Fundamental Studies of Selective Oxidation Reactions on Gold and Silver Surfaces

Abstract

This thesis explores the fundamental chemistry of selective oxidation reactions on gold and silver surfaces, developing a predictive framework for oxidative catalysis, which is crucial for rational design of catalytic systems. We begin with an introduction covering the history of precious metal catalyst development, with emphasis on the roles of silver and gold (Chapter 1). Next, we explore selectivity control for oxidative reactions on gold. Specifically, we address the role of coadsorbed oxygen with respect to stability and selectivity control in the reaction of adsorbed acetate (Chapters 2 and 3), the importance of van der Waals forces in controlling the selectivity for cross-coupling reactions (Chapter 4), and the influence of CF3 on alkoxide stability on gold (Chapter 5). Further, we study various oxidative coupling and partial oxidation reactions on silver. In each case we elucidate reaction mechanisms, with attention to control of reaction selectivity. First, we establish oxidative coupling between dimethylamine and formaldehyde to form dimethylformamide (Chapter 6). Then we explore the role of hydroxyl in oxidative reactions silver, establishing its reactivity as a nucleophile in reaction with formaldehyde (Chapter 7). Finally, we directly compare the reactivity of gold and silver, in the acetylation of dimethylamine using acetaldehyde (Chapter 8). Appendices are included which investigate the oxidation of dimethylamine on silver (Appendix A), selectivity control for alcohol and aldehyde coupling on silver (Appendix B), and reactivity of hydroxyl on silver as a Bronsted base (Appendix C). A MATLAB code, which was developed for quantitative analysis of temperature program reaction spectroscopy experiments is also presented (Appendix D), as well as Supporting Material (Appendix E).