Spectroscopic and kinetic studies of water and aqueous systems.

The role of water as a solvent or medium is reviewed and examined using near infrared spectroscopy for direct probing of water structure and ultra-violet spectroscopy for kinetic spheres. The kinetic behaviour of water in the SN1 hydrolysis of t-butyl iodide is studied by monitoring the rate of loss of absorbance of the n?o* electronic transition for the C-I bond in the ultra-violet spectral region as opposed to the normal conductiometric methods of measuring this type of hydrolysis. The effects of added basic cosolvents and electrolytes on the rate of reaction are studied and the results show good agreement with those obtained from conductiometric methods. A direct probe of the water structure is made by studying temperature variations and its effects on the pure water system and water/basic cosolvent mixtures. The observed results are linked to a theoretical model by mathematical predictions. A search for spectroscopic evidence for the type of 'intermediates' postulated in the mechanism for the SN1 hydrolysis reaction is made. The results support the concept of a solvated alkyl halide species --- this being formed before the heterolytic bond fission of the carbon halide bond. Free energies of interaction and equilibrium constants are also calculated. For this work both methanol and water are used. Cosolvent and electrolyte additions to the water structure are probed and linked to their effect on the rate of hydrolysis of t-butyl iodide. Use of deconvolution techniques are made to elucidate their behaviour.