【摘要】 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-（C₆H₅N=N）-C₁₀H₆,它的Pk_a值较小,q_N适中,所以协萃能力最大。相反,1-（C₆H₅N=N）-8-OH-C₁₀H₆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。更多还原

【Abstract】 The synergistic extraction of lithium with a solution of ο-phenylazophenols（HAX） and trioctylphosphine oxide （TOPO） or other trialkylphosphine oxide（TRPO, R=C₈～10） inο-dichlorobenzene from aqueous solution of lithium hydroxide was reported. The structural effect ofο-phenylazophenols on extraction of lithium has been examined. Theο-phenylazophenols studied were divided into two groups:（1）1-（p-X-phenylazo）-2-naphthol （X=H, CH₃, Bu, OH₃O）; （2）2-phenylazo-1-naphthol （1）;1-phenylazo-2-naphthol （2）, 3-phenylazo-2-naphthol（3）,8-phenylazo-1-naphthol（4） , 1-phenylazo-2-anthrol（5）,9-phenylazo-10-phenanthrol（6）and 2-phenylazo-4-methyl-1-phenol （7）.In the case of 1-（p-X-phenylazo）-2-naphthols, the HMO calculation shows that the charge density of azo nitrogen atom （the donor atom, denote azo N） and hydroxyl oxygen atom does not vary apparently, so that the stability of their chelates with lithium has no obvious variations as well. In this case their ability to extract lithium is chiefly governed by the pK_a of the compound. The results of extraction prove that there is a linear correlation between the extraction constant K_ex and pK_a.However, for the second group of chelating agents, the change of their structure leads to the change of both pK_a and stability of chelates. The results of extraction and HMO calculation show that the stability of chelates is mainly influenced by the strength of the coordination bond, i.e. the larger the charge density of azo N（q_N） , the more stable the chelate will be. Therefore, their ability to extract lithium is roughly directly proportional to the stability of chelates and inversely to the pK_a For example, compound 1 possesses the lowest pK_a and midium q_N values, so that it has the highest extraction ability. Compound 4 has the smallest q_N, midium pK_a, values and the lowest extraction ability.The strength of coordination bond for the chelates can be experimentally measured by means of the strength of intramolecular hydrogen bond of chelating agent, △б_OH （the difference of chemical shift of hydroxyl proton in free and bonded state）. Therefore, the ratio, △б_OH/pK_a, can be used to evaluate the extraction ability of chelating agents to lithium. We find that it is approximately proportional to the distribution ratio （D） （see Table 4 in. the Chinese Text）.更多还原