Synthesis, catalysis, and electrochemistry of some organic and organometallic compounds

Abstract

Previous research results have demonstrated that vitamin E can undergo a series of reversible electron-transfer and proton-transfer reactions affording unusual long-lived phenoxonium cations under electrochemical oxidation. The purpose of the sequential study is to investigate what structural aspects of a-tocopherol are important in increasing the lifetime of its related phenoxonium cation. In chapter 1, a number of phenolic compounds have been synthesized and their electrochemical behavior tested by CV (cyclic voltammetry) and CPE (controlled potential electrolysis) experiments. In general, these phenols can be classified into two classes. Class 1 compounds can be oxidized to give long-lived phenoxonium cations, which showed similar electrochemical behavior to a-tocopherol. For class 2 compounds, the corresponding phenoxonium cations are voltammetrically undetectable at slow scan rates, and undergo further rapid reactions or convert into p-quinones. The methyl group in the aromatic ring and the chromanol structure of vitamin E played crucial roles in stabilizing phenoxonium cations. In addition, in chapter 2, several heterocyclic ethers without free hydroxyl groups have been synthesized and examined as model compounds to study the one-electron oxidation process of vitamin E by a series of electrochemical methods (CV and CPE) and spectroscopic experiments (UV-vis and FTIR).