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1.
The yields of C5 and C6 alkyl nitrates from neopentane, 2-methylbutane, 2-methylpentane, 3-methylpentane, and cyclohexane have been measured in irradiated CH3ONONO-alkane-air mixtures at 298 ± 2 K and 735-torr total pressure. Additionally, OH radical rate constants for neopentyl nitrate, 3-nitro-2-methylbutane, 2-nitro-2-methylpentane, 2-nitro-3-methylpentane, and cyclohexyl nitrate, relative to that for n-butane, have been determined at 298 ± 2 K. Using a rate constant for the reaction of OH radicals with n-butane of 2.58 × 10?12 cm3 molecule?1 s?1, these OH radical rate constants are (in units of 10?12 cm3 molecule?1 s?1): neopentyl nitrate, 0.87 ± 0.21; cyclohexyl nitrate, 3.35 ± 0.36; 3-nitro-2-methylbutane, 1.75 ± 0.06; 2-nitro-2-methylpentane, 1.75 ± 0.22; and 2-nitro-3-methylpentane, 3.07 ± 0.08. After accounting for consumption of the alkyl nitrates by OH radical reaction and for the yields of the individual alkyl peroxy radicals formed in the reaction of OH radicals with the alkanes studied, the alkyl nitrate yields (which reflect the fraction of the individual RO2 radicals reacting with NO to form RONO2) determined were: neopentyl nitrate, 0.0513 ± 0.0053; cyclohexyl nitrate, 0.160 ± 0.015; 3-nitro-2-methylbutane, 0.109 ± 0.003; 2-nitro-2methylbutane, 0.0533 ± 0.0022; 2-nitro-2-methylpentane, 0.0350 ± 0.0096; 3- + 4-nitro-2-methylpentane, 0.165 ± 0.016; and 2-nitro-3-methylpentane, 0.140 ± 0.014. These results are discussed and compared with previous literature values for the alkyl nitrates formed from primary and secondary alkyl peroxy radicals generated from a series of n-alkanes.  相似文献   

2.
Using a relative rate technique, rate constants have been determined for the gas phase reactions of Cl atoms with a series of organics at 296 ± 2 K and atmospheric pressure of air. Using a rate constant of 1.97 × 10?10 cm3 molecule?1 s?1 for the reaction of Cl atoms with n-butane, the following rate constants (in units of 10?11 cm3 molecule?1 s?1) were obtained: ethane, 6.38 ± 0.18; propane, 13.4 ± 0.5; isobutane, 13.7 ± 0.2; n-pentane, 25.2 ± 1.2; isopentane, 20.3 ± 0.8; neopentane, 11.0 ± 0.3; n-hexane, 30.3 ± 0.6; cyclohexane, 31.1 ± 1.4; 2,3-dimethylbutane, 20.7 ± 0.6; n-heptane, 34.1 ± 1.2; acetylene, 6.28 ± 0.18; ethene, 10.6 ± 0.3; propene, 24.4 ± 0.8; benzene, 1.5 ± 0.9; and toluene, 5.89 ± 0.36. These data are compared and discussed with the available literature values.  相似文献   

3.
The relative rate technique has been used to determine the rate constants for the reaction of chlorine atoms with a series of oxygenated organic species. Experiments were performed at 295 ± 2 K and atmospheric pressure of synthetic air or nitrogen. The decay rates of the organic species were measured relative to that of ethane or n-butane. Using rate constants of 5.7 × 10?11 cm3 molecule?1 s?1, and 2.25 × 10?10 cm3 molecule?1 s?1 for the reaction of Cl with ethane and n-butane respectively the following rate constants were derived, in units of 10?11 cm3 molecule?1 s?1: propane, (16.0 ± 0.4);i-butane, (15.1 ± 0.9) n-pentane, (31.0 ± 1.6); n-hexane, (34.5 ± 2.3); cyclohexane, (36.1 ± 1.5); methanol, (4.57 ± 0.40); ethanol, (8.45 ± 0.91); n-propanol, (14.4 ± 1.2); t-butylalcohol, (3.26 ± 0.19); acetaldehyde, (8.45 ± 0.79); propionaldehyde, (11.3 ± 0.9); dimethylether, (20.5 ± 0.8); diethylether, (35.6 ± 2.8); and methyl-t-butylether, (16.6 ± 1.2). Quoted errors represent 2σ, and do not include any errors due to uncertainties in the rate constants used to place our relative measurements on an absolute basis. The results are discussed with respect to the mechanisms of these reactions and to previous literature data.  相似文献   

