【摘要】 在离子强度μ=0.5的NaClO₄介质中,用阳离子交换法研究了Am（Ⅲ）、Cm（Ⅲ）同α-羟基-α-甲基丁酸的络合作用。在实验范围内,形成MA²⁺,MA₂⁺和MA₃三种络合物。按S·Fronae-ous 法并分别用作图法和计算机处理实验数据,结果基本一致。Am（Ⅲ）络合物的累积稳定常数为:β₁=（3.45±0.05）×10²,β₂=（1.59±0.10）×10⁵,β₃=（4.6±0.2）×10⁵。Cm（Ⅲ）络合物的累积稳定常数为:β₁=（3.84±0.06）×10²,β₂=（2.32±0.17）×10⁴,β₃=（8.5±0.3）×10⁵。初步讨论了在羟基羧酸系列中以烷基取代α-碳位置上的氢原子对络合常数的影响.数据表明,以α-羟基-α-甲基丁酸作为阳离子交换分离镅和锔的淋洗剂,可望得到比α-羟基异丁酸更好的效果。更多还原

【Abstract】 The equilibria between Am(Ⅲ), Cm(Ⅲ) and α-hydroxy-α-methylbutyrate (HMBA) were investigated by a cation exchange method at 25℃ and at a constant ionic strength μ=0.5. Sodium perchlorate was used as a supplementary salt in the solution. The radioactivity of americium and curium was determined using a Intertechnique SL-30 liquid scintillation spectrometer with a relative accuracy≤3%.Stoichiometric over-all constants were computed in two ways: by Fronaeous’s graphical method and via a weighted least squares technique using a PDF 11/34 computer. The results agree quite well and prove the existence of three mononuclear complexes, viz MA2+, MA+2 and MA3. The over-all stability constants of the complexes formed are: for Am (Ⅲ) β1 = (3.45±0.05) ×102; β2 = (1.59±0.10)×104; β3 = (4.6±0.2)×105.for Cm (Ⅲ) β1 = (3.84±0.06) ×102; β2 = (2.32±0.17)×104; β3 = (8.5±0.3)×105.Since HMBA is part of a series where the amount of alkyl substitution on the alpha carbon varies, there are two different effects that should be taken into account. The first is the basicity of the donor oxygen atoms. The inductive effect of an alkyl group alpha to the carboxylate is to increase the basicity. The second factor is the steric factor. For HMBA, however, the inductive effect is the dominating factor. By comparison of the stability constants of the HMBA, HIBA and lactic complexes (Table 1), it can be expected, that HMBA is superior to HIBA and lactic acid as an eluant for the cation exchange separation of americium and curium. Table 1 The stability constants of some α-hydroxycarboxylate complexes of Am and Cm更多还原