L-丝氨酸在正丙醇-水混合溶剂中的体积性质

Volumetric Properties of L-Serine in n-propanol-Water Mixed Solvents at 298.15 K

应用精密数字密度计测定了298.15K时不同组成的L-丝氨酸-正丙醇-水体系的密度,计算丝氨酸的表观摩尔体积、极限偏摩尔体积、迁移偏摩尔体积和水化数.根据结构水合作用模型讨论了迁移偏摩尔体积和水化数的变化规律.结果表明,丝氨酸两性离子部分和亲水侧链与正丙醇羟基间的相互作用对其迁移体积有正贡献,且占主导地位.丝氨酸在正丙醇-水混合溶剂中的迁移偏摩尔体积为正值,且随醇浓度的增大而增大.丝氨酸在正丙醇-水混合溶剂中的水化数随溶液中醇浓度的增加而减小.

Densities of L-serine-n-propanol-water ternary solutions have been measured at 298.15 K by an oscillating-tube densimeter. Apparent molar volumes, limiting partial molar volumes, transfer partial molar volumes and hydration numbers for L-serine have been calculated. The transfer volumes from water to n-propanolwater mixtures and hydration numbers have been discussed in terms of the structural hydration interaction model. The results show that a dominant interaction between -OH group of n-propanol and the zwitterionic group of serine gives positive contribution to the transfer volume. The transfer volumes of serine from water to n-propanolwater mixed solvents are positive, and increase with increasing n-propanol concentration, while the hydration numbers decrease with increasing n-propanol concentration.