Files in this item



application/pdf8302944.pdf (6MB)Restricted to U of Illinois
(no description provided)PDF


Title:Mechanistic Studies of Rhodium Oxidation Catalysts
Author(s):Nyberg, Eric David
Department / Program:Chemistry
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Chemistry, Inorganic
Abstract:Over the past eight years a number of catalytic processes for the O(,2) oxidation of terminal olefins have been proposed to proceed through non-free radical, non-Wacker mechanisms involving the coordination of O(,2) and olefin to a rhodium(I) catalyst. One particularly promising system is the Rh/Cu co-catalyzed O(,2) oxidation of terminal olefins to almost exclusively 2-hexanone. The relatively short lifetimes of the homogeneous catalysts for this olefin oxidation encouraged us to seek a functionalized solid support to site-isolate the rhodium complexes. This approach is based on the assumption that the catalyst deactivation process is multi-ordered in rhodium. In chapter 2 is described the immobilization of {Rh(CO)(,2)S'(,n)}BF(,4) using a silica gel bound organosulfide ligand, {SG}-SH. When solid supports possessing site-isolated sulfide are employed, the monomeric rhodium carbonyl complexes, {SG}-SRh(CO)(,2)S'(,n), are formed. These produce catalysts for the oxidation of 1-hexene to 2-hexanone, and are more stable to deactivation than the analogous homogeneous reaction using {Rh(CO)(,2)S'(,n)}BF(,4). The O(,2) oxidation of {Rh(CO)(,2)Cl}(,2) was studied as part of an investigation to determine the character of the catalyst for the homogeneous Rh/Cu co-catalyzed oxidation of 1-hexene. In chapter 3 are presented the result of a detailed investigation of the mechanism of the O(,2) oxidation of {Rh(CO)(,2)Cl}(,2) to RhCl(,3)(H(,2)O)(,2)CH(,3)CH(,2)OH. This has been found to proceed by an unusual process involving the coordination of in situ generated HOOH to {Rh(CO)(,2)Cl}(,2), forming H(,2){Rh(CO)Cl(,2)(OOH)} as a stable intermediate. The observations that the O(,2) oxidation of {Rh(CO)(,2)Cl}(,2) produces rhodium(III) trichloride, and that this process corresponds to the initiation of the O(,2) oxidation of 1-hexene to 2-hexanone, has led to the characterization of the catalyst for the Rh/Cu co-catalyzed oxidation of 1-hexene at 40.C as RhCl(,2)S'(,4)('+). These results, and a general investigation of the mechanism of this catalytic 1-hexene oxidation, are presented in chapter 4. It has been found that RhCl(,3) 3 H(,2)O catalyzes the HOOH oxidation of 1-hexene to 2-hexanone, indicating peroxide is the direct oxidant in this system. Mechanisms for the Rh-only and Rh/Cu co-catalyzed oxidations of 1-hexene are proposed which are consistant with both the earlier reported results, and those presented in this study.
Issue Date:1982
Description:215 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1982.
Other Identifier(s):(UMI)AAI8302944
Date Available in IDEALS:2014-12-15
Date Deposited:1982

This item appears in the following Collection(s)

Item Statistics