Interaction of boric acid with salicyl derivatives as an anchor group of boron-selective adsorbents
Interaction of boric acid with salicyl derivatives as an anchor group of boron-selective adsorbents
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DOI：
10.1016/j.poly.2008.06.007
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发表时间：
2008-09-10
期刊：
影响因子：
2.6
通讯作者：
Yoshimura, Kazuhisa
中科院分区：
文献类型：
--
作者：
Miyazaki, Yoshinobu;Matsuo, Hidenobu;Yoshimura, Kazuhisa
采用B-11核磁共振技术详细研究了硼酸与水杨酸、水杨醇及双（羟甲基）酚衍生物的络合反应。硼酸通过配体的亲核攻击接受电子对，随后发生缩合反应，形成1:1的单螯合络合物。然后单螯合物与配体通过缩合反应反应生成1:2的双螯合物。在所研究的水杨基衍生物中，双（羟甲基）苯酚衍生物形成了相当稳定的螯合配合物。分子模拟计算表明，从焓的角度来看，与双（羟甲基）苯酚衍生物的络合是非常有利的。以3,5-二（羟甲基）-4-羟基苯甲酸酯为预吸附剂的阴离子交换树脂在较宽的pH范围内对硼具有较强的吸附能力。吸附剂定量地去除了负载配体中约一半量的硼，这表明吸附在树脂上的硼主要以-3带电1:2双螯合物的形式存在。与3,5-二（羟甲基）-4-羟基苯甲酸酯的1:2双螯合物在树脂相中的形成常数估计为log (beta) / bar (f(BLAc2)) = 5.0，与水杨醇衍生物在水溶液中的形成常数基本一致。(C) 2008 Elsevier Ltd版权所有。
The complexation ofboricacid with salicylic acid, salicyl alcohol and bis(hydroxymethyl)phenol derivatives has been investigated in detail using B-11 NMR spectroscopy. Boric acid accepts an electron pair through the nucleophilic attack of the ligand, followed by a condensation reaction, to form the 1: 1 monochelate complex. The monochelate complex then reacts with the ligand through the condensation reaction to give the 1:2 bischelate complex. Bis(hydroxymethyl)phenol derivatives formed quite stable chelate complexes among the examined salicyl derivatives. it was clarified by molecular modeling calculations that the complexation with bis(hydroxymethyl)phenol derivatives was highly favorable from an enthalpy viewpoint. An anion-exchange resin presorbed with 3,5-bis(hydroxymethyl)-4-hydroxybenzoate had a strong adsorbability of boron over a wide pH range. The adsorbent quantitatively removed boron up to approximately a half amount of the loaded ligand, which indicated that the boron species adsorbed onto the resin was predominantly present as the -3 charged 1:2 bischelate complex. The formation constant of the 1:2 bischelate complex with 3,5-bis(hydroxymethyl)-4-hydroxybenzoate in the resin phase was estimated to be log (beta) over bar (f(BLAc2)) = 5.0, which almost agreed with those of the salicyl alcohol derivatives in aqueous solutions. (C) 2008 Elsevier Ltd. All rights reserved.