Atmospheric chemical degradation of unsaturated polyfunctional compounds initiated by NO3 radicals and O3 molecules

M. B .BLANCO, I. BARNES, P. WIESEN

Tübingen

Encuentro; Network Meeting of Alexander von Humboldt Foundation; 2011

Unsaturated carbonyl compounds, such as esters and ketones, are emitted into the environment from different sources; from mechanical and biological treatment plants, as intermediate products resulting from the synthesis of perfume, insecticides and fungicides and also from biomass burning in Europe. Unsaturated esters are also widely used in polymer and resin production and the source of their emissions are numerous, such as plastics, aircraft and electronic components. Field and laboratories studies show that these compounds are also released into the atmosphere by the wounded leaves of variety of plants. The atmospheric degradation of these unsaturated oxygenates compounds is controlled mainly by chemical reaction with OH radicals, NO3 radicals, O3 molecules and Cl atoms contributing to the tropospheric ozone production and the formation of other photooxidants in polluted areas (photochemical smog). Knowledge of both, the rate coefficients for the reactions of these unsaturated compounds with tropospheric oxidants, and the degradation pathways of these reactions, is required to estimate the persistence, fate and harmful effects of these unsaturated oxygenated organics in the atmosphere. In this work we report an example of the product study for the reactions of O3 molecules and NO3 radicals with vinyl acetate (CH3C(O)OCH=CH2) and allyl acetate (CH3C(O)OCH2CH=CH2). The experiments were conducted using a 1080 liters quartz-glass environmental chamber at (298 ± 2) K in one atmosphere of synthetic air using in situ FTIR spectroscopy to monitor the organics. Product identification and quantification under atmospheric conditions were performed for the first time for the reactions cited above. The results are used to postulate atmospheric chemical mechanisms which can be incorporated into chemistry transport models to obtain estimations of the contributions of emissions of such compounds to ozone and other photooxidant formation in the troposphere. This work is a part of an ongoing plan in our laboratory to study the kinetics and product distribution of the unsaturated compounds degradations and their impact on air quality.