4.
Relative rate constants for the gas-phase reactions of Cl-atom with thirteen atmospherically interesting alkanes (C2? C8) have been determined at 296 ± 2 K based on GC/FID measurements of their relative decays in the UV (λ ≥ 300 nm) photolysis of mixtures containing Cl2 and the entire series of the selected alkanes in the mtorr range in 750 torr of N2. The following absolute rate constants (in units of 10?10 cm3 molecule?1 s?1) have been derived from the relative rate constants combined with the value of 1.94 × 10?10 cm3 molecule?1 s?1 for the Cl + n-butane reaction: ethane (0.57 ± 0.05); propane (1.27 ± 0.02); 2-methyl propane (1.30 ± 0.01), 2-methyl butane ((1.96 ± 0.02)), n-pentane (2.50 ± 0.02); 2,3-dimethyl butane (2.00 ± 0.06); 2-methyl pentane (2.58 ± 0.08); n-hexane (3.05 ± 0.04); 2-methyl hexane (3.12 ± 0.04); n-heptane (3.65 ± 0.06); 2,2,4-trimethyl pentane (2.25 ± 0.08); and n-octane (4.09 ± 0.12). The uncertainties indicated are two least-squares standard deviations (2σ). These rate constants are compared with literature values and their applicability to Arctic tropospheric conditions is discussed. © 1995 John Wiley & Sons, Inc.  相似文献   

5.
Rate constants for the reactions of Cl atoms with cycloheptane, cyclooctane, cyclodecane, cyclohexanone, cycloheptanone, cyclooctanone, and cyclodecanone have been measured at 297 ± 2 K and atmospheric pressure of air using a relative rate method. n‐Butane, with a rate constant of 2.05 × 10?10 cm3 molecule?1 s?1, was used as the reference compound, and the rate constants obtained (in units of 10?10 cm3 molecule?1 s?1) were cycloheptane, 4.22 ± 0.15; cyclooctane, 4.57 ± 0.15; cyclodecane, 5.13 ± 0.15; cyclohexanone, 1.79 ± 0.06; cycloheptanone, 2.46 ± 0.07; cyclooctanone, 2.97 ± 0.09; and cyclodecanone, 3.65 ± 0.15, where the indicated errors are two least‐squares standard deviations and do not include uncertainties in the rate constant for the reference compound n‐butane. Room temperature rate constants for the C5–C10 cycloketones indicate that the ? CH2? groups adjacent to the carbonyl group are almost totally deactivated toward H‐atom abstraction by Cl atoms, and this also applies to acyclic ketones. A previous structure–reactivity relationship for Cl + alkanes has been extended to include acyclic and cyclic ketones. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 45: 52–58, 2013  相似文献   

6.
Using a relative rate technique, rate constants have been determined for the gas-phase reactions of Cl atoms with the cholorethenes and ethane at 298 ± 2 K and 735 torr total pressure of air. Using a rate constant of 1.97 × 10?10 cm3 molecule?1 s?1 for the reaction of Cl atoms with n-butane, the following rate constants (in units of 10?11 cm3 molecule?1 s?1) were obtained: vinyl chloride, 12.7 ± 0.2; 1,1-dichloroethene, 14.0 ± 0.2; cis-1,2-dichloroethene, 9.65 ± 0.10; trans-1,2-dichloroethene, 9.58 ± 0.18; trichloroethene, 8.08 ± 0.10; tetrachloroethene, 4.13 ± 0.23; and ethane, 6.17 ± 0.08 (where the indicated error limits do not include the uncertainties in the rate constant for n-butane). A small amount of cis-trans isomerization was observed for the reactions involving the cis- and trans-1,2-dichloroethenes. These data are compared and discussed with the available literature data.  相似文献   

