新型含氟有机萃取剂的高效合成及其在锂同位素分离中的应用

The lithium element has two natural isotopes: Li-7 and Li-6, and both of them are very important energy materials and strategic resources. Li-6 is the nuclear fusion fuel, and Li-7 is the essential molten salt coolant. However, only lithium amalgam process was used for lithium isotope separation, which is very toxicity and high maintenance costs. So, the development of new organic extractants, synthesis of special organic molecules, and screening out the specific extractants for lithium isotope separation, are very important research topics. This project will combine the characteristics of organic fluorine chemistry with traditional extractants. Through cleverly designing the structures of fluorinated organic extractants, and the efficient introduction of fluorine-containing groups, new fluorinated lithium isotopes extractants will be synthesized. The introduction of the fluorine-containing group will adjust the ligand environment of lithium atoms, and change the force constant of lithium-oxygen bond, which will increase the extraction ability of the extractant and isotope separation ability, while the fluorine-containing extractants also having a good chemical stability and oil solubility. Therefore, the design and synthesis of new fluorinated extractants, screening and obtaining the fluorinated extractants with good extraction capability and high separation will be a meaningful work, and will play an important role in the separation of lithium isotopes.

锂元素的两种天然同位素Li-7和L-6i是非常重要的能源材料和战略资源，如Li-6是核聚变堆中的燃料，Li-7是必不可少的熔盐冷却剂。然而，锂同位素分离仅有的汞齐法工艺毒性非常大、维护成本高。因此，开发新型的有机萃取剂，即通过合成特殊的有机分子，筛选出用于特定锂同位素分离的萃取剂，是十分重要的研究课题。 本项目将在已有的萃取剂基础上，结合有机氟化学的特色，巧妙地设计含氟有机萃取剂，通过高效地引入含氟基团，合成新型的含氟锂同位素萃取剂。含氟基团的引入，将会调节锂原子的配位环境和改变锂氧键的力常数，因而会提高萃取剂的萃取能力和同位素分离能力，同时含氟萃取剂还具有化学稳定性好和油溶性好的特点。因此，设计和合成出新型的含氟萃取剂，筛选优化得到萃取能力强、分离系数高的含氟分子结构，将是一项有意义的工作，势必会在锂同位素分离中发挥重要作用。

设计和合成了多种用于锂同位素分离的新型含氟有机萃取剂，开发了多种新型、高效的氟烷基化、氟化方法。合成的新型含氟萃取剂包括：含氟偶氮类萃取剂、亚胺类萃取剂、含氟多环类萃取剂、含氟酮类萃取剂。开发了精确测定锂同位素丰度的分析方法，并对多种含氟萃取剂分离锂同位素的综合性能进行测试与评价。综合考虑萃取剂的合成方法、溶解度、长期稳定性等因素，优选两种含氟萃取剂作为新型、高效的锂同位素分离专用萃取剂。与普通的萃取剂相比较，这两种萃取剂具有分离系数高、分配比合适、合成方便等优点，特别具有抗氧化性和抗酸碱性能，具备长期的萃取稳定性，是一类优良的锂同位素分离萃取剂。