Boronic acid-facilitated α-hydroxy-carboxylate anion transfer at liquid/liquid electrode systems: the EICrev mechanism
Boronic acid-facilitated α-hydroxy-carboxylate anion transfer at liquid/liquid electrode systems: the EICrev mechanism
复制标题
硼酸促进液/液电极系统中的 α-羟基羧酸根阴离子转移：EICrev 机制
DOI：
10.1007/s10008-008-0709-x
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发表时间：
2009
影响因子：
2.5
通讯作者：
F. Marken
中科院分区：
文献类型：
--
作者：
Najoua Katif;R. A. Harries;A. Kelly;J. Fossey;T. James;F. Marken
在三相界面电极体系中，研究了乙醇酸、乳酸、扁桃酸和葡萄糖酸的α-羟基羧酸盐从水电解质相中向有机相4-（3-苯丙基）-吡啶（PPP）的转移.四苯基卟啉配合物MnTPP溶解在PPP中驱动阴离子转移反应，萘-2-硼酸（NBA）被用作促进剂。在不存在促进剂的情况下，α-羟基-羧酸盐转移到有机相中的能力提高，与疏水性考虑一致，得到葡萄糖酸盐>乙醇酸盐>乳酸盐>扁桃酸盐的相对转移电位（对于0.1 M水溶液）。在NBA的存在下，可逆转移电位向更负的值的偏移表明快速可逆结合（电极过程的机制是EICrev），并且结合常数被确定为K乙醇酸盐= 2 M−1，K扁桃酸盐= 60 M−1，K乳酸盐= 130 M−1和K葡萄糖酸盐= 2，000 M−1。基于葡萄糖酸盐阴离子和NBA之间的次级相互作用，葡萄糖酸盐的令人惊讶的强相互作用是合理的。
The transfer of the α-hydroxy-carboxylates of glycolic, lactic, mandelic and gluconic acid from the aqueous electrolyte phase into an organic 4-(3-phenylpropyl)-pyridine (PPP) phase is studied at a triple-phase boundary electrode system. The tetraphenylporphyrinato complex MnTPP dissolved in PPP is employed to drive the anion transfer reaction and naphthalene-2-boronic acid (NBA) is employed as a facilitator. In the absence of a facilitator, the ability of α-hydroxy-carboxylates to transfer into the organic phase improves, consistent with hydrophobicity considerations giving relative transfer potentials (for aqueous 0.1 M solution) of gluconate>glycolate>lactate>mandelate. In the presence of NBA, a shift of the reversible transfer potential to more negative values is indicating fast reversible binding (the mechanism for the electrode process is EICrev) and the binding constants are determined as Kglycolate = 2 M−1, Kmandelate = 60 M−1, Klactate = 130 M−1 and Kgluconate = 2,000 M−1. The surprisingly strong interaction for gluconate is rationalised based on secondary interactions between the gluconate anion and NBA.