双取代直链烷基苯磺酸钠的合成及其界面活性的研究

Synthesis of Sodium Di-n-alkylbenzenesulfonates and Study of Their Interfacial Activities

为了研究不同结构的双直链烷基苯磺酸钠的分子结构与界面活性之间的关系,以邻二氯苯为原料,经交叉耦合反应、磺化反应和中和反应等步骤,合成了邻二正戊烷基、正己烷基和正庚烷基苯磺酸钠 3种化合物, 3种产物的收率为 55% ~65%,用两相滴定法测定了产物的质量分数,均大于 99. 0%,用核磁共振氢谱和碳谱对产物进行了结构鉴定。用Wilhelmy-Plate法测定了双直链烷基苯磺酸钠NaCl水溶液与正壬烷的界面张力,发现随着疏水链碳数的增加,临界胶束浓度CMC减小,饱和吸附量Γmax先减小后增大,临界胶束浓度下的界面张力γCMC和饱和吸附面积Amin则是先增大后减小。

In order to study correlation between the structure and interfacial activity,o-di-n-pentyl,o-di-n-hexyl,and o-di-n-heptylbenzenesulfonate were synthesized from o-dichlorobenzene through three-step process,including cross-coupling reaction,sulfonation and neutralization.The product yields were 55%～65%.The contents of sodium di-n-alkylbenzenesulfonates in the products were all above 99.0% as determined by two-phase titration.Their structures were identified by ~1HNMR and ^(13)CNMR.The interfacial tension between di-n-alkylbenzenesulfonates in NaCl solution and nonane was tested by Wilhelmy-plate method.It was observed that,with the increase of carbon numbers of the hydrophobic side chains,CMC (the critical micelle concentration) decreased,Γ_(max) (the maximum surface excess concentration) reflected an initial decrease followed by an increase,while γ_(CMC) (the interfacial tension at CMC) and A_(min)(the minimum area per surfactant molecule) increased at first and then decreased.