pH值对苯甲酸类正辛醇／水分配系数的影响

苯甲酸类化合物是自然水体中的常见有机污染物,属于有机酸。为了考察水相的pH值对该类化合物正辛醇／水分配系数的影响,采用摇瓶法测定了苯甲酸、邻氯基苯甲酸、间硝基苯甲酸和对甲基苯甲酸在不同pH值下的正辛醇／水分配系数,测定结果表明,4种化合物的正辛醇／水分配系数随pH值的升高而降低,且pH值在3～5范围内变化显著。     

2,4-二氯苯酚在水中溶解度的测定及关联

在pH值为6.2或9.3条件下,采用综合法测定了2,4-二氯苯酚在水中的固液平衡数据,分别用经验方程、W ilson方程、固液平衡λH方程对实验数据进行了拟合处理。结果说明,在pH值为9.3条件下,2,4-二氯苯酚的水溶解度增大;W ilson方程、λH方程模型均能很好地关联2,4-二氯苯酚的水溶解度数据,pH=9.3时平均相对误差分别为3.00%,1.17%,其中λH方程拟合效果更好。     

取代苯甲酸类化合物在正辛醇中的固液平衡

The solid-liquid equilibrium of benzoic acid derivatives in 1-octanol was first determined in this article. Using a laser monitoring observation technique, the solubility data of o-amino-benzoic acid, p-amino-benzoic acid,o-chloro-benzoic acid, and m-nitro-benzoic acid in 1-octanol were measured by the polythermal method in the temperature range of 20-50℃. The experimental data were regressed with the. Wilson equation and the λH equation. The experimental results showed that the solubility of the four chemicals in 1-octanol increased significantly with temperature. The results indicate that the molecular structure and interactions affect the solubility significantly.The solubility order of the benzoic acid derivatives is as follows： m-nitro-benzoic acid〉o-chloro-benzoic acid〉 o-amino-benzoic acid〉p-amino-benzoic acid. Both the Wilson equation and λH equation are in good agreement with the experimental data.