7.
A high‐resolution IR diode laser in conjunction with a Herriot multiple reflection flow‐cell has been used to directly determine the rate coefficients for simple alkanes with Cl atoms at room temperature (298 K). The following results were obtained: k(Cl + n‐butane) = (1.91 ± 0.10) × 10?10 cm3 molecule?1 s?1, k(Cl + n‐pentane) = (2.46 ± 0.12) × 10?10 cm3 molecule?1 s?1, k(Cl + iso‐pentane) = (1.94 ± 0.10) × 10?10 cm3 molecule?1 s?1, k(Cl + neopentane) = (1.01 ± 0.05) × 10?10 cm3 molecule?1 s?1, k(Cl + n‐hexane) = (3.44 ± 0.17) × 10?10 cm3 molecule?1 s?1 where the error limits are ±1σ. These values have been used in conjunction with our own previous measurements on Cl + ethane and literature values on Cl + propane and Cl + iso‐butane to generate a structure activity relationship (SAR) for Cl atom abstraction reactions based on direct measurements. The resulting best fit parameters are kp = (2.61 ± 0.12) × 10?11 cm3 molecule?1 s?1, ks = (8.40 ± 0.60) × 10?11 cm3 molecule?1 s?1, kt = (5.90 ± 0.30) × 10?11 cm3 molecule?1 s?1, with f( ? CH2? ) = f (? CH2? ) = f (?C?) = f = 0.85 ± 0.06. Tests were carried out to investigate the potential interference from production of excited state HCl(v = 1) in the Cl + alkane reactions. There is some evidence for HCl(v = 1) production in the reaction of Cl with shape n‐hexane. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 34: 86–94, 2002  相似文献   

8.
Rate constants for the reactions of Cl atoms with two cyclic dienes, 1,4‐cyclohexadiene and 1,5‐cyclooctadiene, have been determined, at 298 K and 800 Torr of N2, using the relative rate method, with n‐hexane and 1‐butene as reference molecules. The concentrations of the organics are followed by gas chromatographic analysis. The ratios of the rate constants of reactions of Cl atoms with 1,4‐cyclohexadiene and 1,5‐cyclooctadiene to that with n‐hexane are measured to be 1.29 ± 0.06 and 2.19 ± 0.32, respectively. The corresponding ratios with respect to 1‐butene are 1.50 ± 0.16 and 2.36 ± 0.38. The absolute values of the rate constants of the reaction of Cl atom with n‐hexane and 1‐butene are considered as (3.15 ± 0.40) × 10?10 and (3.21 ± 0.40) × 10? 10 cm3 molecule?1s?1, respectively. With these, the calculated values are k(Cl + 1,4‐cyclohexadiene) = (4.06 ± 0.55) × 10?10 and k(Cl + 1,5‐cyclooctadiene) = (6.90 ± 1.33) × 10?10 cm3 molecule?1 s?1 with respect to n‐hexane. The rate constants determined with respect to 1‐butene are marginally higher, k(Cl + 1,4‐cyclohexadiene) = (4.82 ± 0.80) × 10? 10 and k(Cl + 1,5‐cyclooctadiene) = (7.58 ± 1.55) × 10? 10 cm3 molecule?1 s?1. The experiments for each molecule were repeated three to five times, and the slopes and the rate constants given above are the average values of these measurements, with 2σ as the quoted error, including the error in the reference rate constant. The relative rate ratios of 1,4‐cyclohexadiene with both the reference molecules are found to be higher in the presence of oxygen, and a marginal increase is observed in the case of 1,5‐cyclooctadiene. Benzene is identified as one major product in the case of 1,4‐cyclohexadiene. Considering that the cyclohexadienyl radical, a product of the hydrogen abstraction reaction, is quantitatively converted to benzene in the presence of oxygen, the fraction of Cl atoms that reacts by abstraction is estimated to be 0.30 ± 0.04. The atmospheric implications of the results are discussed. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 431–440, 2011  相似文献   

9.
The relative rate technique has been used to determine the rate constants for the reactions Cl + CH3OCHCl2 → products and Cl + CH3OCH2CH2Cl → products. Experiments were carried out at 298 ± 2 K and atmospheric pressure using nitrogen as the bath gas. The decay rates of the organic species were measured relative to those of 1,2‐dichloroethane, acetone, and ethane. Using rate constants of (1.3 ± 0.2) × 10?12 cm3 molecule?1 s?1, (2.4 ± 0.4) × 10?12 cm3 molecule?1 s?1, and (5.9 ± 0.6) × 10?11 cm3 molecule?1 s?1 for the reactions of Cl atoms with 1,2‐dichloroethane, acetone, and ethane respectively, the following rate coefficients were derived for the reaction of Cl atoms (in units of cm3 molecule?1 s?1) with CH3OCHCl2, k= (1.04 ± 0.30) × 10?12 and CH3OCH2CH2Cl, k= (1.11 ± 0.20) × 10?10. Errors quoted represent two σ, and include the errors due to the uncertainties in the rate constants used to place our relative measurements on an absolute basis. The rate constants obtained are compared with previous literature data and used to estimate the atmospheric lifetimes for the studied ethers. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 420–426, 2005  相似文献   

