几种有机配体与硫酸亚铁的配合物稳定常数

Stability Constants of Several Organic Ligands and FeSO_4 Coordination Compounds

采用电位滴定法、酸碱中和滴定法及分光光度法,对硫酸亚铁、间苯二酚、没食子酸、葡萄糖醛酸以及HCl和NaOH标准溶液浓度进行标定。在恒定离子强度(I=0.1)条件下,利用pH电位法测定了间苯二酚、没食子酸、葡萄糖醛酸3种配体,在不同温度(10、20、30℃)下的加质子常数及与FeSO4的配合物稳定常数。结果显示:没食子酸加质子常数最大;配体加质子常数及配合物稳定常数,均随温度的升高而降低;3种配体与FeSO4的配位能力差别较大,没食子酸(lgK1=10.72,10℃)>间苯二酚(lgK1=7.28,10℃)>葡萄糖醛酸(lgK1=2.43,10℃)。

The concentrations of FeSO4, resorcinol, gallic acid, glucuronic acid, NaOH standard solution and HCl standard solution were determined by potentiometric titration, acid -base titration and spectrophotometry. The protonation constants of the ligands and the stability constants of coordination compounds formed with FeSO4 were studied by equilibrium pH method at different temperature （10℃, 20℃ ,30℃ ） and constant ionic strength（ I = 0.1 ）. The results show that gallic acid has the highest pro- tonation constants. Protonation constants and stability constants of coordination compounds decrease with increasing temperature. The Coordination capacities with FeSO4 of the three ligands are in big difference, the sequence is as follows： gallic acid（ IgK1 = 10.72, 10℃ ） 〉 resorcin（IgK1 = 7.28, 10℃ ） 〉 glucuronic acid（IgK, = 2.43, 10℃ ）.