甲基碳酸酯季铵盐的合成与表征

Synthesis and Characterization of Quaternary Ammonium Salts Methyl Carbonate

摘要:

研究了碳酸二甲酯与长链烷基叔胺的季铵化反应。考察了反应温度、反应时间、物料摩尔比和溶剂用量等反应条件对十二烷基二甲基叔胺季铵化反应的影响，确定了优化条件：反应温度130 ℃、反应时间5 h、n (碳酸二甲酯)︰n (烷基叔胺)=5、甲醇用量（相对于反应原料的质量分数）10%。在此条件下，不同碳链长度的单烷基叔胺的季铵化率均达到98%以上，而双碳十和双碳十八叔胺的转化率较低，分别为88.09%和68.77%。这说明空间位阻是影响季铵化反应进程的重要因素，与分子空间结构模拟的结果一致。通过增加反应时间，双碳十叔胺反应7 h季铵化率为98.85%，双十八烷基甲基叔胺反应12 h季铵化率为95.68%。采用1H-NMR与IR对合成季铵盐的结构进行了表征，结果表明成功合成了甲基碳酸酯季铵盐。

Abstract:

The quaternization of long chain alkyl tertiary amine with dimethyl carbonate was studied. The effects of reaction temperature, reaction time, material mol ratio and solvent dosage on quaternization of N, N-dimethyldodecylamine were examined, and the optimized reaction condition was determined. The optimized condition was : reaction temperature 130 ℃, reaction time 5 h, n (dimetyl carbonate)︰n (alkyl tertiary amine)=5, methanol dosage (based on the materials) 10%. Under the optimized conditions, the conversions of mono-alkyl tertiary amines with different carbon chain length could reach over 98%, while the conversions of N-methyldidecadeamine and N-methyldioctadecylamine were 88.09% and 68.77% respectively. These indicated that space steric hindrance was the main factor for the quaternization process, consisting with the results of molecular space structure simulation. Through extending reaction time, the conversion of N-methyldidecadeamine can reach to 98.96% after 7 h and N-methyldioctadecylamine can reach to 95.68% after 12 h. The quaternary ammonium salts were characterized by 1H-NMR and IR. The results showed that quaternary methyl carbonates were synthesized successfully.