THE GLUCONATE COMPLEXES .2. THE FERRIC-GLUCONATE SYSTEM
THE GLUCONATE COMPLEXES .2. THE FERRIC-GLUCONATE SYSTEM
复制标题
DOI：
10.1021/ja01611a025
复制
发表时间：
1955-01-01
影响因子：
15
通讯作者：
SANDERA, J
中科院分区：
文献类型：
--
作者：
PECSOK, RL;SANDERA, J
随着pH值的增加，铁离子和葡萄糖酸形成一系列络合物。通过极谱法、光谱法、pH滴定法和电位测定法对配合物进行了研究。该系列由以下物质组成（HGH4= 葡萄糖酸；酸电离的 pK 值插入公式之间）：HFeGHa" 1"" 1", 4.6（两步），HFeGH，4.0，FeGH-，13.3，FeGH (OH)-。由铁离子和葡萄糖酸离子形成 FeGH- 的平衡常数为 3 X 10-6，涉及 3 个质子，使得该复合物在高 pH 下极其稳定。在知道葡萄糖酸的第二、第三和第四解离常数之前，无法获得复合物的真实稳定常数。提出了与数据兼容的结构。尽管由于同时存在几种铁物质，处理在某些方面是近似的，但这代表了对此类络合物的首次详细研究。Prescott等人1提出了葡萄糖酸铁络合物的稳定性，他们声称在pH大于6的任何溶液中，按重量计算，葡萄糖酸比乙二胺四乙酸更有效。他们进一步指出，葡萄糖酸作为苛性碱中的铁螯合剂是有效的。浓度高达 35%(12 M) 的苏打溶液。最近，Mehltretter 等人 2 比较了多种糖酸的螯合能力，发现葡萄糖酸作为铁螯合剂，在非常高的 pH 值下通常优于除糖酸钠之外的所有其他螯合剂。 Traube 等人将葡萄糖酸铁复合物沉淀为双钙盐。 3 他们提出了公式 [CsHvOiFeJCa，并在对碳、铁和钙的元素分析的基础上，他们提出三个氢离子被取代
Ferric ion and gluconic acid form a series of complexes with increasing pH. The complexes havebeen studied by means of polarography, spectra, pH titration and potentiometry. The series consists of the following species (HGH4= gluconic acid; pK values for the acid ionizations are inserted between formula): HFeGHa" 1"" 1", 4.6 (two step), HFeGH, 4.0, FeGH-, 13.3, FeGH (OH)-. The equilibrium constant for the formation of FeGH-from ferric ion and gluconate ion is 3 X 10-6 and involves 3 protons, making the complex extremely stable at high pH. The true stability constant of the complex cannot be obtained until the second, third and fourth dissociation constants of gluconic acid are known. Structures are proposed which are compatible with the data. Although the treatment is approximate in some respects due to the simultaneous pres-ence of several iron species, this represents the first detailed study of this type of complex.The stability of the glucono-ferric complex has been suggested by Prescott, et al., 1 who claimedthat gluconic acid is more effective on a weight basis than ethylenediaminetetraacetic acid in any solu-tion withpH greater than 6. They further state that gluconic acid is effective as an iron sequestrant in caustic soda solutions up to 35%(12 M) concen-trations. More recently, Mehltretter, et al., 2 have compared the sequestering power of a number of sugar acids, andfound that gluconic acid is gener-ally superior to all others as an iron sequestrant ex-cept for sodium saccharate at very high pH. The glucono-ferric complex was precipitated as a double calcium salt by Traube, et al. 3 They proposed the formula [CsHvOiFeJCa, and on the basis of an ele-mental analysis for carbon, iron and calcium, they suggested that three hydrogen ions are displaced