Design, synthesis and evaluation of calixarene-based extractants for actinide(IV) ions and new synthetic methodology for the preparation of 3-hydroxy-2-pyridinone chelators.

摘要

The goals of this research project were two fold. The first goal was to design, synthesize and evaluate a number of ligand functionalized calixarenes for the selective extraction of actinide(IV) ions from aqueous systems. The second goal was to develop convenient synthetic methodology for the preparation of polyhydroxypyridinone chelating systems.; In accord with the first goal, a number of ligand types such as hydroxamic acids (compounds 41 and 42), hydroxypyridinones (compounds 84 and 85) and iminocarboxylates (compound 62) were appended to the lower rim of the calix[4]arene scaffold to provide chelators which are theoretically capable of forming a ML complex with the actinide(IV) ion and achieve its selective extraction. In order to more fully understand the complexation behavior of these new calix[4]arene metal ion binding systems, a number of cyclic and acyclic analogs were also synthesized. These include the 1,3 distally substituted calix[4]arene hydroxamate 44, the 1,3 distally substituted calix[4]arene hydroxypyridinones 91 and 101, calix[4]arene iminocarboxylates 61, 63 and 64 and some related acyclic hydroxamate 45–48 and hydroxypyridinone 100 and 102 analogs. All new chelators were prepared in a relatively straightforward manner using short synthetic sequences from readily available starting materials.; Our quest to develop a number of hydroxypyridinone extractants also led us to develop new methodology for the incorporation of the 3-hydroxy-2-pyridinone chelating moiety into a variety of systems. Particularly, a new method that would allow the incorporation of this chelating moiety without the formation of an amide linkage in the coupling stage was desired. This became the second objective of this work. This led us to prepare the novel cyclic iminium ester mesylate salt 160 which is a good electrophile for coupling with amines and alcohols. The salt was shown to have two possible modes of reaction with amines (path a or b). The reaction of 160 with primary amines was found in most cases to give an amidine type product (via path a) while the similar reaction of 160 with secondary amines gave the desired amine hydroxypyridinone products (path b). Alcohols, although less reactive, were shown to give the desired ether based hydroxypyridinone products upon reaction with 160. (Abstract shortened by UMI.)