People
James W. Pavlik
Adjunct Professor
Faculty Listing
Office: Goddard Hall, 311A
Phone: +1-508-831-5283
Fax: +1-508-831-5933
jwpavlik@wpi.edu
Educational Background
- B.A., Carthage College, 1959
- M.S., Virginia Polytechnic and State University, 1961
- Ph.D., The George Washington University, 1970
- Post-doct, The George Washington University, 1970
Research & Teaching Interests
Organic chemistry; photochemistry of hetero-aromatic compounds
Research
Research in the Organic Photochemistry Laboratory is directed toward understanding the phototransposition chemistry of aromatic heterocycles. Phototransposition reactions are isomerizations that scramble the order of atoms in an aromatic ring and result in deep-seated molecular rearrangements. These reactions are of interest because of their synthetic utility and because their study is providing information about primary processes in aromatic photochemistry.
The goals of this work are to define how and why phototranspositions occur in these heterocyclic systems. The technique of permutation pattern analysis is particularly suitable for determining the number of transposition mechanisms operating in a molecular system. A permutation pattern provides a map of the transposition by determining where each ring atom in the product originated in the reactant. This knowledge restricts the pathways possible and helps to define the structures of intermediates formed from the excited states.
We are applying permutation pattern analysis to the phototransposition chemistry of five-membered heterocycles containing two heteroatoms. Initially we have investigated the phototransposition of N-methylpyrazoles(1)to N-methylimidazoles (2). By utilizing deuterium, methyl, and phenyl groups as positional labels we have been able to show that this formally simple photoisomerization takes place by the four different mechanistic pathways shown. Some of the suggested intermediates, such as enaminonitrile I[sub]3 and the unusual alpha, beta-unsaturated isonitrile I2, have actually been isolated and characterized, while others, such as 1,5-diazabicyclo[2.1.0]pentene I1, have been trapped as a Diels-Alder adduct with furan.
To understand why the transpositions occur by the experimentally defined pathways we are collaborating with members of the Molecular Spectroscopy Laboratory to use ab initio and semiempirical calculations to determine the energies of the low lying states at their optimized geometries and to calculate the energetics of the transposition pathways suggested by our experimental analysis. Our goal is to understand the potential energy surfaces including the heights of barriers on the excited state surfaces and the presence of excited state minima that can serve as cross-over pathways to the ground-state energy surfaces of observed products.
Research in organic photochemistry provides students with a broad education in modern synthetic, analytical, and computational techniques that are applicable to all areas of modern research. Students also become acquainted with the theory of excited state chemistry which is basic to a wide range of modern technologies.
For more in-depth discussions of our work in heterocyclic photochemistry, see the following references.
Recent Publications
Years of Service at WPI
- Associate Professor, 1974-80
- Professor and Department Head, 1980-1995
- Professor, 1980-
- Professor and Interim Department Head, 2005-2006