Direct and relative rate coefficients for the gas-phase reaction of OH radicals with 2-methyltetrahydrofuran at room temperature

Abstract

2-Methyltetrahydrofuran (2-MTHF) is a renewable green solvent, a platform molecule for organic syntheses and a potential automotive fuel or fuel additive that can be produced efficiently from lignocellulosic biomass. Its reaction with OH radicals is important concerning both of its atmospheric fate and combustion. The kinetics of the overall reaction OH + 2-MTHF → products (1) was studied at room temperature (T = 298 ± 1 K) using both direct and relative kinetic methods. The low pressure fast discharge flow (DF) experiments coupled with resonance fluorescence detection of OH have provided the direct rate coefficient of k 1 (298 K, 2.64 mbar He) = (1.21 ± 0.14 (±2σ)) × 10−11 cm3 molecule−1 s−1. The relative-rate experiments with gas-chromatographic analysis were performed at higher pressure in synthetic air using the reaction OH + cyclohexane (c-C6H12) → products (2) as reference. The determined rate coefficient ratio k 1/k 2 = 3.80 ± 0.17 (±2σ) has been converted to k 1(298 K, 1030 mbar air) = (2.65 ± 0.55 (±2σ)) × 10−11 cm3 molecule−1 s−1. This k 1 value agrees reasonably well with the only other rate coefficient reported which was determined also at higher pressures. Comparison with the DF result indicates a possible pressure dependence of the reaction. Impact of 2-MTHF on the chemistry of the atmosphere has been briefly discussed.