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1.
Rate 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. 相似文献
2.
The kinetics of the gas-phase reactions of O3 with a series of alkenes have been investigated at atmospheric pressure (ca. 740 torr) of air and 296 ± 2 K, using a relative rate method in the presence of sufficient n-octane to scavenge any OH radicals generated in these reactions. Relative to k(O3 + propene) = 1.00, the rate constants obtained were: 1-butene, 0.975 ± 0.030; 2-methylpropene, 1.14 ± 0.04; 2-methyl-1,3-butadiene (isoprene), 1.21 ± 0.02; 1,4-cyclohexadiene, 4.75 ± 0.23; cyclohexene, 7.38 ± 0.48; cis-2-butene, 12.8 ± 0.8; trans-2-butene, 21.5 ± 1.5; 2-methyl-2-butene, 42.1 ± 2.8; cyclopentene, 64.9 ± 4.3; and 2,3-dimethyl-2-butene, 123 ± 11. These relative rate constants have been placed on an absolute basis using a rate constant for the reaction of O3 with propene of 1.01 × 10?17 cm3 molecule?1 s?1 at 296 K derived from an analysis of the available literature data. The resulting rate constants then lead to a self-consistent set of room temperature data for the reactions of O3 with these alkenes. © John Wiley & Sons, Inc. 相似文献
3.
Using methyl nitrite photolysis in air as a source of hydroxyl radicals, relative rate constants for the reaction of OH radicals with a series of alkanes and alkenes have been determined at 299 ± 2 K. The rate constant ratios obtained are: relative to n-hexane = 1.00, neopentane 0.135 ± 0.007, n-butane 0.453 ± 0.007, cyclohexane 1.32 ± 0.04; relative to cyclohexane = 1.00, n-butane 0.341 ± 0.002, cyclopentane 0.704 ± 0.007, 2,3-dimethylbutane 0.827 ± 0.004, ethene 1.12 ± 0.05; relative to propene = 1.00, 2-methyl-2-butene 3.43 ± 0.13, isoprene 3.81 ± 0.17, 2,3-dimethyl-2-butene 4.28 ± 0.21. These relative rate constants are placed on an absolute basis using previous absolute rate constant data and are compared and discussed with literature data. 相似文献
4.
Rate constants for the gas-phase reactions of the Cl atom with a series of alkanes have been determined at 296 ± 2 K using a relative rate method. Using a rate constant for the Cl atom reaction with n-butane of 1.94 × 10?10 cm3 molecule?1 s?1, the rate constants obtained (in units of 10?11 cm3 molecule?1 s?1) were: 2-methylpentane, 25.0 ± 0.8; 3-methylpentane, 24.8 ± 0.6; cyclohexane, 30.8 ± 1.2; cyclohexane-d12, 25.6 ± 0.8; 2,4-dimethylpentane, 25.6 ± 1.2; 2,2,3-trimethylbutane, 17.9 ± 0.7; methylcyclohexane, 34.7 ± 1.2; n-octane, 40.5 ± 1.2; 2,2,4-trimethylpentane, 23.1 ± 0.8; 2,2,3,3-tetramethylbutane, 15.6 ± 0.9; n-nonane, 42.9 ± 1.2; n-decane, 48.7 ± 1.8; and cis-bicyclo[4.4.0]decane, 43.1 ± 0.8, where the indicated errors are two least-squares standard deviations and do not include the uncertainties in the n-butane rate constant. These data have been combined with rate constants obtained previously for ten C2? C7 alkanes and this entire data set has been used to develop an estimation method allowing the room temperature rate constants for the reactions of the Cl atom with alkanes to be calculated. © 1995 John Wiley & Sons, Inc. 相似文献
5.
Perfluorobutylperoxyl radicals were produced by radiolytic reduction of perfluorobutyl iodide in aerated methanol solutions. Rate constants for the reactions of this peroxyl radical with various organic compounds were determined by kinetic spectrophotometric pulse radiolysis. The rate constants for alkanes and alkenes were determined by competition kinetics using chlorpromazine as a reference. The results indicate that hydrogen abstraction from aliphatic compounds takes place with a rate constant that is too slow to measure in our system (<105 M?1 s?1), and that abstraction of allylic and doubly allylic hydrogens is slow compared with addition. Addition to alkenes takes place with rate constants of the order of k = 106 ? 108 M?1 s?1. Good correlation was obtained between log k and the Taft substituent constants σ* for the various substituents on the double bond. Perfluorobutylperoxyl radical is found to be more reactive than trichloromethylperoxyl and other peroxyl radicals. 相似文献
6.
