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Title An investigation of phase transfer catalysis employing quantitative structure-activity relationships
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Publication Date
Date Accessioned
Degree PhD
Discipline/Department 0335
Degree Level doctoral
University/Publisher University of Illinois – Urbana-Champaign
Abstract The application of quantitative structure activity relationships to phase transfer catalysis (PTC) has been explored. The primary focus was on hydroxide-initiated PTC reactions, such as enolate alkylations. The tandem [4+2]/[3+2] cycloaddition of nitroalkenes was applied as the key transformation in the preparation of enantioenriched, tricyclic 1-hydroxy-cyclopentapyrrolizidine ring systems. A three-step parallel synthesis procedure was developed to prepare libraries of quaternary ammonium ions sharing a common core scaffold. In total, 80 quaternary ammonium bromides were prepared in this way. A kinetic method for the analysis of liquid-liquid PTC reactions was refined. The kinetic profile for an enolate alkylation reaction was determined for 102 different quaternary ammonium bromides catalysts under a standard set of conditions. The data ranges over three orders of magnitude in catalyst activity. QSAR models were developed to describe the activity of the catalysts. Three types of models were considered: (1) linear combinations (2) parabolic combinations, and (3) bilinear combinations. The models that best account fit the catalyst activity data and retain the smallest number of descriptors included parabolic or binlinear contributions from logP and XSA (XSA = cross-sectional area). Analysis of the model in the context of an interfacial mechanism led the hypothesis that the largest differences in catalyst activities were due to the sum of the interfacial adsorption and desorption rate constants. This hypothesis was tested by comparing the rate constants for the stoichiometric alkylation of quaternary ammonium phenoxides to the catalytic rate constants for a series of Td symmetric homologous. It is suggested that the hypothesis could be tested further by measuring the surface activity of the catalysts at the interface of a water-organic biphasic mixture.
Subjects/Keywords phase transfer catalysis; quantitative structure-activity relationship
Contributors Denmark, Scott E. (advisor); Denmark, Scott E. (Committee Chair); Burke, Martin D. (committee member); Hergenrother, Paul J. (committee member); Gerlt, John A. (committee member)
Language en
Rights Copyright 2011 Nathan W. Duncan-Gould
Country of Publication us
Record ID handle:2142/26285
Repository uiuc
Date Retrieved
Date Indexed 2018-11-19
Grantor University of Illinois at Urbana-Champaign
Issued Date 2011-08-26 15:21:28

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