Kinetic and mechanistic studies of atmospheric degradation of diethyl pyrocarbonate initiated by OH radicals and chlorine atoms

Abstract

The atmospheric reactivity of dicarbonyl compounds is becoming an increasing environmental concern due to the growth in their emissions, tracked by their usage as solvents and industrial additives during the last decades. In this paper, the gas phase degradation of diethyl pyrocarbonate (DEPC) initiated by both hydroxyl radicals and chlorine atoms was studied. The rate coefficients for the reaction between DEPC with OH radicals (kOH) and chlorine atoms (kCl) were determined, being kOH = 1.2 × 10−12 cm3 molec−1 s−1 and kCl = 3.4 × 10−12 cm3 molec−1 s−1. The analysis of the photo-oxidation products and the reaction mechanism were both experimentally determined by infrared spectroscopy and supported by theoretical calculations. Formations of dicarbonyl compounds (CH3CH2OC(O)OC(O)CH3, CH3CH2OC(O)OC(O)H), acetic acid, formic acid, formaldehyde, carbon monoxide, and carbon dioxide were observed. Finally, environmental implications are concluded based on the atmospheric lifetime of DEPC.