Development of 4-pyridones as Industrial Extractants for Rare Metals

合成了烷基链上有1 ~ 12个碳原子的1-（4-烷基苯基）-3-羟基-2-甲基-4-吡啶酮（AHMP或HL），并详细研究了AHMP从水溶液中萃取铟（III）和某些类镧（III），包括镨（III）、铕（III）和镱（III）的过程。所有AHMP提取的金属均为ML_3，其中M为上述金属。AHMP的配分系数K_D和In (III)-AHMP配合物的分布常数K_<DC>随烷基链碳数的增加而增大。每个碳原子的log K_D和log K_<DC>的增量分别为0.52和1.67。以1-（4-甲基苯基）-3-羟基-2-甲基-4-吡酮配合物为例，其萃取、分布及形成常数见表1。测定了AHMP的酸解常数。此外，配合物的提取速度快，定量好。从这些结果可以看出，AHMP不仅可以作为In (III), Pr (III), Eu （III）和Yb （III）的萃取剂，还可以作为其他金属离子的萃取剂，这些金属离子被归类为所谓的硬酸。

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.