LDRD final report on new homogeneous catalysts for direct olefin epoxidation (LDRD 52591).

Goldberg, Karen (University of Washington) ; Smythe, Nicole A. (University of Washington) ; Moore, Joshua T. ; Stewart, Constantine A. ; Kemp, Richard Alan ; Miller, James Edward ; Kornienko, Alexander (New Mexico Institute of Mining and Technology) ; Denney, Melanie C. (University of Washington) ; Cetto, Kara L. (University of Washington)

Sandia National Laboratories

关键词: Hydrides;    Transition Elements Alkenes.;    08 Hydrogen;    Catalysts.;    Oxygen;   

DOI  :  10.2172/878587
RP-ID  :  SAND2005-6754
RP-ID  :  AC04-94AL85000
RP-ID  :  878587

美国|英语

来源: UNT Digital Library

【 摘 要 】

This report summarizes our findings during the study of a novel homogeneous epoxidation catalyst system that uses molecular oxygen as the oxidant, a ''Holy Grail'' in catalysis. While olefins (alkenes) that do not contain allylic hydrogens can be epoxidized directly using heterogeneous catalysts, most olefins cannot, and so a general, atom-efficient route is desired. While most of the work performed on this LDRD has been on pincer complexes of late transition metals, we also scouted out metal/ligand combinations that were significantly different, and unfortunately, less successful. Most of the work reported here deals with phosphorus-ligated Pd hydrides [(PCP)Pd-H]. We have demonstrated that molecular oxygen gas can insert into the Pd-H bond, giving a structurally characterized Pd-OOH species. This species reacts with oxygen acceptors such as olefins to donate an oxygen atom, although in various levels of selectivity, and to generate a [(PCP)Pd-OH] molecule. We discovered that the active [(PCP)Pd-H] active catalyst can be regenerated by addition of either CO or hydrogen. The demonstration of each step of the catalytic cycle is quite significant. Extensions to the pincer-Pd chemistry by attaching a fluorinated tail to the pincer designed to be used in solvents with higher oxygen solubilities are also presented.