Tropospheric degradation of nerol: Kinetics with OH radicals, product distribution in the presence of NOx and atmospheric implications

Abstract

One of the principal diurnal oxidation pathways of biogenic volatile organic compounds, including terpenes and their oxygenated derivatives, is the reaction with the hydroxyl radical (OH). This work presents a kinetic and product study for the reaction of OH radicals with the terpenoid (Z)-3,7-dimethylocta-2,6-dien-1-ol (nerol) in the gas phase at (298 ± 2) K and atmospheric pressure. To our knowledge, the present study provides the first kinetic determination and product identification of the nerol + OH reaction. A conventional relative-rate technique was used to determine the rate coefficient: k(OH+nerol)= (1.6 ± 0.2) x 10−10, in units of cm3 molecule−1s−1. The kinetic result is compared with the value estimated by the structure-reactivity relationship (SAR) method and with the experimental value reported in the literature for its isomer. In addition, the main reaction products in the gas phase and in presence of NOx (nitrogen oxides) were identified: 6-methyl-5-hepten-2-one, glycolaldehyde, acetone and formaldehyde. Under our experimental conditions, yields of 6 % and 50 % were found for formaldehyde and acetone, respectively. A general scheme of the reaction mechanism is proposed based on the identified products. Finally, an approximation of the atmospheric implications of their emission to the troposphere is discussed based on the experimental results obtained in this work.