Gas-phase reaction of chlorine atoms with acrylonitrile. Temperature and pressure dependence (original) (raw)
Related papers
Atmospheric Environment, 2007
Rate coefficients for the reactions of hydroxyl radicals and chlorine atoms with acrylic acid and acrylonitrile have been determined at 298 K and atmospheric pressure. The decay of the organics was followed using a gas chromatograph with a flame ionization detector (GC-FID) and the rate constants were determined using a relative rate method with different reference compounds. Room temperature rate constants are found to be (in cm 3 molecule À1 s À1): k 1 (OH+CH 2 Q CHC(O)OH) ¼ (1.7570.47) Â 10 À11 , k 2 (Cl+CH 2 QCHC(O)OH) ¼ (3.9970.84) Â 10 À10 , k 3 (OH+CH 2 QCHCN) ¼ (1.1170.33) Â 10 À11 and k 4 (Cl+CH 2 QCHCN) ¼ (1.1170.23) Â 10 À10 with uncertainties representing 72s. This is the first kinetic study for these reactions under atmospheric pressure. The rate coefficients are compared with previous determinations taking into account the effect of pressure on the rate constants. The effect of substituent atoms or groups on the overall rate constants is analyzed in comparison with other unsaturated compounds in the literature. In addition, atmospheric lifetimes based on the homogeneous sinks of acrylic acid and acrylonitrile are estimated and compared with other tropospheric sinks for these compounds.
Low-pressure study of the reactions of Cl atoms with acrylic acid and allyl alcohol
Atmospheric Environment
The kinetics of the gas-phase reactions of chlorine atoms with acrylic acid (1) and allyl alcohol (2) have been investigated at low pressure (0.5-3 Torr) in the temperature range 260-333 K using the mass spectrometric discharge-flow method. The temperature dependence of the reaction rate constants at 1 Torr have been determined under pseudo-first-order conditions in excess of organic compound over Cl atoms, giving: k 1 ¼ ð1:370:9Þ Â 10 À13 expð16007200Þ=T cm 3 molecule À1 s À1 and k 2 ¼ ð1:170:5Þ Â 10 À11 expð4707135Þ=T cm 3 molecule À1 s À1 : At room temperature and 1 Torr; products of abstraction and addition channels have been detected for reactions (1) and (2). By mass spectrometric quantification, the branching ratio for channels giving HCl, was determined as 0:1370:05 for reaction (1) and 0:5770:06 for reaction (2). The results obtained are related to previous studies, and the atmospheric implications are also discussed in relation to the homogeneous sinks of acrylic acid and allyl alcohol. r
Journal of Atmospheric Chemistry, 2000
The reaction of Cl with cyclohexanone (1) was investigated, for the first time, as a function of temperature (273-333 K) and at a low total pressure (1 Torr) with helium as a carrier gas using a discharge flow-mass spectrometry technique (DF-MS). The resulting Arrhenius expression is proposed, k 1 = (7.7 ± 4.1) × 10 −10 exp[-(540 ± 169)/T]. We also report a mechanistic study with the quantitative determination of the products of the reaction of Cl with cyclohexanone. The absolute rate constant derived from this study at 1 Torr of total pressure and room temperature is (1.3 ± 0.2) × 10 −10 cm 3 molecule −1 s −1 . A yield of 0.94 ± 0.10 was found for the H-abstraction channel giving HCl. In relative studies, using a newly constructed relative rate system, the decay of cyclohexanone was followed by gas chromatography coupled with flame-ionisation detection. These relative measurements were performed at atmospheric pressure with synthetic air and room temperature. Rate constant measured using the relative method for reaction (1) is: (1.7 ± 0.3) × 10 −10 cm 3 molecule −1 s −1 . Finally, results and atmospheric implications are discussed and compared with the reactivity with OH radicals.
