磷钨酸催化合成尼龙酸二正辛酯

Esterification of Nylon Acid with n-Octanol Catalyzed by Phosphotungstic Acid

以钨酸钠和磷酸氧二钠为原料,采用盐酸酸化-乙醚萃取法制备了 Keggin 型磷钨酸催化剂;以尼龙酸和正辛醇为原料、Keggin 型磷钨酸为催化剂、甲苯为带水剂,合成了尼龙酸二正辛酯。由均匀设计实验考察了 n(正辛酶):n(尼龙酸)、反应时间、带水剂用最和催化剂用量对酯化率的影响,采用二次回归模型分析均匀设计实验结果,并经单因素实验优化得到的最佳工艺条件为:n(正辛醇):n(尼龙酸)=2.8,甲苯相对于尼龙酸的质量分数为75%,催化剂相对于尼龙酸的质量分数为1.2%,反应时间3 h。在此条件下,酯化率达99.18%。该反应体系具有环境友好、催化剂用量少、反应条件温和、酯化率高、后处理简单等优点。

Phosphotungstic acid with Keggin structure was prepared from sodium tungstate and disodium hydrogen phosphate by acidification-aether extraction method and used as catalyst in synthesis of di-n-octyl nylon acid ester from nylon acid （mixed biatomic acids including butanedioic acid 26.48%, pentane diacid 62.50% and hexane diacid 11.02% ） and n-octanol, using toluene as water entrainer. Effects of mole ratio of n-octanol to nylon acid, reaction time, entrainer dosage and catalyst dosage on the esterification were studied by homogeneous design. Quadratic regression analysis was adopted to process the results of the experiments. The reaction conditions optimized by single-factor experiment were ： n （n-octanol） ： n （nylon acid） 2.8, entrainer mass fraction 75% based on mass of nylon acid, catalyst mass fraction 1.2 % based on mass of nylon acid and reaction time 3 h. Under the optimized conditions, esterification yield reached 99. 18%. The esterification process catalyzed by phosphotungstic acid is proved to be mild and environment-friendly with small catalyst dosage and high product yield. The after-treatment of product is simple.