对-烷基-苄基聚氧乙烯醚羧酸甜菜碱的合成与表面活性

Synthesis and Surface Properties of p-(n-alkyl)-benzyl Polyoxyethylene ether Carboxybetaine

摘要:

以脂肪酸、苯、二缩三乙二醇为原料，经酰化反应、黄鸣龙还原反应、氯甲基化反应、威廉逊成醚反应、卤化反应、季铵化反应等步骤，合成出了3种对-烷基-苄基聚氧乙烯醚羧酸甜菜碱两性离子表面活性剂。用IR、1HNMR和ESI-MS对产物进行了结构鉴定。用Wilhelmy-plate法测定了30℃时它们在水溶液中的临界胶束浓度（CMC）和临界胶束浓度下的表面张力（γCMC）。实验表明，纯水溶液中表面活性剂的临界胶束浓度 (CMC) 为10–4 ~10–6mol/L，临界胶束浓度下的表面张力 γCMC) 为27~30 mN/m；随着苯环上长链烷基碳数（n=8、10、12）的增加，CMC分别为1.12×10-4、1.51×10-5、6.21×10-6 mol/L；γCMC分别为27.9、28.4、29.9mN/m。结果表明，此类表面活性剂具有比较好的表面活性。

Abstract:

Three novel surfactants, p-(n-alkyl)-benzyl Polyoxyethylene ether Carboxybetaine ,were synthesized from fatty acid ,benzene and Triethylene Glycol through Friedel-Crafts acylation, Huang-Minlon reduction, chloromethylation, Williamson reaction, halogenation and quaterisation reaction. The structures of the products were characterized by IR, 1HNMR and ESI-MS methods. The critical micelle concentration (CMC) and the surface tension at the CMC (γCMC) of the surfactants in aqueous solution at 30℃ were measured by means of the Wilhelmy-plate method. The results showed that the values of CMC (mol/L) reached to the order of magnitude of 10–4~10-6 and the values of γCMC were 27-30mN/m. The CMC (respectively 1.12×10-4、1.51×10-5、6.21×10-6 mol/L) was observed to decrease, as the change of carbon atom number (n=8,10,12) of the substituted hydrophobic chain of benzene ring, however, γCMC(respectively 27.9，28.4，29.9 mN/m) increased as the number of carbon atoms increases. The experiment results showed that these surfactants have high surface activities.