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 Keywords
- hydroformylation
- rhodium
- bimetallic cooperativity
- spectroscopy
Date of Defense 2012-03-07 Availability unrestricted Abstract 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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