The pulsed laser photolysis‐resonance fluorescence technique has been used to determine the absolute rate coefficient for the Cl atom reaction with a series of ketones, at room temperature (298 ± 2) K and in the pressure range 15–60 Torr. The rate coefficients obtained (in units of cm3 molecule−1 s−1) are: acetone (3.06 ± 0.38) × 10−12, 2‐butanone (3.24 ± 0.38) × 10−11, 3‐methyl‐2‐butanone (7.02 ± 0.89) × 10−11, 4‐methyl‐2‐pentanone (9.72 ± 1.2) × 10−11, 5‐methyl‐2‐hexanone (1.06 ± 0.14) × 10−10, chloroacetone (3.50 ± 0.45) × 10−12, 1,1‐dichloroacetone (4.16 ± 0.57) × 10−13, and 1,1,3‐trichloroacetone (<2.4 × 10−12). © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 62–66, 2000 相似文献
7.
The laser photolysis–resonance fluorescence technique has been used to determine the absolute rate coefficient for the Cl atom reaction with a series of ethers, at room temperature (298 ± 2) K and in the pressure range 15–60 Torr. The rate coefficients obtained (in units of cm3 molecule−1 s−1) are dimethyl ether (1.3 ± 0.2) × 10−10, diethyl ether (2.5 ± 0.3) × 10−10, di‐n‐propyl ether (3.6 ± 0.4) × 10−10, di‐n‐butyl ether (4.5 ± 0.5) × 10−10, di‐isopropyl ether (1.6 ± 0.2) × 10−10, methyl tert‐butyl ether (1.4 ± 0.2) × 10−10, and ethyl tert‐butyl ether (1.5 ± 0.2) × 10−10. The results are discussed in terms of structure–reactivity relationship. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 105–110, 2000 相似文献
8.
The rate constants for the reactions of OH radicals with fully fluorinated alkenes containing different numbers of -CF(3) groups next to olefinic carbon, CF(2)═CF(2), CF(2)═CFCF(3), CF(3)CF═CFCF(3), and (CF(3))(2)C═CFC(2)F(5), were measured between 230 and 480 K using the flash photolysis resonance fluorescence technique to give the following expressions: k(C(2)F(4))(250-480 K) = 1.32 × 10(-12) × (T/298 K)(0.9) × exp(+600 K/T) cm(3) molecule(-1) s(-1), k(C(3)F(6))(230-480 K) = 9.75 ×10(-14) × (T/298 K)(1.94) × exp(+922 K/T) cm(3) molecule(-1) s(-1), k(trans-C(4)F(8))(230-370 K) = 7.50 × 10(-14) × (T/298 K)(1.68) × exp(+612 K/T) cm(3) molecule(-1) s(-1), k(cis-C(4)F(8))(230-370 K) = 2.99 × 10(-14) × (T/298 K)(2.61) × exp(+760 K/T) cm(3) molecule(-1) s(-1), and k(C(6)F(12))(250-480 K) = 2.17 × 10(-15) × (T/298 K)(3.90) × exp(+1044 K/T) cm(3) molecule(-1) s(-1). The kinetics of the OH reaction in an industrial sample of octofluoro-2-propene (a mixture of the cis- and trans-isomers of CF(3)CF═CFCF(3)) was studied to determine the "effective" reaction rate constant for the typically industrial mixture: k()(230-480 K) = 7.89 × 10(-14) × (T/298 K)(1.71) × exp(+557 K/T) cm(3) molecule(-1) s(-1). On the basis of these results, the atmospheric lifetimes were estimated to be 1.2, 5.3, 21, 34, and 182 days for CF(2)═CF(2), CF(3)CF═CF(2), trans-CF(3)CF═CFCF(3), cis-CF(3)CF═CFCF(3), and (CF(3))(2)C═CFC(2)F(5), respectively. The general pattern of halolalkene reactivity toward OH is discussed. 相似文献
9.
Direct determinations of the rate constants (cm3/molec · sec) k1, k2, and k3 from 298 to 299°K are reported, using atomic resonance fluorescence in discharge flow systems: 1 One standard deviation. The rate constant k1, which has not been determined previously, was found to possess an insignificant temperature coefficient (EA = (0 ± 700) J/mole) in the range of 299 to 619°K. The present result for k2 agrees well with reinterpreted values from the one previous determination. Measurements of O atom consumption rates and Br atom production rates in the O + Br2 reaction are interpreted to give an estimate of the rate constant k4, which has not been reported previously, at 298°K: k3 has been measured at three temperatures between 299 and 602°K. The present and previous results for k3 were combined to give the following rate expression: 相似文献
10.