The Journal of Physical Chemistry, 1991
The gas-phase kinetics of the reactions of four partially halogenated methyl radicals (CH,Cl, CH2Br, CH21, and CHC12) with Cl, have been studied as a function of temperature using a tubular reactor coupled to a photoionization mass spectrometer. Radicals were homogeneously generated by pulsed 193-and/or 248-nm laser photolysis. Decays of the radical concentrations were monitored in time-resolved experiments as a function of [Cl,] to obtain bimolecular rate constants for the R + C1,-RCI + C1 reactions studied. The following Arrhenius expressions (k = A exp(-E/RT)) were obtained (the numbers in brackets are log (A/(" molecule-' s-')), E/(kJ mol-I); the temperature ranges are also indicated): R = CH2Cl [-11.82 f 0.12, 4.1 f 1.3, 295-719 K]; R = CH2Br [-11.91 * 0.14,2.4 f 1.4, 295-524 K]; R = CH21 [-11.94 * 0.19, 0.8 & 2.2, 295-524 K]; R = CHC12 [-12.07 * 0.15, 10.3 f 2.0, 357-719 K]. Errors are lu, including both random and an estimated 20% systematic error in the individual bimolecular rate constants. The Arrhenius parameters of these and two other R + C12 reactions are compared with theoretical determinations based on semiempirical AM1 calculations of transition-state energies, structures, and vibration frequencies. The calculations qualitatively reproduce the obsehed trends in both the Arrhenius A factors and in the activation energies. The use of molecular properties to account for reactivity differences among all the R + C12 reactions which have been studied to date are also explored using free-energy correlations with these properties.
International Journal of Chemical Kinetics, 2010
The rate coefficient for the gas-phase reaction of chlorine atoms with acetone was determined as a function of temperature (273-363 K) and pressure (0.002-700 Torr) using complementary absolute and relative rate methods. Absolute rate measurements were performed at the low-pressure regime (∼2 mTorr), employing the very low pressure reactor coupled with quadrupole mass spectrometry (VLPR/QMS) technique. The absolute rate coefficient was given by the Arrhenius expression k(T ) = (1.68 ± 0.27) × 10 −11 exp[-(608 ± 16)/T ] cm 3 molecule −1 s −1 and k(298 K) = (2.17 ± 0.19) × 10 −12 cm 3 molecule −1 s −1 . The quoted uncertainties are the 2σ (95% level of confidence), including estimated systematic uncertainties. The hydrogen abstraction pathway leading to HCl was the predominant pathway, whereas the reaction channel of acetyl chloride formation (CH 3 C(O)Cl) was determined to be less than 0.1%. In addition, relative rate measurements were performed by employing a static thermostated photochemical reactor coupled with FTIR spectroscopy (TPCR/FTIR) technique. The reactions of Cl atoms with CHF 2 CH 2 OH (3) and ClCH 2 CH 2 Cl (4) were used as reference reactions with k 3 (T ) = (2.61 ± 0.49) × 10 −11 exp[−(662 ± 60)/T ] and k 4 (T ) = (4.93 ± 0.96) × 10 −11 exp[−(1087 ± 68)/T] cm 3 molecule −1 s −1 , respectively. The relative rate coefficients were independent of pressure over the range 30-700 Torr, and the temperature dependence was given by the expression k(T ) = (3.43 ± 0.75) × 10 −11 exp[−(830 ± 68)/T ] cm 3 molecule −1 s −1 and k(298 K) = (2.18 ± 0.03) × 10 −12 cm 3 molecule −1 s −1 . The quoted errors limits (2σ ) are at the 95% level of confidence and do not include systematic uncertainties. C 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: [724][725][726][727][728][729][730][731][732][733][734] 2010
Kinetics and Thermochemistry of the Reaction of 1-Chloroethyl Radical with Molecular Oxygen
The Journal of Physical Chemistry, 1995
