INVESTIGATION ON DEVELOPMENT AND MOLECULAR DESIGN OF HIGH-PERFORMANCE SOLVENT EXTRACTION REAGENTS FOR RARE EARTHS

合成了含羧酸、羟肟酸和膦酸官能团的三种化学改性杯芳烃，考察了它们对三价稀土的溶剂萃取行为。将羧酸和羟肟酸的官能团引入杯芳烃[4或6]的下缘，合成羧酸型和羟酸型杯芳烃。还合成了羧酸酯的单体和线性三聚类似物，比较了它们与羧酸杯芳烃的萃取行为。结果表明，杯芳烃羧酸衍生物与单体和线性三聚体类似物相比，具有更高的伸展性和稀土元素相互分离的选择性；而杯芳烃衍生物的环大小不影响其选择性。杯芳烃的羟基甲酸酯衍生物通过阳离子交换机制提取金属离子，与相应的羧酸衍生物相比，对三价铟和镓具有较高的选择性。在合成杯芳烃酸性膦酸衍生物的初期，虽然曾试图将官能团引入杯芳烃的下缘，但由于官能团的体积较大而无法实现，这一点也被计算机模拟所证实。因此，在去除叔丁基后，它们被引入对叔丁基杯芳烃的上边缘；通过将酚羟基上的氢原子取代烷基，将丙基和辛基等烷基引入下环。并合成了单体类似物，比较了其与杯芳烃衍生物的萃取行为。这三种化合物对稀土的选择性没有差异，这是由于在上缘引入膦酸官能团导致杯芳烃环失去了对离子半径的大小识别，计算机模拟也证实了这一点。预计在下缘引入2-乙基己基等大体积烷基可以提高反应的选择性。少

Three types of chemically modified calixarenes containing functional groupes of carboxylic acid, hydrxamic acid and phosphonic acid were synthesized to be examined on their solvent extraction behaviors for trivalent rare earths. Carboxylate and hydroxamate types of calixarenes were synthesized by introducing functional groups of carboxylic acid and hydroxamic acid into lower rim of calix [4 or 6] arenes. Monomeric and linear trimeric analogues of carboxylates were also synthesized to compare their extraction behavior with carboxylate calixarenes. It was found that the carboxylate derivatives of calixarenes have much higher extability and selectivity for mutual separation of rare earth elements compared with the monomeric and linear trimeric analogues ; but, the ring size of the calixarene derivatives does not affect the selectivity. The hydroxamate derivatives of calixarene was found to extract metal ions by cation-exchange mechanism and have high selectivity to trivalent indium and ga … More llium in particular compared with the corresponding carboxylate derivatives. At the initial stage of the synthesis of acidic phosphonate derivatives of calix [4] arene, although it was attempted to introduce the functional groups into the lower rim of the calixarene, it was found impossible owing to the bulkiness of the functional groups, which was confirmed also by the computer simulation. Consequently, they were introduced into the upper rim of the p-tert-butylcalix [4] -arene after removal of the tert-butyl groups ; alkyl groups such as propyl and octyl groups were introduced into the lower rim by substituting the hydrogen atoms of phenolyc hydroxy groups for the alkyl groups. Monomeric analogue was also synthesized to compare the extraction behavior with the calixarene derivatives. No differences of the selectivity to rare earths were found among these three kinds of compounds, which was attributed to the loss of the size recognition for ionic radii by calixarene ring caused by the introduction of the phosphonate functional groupes into upper rim, which was also confirmed by the computer simulation. It was expected that the introduction of bulky alkyl groups such as 2-ethylhexyl group into the lower rim would enhance the selectivity. Less