氨基酸在氯乙醇水溶液中的体积性质

利用精密数字密度计测定了甘氨酸、L-丙氨酸和L-丝氨酸在不同质量分数的氯乙醇水溶液中的密度，计算了这些氨基酸在氯乙醇水溶液中的表观摩尔体积、极限偏摩尔体积、迁移偏摩尔体积、理论水化数和体积作用系数，讨论了迁移偏摩尔体积和理论水化数的变化规律. 结果表明，三种氨基酸在氯乙醇水溶液中的迁移偏摩尔体积均为正值, 且随氯乙醇浓度的增大而增大. 氨基酸侧链对迁移偏摩尔体积的贡献与侧链性质密切相关. 三种氨基酸在氯乙醇水溶液中的理论水化数均随溶液中氯乙醇浓度的增加而减小. 甘氨酸与氯乙醇分子间的相互作用主要以1 : 1和1 : 2形式为主， L-丙氨酸和L-丝氨酸与氯乙醇分子间的相互作用主要以1 : 1形式为主.

Volumetric Properties of Amino Acids in 2-chloroethanol-Water Mixed Solvents

Densities of glycine, L alanine and L serine in 2 chloroethanol water mixed solvents have been measured at 298.15 K by an oscillating tube densimeter. Apparent molar volumes, limiting partial molar volumes, transfer partial volumes, hydration numbers and volumetric interaction coefficients for these amino acids have been calculated. The results show that all of the transfer partial volumes from water to 2 chloroethanol water mixed solvents are positive, and increase with increasing 2 chloroethanol concentration; all the hydration numbers decrease with increasing 2 chloroethanol concentration. From the results of the volumetric interaction coefficients, it is concluded that interaction between glycine and 2 chloroethanol is dominated by 1 :1 and 1 :2 forms, and interactions between alanine, serine and 2 chloroethanol molecule are dominated by 1:1 form.