Cl-initiated photo-oxidation reactions of methyl propionate in atmospheric condition
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Cl-initiated photo-oxidation reaction of methyl propionate was investigated experimentally using relative rate method. Gas chromatography/mass spectrometry (GC-MS) and GC/infrared spectroscopy (GC-IR) were used as analytical tools to follow the concentrations of reactants and products during reaction. The gas-phase kinetics of methyl propionate with Cl atoms was measured over the temperature range of 263–363 K at 760 Torr in N2 atmosphere using C2H6 and C2H4 as reference compounds. The temperature-dependent rate coefficient for the reaction of methyl propionate with Cl atom was obtained as k(T) = [(3.25 ± 1.23) × 10−16] T2 exp [− (33 ± 4) / T] cm3 molecule−1 s−1. Theoretical calculations were also performed at CCSD(T)/cc-pVDZ//B3LYP/6-31G(d,p) level of theory, and the rate coefficients for H abstraction reactions were evaluated using canonical variational transition state theory (CVT/SCT) with interpolated single point energy (ISPE) method over the temperature range of 200–400 K. The rate coefficients over the studied temperature range yielded the Arrhenius expression k(T) = (7.22 × 10−16) T1.5 exp (466 / T) cm3 molecule−1 s−1. The reaction mechanism based on product analysis, thermochemistry, branching ratios, atmospheric implications, degradation pathways, and cumulative lifetime of methyl propionate is also presented in this manuscript.
KeywordsMethyl propionate Atmospheric oxidants Rate coefficients Cumulative lifetimes Product analysis and relative rate method
Authors wish to acknowledge Professor D.G. Truhlar for providing the GAUSSRATE 2009A as well as POLYRATE 2008 programs. The authors acknowledge Mr. V. Ravichandran and HPCE for supercomputing facility. BR acknowledges the Department of Science and Technology, Government of India for the financial support.
- Atkinson R, Baulch DL, Cox RA, Crowley JN, Hampson RF, Kerr JA, Rossi MJ, Troe J(2001) Summary of evaluated kinetic and photochemical data for atmospheric chemistry, Web VersionGoogle Scholar
- Bendtz K (2007) EU-25 - oilseeds and products: biofuels situation in the European Union 2005, GAIN report. USDA and Foreign Agricultural Service, Washington DCGoogle Scholar
- European Biodiesel Board (2010). http://www.ebb-eu.org/stats.php
- Frisch MJ, Trucks GW, Schlegel HB, Scuseria GE, Robb MA, Cheeseman JR, Scalmani G, Barone V, Mennucci B, Petersson GA et al (2010) Gaussian 09, revision B.01. Gaussian, Inc., WallingfordGoogle Scholar
- Worldwatch Institute Biofuels for transport. London: Earthscan: Oxford (2007)Google Scholar