Renewable Monomer Feedstocks via Olefin Metathesis: Fundamental Mechanistic Studies of Methyl Oleate Ethenolysis with the First-Generation Grubbs Catalyst

Abstract

The conversion of seed oil based feedstocks such as methyl oleate into useful commercial raw materials via olefin metathesis has been a research focus for decades, due to their low cost and renewable supply, but technical success has been limited due to poor catalyst activities and turnovers. We report here recent studies on the cross-metathesis of methyl oleate with ethylene (ethenolysis) catalyzed by bis(tricyclohexylphosphine)benzylideneruthenium dichloride (1). At 25 °C/60 psig of ethylene, catalysis by 1 results in the highly selective formation of 1-decene and methyl 9-decenoate. However, reactivity losses limit the catalyst turnovers well below commercial viability in batch reactor operation. In an attempt to address the limitations of this chemistry, a combination of an experimental evaluation of the impact of process parameters, a detailed analysis of the fundamental reaction steps, kinetic modeling, and molecular modeling has been applied to develop a more detailed understanding of this complex catalytic pathway. These fundamental studies have led to a more complete understanding of the factors impacting catalyst performance and the identification of approaches necessary to achieve an economically viable process.