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在25℃及0.10M NaClO_4存在下,用pH法测定了N-环己烷胺基乙酸(CyG)在水中和在30％(体积)乙醇溶液中的表观离解常数,及其与铜(Ⅱ)和镍(Ⅱ)在相同条件下的生成常数.实验结果表明CyG的碱性较氨基乙酸(G)为强,是因诱导效应所致;而其酸性较G为弱,当系溶剂化能量改变的结果.CyG的碱性大于N-苯胺基乙酸(φG)的碱性约十万倍,是由于后者分子中存在共轭效应之故.CyG与Cu(Ⅱ)和Ni(Ⅱ)生成的络合物,其稳定性小于G的相应络合物的稳定性,这是因为前者存在位阻效应;而CyG络合物的稳定性大于φG的相应络合物的稳定性,则是由于配位体的碱性强度起决定作用.溶剂的介电常数对络合物稳定性的影响在此亦有所表现.
The apparent dissociation constants of N-cyclohexanecarboxylic acid (CyG) in water and in 30% ethanol solution were determined by pH method at 25 ℃ and 0.10M NaClO_4, ) And nickel (Ⅱ) under the same conditions.The experimental results show that the basicity of CyG is stronger than that of aminoacetic acid (G), which is due to the induction effect, while its acidity is weaker than that of G, and when the solvating energy The results show that the basicity of CyG is about 100,000 times higher than that of N-phenylalanine acetic acid (φG), which is due to the conjugate effect of CyG with Cu (Ⅱ) and Ni (Ⅱ) , Which is less stable than the corresponding complex of G due to the steric hindrance of the former, whereas the stability of the CyG complex is greater than the stability of the corresponding complex of [Phi] G due to The basic strength of the ligand plays a decisive role, and the effect of the dielectric constant of the solvent on the stability of the complex is also demonstrated here.