离子液体介质中木薯淀粉琥珀酸酯的均相合成

Homogeneous Synthesis of Tapioca Starch Succinate in Ionic Liquid

摘要:

以离子液体（ILs）1-烯丙基-3-甲基咪唑氯盐（AMIMCl）为反应介质，研究无催化剂条件下木薯淀粉琥珀酸酯的均相合成。实验结果表明，将木薯淀粉在105 ℃的AMIMCl介质中预处理30 min，可使淀粉溶解，表明可利用这种预处理方法将淀粉均相化，作为后续化学改性的反应介质。通过浊度法测定结果表明，木薯淀粉在105 ℃的离子液体AMIMCl介质中的溶解度为10.2%。在离子液体AMIMCl介质中，通过探讨反应条件对木薯淀粉酯化产物取代度的影响，得到最佳反应条件为：琥珀酸酐与脱水葡萄糖单元（AGU）的摩尔比4:1，反应温度110 ℃，反应时间3 h，在此条件下，最大取代度为0.518。FT-IR结果显示在1733 cm-1出现了琥珀酸酐的伸缩振动峰，表明淀粉与琥珀酸酐发生了酯化反应，SEM结果表明，所合成的淀粉琥珀酸酯不存在原淀粉的完整颗粒结构，较高取代度的木薯淀粉琥珀酸酯的XRD曲线在2θ为8°处出现弥散峰，表明形成了新的结晶型式。

Abstract:

Tapioca starch succinate was homogeneously synthesized using ionic liquid (ILs) 1-butyl-3-methylimidazolium (AMIMCl) as reaction medium without any catalyst. The starch was dissolved in AMIMCl at 105 ℃ for 30 min before reaction, which could provide feasible reaction environment for starch functionalization. The results of turbidimetric measurement suggested that the solubility of starch dissolved in AMIMCl at 105 ℃ was 10.2%. Tapioca starch succinate achieved the highest DS of 0.518 under the following conditions: succinic anhydride/ anhydroglucose unit molar ratio of 4:1, reaction temperature of 110 ℃, and reaction time of 3 h. FT-IR result showed the peak at 1733 cm-1 attributed to the stretching vibration of ester carbonyl group , which indicated that the esterification of corn starch with succinic anhydride was successfully accomplished. The results of SEM showed that tapioca starch succinate lost individuality and smoothness which native starch granules had. XRD of starch succinate with high DS had new diffraction peaks at 8°, which suggested that the new crystalline pattern was formed.