Title page for ETD etd-04222012-152528

Type of Document Dissertation
Author Polakova, Darina
Author's Email Address darinca99@hotmail.com, dpolak1@lsu.edu
URN etd-04222012-152528
Title Studies on a Dirhodium Tetraphosphine Hydroformylation Catalyst
Degree Doctor of Philosophy (Ph.D.)
Department Chemistry
Advisory Committee
Advisor Name Title
Stanley, George G. Committee Chair
Chan, Julia Y, Committee Member
Crowe, William E. Committee Member
Maverick, Andrew W. Committee Member
Board, James E. Dean's Representative
  • hydroformylation
  • rhodium
  • bimetallic cooperativity
  • spectroscopy
Date of Defense 2012-03-07
Availability unrestricted
The dirhodium tetraphosphine catalyst [Rh2(nbd)2(rac-et,ph-P4)](BF4)2 was investigated in acetone and water/acetone in order to explain better hydroformylation results in the latter solvent. In-situ NMR spectroscopy showed slower degradation in water/acetone. Less tendency to form penta/hexacarbonyl complexes in water/acetone was shown by 31P{1H} NMR and FT-IR. A pH decrease and hydroformylation studies in presence of a base indicated formation of a monocationic monohydride species. A new reaction mechanism was suggested that takes into account the observed differences from the acetone solvent system.

The presence of water enabled production of hydride species when the dirhodium catalyst was exposed to CO gas. We believe this was caused by water-gas shift chemistry (H2O + CO = H2 + CO2). However, a subsequent experiment in a Parr autoclave showed that the process was not fast or efficient enough to serve as a hydrogen source for hydroformylation.

The cationic character of the dirhodium catalyst was utilized for its attachment to the surface of silica gel. The purpose of immobilization is to enable easy separation of the catalyst from hydroformylation products. At room temperature in dichloromethane solution the immobilization was successful, but during hydroformylation conditions in acetone, the catalyst was released into solution.

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