月桂酸酯季铵盐阳离子表面活性剂的合成与表征

以十二烷基二甲基叔胺、环氧氯丙烷为原料,合成了中间体DMAC〔(2,3-环氧丙基)十二烷基二甲基氯化铵〕,再与月桂酸反应,生成月桂酸酯季铵盐阳离子表面活性剂HDAC〔(2-羟基-3-月桂酰氧基丙基)十二烷基二甲基氯化铵〕。通过正交实验确定了最佳合成条件:以异丙醇为溶剂,n(DMAC)∶n(LAC)=1∶1.2,反应时间6 h,反应温度50℃,产率大于90%,Krafft点-4.52℃。通过元素分析、傅立叶变换红外光谱、飞行时间质谱(TOF-MS)、1HNMR,确证了目的产物的结构。测定产物的临界胶束浓度CMC为8.91×10-4mol/L,γCMC为34.12 mN/m。表明所合成的月桂酸酯季铵盐阳离子表面活性剂具有较高的表面活性。

Synthesis and Characterization of Quaternary Ammonium Salt Cationic Surfactant with Dilaurate Groups

(2,3-Epoxypropyl)dimethyl-ammonium chloride(DMAC) was synthesized with N,N-dimethyl dodecylamine and epichlorohydrin as raw material in this article.Secondly,(2-hydroxy-3-lauryl acyloxypropyl)dodecyl dimethyl ammonium chloride(HDAC) was prepared by the DMAC with laurie acid.Through the orthogonal experiment,the optimal preparation condition was investigated:using isopropanol as the solvent,n(DMAC)∶n(LAC) was 1∶1.2,reaction time was 6 h,reaction temperature 50 ℃,the yield was higher than 90% and Krafft point was-4.52 ℃.The structure of HDAC was characterized by elementary analysis,FTIR spectrum,time-of-flight mass spectrometry and 1HNMR.The surface activities of the product were measured;their surface tension was 34.12 mN/m,critical micelle concentration(CMC) 8.91×10-4 mol/L.The results showed that quaternary ammonium salt cationic surfactants with dilaurate groups exhibited a higher surface activity.