Molecular Structures And Pulsed Discharge Emission Studies Of Volatile Organic Compound Derivatives

Abstract

Understanding the structure and reactivity of volatile organic compounds (VOCs), hydrochlorofluorocarbons (HCFCs) and their derivatives is a fundamental concern in the study of atmospheric chemistry. Recently, a series of studies were done aimed at constructing and optimizing a rapid-scan, midinfrared spectrometer in order to study the structure and intermolecular interactions of these compounds. Visible emission spectroscopy was used to optimize the pulsed discharge nozzle that would be used within the infrared spectrometer. The emission spectra of toluene and xylene were used to characterize production of free radical compounds. In addition, control programs were written in the Lab VIEW programming language to control the emission spectrometer and nozzle.

Fourier-transform and chirped-pulse Fourier-transform microwave spectroscopy were used to study the gas phase VOC derivatives 2,3,4,5,6- pentafluorotoluene, or PFTOL, and 1-chloro-2,3,4,5,6-pentafluorobenzene, or CPFB. These microwave studies were done to gain background information on the pentafluorobenzyl radica, precursor, PFTOL. Heavy-atom structures of both compounds were determined using assigned rotational constants for all single 13C isotopologues. The ground state rotational constants for PFTOL are A= 1036.61221 (15) MHz, B = 1030.94086(16) MHz, and C = 516.92066(11) MHz. The ground state rotational constants for CPFB are A= 1028.5412(2) MHz, B = 751.82072(17) MHz and C = 434.3531 (3) MHz for 35CI and A = 1028.5439(7) MHz, B = 734.47954(18) MHz and C = 428.5081 (2) MHz for 37 Cl. These spectra are to be compared with chlorobenzene, toluene and pentafluorobenzene to observe the effects on the structure of the benzene ring when substituting a chlorine atom for a methyl group. Through these studies, PFTOL is estimated to have a low energy barrier (

Date of Award	2009
Original language	American English
Awarding Institution	Eastern Illinois University
Supervisor	Rebecca A. Peebles (Supervisor)