University of Ljubljana, Faculty of Chemistry and Chemical Technology, Aškerčeva 5, SI-1000 Ljubljana, Slovenia.
Phys Chem Chem Phys. 2012 May 21;14(19):6805-11. doi: 10.1039/c2cp40571g. Epub 2012 Apr 10.
Enthalpies of mixing of aliphatic 3,3 and 6,6-ionene fluorides with low molecular weight salts (sodium formate, acetate, nitrate, chlorate(v), and thiocyanate), all dissolved in water, were determined. In addition, to complement our previous study (Lukšičet al., Phys. Chem. Chem. Phys., 2012, 14, 2024), new measurements were performed where aqueous solutions of 3,3 and 6,6-ionene bromides were mixed with solutions of sodium fluoride, chloride, bromide, and iodide. Electrostatic theory, based on Manning's limiting law or the Poisson-Boltzmann equation, predicted the enthalpy of mixing to be endothermic in all the cases, while experiments showed that this is not always true. When an aqueous solution of 3,3-ionene fluoride was mixed with a solution of sodium fluoride (or formate and acetate) in water, the effect was indeed endothermic. For all other salts, i.e. sodium chlorate, nitrate, and thiocyanate, heat was released upon mixing. The situation was similar for 6,6-ionene fluoride solutions with an exception of mixing with sodium chlorate, where the effect was endothermic. The enthalpy of mixing was strongly correlated with the enthalpy of hydration of the counterion of the low molecular weight salt. A lyotropic series, similar to that of Hofmeister, was obtained. To examine also the effect of co-ions, ionene bromides were titrated with tetramethyl-, tetraethyl-, or tetrapropylammonium bromides. The enthalpy was exothermic for all mixtures while, somewhat unexpectedly, the co-ion specific effect was quite strong.
测定了脂肪族 3,3 和 6,6-二烯丙基芐氟化物与低分子量盐（甲酸钠、乙酸盐、硝酸盐、氯酸盐(v)和硫氰酸盐）在水中混合的混合焓。此外，为了补充我们之前的研究（Lukšičet al.，Phys. Chem. Chem. Phys.，2012，14，2024），还进行了新的测量，其中将 3,3 和 6,6-二烯丙基芐溴化物的水溶液与氟化钠、氯化物、溴化物和碘化物的溶液混合。基于 Manning 极限定律或泊松-玻尔兹曼方程的静电理论预测混合焓在所有情况下都是吸热的，而实验表明情况并非总是如此。当 3,3-二烯丙基芐氟化物的水溶液与氟化钠（或甲酸钠和乙酸盐）在水中混合时，效果确实是吸热的。对于所有其他盐，即氯酸钠、硝酸盐和硫氰酸盐，混合时会释放热量。6,6-二烯丙基芐氟化物溶液的情况类似，但与氯酸钠混合时效果是吸热的。混合焓与低分子量盐的抗衡离子的水合焓强烈相关。得到了类似于 Hofmeister 的溶致系列。为了检验同离子的影响，还滴定了溴化芐盐与四甲基、四乙基或四丙基溴化铵。所有混合物的焓都是放热的，而有些出人意料的是，同离子的特定效应相当强。
