Kinetics and mechanism of the tropospheric reaction of tetrahydropyran with Cl atoms

Relative rate coefficients for the gas-phase reaction of chlorine atoms (Cl) with tetrahydropyran (THP) have been determined by Fourier transform infrared (FTIR) spectroscopy and gas chromatography coupled to a mass spectrometer (GC–MS). The averaged rate coefficient is (2.21 ± 0.32) × 10−10 cm3 molecule−1 s−1 (with 2σ uncertainty) and was obtained using different reference compounds, Cl precursors, and bath gases at 740 ± 5 Torr and 298 ± 2 K. Products of the title reaction were identified and quantified by solid-phase microextraction (SPME) coupled to a GC–MS. Additionally, the first step of the reaction was theoretically studied by ab initio calculations. Reaction mechanism seems to proceed mainly by the H-abstraction from α and γ positions. THP tropospheric lifetime is estimated from the rate coefficient reported here. The atmospheric implications of the Cl reactivity are also discussed.