10.
Relative rate constants for the reaction of OH radicals with a series of n-alkanes have been determined at 299 ± 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 n-butane of 2.58 × 10?12 cm3 molecule?1s?1, the rate constants obtained are (X1012 cm3 molecule?1 s?1): propane 1.22 ± 0.05, n-pentane 4.13 ± 0.08, n-heptane 7.30 ± 0.17, n-octane 9.01 ± 0.19, n-nonane 10.7 ± 0.4, and n-decane 11.4 ± 0.6. The data for propane, n-pentane, and n-octane are in good agreement with literature values, while those for n-heptane, n-nonane, and n-decane are reported for the first time. These data show that the rate constant per secondary C—H bond is ∽40% higher for —CH2— groups bonded to two other —CH2— groups than for those bonded to a —CH2— group and a —CH3 group.  相似文献   

11.
The kinetics and products of the homogeneous gas-phase reactions of the OH radical with the chloroethenes were investigated at 298 ± 2 K and atmospheric pressure. Using a relative rate technique and ethane as a scavenger for the chlorine atoms produced in these OH radical reactions, rate constants (in units of 10?12 cm3 molecule?1s?1) of 8.11 ± 0.24, 2.38 ± 0.14, and 1.80 ± 0.03 were obtained for 1,1-dichloroethene, cis-1, 2-dichloroethene and trans-1,2-dichloroethene, respectively. Under these conditions, the major products observed by long pathlength FT-IR absorption spectroscopy were HCHO and HC(O)Cl from vinyl chloride; HC(O)Cl from cis- and trans-1,2-dichloroethene; HCHO and COCl2 from 1,1-dichloroethene; HC(O)Cl and COCl2 from trichloroethene; and COCl2 from tetrachloroethene. In the absence of a Cl atom scavenger, significant yields of the chloroacetyl chlorides, CHxCl3?xC(O)Cl, were observed from 1,1-dichloro-, trichloro- and tetrachloroethene, indicating that these products resulted from reactions involving chlorine atoms. The yields of all of these products are reported and the mechanisms of these gas-phase reactions discussed. In addition, OH radical reaction rate constants were redetermined, in the presence of a Cl atom scavenger, for cis- and trans-1,3-dichloropropene and 3-chloro-2-chloromethyl-1-propene, being (in units of 10?12 cm3 molecule?1 s?1) 8.45 ± 0.41, 14.4 ± 0.8, and 33.5 ± 3.0, respectively.  相似文献   

12.
Absolute rate constants for the reaction of O(3P) atoms with n-butane (k2) and NO(M  Ar)(k3) have been determined over the temperature range 298–439 K using a flash photolysis-NO2 chemiluminescence technique. The Arrhenius expressions obtained were k2 = 2.5 × 10?11exp[-(4170 ± 300)/RT] cm3 molecule?1 s?1, k3 = 1.46 × 10?32 exp[940 ± 200)/ RT] cm6 molecule?2 s?1, with rate constants at room temperature of k2 = (2.2 ± 0.4) × 10?14 cm3 molecule?1 s?1 and k3 = (7.04 ± 0.70)×10?32 cm6 molecule?2 s?1. These rate constants are compared and discussed with literature values.  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.
Rate coefficients for the reaction of Cl atoms with cycloalkenes have been determined using the relative rate method, at 298 K and atmospheric pressure of N2. Reference molecule was n‐hexane, and the concentrations of the organics were followed by gas chromatographic analysis. Cl atoms were prepared by photolysis of trichloroacetyl chloride at 254 nm. The relative rates of reactions of Cl atoms with cycloalkenes, with respect to n‐hexane, are measured as 1.12 ± 0.38, 1.31 ± 0.14, and 1.69 ± 0.18 for cyclopentene, cyclohexene, and cycloheptene, respectively. Considering the absolute value of the rate coefficient of the reaction of Cl atom with n‐hexane as 3.03 ± 0.06 × 10?10 cm3 molecule?1 s?1, the rate coefficient values for cyclopentene, cyclohexene, and cycloheptene are calculated to be (3.39 ± 1.08) × 10?10, (3.97 ± 0.43) × 10?10, and (5.12 ± 0.55) × 10?10 cm3 molecule?1 s?1, respectively. The experiments for each molecule were repeated six to eight times, and the slopes and the rate coefficients given above are the average values of these measurements, and the quoted error includes 2σ as well as all other uncertainties in the measurement and calculations. The rate coefficient increases linearly with the number of carbon atoms, with an increment per additional CH2 group being (8.7 ± 1.6) × 10?12 cm3 molecule?1 s?1. Chloroketones and chloroalcohols, along with unsaturated ketones and alcohols, were found to be the major products of Cl‐atom‐initiated oxidation of cycloalkenes in the presence of air. The atmospheric implications of these results are discussed, along with a comparison with the reported structure activity relationships. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 42: 98–105, 2010  相似文献   

