一种非对称双尾阳离子表面活性剂的合成及表面活性

Synthesis and Surface Activity of an Asymmetric Twin-tailed Cationic Surfactant

以N,N-二甲基丙二胺、1-溴-十四烷、辛酸等为原料,通过酰化和季铵化反应合成了3个非对称双尾阳离子表面活性剂,用IR和1HNMR表征了中间体和目标产物。酰胺化反应的最佳条件为:投料比n(正辛酸)∶n(N,N-二甲基丙二胺)=1∶1.1,反应温度为120℃,反应时间为10 h。目标产物的最低表面张力(γCMC)均在20～30mN/m,临界胶束浓度(CMC)均在10-5～10-6 mol/L,γCMC和CMC均远低于结构类似单尾表面活性剂的γCMC和CMC。双尾阳离子表面活性剂的泡沫半衰期(T1/2)为22～31 min,泡沫稳定性强于单尾表面活性剂。

A kind of asymmetric twin-tailed cationic surfactant has been synthesized by acylation and quaternization using N, N-dimethyl propyl diamine, bromote-tradecane and carboxylic acid as the starting materials. The structures of the intermediate products and the title product were characterized by means of IR and l HNMR. The optimum conditions for acylation were as follows ： n （ caprylic acid） ： n（N,N-dimethyl propyl diamine） = 1：1.1 ,temperature of oil bath was 120 ℃ and reaction time was 10 h. The surface tension could decrease to 20 -30 mN/m and the critical micelle concentration （CMC） was found to be 10-5 - 10-6 moL/L, which were all far lower than those of the corresponding traditional quaternary ammonium salt. The foam half time was 22 - 31 rain. The foam of the asymmetric twin-tailed cationic surfactants was more steady than that of the traditional quaternary ammonium salt.