I. Phase transfer catalysis of deuterium exchange reactions. II. Kinetic and mechanistic studies of the thermal decomposition of glycolate and HEDTA in the presence of the sodium salts of hydroxide, nitrate, nitrite, aluminate and carbonate.

摘要

The technique of phase transfer catalysis has proven to be a valuable tool in organic synthesis and its use has been well documented in the literature. The mechanism by which catalysis takes place however, has been the subject of some research and much controversy. This is especially true in phase transfer catalysis reactions involving hydroxide ion as the anionic reagent. Two separate pathways have been proposed to account for the experimental observations. The first pathway is based on the extraction mechanism by Starks and subsequently modified by Landini et al. The second pathway is the interfacial mechanism as proposed by Makosza. The critical differences between them is what provided the foundation for this research. In order to distinguish between these two mechanisms research was concentrated on the proton abstraction step. In particular isotope exchange studies were chosen as the tool to distinguish between the two mechanisms.;This investigation clearly showed that neither the extraction mechanism nor the interfacial mechanism was supported by the new results. Based on these new results the "Modified Interfacial Mechanism" was proposed.;An investigation of the episodical gas release from an underground nuclear waste storage tank (tank 241-SY-101) at the Hanford Site, in the State of Washington, was undertaken. The focus of the investigation was on the mechanism and kinetics concerning the evolution of gas and the components of the thermal degradation of the organic component (HEDTA, EDTA and glycolate). A synthetic waste slurry, mimicking the actual tank waste, was used to identify which organic and inorganic species played a role in gas evolution. Experimentation initially focused on HEDTA as the organic component. Qualitative gas analysis was possible but, analysis of the nonvolatile products showed an intractable complex mixture. Thus, glycolate was chosen as a simple model organic system in order to give mechanistic insights.;The data from this experimentation, in conjunction with results from Konda, Doctorovich and Zhang led to a proposed mechanism to account for the formation of the products from the thermal degradation of glycolate.