KINETIC AND PRODUCT YIELDS OF THE GAS-PHASE REACTIONS OF ISOPRENE HYDROPEROXIDES WITH ATMOSPHERIC OXIDANTS

Abstract:

Isoprene is a volatile organic compound (VOC) that is emitted into the atmosphere by plants and trees. It has the largest emission rate of any non-methane VOC and is very reactive, and therefore has a major impact on the chemical composition of the atmosphere. Isoprene Hydroperoxides (IHP) are formed in the atmosphere from the chemical degradation of isoprene. These compounds can then potentially react in the atmosphere with atmospheric oxidants (ozone, OH, NO3) to produce secondary products. This chemistry is potentially important as it may contribute to particle growth and to mediation of ozone concentrations. In this work, the kinetics and mechanisms of the reactions of two IHPs with ozone were investigated. IHPs were synthesized and purified, and were characterized by NMR and HPLC. The gas phase chemistry of these compounds was then studied in chamber experiments using PTRMS as the primary analytical tool. The rate coefficients for reaction with ozone were measured at room temperature and 1 atmosphere using the relative rate technique, and yields of major gas phase reaction products were measured. Implications of these results will be discussed.