrogen dioxide with tetrafluoroethylene
Authors: Spicer Chester W. , Heicklen Julian 
Published: January 2005

AbstractThe reaction of NO2 with C2F4 was studied at 30°, 68°, 114°, and 157°C by in situ monitoring the infrared absorption bands of the products. The major primary products of the reaction are O2NCF2CFO and FNO. Smaller amounts of CF2O (and presumably NO) are also produced. There was no evidence for other primary products, though they may have been produced in minor amounts. The rate laws for the production of both O2NCF2CFO and CF2O are first order in both [NO2] and [C2F4]. CF2O production is at least partly heterogeneous as demonstrated by packing the quartz reaction vessel with Pyrex beads and by using a Monel cell. The homogeneous rate constant obtained from the high‐temperature results gives a rate constant of 3.4 × 108 exp (minus;17000/RT) M−1sec−1 for CF2O production. Actually these Arrhenius parameters represent lower limits, since the heterogeneous reaction may still be playing a significant role. The production rate of O2NCF2CFO is not much affected by changing the nature of the surface or the surface to volume ratio. However the reaction may be heterogeneous, since the rate constant for its formation of 1.3 × 104 e×p (−7500/RT) M−1sec−1 has an abnormally low pree×ponential factor. E×periments in the presence of NO indicate that the mechanism for O2NCF2CFO formatlon is

The intermediate can also react with NO:

with k13/k12 = 1.3.
Absolute rate constants for reactions of free radicals in the high‐temperature photolysis of formamide vapor. Part I. Carbamyl radicals
Authors: Yokota T. , Back R. A. 
Published: January 2005

AbstractThe photolysis of formamide vapor at 2062 Å has been studied in a flow system with results essentially similar to those obtained previously under static conditions and higher conversions. The rotating‐sector technique has been applied to the radical‐chain decomposition of formamide under conditions (305°C, 11.5 torr) such that decomposition of the carbamyl (NH2CO) radical was rate controlling, so that [NH2CO] ≫ [NH2]. A rate constant of (3.1 ± 1.0) × 1010(M·sec)−1 was obtained for bimolecular chain termination by carbamyl radicals. A concurrent first‐order radical loss, probably at the surface, was taken into account by the treatment described by Shepp. Both oxamide and HNCO were tentatively identified as termination products, suggesting the occurrence of both combination and disproportionation,

but quantitative estimates of the relative rates were not possible. From the rate constant for chain termination, and relative rate constants obtained previously, Arrhenius parameters A∞ = (5.9 ± 2.0) × 1012 sec−1 and A0 = (1.04 ± 0.35) × 1014 (M·sec)−1 were estimated for the unimolecular decomposition of carbamyl radicals in the high and low pressure limits.
The reaction of O(1D) with H2O and the reaction of OH with C3H6
Authors: Simonaitis R. , Heicklen Julian 
Published: January 2005

AbstractN2O was photolyzed at 2139 Å to produce O(1D) atoms in the presence of H2O and CO. The O(1D) atoms react with H2O to produce HO radicals, as measured by CO2 production from the reaction of OH with CO. The relative importance of the various possible O(1D )–H2O reactions is
equation image
The relative rate constant for O(1D) removal by H2O compared to that by N2O is 2.1, in good agreement with that found earlier in our laboratory. In the presence Of C3H6, the OH can be removed by reaction with either CO or C3H6:
equation image
From the CO2 yield, k3/k2 = 75,0 at 100°C and 55.0 at 200°C to within ± 10%. When these values are combined with the value of k2 = 7.0 × 10−13exp (–1100/RT) cm3/sec, k3 = 1.36 × 10−11 exp (–100/RT) cm3/sec. At 25°C, k3 extrapolates to 1.1 × 10−11 cm3/sec.
Heats of formation and kinetics of decomposition of nitroalkanes
Authors: Shaw Robert 
Published: January 2005

