乙二胺四乙酸根合钍与某些氨基酸的络合反应

COMPLEX FORMATION OF Th(edta)CHELATE WITH SOME AMINO-ACIDS

用电位法研究含有Th(NO_(3))_(4)的乙二胜四乙酸二钠盐与某些氨基酸(丝氨酸、苏氨酸、白氨酸、α-氨基异丁酸)溶液的络合反应,证明有1:1:1的混合络合物生成,并测得在30°±0.1℃及离子强度μ=0.15(KNO_(3))时的稳定常数logK^(ThY)_(LThY).其稳定性按次级配体排列有如下顺序:α-氨基异丁酸>白氨酸>苏氨酸≌丝氨酸,该顺序与次级配体的碱度顺序一致,可以用下式表示:log_(ThYL)^(ThY)=1.40pK_(HL)-8.29.

The solutions containing equimolar t horium nit rate,EDTA and an amino-acid(serine,threonine,leucine,or α-amino-isobutyric acid)have been investigated potentiometrically.The results indicate the formation of 1:1:1 mixed ligand chelates.The formation constants logK^(ThY)_(LThY) at 30°±0.1℃ and ionic strength μ=0.15(KNO_(3))have been calculated.The order of stabilities in terms of the secondary ligand amino-acids,is as follows.a-amino-isobuturic>leucine>threonine≈serine.This order agrees with that of the basicity of the amino-acids and can be represented by a linear equation :log_(ThYL)^(ThY)=1.40pK_(HL)-8.29.