Night-time reaction of 2-chloroethyl methyl ether (CH 3 OCH 2 CH 2 Cl) initiated by NO 3 radical: A theoretical insight (original) (raw)
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2019
The quantum mechanical calculations of the decomposition pathways of 1, 2-hydroxy alkoxy radical i.e., CH2(OH)C(O)(CH3)CH2Cl radical have been performed. This radical species has been formed from the successive reactions with O2 molecule and NOx or HO2 radicals with the most stable primary oxidation product of 3-chloro-2-methyl-1propene and OH radical reaction. Geometry optimization and frequency calculations of all the stable species including transition states in the three possible C-C bond scission pathways (i.e., C-CH3, C-CH2Cl and C-CH2OH) of CH2(OH)C(O)(CH3)CH2Cl radical have been performed at M06-2X/6-31+G(d,p) level of theory. Single point energy calculations of all the optimized species at the higher level of CCSD(T) method along with cc-pVTZ triple-zeta basis set have been performed. The rate constants for the various decomposition reactions have been evaluated using Canonical Transition State Theory (CTST) within the temperature range of 250–400 K. Rate constants for C–C ...
Journal of Atmospheric Chemistry, 2001
The absolute rate constants for the gas-phasereactions of the NO3 radical with a series ofaldehydes such as acetaldehyde, propanal, butanal,pentanal, hexanal and, heptanal were measured overthe temperature range 298–433 K, using a dischargeflow system and monitoring the NO3 radical byLaser Induced Fluorescence (LIF).The measured rate constants at 298 K for thereaction of NO3, in units of 10−14 cm3molecule−1 s−1, were as follows:acetaldehyde 0.32 ± 0.04, propanal 0.60 ± 0.06, butanal 1.46± 0.16, pentanal 1.75 ±0.06, hexanal 1.83 ± 0.36, and heptanal 2.37 ±0.42. The proposed Arrhenius expressions arek1 = (6.2 ± 7.5) × 10−11 exp[−(2826 ± 866)/T] (cm3 molecule−1s−1),k2 = (1.7 ± 1.0) × 10−11 exp[−(2250 ± 192)/T] (cm3 molecule−1s1), k3 =(7.6 ± 9.8) × 1011 exp[−(2466 ± 505)/T] (cm3 molecule−1s−1),k4 = (2.8 ± 1.4) × 10−11 exp[−(2189 ± 156)/T] (cm3 molecule−1s−1), k5 = (7.0 ± 1.8) ×10−11 exp [−(2382 ± 998)/T](cm3 molecule−1 s−1), andk6 = (7.8 ± 1.0) × 10−11 exp[−(2406 ± 481)/T](cm3 molecule−1 s−1).Tropospheric lifetimes for these aldehydes werecalculated at night and during the day for typicalNO3 and OH average concentrations and showed thatboth radicals provide an effective tropospheric sinkfor these compounds and that the night-time reactionwith the NO3 radical can be an important, if notdominant, loss process for these emitted organics andfor NO3 radicals.
Kinetic Study of the Gas Phase Reactions of a Series of Alcohols with the NO 3 Radical
The Journal of Physical Chemistry A, 2012
The rate coefficients for the reaction of NO 3 radical with 2-butanol, 3-methyl-2-butanol, and 2,3-dimethyl-2butanol were determined using relative rate technique in a 50 L glass pyrex photoreactor using in situ FT-IR spectroscopy at room temperature and a pressure of 350−670 Torr. The rate coefficient for the reaction of 2-methyl-2-butanol with NO 3 radical was also determined using, in this case, GC/MS. The rate coefficients calculated (in units of cm 3 molecule −1 s −1) were (2.51 ± 0.42) × 10 −15 , (3.06 ± 0.52) × 10 −15 , (2.67 ± 0.3) × 10 −15 , and (1.57 ± 0.16) × 10 −15 , respectively. Results indicate that the reaction occurs by an initial H-abstraction of the alcohols by the NO 3 radical and that NO 3 is more reactive toward a H atom attached to a tertiary carbon than that attached to a secondary or primary carbon. Results are also discussed as related to their homologous structural alkanes and in comparison with the reactivity of other atmospheric oxidants. Atmospheric relevance of the considered reactions is evaluated, concluding that they are potential ozone generators, they have no significant influence on global warming, and the dominant atmospheric loss process for these alcohols is their daytime reaction with OH radicals.