Rate constants of the reactions of O(3P) atoms with Br2 and NO2 over the temperature range 220-950 K
The kinetics of the reactions of Br2 and NO2 with ground state oxygen atoms have been studied over a wide temperature range, T = 220-950 K, using a low-pressure flow tube reactor coupled with a quadrupole mass spectrometer: O + NO2 → NO + O2 (1) and O + Br2 → Br + BrO (2). The rate constant of reaction (1) was determined under pseudo–first-order conditions, either monitoring the kinetics of O-atom or NO2 consumption in excess of NO2 or of the oxygen atoms, respectively: k1 = (6.1 ± 0.4) × 10−12 exp((155 ± 18)/T) cm3 molecule−1 s−1 (where the uncertainties represent precision at the 2σ level, the estimated total uncertainty on k1 being 15% at all temperatures). The temperature dependence of k1, found to be in excellent agreement with multiple previous low-temperature data, was extended to 950 K. The rate constant of reaction (2) determined under pseudo–first-order conditions, monitoring the kinetics of Br2 consumption in excess of O-atoms, showed upward curvature at low and high temperatures of the study and was fitted with the following three-parameter expression: k2 = 9.85 × 10−16 T1.41 exp(543/T) cm3 molecule−1 s−1 at T = (220-950) K, which is recommended from the present study with an independent of temperature conservative uncertainty of 15% on k2. 相似文献
11.
Laser flash photolysis (at 248 or 308 nm) or aryl iodides in water or water/methanol solutions produces iodine atoms and phenyl radicals. Iodine atoms react rapidly with added I? to form I2? but do not react rapidly with O2 (k ? 107 L mol?1 s?1). Iodine atoms oxidize phenols to phenoxyl radicals, with rate constants that vary from 1.6 × 107 L mol?1 s?1 for phenol to about 6 × 109 L mol?1 s?1 for 4-methoxyphenol and hydroquinone. Ascorbate and a Vitamin E analogue are also oxidized very rapidly. N-Methylindole is oxidized by I atoms to its radical cation with a diffusion-controlled rate constant, 1.9 × 1010 L mol?1 s?1. Iodine atoms also oxidize sulfite and ferrocyanide ions rapidly but do not add to double bonds. The phenyl radicals, produced along with the I atoms, react with O2 to give phenylperoxyl radicals, which react with phenols much more slowly than I atoms. © 1995 John Wiley & Sons, Inc. 相似文献
12.
Rate 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. 相似文献
13.
A relative rate method has been used to determine rate constants for the gas-phase reactions of a series of hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) at 298 ± 2 K and atmospheric pressure of air. Based on a rate constant for the reaction of the Cl atom with CH4 of (1.0 ± 0.2) ? 10?13 cm3 molecule?1 s?1 at 298 K, the following Cl atom reaction rate constants (in units of 10?15 cm3 molecule?1 s?1) were obtained: CH3F, 340 ± 70; CH3CHF2, 240 ± 50; CH2FCl, 110 ± 25; CHFCl2, 21 ± 4; CHCl2CF3, 14 ± 3; CHFClCF3, 2.7 ± 0.6; CH3CFCl2, 2.4 ± 0.5; CHF2Cl, 2.0 ± 0.4; CH2FCF3, 1.6 ± 0.3; CH3CF2Cl, 0.37 ± 0.08; and CHF2CF3, 0.24 ± 0.05. These Cl atom reaction rate constants are compared with literature data and with the corresponding OH radical reaction rate constants. © John Wiley & Sons, Inc. 相似文献
14.
15.
The rate constants for the gas-phase reactions of isopropyl- and tert-butylperoxy radicals with nitric oxide (NO) have been studied at 298 +/- 2 K and a total pressure of 3-4 Torr (He buffer) using a laser flash photolysis technique coupled with a time-resolved negative-ionization mass spectrometry. The alkyl peroxy radicals were generated by the reaction of alkyl radicals with excess O(2), where alkyl radicals were prepared by laser photolysis of several precursor molecules. The rate constants were determined to be k(i-C(3)H(7)O(2) + NO) = (8.0 +/- 1.5) x 10(-12) and k(t-C(4)H(9)O(2) + NO) = (8.6 +/- 1.4) x 10(-12) cm(3) molecule(-1) s(-1). The results in combination with our previous studies are discussed in terms of the systematic reactivity of alkyl peroxy radicals toward NO. 相似文献
16.
