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本文通过对-取代苯基偶氮-2-萘酚及邻-取代苯基偶氮-芳香酚两种类型共十一种螯合剂与TOPO(或TRPO)协草锂的性能研究及HMO计算,讨论了该类螫合剂与中性协萃剂协萃锂时的结构效应。结果表明:(1)对-取代苯基偶氮-2-萘酚类赘合剂的苯基偶氮的配键N原子的电荷密度q_N与羟基氧原子的电荷密度qo_H无明显变化,萃取能力只受螯合剂pK_a的影响,协萃锂的表观平衡常数随整合剂pK_a值的下降而上升;(2)邻苯基偶氮-芳香酚类螯合剂由HMO计算表明,它们的羟基氧原子的电荷密度qo_H、配键N原子的电荷密度q_N及pk_a值都发生明显的变化,它们与TRPO的协萃能力随配键强度的增加而上升,并随PK_a值的上升而下降,其中最合适的结构是1-OH-2-(C_6H_5N=N)-C_(10)H_6,它的Pk_a值较小,q_N适中,所以协萃能力最大。相反,1-(C_6H_5N=N)-8-OH-C_(10)H_6的q_N最小,pK_a居中,协萃能力最小;(3)螯合物的稳定性主要由配键控制。因此,以螯合物分子的内氢键强度Δδo_H来量度配键强度,发现螯合剂萃取锂的分配系数随其分子的Δδ_OH/pk_a值的增大而递增。
In this paper, the properties of eleven sequestering agents chelating with TOPO (or TRPO) and the HMO calculations of two kinds of compounds, The structural effects of the combination of these chelating agents with neutral co-extracting agents on lithium are discussed. The results showed that: (1) The charge density of the azo bond of p-substituted phenyl azo-2-naphthol phenanthrene q_N did not change significantly with the charge density qo_H of hydroxyl oxygen atom. The extraction ability Affected by the chelating agent pK_a, the apparent equilibrium constant of the lithium complex increased with the decrease of the pK_a concentration of the integrator. (2) The results of HMO calculation showed that the ortho-phenylazo-aromatic phenol chelating agents charge density qo_H, with the key N atom charge density q_N and pk_a values are significant changes, which differ TRPO synergistic extraction ability with the distribution key to increase the strength rises, and with increasing pK_a value decreases, the most appropriate The structure is 1-OH-2- (C_6H_5N = N) -C_ (10) H_6, its Pk_a value is small, q_N is moderate, so the strongest extraction ability. On the contrary, q_N of 1- (C_6H_5N = N) -8-OH-C_ (10) H_6 is the smallest, pK_a is the center, and the ability of stripping is the lowest. (3) The chelate stability is mainly controlled by the coordinate. Therefore, the intramolecular hydrogen bond strength Δδo_H of the chelate molecule was used to measure the bond strength. It was found that the partition coefficient of lithium extracted by the chelating agent increased with the increment of Δδ_OH / pk_a of the molecule.