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Albert J. Fry, PhD
(860) 685-2622
afry@wesleyan.edu
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We have two major projects underway. In one, we are studying the electrochemical oxidation of conjugated alkenes, 1,1-and 1,2-diphenylethylenes (stilbenes). The course of reaction seems to depend on the nature of the substituents on the aromatic rings. Stilbenes in which the benzene rings bear anywhere from two to four strong electron-withdrawing groups undergo conversion to aldehydes in high yield in acentonitrile containing a small amount of water. We have termed this an electrochemical equivalent of ozonolysis. On the other hand, stilbenes bearing electron-supplying or weakly electron-withdrawing groups are converted into benzophenones under the same conditions. We suspect that the two types of reaction both involve a b-hydroxy carbocation. This could either (a) react with water to afford a vic-diol, which would then be oxidatively cleaved to two aldehyde molecules, or (b) undergo a pinacol-type rearrangement to afford a diarylacetaldehyde, which could be oxidatetively converted to the benzophenone via its enol. Mechanistic studies are being carried to establish the origin of the substituent effect. In related work, the anodic oxidation of cycloocatetraene is being studied in hydrolytic solvents. Here too, the same dichotomy between either reaction of an intermediate b-oxy carbocation or carbon skeletal rearrangement seems to be operative. We are studying the dependence of the products upon the nature of the solvent to both better understand the mechanism of the reactions and search for synthetic applications.
A second project involves application of quantum chemical
computational techniques to electrochemical problems that cannot be solved by
experimental means. Much of the work has involved dissecting the relative
contributions of solvation and ion-pairing to the electrochemical behavior of
polycyclic aromatic hydrocarbons and thus explaining anomalies in such
behaviors. Other work has involved: (a) elucidation of the mechanism of anodic
oxidation of cycloocatetraene in hydroxylic solvents; (b) development of highly
accurate and methods for treatment of substituent effects upon the
electrochemical reduction and oxidation of organic substrates; and (c) the
discovery by computational means that many organic cations are surrounded by a
strongly held sheath of solvent molecules and that this sheath often has
dramatic effect upon the electrochemical behavior of such cations.
Selected Publications
"Tetraalkylammonium Ions Are Surrounded By An Inner
Solvation Shell in Strong Electron Pair Donor Solvents", Fry, A. J.;
Electrochemistry Communications, 11, 309, (2009)
"Substituent Effects on the Redox Properties and
Structure of Substituted Triphenylamines. An Experimental and Computational
Study", Wu, X.; Davis, A.; Lambert, P. C.; Steffen, L. K.; Toy, O.; Fry, A
.J.; Tetrahedron, 65, 2408, (2009).
"Computational Examination of Substituent Effects on
the Interconversion of 1.3.5- Cyclooctatriene and Bicyclo[4.2.0]-2.4-octadiene.",
Fry, A. J.; Tetrahedron, 64, 2101 (2008)
"Strong Ion-Pairing Effects in a Room Temperature Ionic Liquid", Fry,
A. J., J. Electroanal.Chem., 546, 35 (2003).
"Anodic Oxidation of Methyl a-Deimethylsilyldihydocinnamate. A Novel Silicon Gamma-Aryl Effect:, Kaimakliotis, C; Fry, A. J., J. Org Chem., 68, 9893 (2003).
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[Chemistry][Wesleyan]
Last updated: August 3, 2009 (AJF/rncb)