16th Annual Stauffer Lectureship (Day 1 of 2): Professor John Bercaw
About the Seminar:
"Olefin Oligomerization and Polymerization with Organochromium and Organozirconium Catalysts"
Catalytic trimerization of ethylene utlizing chromium(III) precursors supported by diphosphine ligand PNP04 = (o MeO C6H4)2PN(Me)P(o MeO C6H4)2 has been investigated. A well defined chromium precursor Cr(PNPO4)(o,o' biphenyldiyl)Br and its cation are effective for catalytic turnover to generate 1 hexene from ethylene adn the trimerization of 2 butyne. Catalytic trimerization, with various (PNP04)Cr precursors, of a 1:1 mixture of C2D4 and C2H4 gives isotopologs of 1 hexene without H/D scrambling (C6D12, C6D8H4, C6D4H8, and C6H12 in a 1:3:3:1 ratio), supporting a mechanism involving metallacyclic intermediates. Reactions of olefins indicate that a-olefins react with cationic biphenyldiyl chromium species to generate products from 1,2 insertion. A study of the reaction of 2 butenes reveal that B-H elmination occurs preferentially from the ring CH rather than the exo-CH bond for the metallacycloheptane intermediates. In other studies synthetic routes have been developed to semi rigid, group 4 nonmetallocene catalysts for a-olefin polymerization and other transformations. Recognizing that ansa-metallocenes have provided the most important framework for single site catalysts for olefin polymerization with tacticity control, we have developed a semi rigid ligand, LX2 type pincer ligand family (L = pyridine, furan, thiophene, pyrazoke; X = phenoxide, anilide) that have some similarites to ansa-metallocenes.
About the Speaker:
John Bercaw received his B. S. degree from North Carolina State University in 1967, his Ph. D. from the University of Michigan in 1971, then undertook postdoctoral research at the University of Chicago. He joined the faculty at the California Institute of Technology as an Arthur Amos Noyes Research Fellow in 1972, and in 1974 he joined the professorial ranks, becoming Professor of Chemistry in 1979. From 1985 to 1990 he was the Shell Distinguished Professor of Chemistry, and in 1993 he was named Centennial Professor of Chemistry. Bercaw has been a Seaborg Scholar at Los Alamos National Laboratory (2004), the Robert Burns Woodward Visiting Professor at Harvard University (1999), The George F. Baker Lecturer at Cornell University (1993), Visiting Miller Professor at the University of California, Berkeley (1990), and a Royal Society of Chemistry Guest Research Fellow at Oxford University (1989-1990). From 2009-2012 he was also KFUPM Visiting Chair Professor at King Fahd University of Petroleum and Minerals. He has served on numerous panels for the Department of Energy and the National Research Council, and beginning in 1999 has been a member of the Science and Technology Committees for national weapons laboratories: Los Alamos National Security and Lawrence Livermore National Security.
Bercaw is a Fellow of the American Association for the Advancement of Science (1986), a member of the National Academy of Sciences (1990), a Fellow of the American Academy of Arts and Sciences (1991), and was awarded an Honorary Doctorate of Science from the University of Chicago in 2001. He has received the American Chemical Society awards in Pure Chemistry (1980), for Organometallic Chemistry (1990), for Distinguished Service in the Advancement of Inorganic Chemistry (1997), the George A. Olah Award for Hydrocarbon or Petroleum Chemistry (1999), and an Arthur C. Cope Scholar Award (2000). He held the Sir Edward Frankland Prize Lectureship of the Royal Society of Chemistry in 1992, received the Basolo Medal (Northwestern, 2005), the Bailar Medal (University of Illinois, 2003), and the Tolman Medal (Southern California Section of the ACS, 2013).
His research interests are in synthetic, structural and mechanistic organotransition metal chemistry. Investigations include catalysts for polymerization of olefins, investigations of hydrocarbon hydroxylation with transition metal complexes, and the development of catalysts for syngas and light alkane conversions to chemicals and fuels. He has published almost 300 peer-reviewed scientific articles.