正丁醇在N,N-二甲基甲酰胺+水溶液中的体积性质

Volumetric Properties of 1-Butanol in N,N-Dimethylformamide+Water Mixed Solvents

测定了 2 98.1 5K时正丁醇 +N ,N -二甲基甲酰胺 ( DMF) +水三元系的密度 .求出正丁醇在 DMF+水混合溶剂中的表观摩尔体积 .观察到 :( 1 ) Φ0 ,E2 ～ fm 与 VEDMF～ fm 之间存在相似变化关系 ,其中 Φ0 ,E2 为正丁醇的过量无限稀释表观摩尔体积 ,VEDMF为 DMF+水二元系中 DMF的过量偏摩尔体积 ,fm 为混合溶剂中DMF的摩尔分数 .( 2 ) B1 ～fm 与 Φ0 ,E2 ～ fm 之间存在反向变化关系 .B1 为体积第二维里系数 .这些关系反映了溶质的溶剂化对溶质间相互作用的影响 .溶质的疏水水化越强 ,溶剂化溶质之间的“同分子对”相互作用就越弱 .利用定标粒子理论 ,讨论了空腔体积和相互作用体积对Φ02 ～ fm,B1 ～ fm

Densities of ternary mixture (1-butanol+N,N-dimethylformamide+water) at 298.15 K have been measured. The apparent molar volumes of 1-butanol in DMF+water mixed solvents have been evaluated from density data. A similar feature between Φ 0,E 2～f m and VE DMF ～f m curves, and opposite feature between B 1 ～f m and Φ 0,E 2 ～f m curves have been observed, where Φ 0,E 2 is the excess apparent molar volume of 1butanol at infinite dilution, VE DMF is the excess partial molar volume of DMF in DMF+water binary mixture, B 1 is the second volumetric virial coefficients and f m is the mole fraction of DMF in DMF+water mixed solvents. These relationships reflec the interplay between solute solvation and solutesolute interactions. For hydrophobic solutes such as 1butanol, the stronger the solute was hydrated, the weaker the solutesolute interactions become. By using the special particle theory, the effect of cavity volume and interaction volume on the features of B 1 ～f m and Φ0 2 ～f m curves have been discussed.