RUI: Mechanistic Studies of Ruthenium-Catalyzed Ester Hydrogenation

Colgate University, Hamilton NY

Investigators

Abstract

With this award, the Chemical Catalysis Program of the NSF Division of Chemistry is supporting the research of Professors Anthony Chianese and Jason Keith at Colgate University to understand how catalysts operate at a molecular level for a chemical process called ester hydrogenation. This reaction is carried out on a very large scale in the chemical industry, often at high temperatures and under high pressures of hydrogen gas. A major goal in the field of chemical catalysis is the development of efficient processes that minimize the production of hazardous waste and operate under energy-efficient conditions. Chianese and Keith are using a combined laboratory and computer-modeling approach to determine how the best-known ester hydrogenation catalysts operate. These studies are contributing to basic scientific knowledge and helping to design the next generation of improved catalysts. All of the research for this project is being conducted by undergraduate students in the investigators' laboratories at Colgate University. Participation in undergraduate research, especially early in a student’s career, is increasingly recognized for its positive impact on students and for broadening participation in the sciences. Professor Chianese and the students working in his research group also devote a day each summer to running an outreach activity for high school students attending Camp Fiver, a residential summer camp that hosts a group of at-risk students New York City and rural upstate New York. In a previous NSF-funded project, Professors Chianese and Keith discovered that ruthenium complexes developed in their laboratory, as well as a widely used ruthenium complex known as Milstein’s catalyst, undergo an irreversible chemical transformation to become active catalysts for ester hydrogenation. This finding called into question previously suggested mechanisms for how Milstein’s catalyst promotes ester hydrogenation, as well as a wide array of related hydrogenations and dehydrogenations of polar bonds. In the current project, Chianese and Keith are undertaking a detailed experimental and computational study to understand precisely how Milstein’s catalyst operates at a molecular level. This project draws upon Chianese’s expertise in experimental mechanistic study and Keith’s expertise in computational analysis of reaction mechanisms. One aim of these studies involves determining how the inactive ruthenium precatalysts convert into their catalytically active forms. Another aim focuses on understanding the individual chemical reactions that make up the catalytic cycle for ester hydrogenation with these complexes. This knowledge is being collected to assist in the rational development of improved catalysts for ester hydrogenation and related processes. This program is also providing valuable training for undergraduate students and opportunities for at-risk high schools students to be introduced to chemical research. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.