Acid-catalyzed interfacial complexation in the extraction kinetics of palladium(II) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol
Acid-catalyzed interfacial complexation in the extraction kinetics of palladium(II) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol
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钯(II)与2-(5-溴-2-吡啶基偶氮)-5-二乙氨基苯酚萃取动力学中的酸催化界面络合
DOI：
10.1016/s0003-2670(98)00167-6
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发表时间：
1998
影响因子：
6.2
通讯作者：
H. Watarai
中科院分区：
文献类型：
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作者：
A. Ohashi;S. Tsukahara;H. Watarai
采用高速搅拌法研究了甲苯中2-(5-溴-2-吡啶基)-5-二乙氨基苯酚(5-Br-PADAP)在酸性水溶液中萃取钯(II)的动力学机理，并采用停流法研究了水相中的络合动力学。 pH<3 时萃取的速率决定步骤是 Pd(II) 配合物、PdCl(n−2)−n(n=2–4) 和吸附在界面上的质子化 5-Br-PADAP 之间的络合。界面络合的速率常数与水相中的速率常数相同的数量级。 pH 值降低导致质子化 5-Br-PADAP 界面浓度增加，从而加快提取速率。酸催化的界面反应揭示了5-Br-PADAP的优越性能；在pH<2的酸性条件下，它可以通过二乙氨基的质子化而吸附在界面上，但由于其吡啶基没有质子化，因此不会失去与金属离子的反应活性。
The extraction kinetic mechanism of palladium(II) in acidic aqueous solution with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) in toluene was investigated by the high-speed stirring method, along with the complexation kinetics in the aqueous phase by the stopped-flow method. The rate-determining step in the extraction at pH<3 was the complexation between the Pd(II) complexes, PdCl(n−2)−n(n=2–4), and the protonated 5-Br-PADAP adsorbed at the interface. The rate constants at the interfacial complexation were the same order of magnitude as those in the aqueous phase. The extraction rate was accelerated by a decrease in pH causing an increase in the interfacial concentration of the protonated 5-Br-PADAP. The acid-catalyzed interfacial reaction revealed the advantageous property of 5-Br-PADAP; it could be adsorbed at the interface by protonation at the diethylamino group under the acidic condition of pH<2, but did not lose reactivity to the metal ion since its pyridyl group was not protonated.
H.Watarai：“Ni(II) 与 2-(5-bromo-2-pyridylazo)-5-diethaminophen 萃取动力学的界面机制以及配体界面反应性的分子动力学模拟” Bull.Chem.Soc.Jpn
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