AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
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Reaction Pathways, Kinetics, and Equilibria of Multifunctional Hydroperoxides in Secondary Organic Aerosol
DEMETRIOS PAGONIS, Paul Ziemann, University of Colorado-Boulder
Abstract Number: 435 Working Group: Aerosol Chemistry
Abstract Multifunctional hydroperoxides are a significant component of secondary organic aerosol produced in low-NOx environments. Products of autoxidation reactions and many proposed structures of extremely low volatility organic compounds (ELVOCs) are thought to be multifunctional hydroperoxides. While knowledge of the sources of multifunctional hydroperoxides has increased in recent years, the fate of these compounds in the atmosphere is still not well understood. Prior work in our lab has shown that particle phase intramolecular and oligomerization reactions are possible for these hydroperoxides, but kinetic and equilibrium data have not been available. In this work we present results of laboratory studies of the reaction pathways of alkoxy hydroperoxyaldehydes, along with measurements of equilibria and constraints for reaction kinetics. We produced these multifunctional hydroperoxides through solution synthesis as well as gas-phase reaction in an environmental chamber. The ability to synthesize these hydroperoxides with high yield allows for utilization of a wide array of analytical techniques, and reaction pathways have been established through thermal desorption particle beam mass spectrometry (TDPBMS), NMR, FTIR and offline iodometric determination of peroxide content. We find that the multifunctional hydroperoxides studied rapidly equilibrate to form peroxyhemiacetals and acetals through unimolecular and bimolecular reactions, and that the equilibria are sensitive to environmental conditions. We also present results on the effects of relative humidity and aerosol acidity on the reactions of multifunctional hydroperoxides to better understand the fates of these compounds in the atmosphere.