| Popis: |
The investigations in this thesis deal with two types of very different oxidations. The first study follows our groups' discovery of a new and unusual class of antioxidants, where the actual antioxidant is, paradoxically, a carbon-centered radical. The radical precursors are dimer molecules that, upon heating, dissociate to form two persistent carbon-centered free radicals, unreactive towards oxygen. These radicals act as chain-breaking antioxidants by rapidly reacting with peroxyl radicals that participate in propagation of autoxidation chain reactions. The solvent effects on antioxidant activity of one of these antioxidants, the HP-136 dimer, has been assessed in a range of solvents of varying hydrogen bond accepting ability, by the Inhibited Oxygen Uptake (IOU) method. The HP-136 dimer was found to show far less solvent effect on antioxidant activity than a representative phenolic antioxidant. In the second part of the thesis, the process of copper nanoparticle (CuNP) oxidation is explored, with a goal of developing new strategies for CuNP stabilization under air. It was found that CuNP oxidize to form Cu 2+ as the major product, in a process that involves oxygen uptake. L-ascorbic acid was found to be a sacrificial stabilizer of CuNP, and a mechanism of CuNP stabilization by ascorbic acid is proposed. |
