Synthesis of new ligands for metal ion complexation



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Texas Tech University


The ability of crown ethers to selectively bind alkali and alkaline earth metal cations was discovered in 1967 and tremendous developments in this field have been achieved to date. Many dibenzocrown ethers with a substituent on each benzo unit have been obtained and investigated in various studies as mixtures of regioisomers. Since the regioisomers may have different complexing properties, a synthetic route has been developed in this thesis to prepare disubstituted dibenzocrown ethers in which the two substituents are in specific positions. Allyl groups were incorporated into these disubstituted dibenzocrown ethers which can be utilized for further transformation.

Nuclear waste treatment is an important and worldwide problem. Recently, interest in applying tridentate organophosphoryl ligands to separate actinides from nuclear waste arose. A synthetic intermediate to these tridentate ligands was synthesized in this thesis with a much improved yield from previous work. In solvent extraction of actinides, long chain carboxylic acids have been used as co-extractants with crown ethers and were found to enhance the extraction efficiency and selectivity. A highly lipophilic carboxylic acid was prepared on large scale to be utilized in actinide extraction.

Calixarenes were developed in the late 1970's and have been investigated as complexing ligands for molecular, cationic and anionic species. However, p-t-butylcalix- [4]arene, the most widely studied calixarene, and its derivatives have limited solubility in organic solvents. A series of calix[4]arenes with r-octyl groups as the para substituents were synthesized and increased solubility in organic solvents was observed.



Calixarenes, Crown ethers, Radioactive wastes -- Purification