Gas-phase studies of phosphenium ions as chemical ionization reagents for the differentiation of diastereomeric organic substrates in a Fourier transform ion cyclotron resonance mass spectrometer

Rukeyser Shylett Thompson, Purdue University

Abstract

There exists a need in the pharmaceutical industry for a simple and rapid method to differentiate stereoisomeric compounds. As a result, a great deal of research has been devoted to developing such a method. It was once believed that mass spectrometry could not provide differentiation of stereoisomers because the most widely used ionization method, electron impact ionization (EI), is insensitive to the stereochemistry of molecules. The work presented in this thesis demonstrates that a chemical ionization (CI) method based on phosphenium ions can be used to rapidly differentiate certain diastereomeric organic substrates in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Both acyclic and cyclic phosphenium ions were used in these studies. When the phosphenium ions were allowed to react with certain substrates, unique reaction products were observed for only one of the isomers of a diastereomeric pair. Structural characterization was performed for some of the most interesting products formed during these reactions. Molecular orbital calculations were also utilized to acquire a better understanding of some of the experimental results.

Degree

Ph.D.

Advisors

Kenttamaa, Purdue University.

Subject Area

Analytical chemistry

COinS