All ETDs from UAB

Advisory Committee Chair

Gary M Gray

Advisory Committee Members

Houston Byrd

Chris Lawson

Sergey Vyazovkin

Charles Watkins

Document Type

Dissertation

Date of Award

2010

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

CONFORMATIONALLY RESTRAINED METALLACROWN ETHERS AS CATALYSTS FOR THE HYDROFORMYLATION OF ALKENES Abha A. Kaisare CHEMISTRY ABSTRACT Chapter1 of this dissertation explores, the monodentatephosphite/ether ligand, (2,2'-C12H8O2)POCH2CH2OCH3 for the in situ hydroformylation of styrene in the presence and absence of alkali metal salts. The catalytic studies with this ligand demonstrate that both the activity and regioselectivity of the catalyst are sensitive to the ligand:Rh molar ratio and to the presence of salts such as LiBPh4*3dme, NaBPh4 and HgCl2. Model complexes for various steps in the catalytic cycle, cis-Mo(CO)4(2,2'-C12H8O2)POCH2CH2OCH3)2, cis-PtCl2(2,2'-C12H8O2)POCH2CH2OCH3)2, and PdCl2(2,2'-C12H8O2)POCH2CH2OCH3)2, have been synthesized and characterized to provide insight into the factors that may affect the rates and regioselectivities of the hydroformylation catalysts. Chapter 2 presents the hydroformylation of styrene catalyzed by complexes formed by the in situ reactions of Rh(acac)(CO)2 and the monodentate phosphite ligand (2, 2'-C12H8O2)POCH3. The effects of addition of alkali metal salts such as LiBPh4*3dme, NaBPh4 and variation in ligand to rhodium molar ratio have been evaluated and compared to the results obtained by complexes of a phosphite/ether ligand (2, 2'-C12H8O2)POCH2CH2OCH3 to better understand the effect of the ether functionality on the catalytic activities and selectivities in the presence of salt. This comparison demonstrates that the ether functionality in (2, 2'-C12H8O2)POCH2CH2OCH3 modifies both activity and regioselectivity of the catalyst in the presence of alkali metal salts. Model complexes of (2, 2'-C12H8O2)POCH3., cis-PtCl2(2, 2'-C12H8O2)POCH3)2, and cis-PdCl2(2, 2'-C12H8O2)POCH3)2, that may mimic the active catalyst species, have been synthesized and characterized to better understand the coordination preferences of ligand (2, 2'-C12H8O2)POCH3 in square planar coordination geometry. Chapter 3 deals with metallacrown ether, with a bis(phosphite) ligand derived from 1,2 bis (2-hydroxyethoxy)benzene, {[(2,2'-O2C12H8)P(C2H4O2)]2C6H4}and explores it's potential for the in situ hydroformylation of styrene to better understand the effects of ligand configuration on the catalytic activities and selectivities, particularly, in the presence of alkali metal salt, LiBPh4*3dme. Model complexes for various steps in the catalytic cycle, cis-Mo(CO)4{[(2,2'-O2C12H8)P(C2H4O2)]2C6H4}, cis-PtCl2{[(2,2'-O2C12H8)P(C2H4O2)]2C6H4}, and cis-PdCl2{[(2,2'-O2C12H8)P(C2H4O2)]2C6H4}, have been synthesized and characterized to better understand the effects of the conformational restraints on the orientation of bis (phosphite) ligand in the octahedral and square-planar coordination geometries.

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