The kinetics of the reaction CH3CHC1+ 0 2 F?. CH3CHC102products (1) has been studied at temperatures 296-839 K and He densities of (3-49) x 10l6 molecule cm-3 by laser photolysis/photoionization mass spectrometry. Rate constants were determined in time-resolved experiments as a function of temperature and bath gas density. At low temperatures (298-400 K) the rate constants are in the falloff region under the conditions of the experiments. Relaxation to equilibrium in the addition step of the reaction was monitored within the temperature range 520-590 K. Equilibrium constants were determined as a function of temperature and used to obtain the enthalpy and entropy of the addition step of the reaction (1). At high temperatures (750-839 K) the reaction rate constant is independent of both pressure and temperature within the uncertainty of the experimental data and equal to (1.2 f 0.4) x cm3 molecule-' s-'. Vinyl chloride (C2H3C1) was detected as a major product of reaction 1 at T = 800 K. The rate constant of the reaction CH3CHC1 + C12 products (6) was determined at room temperature and He densities of (9-36) x 10l6 molecule cm-3 using the same technique. The value obtained is k6 = (4.37 f 0.69) x cm3 molecule-' s-'. An estimate of the high-pressure limit for reaction 1 was determined using this measured k6 and the kl/k6 ratio obtained by Kaiser et al.:l k"1 (T=298K) = (1.04 f 0.22) x lo-" cm3 molecule-' s-'. In a theoretical part of the study, structure, vibrational frequencies, and energies of nine conformations of CH3CHC102 were calculated using ab initio UHF/6-31G* and MP2/6-31G** methods. The theoretical results are used to calculate the entropy change of the addition reaction As0298 =-152.3 f 3.3 J mol-' K-'. Th~s entropy change combined with the experimentally determined equilibrium constants resulted in a CH3CHC1-02 bond energy m 2 9 8 =-131.2 f 1.8 kJ mol-l. The rooq-temperature entropy (S O 2 9 8 = 341.0 f 3.3 J mol-' K-') and the heat of formation (A H f o~9 8 =-54.7 f 3.7 kJ mol-') of the CH3CHC102 adduct were obtained.
International Journal of Chemical Kinetics, 1986
The kinetics of the reactions of CH21, CH2Br, CH2CI, and CHCI2 with HI were studied in a tubular reactor coupled to a photoionization mass spectrometer. Rate constants were measured as a function of temperature (typically between 294 and 552 K) to determine Arrhenius parameters. For these and other R + HI reactions studied to date (Le,, those involving alkyl radicals), a linear free energy relationship was discovered which correlates the large differences in reactivity among all these R + HI reactions with the inductive effect of the substituent atoms or groups on the central carbon atom.
International Journal of Chemical Kinetics, 2005
The relative rate technique has been used to determine the rate constants for the reactions Cl + CH 3 OCHCl 2 → products and Cl + CH 3 OCH 2 CH 2 Cl → 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 cm 3 molecule −1 s −1 , (2.4 ± 0.4) × 10 −12 cm 3 molecule −1 s −1 , and (5.9 ± 0.6) × 10 −11 cm 3 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 cm 3 molecule −1 s −1 ) with CH 3 OCHCl 2 , k = (1.04 ± 0.30) × 10 −12 and CH 3 OCH 2 CH 2 Cl, 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. C 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: [420][421][422][423][424][425][426] 2005
Kinetic study of the gas-phase reaction of atomic chlorine with a series of aldehydes
Atmospheric Chemistry and Physics, 2005
The reactions of Cl atoms with a series of unsaturated aldehydes have been investigated for the first time using a relative method. In order to obtain additional information for a qualitative structure versus reactivity discussion, we have also determined the rate coefficients for the reactions of atomic chlorine with their respective saturated aldehydes. These relative measurements were performed at room temperature and atmospheric pressure of air and N 2 , by using ethane, propene and 1-butene as reference compounds. The weighted average relative rate constants obtained, k Cl ±2σ (in units of cm 3 molecule −1 s −1 ) were: trans-2-pentenal (1.31±0.19)×10 −10 ; trans-2-hexenal (1.92±0.22)×10 −10 ; trans-2-heptenal (2.40±0.29)×10 −10 ; n-pentanal (2.56±0.27)×10 −10 ; n-hexanal (2.88±0.37)×10 −10 ; n-heptanal (3.00±0.34)×10 −10 .