Title

The ozonolysis of a-terpineol in an aqueous environment : a model for atmospheric cloud chemistry.

Author

Dani Leviss

Date of Award

5-1-2016

Document Type

Thesis

School

College of Liberal Arts

Degree Name

Bachelor in Arts

Abstract

Ozone is a major atmospheric pollutant, a central component of smog, a lung irritant, and able to react with abundant organic atmospheric aerosols. The gas phase ozonolysis of volatile organic compounds has been extensively studied and shown to be a major pathway for the formation of secondary organic aerosol (SOA). Although recent work indicates that aqueous processes account for a major fraction of SOA, little is known about aqueous phase ozonolysis. In the present research, we studied the ozonolysis of a-terpineol in aqueous solutions to model the chemistry of atmospheric droplets at varied ozone concentrations (131, 480, and 965 ppb). 1 H Nuclear Magnetic Resonance Spectroscopy (NMR) monitored the experimental progress of this reaction, and one-and two-dimensional NMR along with Gas Chromatography-Mass Spectrometry (GCMS) and Infrared Spectroscopy (IR) identified products. (What follows are illustrations of chemical structures for a-terpineol, cis-lactol, trans-lactol and lactone.) The second-order rate coefficient of the aqueous reaction is 9.93 x 106 M-1 s-1 with a lifetime of 5.2 min, 15 times shorter than in the gas phase (lifetime of 79 min). Formation of products of decreased volatility suggests ozonolysis of a-terpineol yields more condensible secondary organic material and therefore potentially increased impact on climate, visibility, and health.