| Summary: | The work described in this thesis is concerned mainly with the application of high frequency conductance measurements to the study of the rapid hydrolyses of cyclic carbonate esters. A high-frequency oscillator with an inductive-type cell has been built and its behaviour towards changes in conductance of electrolyte solutions is accounted for by a theoretical equivalent circuit representing the cell and its contents. An equation relating the parameters of the oscillatory circuit and of the cell is derived and verified experimentally. The importance, with regard to reaction-rate measurements, of the dispersion of conductance and dielectric constant of electrolyte solutions is determined. The suitability of the apparatus for following conductance changes, associated with the relatively rapid hydrolyses of organic esters, is demonstrated by following the alkaline hydrolysis of methyl acetate at several temperatures. Values for the rate constants and the energy of activation are determined. The apparatus is then applied to the studies of the alkaline hydrolyses of ethylene, propylene, and vinylene carbonates at several temperatures. The rate constants and the energies of activation for these hydrolyses are determined. The effects of substituents and structure in cyclic carbonates on the rates and kinetics of their hydrolyses are discussed. Differences in the rate constants for the hydrolyses of ethylene and propylene carbonates from those of previous authors are accounted for. A mechanism for the hydrolysis is suggested and evidence in its favour discussed. The dielectric constant and the dipole moment of vinylene carbonate are determined, and the significance of the results in terms of intermolecular interaction is indicated. The reaction of o-phenylene carbonate in alkaline solution is studied; a method suitable for following this extremely rapid hydrolysis is described, and a value for the half-life of the reaction is determined.
|
|---|
