Electron spin resonance studies of some organo-phosphorus radicals.

The opening Chapter entitled Principles of Electron Spin Resonance (ESR) gives a brief introduction to the technique of ESR spectroscopy. Following this Chapter the thesis is divided into two parts; A and B. In Part A, the application of ESR spectroscopy to the study of solvent degradation in nuclear fuel reprocessing is discussed. Chapter 1 gives a brief account of nuclear fuel reprocessing, describing in particular the "Purex process". The causes, and chemical aspects, of solvent degradation are also discussed. Chapter 2 discusses how ESR spectroscopy was used to gain insight into the mechanism of solvent degradation caused by ?-irradiation. Firstly, individual components, such as OP(OBun)3 (TBP), were studied and then combined components, until near simulated "Purex process" conditions were reached. Particular attention is paid to the detection of radicals formed by ?-radiolysis (at 77 K) of TBP and also OP (OMe)3. A mechanism of formation is proposed. Also, comments are made on radical yields, and the effect changes in the diluent has. Part B considers the electron-loss and electron-gain processes involved when tervalent and trivalent phosphorus compounds are exposed to ionizing radiation (at 77 K). Chapter 1 discusses the formation of tervalent phosphorus radical cations. Attention is focused on the freon method of generation. A number of cations such as oPMe3+, oP(OMe)3+ and oPCl3+ are identified. Chapter 2 discusses the formation of tetravalent phosphorus radical cations. Attempts to generate and detect the radical cations OP (OMe)3+ and O?(OBun) + using the freon method are described. A study of other 31 electron PL4 radicals, including (L3P-PL3)+, is discussed. In Chapter 3 the detection of radicals produced by ?-radiolysis (at 77 K) of tervalent phosphorus compounds, particularly P(OMe)3 and PMe3 is discussed. Attention is concentrated on the identification, and on the mechanism of formation, of those radicals formed by electron- gain processes. Special attention is given to the postulated parent electron-gain species (:?L3-) and also to phosphinyl radicals :?L2. Chapter 4 discusses the ?-radiolysis (at 77 K) of tetravalent phosphorus compounds; various (RO)2 PXS- salts and corresponding disulphides [(RO)2 P (X) S]2 (where X = S or O). Attention is focused on the identification and on the mechanism of formation of radicals produced by electron-gain processes.