柠檬酸三酯三季铵盐阳离子表面活性剂的合成

Synthesis of cationic surfactant citric triesters of tri-quaternary ammonium chloride

采用柠檬酸、环氧氯丙烷和十二烷基二甲基叔胺合成三烷基三季铵盐阳离子表面活性剂。得到较佳工艺条件:n(柠檬酸)∶n(十二烷基二甲基叔胺)∶n(环氧氯丙烷)为1∶3∶3,于85℃下反应12 h,得到产率大于90%的目的产物。测定了产物的cmc为3.3×10-4mol/L。研究了反应条件对目的产物产率的影响。结果表明:随反应温度的升高,产率逐渐增加,当升温到一定程度后,产率略有下降;反应12 h后产率基本不再变;十二烷基二甲基叔胺及环氧氯丙烷与柠檬酸的投料比大于3时,对三烷基三季铵盐阳离子表面活性剂产率的增加影响不大;异丙醇溶剂有利于反应产率的提高,但随着溶剂量的增多,反应产率会下降。

Citric triesters of tri - quaternary ammonium chloride （CTTAC） was prepared using citric acid, epoxy chloropropane and dodecyl dimethyl amine as starting materials. The yield of CTTAC is 〉 90 % with conditions of reaction time 12 h, temperature 85 ℃, molar ratio n（citric acid） ： n（dodecyl dimethyl amine） ： n（epoxy chloropropane） 1：3：3. The critical micelle concentration was determined by means of surface tension measurements as 3.3 × 10^-4 mol/L at 25 ℃. The effects of temperature, reaction time and the molar ratio of the reactants on the yield were studied correspondingly. The results showed that the yield of CTTAC increases with the temperature rising up to a maximum and then decreases a little for further temperature rising. Reaction gets to equilibrium as the reaction time reaches 12 h. Increase of molar ratio of dodecyl dimethyl amine or epoxy chloropropane to citric acid has little influence when the molar ratio is above 3. The addition of isopropanol as solvent can increase the yield of CTTAC up to a maximum value and then decreases for further addition of the solvent.