Experimental and theoretical rate coefficients for the gas phase reaction of β-Pinene with OH radical

Abstract

Rate coefficient for the reaction of β-pinene with OH radicals was determined at 298 K and 800 Torr of N2 using the relative rate technique. Isobutylene was used as a reference compound and the concentrations of the organics were followed by gas chromatographic analysis. The rate coefficient for the reaction of β-pinene with OH radical was measured to be (9.35 ± 2.79) × 10−11 cm3 molecule−1 s−1. Theoretical kinetic calculations were also performed for the title reaction using canonical variational transition state theory (CVT) with small-curvature tunneling (SCT). The kinetics data obtained over the temperature range of 200–400 K were used to derive the Arrhenius expression: k(T) = 8.24 × 10−23 T3.41 exp[2421/T] cm3 molecule−1 s−1. The OH-driven atmospheric lifetime (τ) and global warming potential (GWP) for β-pinene were computed and concluded that β-pinene is very short lived (2.5 h) in the Earth's atmosphere with a GWP of 1.6 × 10−2 at 20 years horizon of time and which is negligible. The ozone formation potential of β-pinene was also calculated and reported in this present work.