碱性离子液体碱化制备N-十二烷基化壳聚糖

Synthesis of N- dodecyl chitosan alkalized by basic ionic liquid

摘要:

合成了1-甲基-3-丁基咪唑醋酸盐（[Bmim]OAc）、1-甲基-3-丁基咪唑碳酸盐（[Bmim]2CO3）及1-甲基-3-丁基咪唑氢氧化物（[Bmim]OH）离子液体，由FT-IR、1HNMR和元素分析对结构进行了确证。首先用离子液体对壳聚糖碱化，再令碱化后壳聚糖与溴代十二烷进行烷基化反应，制备高取代度的N-十二烷基化壳聚糖。用FT-IR、1HNMR 、XRD对烷基化产物进行了表征。考察时间、温度及物料配比对N-十二烷基壳聚糖取代度的影响，得到较佳的反应条件: n([Bmim]OH):n(壳聚糖原料)=3:1，45℃碱化1h，n(溴代十二烷):n(碱化后壳聚糖)=2:1，烷基化反应温度80℃，反应时间3h, 在该条件下十二烷基壳聚糖的取代度达到81%以上。离子液体具有重复使用性，反应后的离子液体重复使用3次后，N-十二烷基壳聚糖的取代度仍大于80%。

Abstract:

The [Bmim]OAc，[Bmim]2CO3 and [Bmim]OH ionic liquid were synthesized and their structure were confirmed by IR、1HNMR and elemental analysis. First, Chitosan was alkalized by ionic liquid. Then the alkalized chitosan reacted with bromododecane. And thus N-dodecyl chitosan with high degree of substitution (DS) was produced. The structure of alkylation product was characterized by IR、1HNMR and XRD. It studied the effects of time, temperature and the ratio of reactant on the DS of N-dodecyl chitosan. The suitable reaction conditions were found as follows：n([Bmim]OH):n(chitosan)=3:1，the chitosan was alkalized for 1h with alkalization temperature 45℃，n(bromododecane): n(alkalized chitosan)=2:1，the alkalized chitosan reacted for 3h with alkylation reaction temperature 80℃. Under above conditions，the DS of N-dodecyl chitosan can be over 81％. The reusability of the ionic liquid was also investigated，and it was found that the DS still could be kept above 80％ after the [Bmim]OH ionic liquid was reused for 3 times without any retreatment.