Kinetics of the Gas-Phase Reactions of Alcohols, Aldehydes, Carboxylic Acids, and Water with the C13 Stabilized Criegee Intermediate Formed from Ozonolysis of 1-Tetradecene

Abstract

Previous studies in our laboratory have shown that the major aerosol products formed in gas-phase ozonolysis of 1-tetradecene in the presence of excess alcohols, carboxylic acids, water vapor, and aldehydes are α-alkoxytridecyl, α-acyloxytridecyl, α-hydroxytridecyl hydroperoxides, and secondary ozonides. These low volatility compounds are formed from reactions of C13 stabilized Criegee intermediates with the acidic compounds and aldehydes. To obtain a more quantitative understanding of the chemical mechanism and determine the importance of such reactions in the atmosphere, relative rate constant measurements were made using real-time quantitative thermal desorption particle beam mass spectrometry (TDPBMS) for aerosol analysis. The rates of reaction of methanol, 2-propanol, formic acid, water, and formaldehyde with C13 stabilized Criegee intermediates were measured relative to heptanoic acid. The results show that the reactivity of the studied compounds varies over 4 orders of magnitude and increases in the order: water ≪ methanol < 2-propanol ≪ formaldehyde < formic acid < heptanoic acid. The rate constants depend primarily on the nature of the functional group and correlate well with the gas-phase acidities, indicating a relatively polar transition state for the reaction. The relative rate constants depend only slightly on the size of the reactant species and are similar to those measured previously for a C1 stabilized Criegee intermediate. The atmospheric implications of these results are also discussed.