AbstractHeats of formation of solid, liquid, and gaseous nitroalkanes have been shown mostly to obey group additivity. Group values have been obtained for carbon atoms attached to one, two, and three nitro groups. The heat of formation of 1,1,1,3,5,5,5,‐heptanitropentane, either solid or liquid, cannot be fitted to the scheme, even allowing for gauche effects. The differences between observed and estimated values for 1,1,1‐fluorodinitroalkanes and 1,2‐dinitroethane are larger than expected and should be further investigated. Activation energies have been calculated for decomposition by five‐center elimination of HONO from mononitro‐ and dinitroalkanes using thermochemistry and estimated activation energies for the reverse reactions. The key data for these estimates were previously reported activation energies for the decomposition of nitroethane and 1,2‐dinitropropane. The calculations also gave values for the heats of formation (in kcal/mole) of nitroethylene 12.4, and 1‐nitropropylene 5.6, and 2‐nitropropylene 1.6. Activation energies were calculated for the competing unimolecular reaction, CN bond fission, from thermochemistry and previously reported activation energies for the decomposition of 1,1‐ and 2,2‐dinitropropane. Comparison of Arrhenius parameters for the two competing processes, namely, HONO and CN bond fission, shows that, for the geminate dinitroethanes and dinitropropanes, CN bond fission is faster about 370°K and, for the mononitroalkanes and for all the mononitroalkanes and dinitroalkanes, CN bond fission is faster above 770°K.
The photochlorination of perfluorocyclopentene
Authors: Alberto Z. R. , Cosa J. J. , Staricco E. H. 
Published: January 2005

AbstractThe gas‐phase photochlorination of perfluorocyclopentene under continuous and intermittent illumination with 4360‐Å radiation was studied between 10° and 60°C. The rate constants for the reactions. (3)

(4)

were measured as k3 = (1.20 + 0.58) × 108 exp (−6.430 ± 177/RT) l·(mole sec) and k4 = (1.86 ± 0.76) × 107 l·(mole sec).
Kinetics of the thermal gas‐phase isomerization of 1,2‐epoxycyclohexane
Authors: Flowers M. C. , Penny D. E. , Pommelet J.‐C. 
Published: January 2005

AbstractThe kinetics of the gas‐phase decomposition of 1,2‐epoxycyclohexane has been studied over the temperature range 680–740 K at pressures between 1.6 and 6 torr. Isomerization to cyclohexanone and 2‐cyclohexen‐1‐ol accounts for ca. 97% of the primary reaction products and occurs by first‐order, homogeneous, nonradical processes:
Kinetics of the thermal gas phase isomerization of bicyclo[4.1.0]heptane
Authors: Flowers M. C. , Penny D. E. 
Published: January 2005

AbstractThe kinetics of the gas‐phase decomposition of bicyclo[4.1.0]heptane has been studied over the temperature range of 708–769 K at pressures between 1 and 17 torr. Isomerization to 1‐methylcyclohex‐1‐ene, methylenecyclohexane, and cycloheptene accounts for 96–98% of the primary reaction products and occurs by first‐order, homogeneous, nonradical processes.
Pyrolysis of 2,4‐dimethylhexene‐l and the stability of isobutenyl radicals
Authors: Tsang Wing 
Published: January 2005

Abstract2,4‐Dimethylhexene‐l has been decomposed in single‐pulse shock tube experiments. Rate expressions for the initial reactions are

and

sec−1 at 1.5–5 atm and 1050°K. This leads to ΔH°f300 (CH2 = C(CH3)CH2) = 124 kJ/mol, or an allylic resonance energy of 50 kJ/mol. Rate expressions for the decomposition of the appropriate olefins which yield isobutenyl radicals and methyl, ethyl, isopropyl, n‐propyl, t‐butyl, and t‐amyl radicals, respectively, are presented. The rate expression for the decomposition of isobutenyl radical is

(at the beginning of the fall‐off region). For the combination of isobutenyl and methyl radicals, the rate constant at 1020°K is

Combination of this number and the calculated rate expression for 2‐methylbutene‐1 decomposition gives S. (1100) = 470 J/mol °K. This yields

It is demonstrated that an upper limit for the rate of hydrogen abstraction by isobutenyl from toluene is
Absolute rate constants for reactions of free radicals in the high‐temperature photolysis of formamide vapor. II. Amino radicals
Authors: Back R. A. , Yokota T. 
Published: January 2005

AbstractThe rotating‐sector method has been applied to the photoinitiated radical‐chain decomposition of formamide at 300°C to measure the rate constant for the bimolecular disappearance of NH2 radicals. The decomposition is propagated by the reactions (1)

(2)

Conditions were chosen so that reaction (1) was rate controlling and NH2 the terminating radical. A flow system was employed with C2F6 as a carrier gas at a pressure of 300 Tort, and the chain reaction was initiated by the photolysis of either formamide or NH3. A value of 4.7(±2.0) × 1010 (M ·sec)−1 was estimated for the termination reaction (3)

and a value of 8.4 × 106 (M ·sec)−1 for reaction (1) in the same system, both at 300°C.
Unexpectedly rapid vapor‐phase reaction between bromine and methyl iodide
Authors: Okafo E. N. , Whittle E. 
Published: January 2005

