Development of 4-pyridones as Industrial Extractants for Rare Metals

合成了烷基含1~12个碳原子的1-(4-Alkylphenyl)-3-hydroxy-2-methyl-4-pyridones(AHMP或HL)，并详细研究了AHMP从水溶液中萃取铟(III)和一些稀土(III)，包括Pr(III)、Eu(III)和Yb(III)到1，2-二氯乙烷中。所有AHMP的萃取态均为ML_3，其中M为上述金属。随着烷基碳数的增加，AHMP的分配系数K_D和In(III)-AHMP络合物的分配常数K&lt；Dc&gt；每碳原子的对数K_D和对数K_t；dc&gt；增量分别为0.52和1.67。作为例子，表1列出了1-(4-methylphenyl)-3-hydroxy-2-methyl-4-pyridone络合物的萃取、分布和形成常数，并测定了其酸解离常数。此外，络合物的提取速度快、定量好。从这些结果发现，AHMP不仅对In(III)、Pr(III)、Eu(III)和Yb(III)有很好的萃取剂作用，而且对其他金属离子也有很好的萃取剂作用。

1-(4-Alkylphenyl)-3-hydroxy-2-methyl-4-pyridones (AHMP or HL) having 1 to 12 carbon atoms in their alkyl chains were synthesized and the extraction of indium (III) and some lanthanoids (III) including praseodymium (III), europium (III) and ytterbium (III) with AHMP from aqueous solutions into 1,2-dichloroethane was investigatedi in detail. The extracted species were ML_3 for all AHMP, where M denotes the above metals. The partition coefficients, K_D, of AHMP and the distribution constants, K_<DC>, of In (III)-AHMP complexes increased with an increase in the carbon number in the alkyl chain. The increments of log K_D and log K_<DC> were 0.52 and 1.67 per a carbon atom, respectively. As an example, the extraction, distribution and formation constants of 1-(4-methylphenyl)-3-hydroxy-2-methyl-4-pyridone complexes were shown in Table 1. The acid dissociation constants of AHMP were also determined. In addition, the extraction of the complexes was rapid and quantitative. From these results, AHMP was found to be useful as the extractant for not only In (III), Pr (III), Eu (III) and Yb (III), but also other metal ions classified into so-called hard acids.