| Popis: |
Electro-organic reactions are becoming increasingly important due to interest in energy efficient and green synthetic methodologies. Compared with traditional thermal organic reactions, however, electro-organic synthesis has inadequate numbers of reaction types, which has limited its widespread use for general chemical synthesis. This is partly because existing electro-organic synthetic methods largely focus on dimerization pathways performed on Pt or carbon electrodes. The goal of this thesis research is to screen for new electro-organic pathways. This required the development of platforms capable of monitoring organic reactions quantitatively and qualitatively in real-time. The hypothesis is based on the use of electrical energy (direct current) to create oxides on electrode surfaces via electro-oxidation. We expected the presence of oxides to open new reaction pathways at the metal electrode that might be different from the typical dimerization reactions. We chose to study Ir and Ru electrodes where the corresponding oxides are commonly employed as electrocatalysts for electrochemical water splitting and oxygen evolution reactions. The reaction screening platform is composed of a nano-electrospray ionization (nESI) emitter, which can be fitted with various metal/alloy electrodes. The traditional nESI emitter often uses Ag electrodes, but this Ag electrode releases the stress induced by the DC potential via the generation of Ag+ ions limiting electro-organic reactions. With Ir and Ru, we expected the in-situ formation of the corresponding oxides when used in nESI. This property of creating oxides on electrode surfaces via electro-oxidation was employed for in-situ generation of the oxides, which were found to facilitate electro-catalytic reaction screening. Two unique electro-organic reactions have been discovered under this Ir/Ru nESI reaction condition: (i) the oxidation reaction system of isosafrole (containing a C=C functional group) was observed to cleave the C=C bond producing the corresponding aldehyde, which was successfully detected using on-line reaction with n-butylamine and (ii) oleic acid was shown to undergo epoxidation, with the epoxidation product giving rise to diagnostic ions upon collision-induced dissociation (CID) fragmentation for structural characterization. |