AbstractThe overall reaction (1)

occurs readily in the gas phase, even at room temperature in the dark. The reaction is much faster than the corresponding process

and does not involve the normal bromination mechanism for gas phase reactions. Reaction (1) is probably heterogeneous although other mechanisms cannot be excluded.The overall reactions (1)

(2)

proceed, for all practical purposes, completely to the right‐hand side in the vapor phase. The expected mechanism is (3)

(4)

(5)

(6)

(7)

where reaction (3) is initiated thermally or photochemically. Reaction (4) is of interest because little kinetic data are available on reactions involving abstraction of halogen by halogen and also because an accurate determination of the activation energy E4 would prmit us to calculate an acccurate value of the bond dissociation energy D(CH3I).
The pyrolysis of 2‐nitrosoisobutane and the bond dissociation energies of nitroso compounds
Authors: Choo K. Y. , Mendenhall G. D. , Golden D. M. , Benson S. W. 
Published: January 2005

AbstractStudy of the reactionby very‐low‐pressure pyrolysis (VLPP) in the temperature range of 550–850°K yields for the high‐pressure Arrhenius parameterswhere θ = 2.303RTin kcal/mole. These in turn yield for the high‐pressure second‐order recombination oftBu + NO,k−1= (3.5 ± 1.7) × 1091./mole·sec at 600°K. For the competing reactionl./mole·sec andE4≥ 4.2 kcal/mole. The bond dissociation energyDHo(tBu‐NO) was determined to be (39.5 ± 1.5) kcal/mole, both from the equilibrium constant and from the activation energy of reaction (1), obtained from RRKM calculations. A ‘free‐volume’ model for the transition state for dissociation is consistent with the data. A limited study of the system at 8–200 torr showed an extremely rapid inhibition by products and a very complex set of products.
Addition of methyl radicals to carbon monoxide: Chemically and thermally activated decomposition of acetyl radicals
Authors: Watkins K. W. , Word William W. 
Published: January 2005

AbstractChemically activated acetyl radicals, with an excitation energy of 78 kJ/mole, were formed by the addition of methyl radicals to carbon monoxide. At 273·K the pressure required to stabilize one half of the excited radicals was 500 torr. From measurements of the acetyl radical yield at pressures in the range of 700–2100 torr, and at temperatures in the range of 260–413 K, extrapolations to infinite pressure yielded kinetic parameters for the addition of methyl radicals to carbon monoxide, and for the thermal decomposition of acetyl radicals. The rate constants were found to be log k[cm3 / (mole·s)] = 11.2–25(kJ/mole/2.3) RT, and log k(s−1) = 13.5−72 (kJ/mole)/2.3RT, respectively. Estimated thermochemical properties of the acetyl radical are ΔHfº = −17 kJ/mole and Sº = 262 J/K°mole.
The oxidation of cis‐ and trans‐CHClCHCl
Authors: Sanhueza Eugenio , Heicklen Julian 
Published: January 2005

AbstractWhen Cl atoms react with CHClCHCl in the presence of O2 at 31°C, a long‐chain oxidation occurs. The products are the geometrical isomer of the starting olefin and CHClO, HCl, CO, and CCl2O. The quantum yields of the oxygen‐containing products are the same with both isomers and are Φ{CHClO} = 30, Φ{CO} = 11.7, and Φ{CCl2O} = 1.29. The chlorine atom adds to the olefin and is followed by O2 addition. The reaction then proceeds
equation image
with k6a/k6b = 19 and k7a/k7 ∼ 0.5, where k7 ≡ k7a + k7b. The CCl2H radical oxidizes to regenerate the chain carrier.O(3P) reacts with CHClCHCl at 25°C with a rate coefficient of 6.6 × 108 M−1 sec−1 for trans‐CHClCHCl and 2.8 × 108 M−1 sec−1 for cis‐CHClCHCl. The reaction channels are
equation image
with k1a/k1 = 0.23 and 0.28, respectively, for the cis and trans compounds. Reaction (1b) occurs < 4% of the time. Reaction (1c) leads to polymer production and presumably, via redissociation, to the geometrical isomer of the starting olefin. In the presence of O2 the same long‐chain oxidation is observed as in the chlorine‐atom initiated oxidation. The chain‐initiating step is
Addition of methoxy radicals to olefins
Authors: Lissi E. A. , Massiff G. , Villa A. 
Published: January 2005

AbstractThe addition of methoxy radicals to several olefins has been studied by a competitive method at 127°C in gas phase. The thermal decomposition of dimethyl peroxide was used as methoxy radical source. The rate of addition to the double bond was measured relative to the oxidation of carbon monoxide. For the addition to ethylene it was obtained that

