The effect of carbonyl carbon atom replacement in acetone molecule (ACN) by sulfur atom (DMSO): Part II. Thermodynamic functions of complex formation of crown ethers with Na+ in mixed solvents
作者:Małgorzata Jóźwiak、Adam Bald、Andrzej Jóźwiak
DOI:10.1007/s10973-009-0015-6
日期:2010.1
The thermodynamic functions of complex formation of benzo-15-crown-5 ether (B15C5) and sodium cation (Na+) in acetone–water mixtures at 298.15 K have been calculated. The equilibrium constants of B15C5/Na+ complex formation have been determined by conductivity measurements. The enthalpic effect of complex formation has been measured by the calorimetric method. The complexes are enthalpy-stabilized but entropy-destabilized in acetone–water mixtures. The effects of hydrophobic hydration, preferential solvation of B15C5 by a molecule of water and acetone, respectively and the solvation of Na+ on the complex formation processes have been discussed. The calculated thermodynamic functions of B15C5/Na+ complex formation and the effect of benzene ring on the complex formation have been compared with analogous data obtained in dimethylsulfoxide–water mixtures. The effect of carbonyl atom replacement in acetone molecule by sulphur atom (DMSO molecule) on the thermodynamic functions of complex formation has been analysed.
计算了在 298.15 K 温度下丙酮-水混合物中苯并-15-冠醚(B15C5)和钠离子(Na+)形成络合物的热力学函数。通过电导测量确定了 B15C5/Na+ 复合物形成的平衡常数。通过量热法测量了络合物形成的焓效应。在丙酮-水混合物中,络合物是焓稳定的,但却是熵不稳定的。讨论了疏水合作用、B15C5 分别被一分子水和丙酮优先溶解以及 Na+ 的溶解对络合物形成过程的影响。将计算得出的 B15C5/Na+ 复合物形成的热力学函数以及苯环对复合物形成的影响与在二甲基亚砜-水混合物中获得的类似数据进行了比较。还分析了丙酮分子中的羰基原子被硫原子(二甲基亚砜分子)取代对络合物形成热力学函数的影响。