Mechanisms of Transition Metal Catalyzed Reactions in Hydrocarbons

California Institute Of Technology, Pasadena CA

Investigators

Abstract

With the support of the Organic Dynamics Program in the Chemistry Division, Professor Robert Grubbs at The California Institute of Technology will continue to work on a family of catalysts that have been able to impact a broad range of applications. The catalysts have displayed high levels of both activity and selectivity, the understanding of which has resulted from studies of mechanisms and structure function relationships. During the next granting period, new methods will be developed and explored for the synthesis of ligands that will aid in the fundamental understanding of the factors that control the efficiency of these systems. Out of these studies will come an efficient method for generating an array of N-heterocyclic carbenes that can be used in many catalytic processes beyond olefin metathesis. Although active metathesis catalysts have been prepared from ruthenium, osmium and iridium, to date there are no reports of even a moderately efficient metathesis catalyst based on iron. Ligand systems that should support and stabilize iron alkylidenes will be prepared and investigated to determine if some of the lessons learned from ruthenium catalysts can be applied to iron-based systems. Another objective of the proposed research is to explore routes to the synthesis of new forms of polyethylene (PE) to be used to develop and test models of structure-property relationships. New routes will be developed to perfect linear and monodispersed PE, continue the exploration of cyclic PEs, and develop new approaches to the synthesis of hyper-branched PE. Collaborations have been established for the full characterization and comparison of the properties of each of these topologically diverse materials. Additionally, a new strategy to develop catalysts for the interchange of functional groups (functional group metathesis) between two olefins, similar to olefin metathesis, which involves the interchange of fragments between two olefins. This strategy will provide new routes for the oxidation, aziridination, and hydration of olefins. Special emphasis will be on the development of a catalyst for the anti Markovnikov addition of water to olefins. To aid in these investigations, rapid screening techniques will be used and fundamental mechanistic studies will be carried out. This proposal by Professor Grubbs at The California Institute of Technology will produce new polymeric materials that other groups both in industry and academia will use to explore structure-property relationships. The past program produced over 65 publications and 14 issued patents related to olefin metathesis chemistry. These publications were either directly funded by NSF or were made possible by catalysts developed using NSF funding. The academic impact of the NSF funded program is demonstrated by being ranked in the top two of most cited programs with 90 citations per paper. The research program has produced a number of students who are now outstanding researchers in major academic and industrial institutions. It brings postdoctoral fellows and students from around the world, and supports 2-4 undergraduates for a ten week period, exposing them to academic research. Professor Grubbs' research is the basis for a number of industrial processes and is creating new employment opportunities in the US.