Journal of Chemical Sciences, 2014
Theoretical investigation has been carried out on the kinetics and reaction mechanism of the gas-phase reaction of 3-hydroxy-2-butanone (3H2B) with OH radical using dual-level procedure employing the optimization at DFT(BHandHLYP)/6-311++G(d,p) followed by a single-point energy calculation at the CCSD(T)/6-311++G(d,p) level of theory. The pre-and post reactive complexes are also validated at entrance and exit channels, respectively. Thus reaction may be proceed via indirect mechanism. The intrinsic reaction coordinate (IRC) calculation has also been performed to confirm the smooth transition from a reactant to product through the respective transition states. The rate coefficients were calculated for the first time over a wide range of temperature (250-450 K) and described by the following expression: k OH = 7.56 × 10 −11 exp[−(549.3 ± 11.2)/T] cm 3 molecule −1 s −1. At 298 K, our calculated rate coefficient 1.20 × 10 −11 cm 3 molecule −1 s −1 is in good agreement with the experimental results. Our calculation indicates that H-abstraction from α-C-H site of 3H2B is the dominant reaction channel. Using group-balanced isodesmic reactions, the standard enthalpies of formation for 3H2B and radicals generated by hydrogen abstraction are reported for the first time. The branching ratios of the different reaction channels are also determined. Also, the atmospheric lifetime of 3H2B is also calculated to be 1.04 days.
Atmospheric reactions Cl+CH3-(CH2)n-OH (n=0-4): A kinetic and theoretical study
Chemical Physics, 2006
The reactions of Cl with a series of linear alcohols: methanol (k1), ethanol (k2), 1-propanol (k3), 1-butanol (k4), and 1-pentanol (k5) were investigated as a function of temperature in the range of 264-382K by laser photolysis-resonance fluorescence. The obtained kinetic data were used to derive the following Arrhenius expressions: k1=(3.55±0.22)×10-10exp[-(559±40)/T], k2=(5.25±0.52)×10-11exp[(190±68)/T], k3=(2.63±0.21)×10-11exp[(525±51)/T], k4=(3.12±0.31)×10-11exp[(548±65)/T], and k5=(3.97±0.48)×10-11exp[(533±77)/T] (in units of cm3molecule-1s-1). To our knowledge, these are the first absolute kinetic data reported for 1-butanol and 1-pentanol and also the first kinetic study as a function of temperature for these two compounds. Results, mechanism, and tropospheric implications are discussed and compared with the reported reactivity with OH radicals. Moreover, a theoretical insight into the mechanisms of these reactions has also been pursued through ab initio Möller-Plesset second-order perturbation treatment calculations with 6-311G** basis sets. Optimized geometries and vibrational frequencies have been obtained for transition states and molecular complexes appearing along the different reaction pathways. Furthermore, molecular energies have been calculated at quadratic configuration interaction with single, double, and triple excitations level in order to get an estimation of the activation energies.
