An investigation of phase transfer catalysis employing quantitative structure-activity relationships

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.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Duncan-Gould, Nathan W.

Contributors dc:contributor

• Denmark, Scott E.
• Burke, Martin D.
• Hergenrother, Paul J.
• Gerlt, John A.

• phase transfer catalysis
• quantitative structure-activity relationship

Statement dc:rights

• Copyright 2011 Nathan W. Duncan-Gould

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/26285

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/26285