Undergraduate Honors Theses

Thesis Defended

Spring 2017

Document Type

Thesis

Type of Thesis

Departmental Honors

Department

Chemistry & Biochemistry

First Advisor

Dr. Veronica Vaida

Second Advisor

Dr. Robert Parson

Third Advisor

Dr. Chris Bowman

Abstract

α-Keto acids react in solution in the presence of sunlight to form complex organic oligomers that can contribute to the formation of organic atmospheric aerosols. The sunlight-initiated reactions of two α-keto acids, pyruvic acid and 2-oxooctanoic acid, were studied under a range of pH’s from 2.35 to 11 to determine how their photochemical reactivity was affected by changing reaction conditions. The acid dissociation constants of both acids in aqueous solution were determined by titration, yielding a pKa of 2.51 ± 0.05 for pyruvic acid and 2.49 ± 0.04 for 2-oxooctanoic acid. The photolysis was conducted using a solar simulator, and the progress of the reaction was monitored with UV-vis and NMR spectroscopy in addition to electrospray ionization mass spectrometry. As the pH of the reaction solution was increased, the rate of the photolysis of pyruvic acid was shown qualitatively to slow down. Additionally, the relative yields and the ratios of products generated from the photolysis of pyruvic acid were observed to be dependent upon the pH of the reaction solution. This has important implications for the fate of α-keto acids in the natural environment, where chemistry occurs in media with a range of differing acidities.

Available for download on Wednesday, October 03, 2018

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