| 链酚胺型N3O配体合成及其Zn(Ⅱ)配合物催化对-硝基苯酚乙酸酯水解研究 |
| Hydrolysis of p-Nitrophenyl Acetate Promoted by Zn(Ⅱ) Complexes of a Linear N3O Amine Phenol Ligand |
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| 摘要: 合成了链酚胺型N3O配体N-(2-羟基苄基)-二乙烯三胺(HL),用元素分析,IR和1H NMR等手段进行了表征。用pH电位滴定法,在25±0.1℃,I=0.10(KNO3)条件下,研究了该配体质子化及其与Zn(Ⅱ)离子配位热力学。在25±0.1℃,I=0.10(KNO3),pH=7～9(50mmol·L-1缓冲溶液)范围内,通过分光光度法测定了配合物催化对硝基苯酚乙酸酯(NA)水解动力学,得到了NA催化水解二级反应速率常数kc。结果表明:Zn(Ⅱ)离子与配体的氨基和酚羟基配位之后,还与一个水分子配位。配位酚羟基和水分子的离解常数pKa值分别为5.22和9.47。在中性pH值可以产生亲核试剂Zn(Ⅱ)…-OH,对NA水解有较好的催化效果,pH=9.0时,kc=3.2×10-2mol-1·L-1·s-1。 |
| 关键词: 酚胺型配体 平衡常数 催化动力学 Zn(Ⅱ)配合物 |
| 基金项目: 国家自然科学基金(No.29773041) |
| Abstract: Tetradentate linear ligand N-(2-hydroxybenzyl) diethylenetriamine (HL) was synthesized and characterized by elemental analysis, IRand 1H NMR. By pH potentiometric titration at 25± 0.1℃ and I=0.1(KNO3), protonation constants of the ligand and equilibria constants of Zn(Ⅱ) complexation with the ligand have been determined. Modes of coordination were discussed, and the dissociation constant for the phenoxyl and water in the complexes were obtained. The kinetics of p nitrophenyl acetate (NA) hydrolysis catalyzed by the complexes was determined spectrophotometrically at 25± 0.1℃ and I =0.1(KNO3) in 10% (V/V) CH3CN at pH7.0～ 9.0 (50m mol· L-1 buffers), and the second rate constants kc for NA hydrolysis were obtained. The experimental results indicate that the ligand coordinate with Zn(Ⅱ) yielding five coordinated complex with three amino groups, one phenoxyl, and an additional water coordinated. And the pKa values for the phenoxyl and the water are 5.22 and 9.47 respectively. Therefore the complexes can yield nucleophile Zn(Ⅱ)…-OH, and this have good catalytic effect on NA ester hydrolysis with a kc value of 3.2× 10-2 mol·L-1·s-1 at pH9.0. |
| Keywords: amine phenol ligands equilibria constants catalytic kinetics Zn(Ⅱ) complexes |
| 投稿时间：1999-11-11 修订日期：2000-01-04 |
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| 解永树,林瑞森,刘清亮.链酚胺型N3O配体合成及其Zn(Ⅱ)配合物催化对-硝基苯酚乙酸酯水解研究[J].无机化学学报,2000,16(4):597-602. |
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