15.
The relative rate technique has been used to measure rate constants for the reaction of chlorine atoms with nitro methane, nitro ethane, nitro propane, nitro butane, nitro pentane, ethyl nitrate, isopropyl nitrate, n-propyl nitrate, 2-pentyl nitrate, and 2-heptyl nitrate. Decay rates of these organic species were measured relative to one or more of the following reference compounds; n-butane, ethane, chloroethane, and methane. Using rate constants of 2.25 × 10?10 5.7 × 10?11, 8.04 × 10?12, and 1.0 × 10?13 cm3 molecule?1 s?1 for the reaction of Cl atoms with n-butane, ethane, chloroethane, and methane, respectively, the following rate constants were derived, in units of cm3 molecule?1 s?1: nitro methane, <7 × 10?15; nitro ethane, (2.05 ± 0.14) × 10?13; nitro propane, (1.13 ± 0.05) × 10?11; nitro butane, (5.13 ± 0.68) × 10?11; nitro pentane, (1.40 ± 0.14) × 10?10; ethyl nitrate, (3.70 ± 0.24) × 10?12; n-propyl nitrate, (2.15 ± 0.13) × 10?11; i-propyl nitrate, (3.94 ± 0.48) × 10?12; 2-pentyl nitrate, (1.00 ± 0.06) × 10?10; and 2-heptyl nitrate, (2.84 ± 0.50) × 10?10. Quoted errors represent 2σ and do not include possible systematic errors due to errors in the reference rate constants. Experiments were performed at 295 ± 2 K and atmospheric pressure (?740 torr) of synthetic air. The results are discussed with respect to the previous literature data and to the modeling of these compounds in the atmosphere.  相似文献   

16.
Relative rate constants for the reaction of OH radicals with a series of branched alkanes have been determined at 297 ± 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 n-butane of 2.58 × 10?12 cm3/molecule · s, the rate constants obtained are (× 1012 cm3/molecule · s): isobutane, 2.29 ± 0.06; 2-methylbutane, 3.97 ± 0.11; 2,2-dimethylbutane, 2.66 ± 0.08; 2-methylpentane, 5.68 ± 0.24; 3-methylpentane, 5.78 ± 0.11; 2,2,3-trimethylbutane, 4.21 ± 0.08; 2,4-dimethylpentane, 5.26 ± 0.11; methylcyclohexane, 10.6 ± 0.3; 2,2,3,3-tetramethylbutane, 1.06 ± 0.08; and 2,2,4-trimethylpentane, 3.66 ± 0.16. Rate constants for 2,2-dimethylbutane, 2,4-dimethylpentane, and methylclohexane have been determined for the first time, while those for the other branched alkanes are in generally good agreement with the literature data. Primary, secondary, and tertiary group rate constants at room temperature have been derived from these and previous data for alkanes and unstrained cycloalkanes, with the secondary and tertiary group rate constants depending in a systematic manner on the identity of the neighboring groups. The use of these group rate constants, together with a previous determination of the effect of ring strain energy on the OH radical rate constants for a series of cycloalkanes, allows the a priori estimation of OH radical rate constants for alkanes and cycloalkanes at room temperature.  相似文献   

17.
Ethers are being increasingly used as motor fuel additives to increase the octane number and to reduce CO emissions. Since their reaction with hydroxyl radicals (OH) is a major loss process for these oxygenated species in the atmoshpere, we have conducted a relative rate study of the kinetics of the reactions of OH radicals with a series of ethers and report the results of these measurements here. Experiments were performed under simulated atmospheric conditions; atmospheric pressure (? 740 torr) in synthetic air at 295 K. Using rate constants of 2.53 × 10?12, and 1.35 × 10?11 cm3 molecule?1 s?1 for the reaction of OH radicals with n-butane and diethyl ether, the following rate constants were derived, in units of 10?11 cm3 molecule?1 s?1: dimethylether, (0.232 ± 0.023); di-n-propylether, (1.97 ± 0.08); di-n-butylether, (2.74 ± 0.32); di-n-pentylether, (3.09 ± 0.26); methyl-t-butylether, (0.324 ± 0.008); methyl-n-butylether, (1.29 ± 0.03); ethyl-n-butylether, (2.27 ± 0.09); and ethyl-t-butylether, (0.883 ± 0.026). Quoted errors represent 2σ from the least squares analysis and do not include any systematic errors associated with uncertainties in the reference rate constants used to place our relative measurements on an absolute basis. The implications of these results for the atmospheric chemistry of ethers are discussed.  相似文献   