This rate constant is similar to the one shown by methyl radicals under similar conditions. From the relative rate of addition to several chlorinated and fluorinated olefins it can be concluded that methoxy radicals show very little “electrophilic” character.
Primary steps in the photolysis of cis‐1,2‐dichloroethylene
Authors: Ausubel R. , Wijnen M. H. J. 
Published: January 2005

AbstractThe photolysis of cis‐1,2‐dichloroethylene has been investigated in the presence of I2 as a function of incident wavelength and as a function of initial cis pressure. The results indicate that at ± > 2200Å the following primary processes occur:

The lifetime of the excited state yielding the above products is estimated at about 2.4×10−9 sec. At shorter wavelengths additional C2H2 is produced by decomposition of a vibrationally excited C2H2Cl radical.Scavenging of the CHClCH radical by I2 produced trans and cis‐CHClCHl in a ratio of 4 to 1, respectively.
Abstraction of chlorine atoms from polychloroalkanes. II. Neighboring group effect on the rates of chlorine abstraction by cyclohexyl radicals
Authors: Katz M. G. , Rajbenbach L. A. 
Published: January 2005

AbstractThe kinetics of chlorine atom abstraction from trichloromethyl groups of the haloethanes (XCCl3), CF3CCl3, CH3CCl3, C2Cl6, C2Cl5H, and CH2ClCCl3, by radiolytically generated cyclohexyl radicals was studied in the liquid phase by a competitive method. The chlorine atom abstraction data were put on an absolute basis by comparing the rates of the metathetical reactions with the known rate of addition of cyclohexyl radicals to C2Cl4.The following Arrhenius parameters were obtained:
equation image
The error limits are the standard deviations from least mean square Arrhenius plots. It is shown that the neighboring group effect on the rate of chlorine atom abstraction from the trichloromethyl groups can be correlated with Taft polar substituent constants.
Chlorine‐photosensitized reactions in the Cl2 + O2 + 1,1,1,2‐C2H2Cl4 system
Authors: Gillotay D. , Olbregts J. 
Published: January 2005

AbstractThe gas‐phase photochlorination (λ = 436 nm) of the 1,1,1,2‐C2H2Cl4 has been studied in the absence and the presence of oxygen at temperatures between 360 and 420°K. Activation energies have been estimated for the following reaction steps:

The dissociation energy D(CCl3CHClO2) ± (24.8 ± 1.5) kcal/mole has also been estimated from the difference in activation energy of the direct and reverse reactions
equation image
The mechanism is discussed and the rate parameters are compared to those obtained for a series of other chlorinated ethanes.
Estimation of the R‐H bond energy from the activation energy for the reaction RH + O2 → R· + HO2·
Authors: Denisov E. T. , Denisova L. N. 
Published: January 2005

AbstractSince the activation energy for the reaction RH + O2 → R· + HO2. is very close to its endothermicity, the R‐H bond energy can be calculated from the activation energy for free radical formation by the reaction RH + O2. The relation between Ei and QR–H was found empirically after measuring Ei by the method of inhibitors for the oxidation of cyclohexane, nheptane, and toluene:

The values of QR–H are calculated from these and earlier experimental data for five hydrocarbons, five phenols, and four aromatic amines.
The isothermal flash photolysis of hydrazoic acid
Authors: Paur Richard J. , Bair Edward J. 
Published: January 2005

AbstractThe flash photolysis of HN3 was studied by coordinated time‐resolved spectroscopic measurements of HN3 NH(a1Δ), NH(X3Σ), NH(c1π), NH(A3π), NH2, and N3 following flash photolysis of mixtures of HN3 with argon or helium. The primary photolysis is complex, but when the wavelength distribution of the flash is limited to values greater than about 200 nm, the major reactive product is NH(1Δ), or states which quickly decay to NH(1Δ). Disappearance of NH(1Δ) occurs predominantly by the process

The process has little, if any, energy of activation, and no detectable dependence on the pressure of inert gas below 1 atm. The rate of formation of NH2 in its ground vibrational state depends on the inert gas pressure in a way that can be accounted for by vibrational relaxation from initial excited vibrational states. The total amount of NH2 is roughly comparable with the amount of HN3 decomposed by primary photolysis. The observed N3 can be attributed to the NH(1Δ) + HN3 reaction, although a smaller amount could also be formed by primary photolysis. The value of k2 is revised upward from the value given in a preliminary report on the basis of a more careful consideration of the effects of Beer's law failure in absorption measurements involving narrow spectral lines.