The Hydrolysis of Hydroxamic Acid Complexants in the Presence of Non-oxidizing Metal Ions 1: Ferric Ions
The Hydrolysis of Hydroxamic Acid Complexants in the Presence of Non-oxidizing Metal Ions 1: Ferric Ions
复制标题
非氧化性金属离子存在下异羟肟酸络合剂的水解 1：铁离子
DOI：
10.1007/s10953-007-9183-9
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发表时间：
2007
影响因子：
1.2
通讯作者：
R. Taylor
中科院分区：
文献类型：
--
作者：
Fabrice P. L. Andrieux;C. Boxall;R. Taylor
摘要
异羟肟酸（XHAs）是一种对Fe ~（3+）、Np ~（4+）和Pu ~（4+）等阳离子具有亲合力的有机化合物，在核燃料后处理中被认为是一种有用的试剂。游离XHA的酸催化水解是众所周知的，并且可能对再处理应用产生负面影响。金属离子-XHA络合物中金属结合的XHA的水解了解较少。借助形态图，我们模拟了紫外-可见分光光度法研究乙酰异羟肟酸（AHA）的酸催化水解结合模型离子Fe（III）。这些研究得到了Fe（AHA）2+络合物中AHA在293 K下水解的以下信息：（i）在速率控制步骤中，[H+]的级数m=0.97，与游离配体的级数相同，表明机理相似;以及（ii）动力学速率参数k1=1.02×10−4 dm 3·mol−1·s−1，大于游离配体的动力学速率参数k 0 =1.84×10−5 dm 3·mol−1·s−1（pH>-0.5），这一结果与Hammett分析的结果一致。
Abstract
Hydroxamic acids (XHAs) are organic compounds with affinities for cations such as Fe3+, Np4+ and Pu4+ and have been identified as useful reagents in nuclear fuel reprocessing. Acid catalyzed hydrolysis of free XHAs is well known and may impact negatively on reprocessing applications. The hydrolysis of metal-bound XHAs within metal ion-XHA complexes is less understood. With the aid of speciation diagrams, we have modelled UV-visible spectrophotometric kinetic studies of the acid-catalyzed hydrolysis of acetohydroxamic acid (AHA) bound to the model ion Fe(III). These studies have yielded the following information for the hydrolysis of AHA in the Fe(AHA)2+ complex at 293 K: (i) the order with respect to [H+] during the rate determining step, m=0.97, is the same as for the free ligand, indicating a similarity of mechanisms; and (ii) the kinetic rate parameter, k1=1.02×10−4 dm3⋅mol−1⋅s−1, is greater than that for the free ligand, k0=1.84×10−5 dm3⋅mol−1⋅s−1 for pH>−0.5, a result that is consistent with a Hammett analysis of the system.