The Synthesis of Rhodium Catalyst-Organic Frameworks for Isomerization and Continuous-Flow Hydrogenation Reactions

• Author / Creator

  Corkum, Elizabeth G

• The development of immobilized asymmetric catalysts is of vital importance as it would allow for easy catalyst recovery from the reaction mixture and reuse. One strategy for immobilization involves the synthesis of insoluble polymer-supported catalysts. Most polymeric catalysts are made by polymerizing a chiral ligand, or grafting the ligand to a polymer support, followed by metallation of the ligand sites. The resulting catalysts are often plagued by poor activity and reusability due to incomplete metallation, limited access to catalytic active sites and metal leaching. The Bergens group developed a method where a ruthenium metal-containing monomer (MCM) is directly polymerized by alternating ring-opening metathesis polymerization (altROMP) and deposited on insoluble barium salts. The resulting catalyst-organic frameworks (COFs) exhibited remarkable reuse with no drop in activity or selectivity and no detectable ruthenium leaching. This dissertation describes the extension of the altROMP methodology to rhodium-BINAP containing catalysts and their use in the intramolecular cycloisomerization of 1,6-enynes, solvent-free allylic alcohol isomerizations and continuous-flow olefin hydrogenations.
  The altROMP of MCMs [RhCl((R)-5,5ʹ-dinorimido-BINAP)]2 (I) and Rh(NBD)((R)-5,5ʹ-dinorimido-BINAP) (II), with cyclooctene as a spacer monomer, and with RuCl2(CHPh)(PCy3)2 as the ROMP catalyst, gave two novel rhodium-BINAP COFs, Ia and IIa respectively, that were subsequently deposited on BaSO4 or Ba-L-tartrate.
  Framework Ia sustained up to six reuses and provided the highest TONs to date (up to 890), with no drop in enantioselectivity (95-99.9% ee), in the cycloisomerization of 1,6-enynes. As well, a key intermediate in the production of pharmaceutical (+)-pilocarpine was afforded in >99.9% ee. Framework Ia also provided the highest TONs to date (up to 38,000) for the rhodium catalyzed isomerization of secondary allylic alcohols with catalyst loadings as low as 0.0025 mol%. In both cases, the COF proved to be more active and selective than the parent homogeneous catalyst. Framework IIa proved to be highly active in the continuous-flow hydrogenation of a variety of olefin-containing substrates and sustained up to 55,700 TOs over a period of 30 days in the H-Cube® continuous-flow reactor. As well, in a preliminary study, >99.9% ee was obtained in the continuous-flow hydrogenation of itaconic acid by framework Ia.

• Subjects / Keywords

  • Catalysis
  • Hydrogenation
  • Heterogeneous
  • Isomerization
  • Rhodium
  • Continuous-Flow
  • BINAP

• Graduation date

  Fall 2013

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3GF0N47Q

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.