18.
The kinetics of the gas-phase reaction of Cl atoms with CF3I have been studied relative to the reaction of Cl atoms with CH4 over the temperature range 271–363 K. Using k(Cl + CH4) = 9.6 × 10?12 exp(?2680/RT) cm3 molecule?1 s?1, we derive k(Cl + CF3I) = 6.25 × 10?11 exp(?2970/RT) in which Ea has units of cal mol?1. CF3 radicals are produced from the reaction of Cl with CF3I in a yield which was indistinguishable from 100%. Other relative rate constant ratios measured at 296 K during these experiments were k(Cl + C2F5I)/k(Cl + CF3I) = 11.0 ± 0.6 and k(Cl + C2F5I)/k(Cl + C2H5Cl) = 0.49 ± 0.02. The reaction of CF3 radicals with Cl2 was studied relative to that with O2 at pressures from 4 to 700 torr of N2 diluent. By using the published absolute rate constants for k(CF3 + O2) at 1–10 torr to calibrate the pressure dependence of these relative rate constants, values of the low- and high-pressure limiting rate constants have been determined at 296 K using a Troe expression: k0(CF3 + O2) = (4.8 ± 1.2) × 10?29 cm6 molecule?2 s?1; k(CF3 + O2) = (3.95 ± 0.25) × 10?12 cm3 molecule?1 s?1; Fc = 0.46. The value of the rate constant k(CF3 + Cl2) was determined to be (3.5 ± 0.4) × 10?14 cm3 molecule?1 s?1 at 296 K. The reaction of Cl atoms with CF3I is a convenient way to prepare CF3 radicals for laboratory study. © 1995 John Wiley & Sons, Inc.  相似文献   

19.
A study was conducted to measure the hydroxyl radical rate constants using a relative rate procedure in which the photolysis of methyl nitrite was the source of OH. During the course of this study, the OH rate constant was measured for a number of chlorinated solvents for which measurements have not previously been reported or for which there are few reliable measurements. Room temperature OH rate constants are presented for six chlorinated hydrocarbons (allyl chloride, benzyl chloride, chlorobenzene, epichlorohydrin, trichloroethylene, and vinylidene chloride) and four oxygenated hydrocarbons (acrolein, methacrolein, methyl ethyl ketone, and propylene oxide). Also included are OH rate constants for alkanes (ethane, propane, isobutane, and cyclohexane), alkenes (trans?2-butene and isoprene), and aromatic hydrocarbons (benzene, toluene, o?, m?, and p-xylene). Rate constants for compounds not previously reported include vinylidene chloride (1.49 ± 0.21 × 10?11 cm3 molecule?1 s?1) and benzyl chloride (2.96 ± 0.15 × 10?12 cm3 molecule?1 s?1). The analysis for chlorinated hydrocarbons included a correction for possible chlorine atom reactions.  相似文献   

20.
The kinetic and mechanism of the reaction Cl + HO2 → products (1) have been studied in the temperature range 230–360 K and at total pressure of 1 Torr of helium using the discharge‐flow mass spectrometric method. The following Arrhenius expression for the total rate constant was obtained either from the kinetics of HO2 consumption in excess of Cl atoms or from the kinetics of Cl in excess of HO2: k1 = (3.8 ± 1.2) × 10?11 exp[(40 ± 90)/T] cm3 molecule?1 s?1, where uncertainties are 95% confidence limits. The temperature‐independent value of k1 = (4.4 ± 0.6) × 10?11 cm3 molecule?1 s?1 at T = 230–360 K, which can be recommended from this study, agrees well with most recent studies and current recommendations. Both OH and ClO were detected as the products of reaction (1) and the rate constant for the channel forming these species, Cl + HO2 → OH + ClO (1b), has been determined: k1b = (8.6 ± 3.2) × 10?11 exp[?(660 ± 100)/T] cm3 molecule?1 s?1 (with k1b = (9.4 ± 1.9) × 10?12 cm3 molecule?1 s?1 at T = 298 K), where uncertainties represent 95% confidence limits. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 317–327, 2001  相似文献   

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