Rate constants have been measured at room temperature for the reactions of Cl atoms with formic acid and with the HOCO radical: Cl + HCOOH → HCl + HOCO (R1) Cl + HOCO → HCl + CO2 (R2) Cl atoms were generated by flash photolysis of Cl2 and the progress of reaction was followed by time‐resolved infrared absorption measurements using tunable diode lasers on the CO2 that was formed either in the pair of reactions ( R1 ) plus ( R2 ), or in reaction ( R1 ) followed by O2 + HOCO → HO2 + CO2 (R3) In a separate series of experiments, conditions were chosen so that the kinetics of CO2 formation were dominated either by the rate of reaction ( R1 ) or by that of reactions ( R1 ) and ( R2 ) combined. The results of our analysis of these experiments yielded: k1 = (1.83 ± 0.12) × 10−13 cm3 molecule−1 s−1 k2 = (4.8 ± 1.0) × 10−11 cm3 molecule−1 s−1 © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 85–91, 2000 相似文献
17.
Reactions of ozone with propene, 1-butene, cis-2-butene, trans-2-butene, 2,3-dimethyl-2-butene, and 1,3-butadiene were carried out in N2 and air diluent at atmospheric pressure and room temperature and, by monitoring the formation of the epoxides and/or a carbonyl compound formed from the reactions of O(3P) atoms with these alkenes, the formation yields of O(3P) atoms from the O3 reactions were investigated. No evidence for O(3P) atom formation was obtained, and upper limits to O(3P) atom formation yields of <4% for propene, <5% for 1.3-butadiene, and <2% for the other four alkenes were derived. The reaction of O3 with 1,3-butadiene led to the direct formation of 3,4-epoxy-1-butene in (2.3 ± 0.4)% yield. These data are in agreement with the majority of the literature data and show that O(3P) atom formation is not a significant pathway in O3—alkene reactions, and that epoxide formation only occurs to any significant extent from conjugated dienes. © 1994 John Wiley & Sons, Inc. 相似文献
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19.
Loison JC Bergeat A Caralp F Hannachi Y 《The journal of physical chemistry. A》2006,110(50):13500-13506
The reactions of the CH radical with several alkanes were studied, at room temperature, in a low-pressure fast-flow reactor. CH(X2Pi, v = 0) radicals were obtained from the reaction of CHBr(3) with potassium atoms. The overall rate constants at 300 K are (0.76 +/- 0.20) x 10(-10) [Fleurat-Lessard, P.; Rayez, J. C.; Bergeat, A.; Loison, J. C. Chem. Phys. 2002, 279, 87],1 (1.60 +/- 0.60) x 10(-10)[Galland, N.; Caralp, F.; Hannachi, Y.; Bergeat, A.; Loison, J.-C. J. Phys. Chem. A 2003, 107, 5419],2 (2.20 +/- 0.80) x 10(-10), (2.80 +/- 0.80) x 10(-10), (3.20 +/- 0.80) x 10(-10), (3.30 +/- 0.60) x 10(-10), and (3.60 +/- 0.80) x 10(-10) cm3 molecule(-1) s(-1), (errors refer to +/-2sigma) for methane, ethane, propane, n-butane, n-pentane, neo-pentane, and n-hexane respectively. The experimental overall rate constants correspond to those obtained using a simple classical capture theory. Absolute atomic hydrogen production was determined by V.U.V. resonance fluorescence, with H production from the CH + CH4 reaction being used as a reference. Observed H branching ratios were for CH4, 1.00[Fleurat-Lessard, P.; Rayez, J. C.; Bergeat, A.; Loison, J. C. Chem. Phys. 2002, 279, 87];1 C(2)H(6), 0.22 +/- 0.08 [Galland, N.; Caralp, F.; Hannachi, Y.; Bergeat, A.; Loison, J.-C. J. Phys. Chem. A 2003, 107, 5419];2 C(3)H(8), 0.19 +/- 0.07; C(4)H(10) (n-butane), 0.14 +/- 0.06; C(5)H(12) (n-pentane), 0.52 +/- 0.08; C(5)H(12) (neo-pentane), 0.51 +/- 0.08; C(5)H(12) (iso-pentane), 0.12 +/- 0.06; C(6)H(14) (n-hexane), 0.06 +/- 0.04. 相似文献