Document Type

Thesis

Degree

Master of Science

Major

Chemistry

Date of Defense

11-17-2011

Graduate Advisor

James S. Chickos PhD.

Committee

Keith J. Stine, Ph.D.

Chung F. Wong, Ph.D.

Abstract

Relatively little vaporization enthalpy data has been published for fluorinated compounds. The increasing commercial use of fluorinated chemicals and their rapid spreading within our biosphere necessitates a better understanding of their thermodynamic properties and long-term stability. This paper presents an initial attempt at applying correlation gas chromatography (C-GC) to investigate its possible use in deriving the enthalpy of vaporization at 298 K for twenty-seven partially or fully fluorinated compounds. Additionally, the behavior of the n-perfluoroalkanes are examined and compared to their hydrocarbon analogues. Although published data for the n-perfluoroalkanes as a function of the number of carbons appears to be slightly non-linear, the experimentally determined trend for the fluorinated series is considered linear with a correlation coefficient > 0.98. This linearity mirrors that of similarly sized hydrocarbon n-alkanes. Results also indicate that n-perfluorinated alkanes behave similarly to hydrocarbon alkanes with vaporization enthalpy values increasing incrementally with the addition of each CF2 unit to the alkane’s chain length. This work also examines what correlative standards to use with gas chromatography to determine the vaporization enthalpies of different structural classes of fluorinated compounds. Experimental results indicate that n-perfluorinated alkanes can successfully be used to evaluate other perfluorinated n-alkanes and perfluorocycloalkanes but cannot be used to evaluate perfluoroamines, perfluoroaromatics or the mono substituted 1H–perfluoroalkanes. Hydrocarbon compounds, both n-alkane and aromatic, were also used as standards in an attempt to correlate them with partially and fully perfluorinated compounds. The hydrocarbon n-alkanes were found to correlate well with mono fluorinated n-alkanes. It was further determined that aromatic hydrocarbons will correlate with partial fluorinated aromatics. However, the same aromatic hydrocarbons do not appear to correlate with fully fluorinated aromatics.

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