Journal of Atmospheric Chemistry, 1999
The aim of this work is to study the reactivity of some naturally emitted terpenes, 2-carene, sabinene, myrcene, α-phellandrene, d-limonene, terpinolene and γ-terpinene, towards NO3 radical to evaluate the importance of these reactions in the atmosphere and their atmospheric impact. The experiments with these monoterpenes have been carried out under second-order kinetic conditions over the range of temperature 298–433 K, using a discharge flow system and monitoring the NO3 radical by Laser Induced Fluorescence (LIF). This work is the first temperature dependence study for the reactions of the nitrate radical with the above-mentioned monoterpenes. The measured rate constants at 298 K for the reaction of NO3 with such terpenes are as follows: 2-carene, 16.6 ± 1.8, sabinene 10.7 ± 1.6, myrcene 12.8 ± 1.1, α-phellandrene 42 ± 10, d-limonene 9.4 ± 0.9, terpinolene 52 ± 9 and γ-terpinene 24 ± 7, in units of 10-12 cm3 molecule-1 s-1. The proposed Arrhenius expressions, for the reactions of NO3 with 2-carene, sabinene, myrcene and α-phellandrene are, respectively k1 = (1.4 ± 0.7) × 10-12 exp[(741 ± 190/T)] (cm3 molecule-1 s-1), k2=(2.3 ± 1.3) × 10-10 exp[−(940 ± 200/T)] (cm3 molecule-1 s-1), k3 = (2.2 ± 0.2) × 10-12 exp[(523 ± 35/T)] (cm3 molecule1 s-1) and k4 = (1.9 ± 1.3) × 10-9 exp[−(1158 ± 270/T)] (cm3 molecule-1 s-1). A decrease in the rate constants when raising the temperature has also been found for the reaction of d-limonene with NO3 while an increase in the rate constant with temperature has been observed for the reactions of terpinolene and γ-terpinene with NO3. Tropospheric half-lives for these terpenes have been calculated at night and during the day for typical NO3 and OH concentrations showing that both radicals provide an effective tropospheric sink for these compounds and that the night-time reaction with NO3 radical can be an important, if not dominant, loss process for these naturally emitted organics and for NO3 radicals.
Physical Chemistry Chemical Physics, 2003
The vapour phase reactions of formaldehyde, formaldehyde-d 2 , 13 C-formaldehyde, acetaldehyde, acetaldehyde-1-d 1 , acetaldehyde-2,2,2-d 3 , and acetaldehyde-d 4 with NO 3 and OH radicals were studied at 298 AE 2 K and 1013 AE 10 mbar using long-path FTIR detection. The values of the kinetic isotope effects at 298 K, as determined by the relative rate method, were: k NO 3 +HCHO /k NO 3 +DCDO ¼ 2.97 AE 0.14, k NO 3 +HCHO / k NO 3 +H 13 CHO ¼ 0.97 AE 0.02, k OH+HCHO /k OH+DCDO ¼ 1.62 AE 0.08, and k OH+H 13 CHO /k OH+DCDO ¼ 1.64 AE 0.12, k OH+HCHO , and k OH+CH 3 CHO /k OH+CD 3 CDO ¼ 1.65 AE 0.08. Quoted errors represent 3s from the statistical analyses. These errors do not include possible systematic errors.
Theoretical study on the mechanism of CH 3 NH 2 and O 3 atmospheric reaction
Journal of Chemical Sciences, 2014
Reaction pathways of methylamine with ozone on the singlet potential energy profile have been investigated at the RB3LYP/6-311++G (3df-3pd) computational level. Calculated results reveal that six kinds of products P 1 (CH 3 NO + H 2 O 2), P 2 (CH 3 NH + OH + O 2), P 3 (NH 2 CH + HO 2 + OH), P 4 (CH 2 NH + H 2 O +O 2), P 5 (NH 2 CH 2 OH + O 2), P 6 (NH 3 + CH 2 O +O 2) are obtained through variety of transformation of one reactant complex C1. Cleavage and formation of the chemical bonds in the reaction pathways have been discussed using the structural parameters. Based on the calculations, the title reaction leads to NH 3 + CH 2 O + O 2 as thermodynamic adducts in an exothermic process by −76.28 kcal/mol in heat realizing and spontaneous reaction by −86.71 kcal/mol in standard Gibbs free energy. From a kinetic viewpoint, the production of CH 3 NH + OH + O 2 adducts with one transition state is the most favoured path.