高取代度玉米淀粉醋酸酯的合成与表征

以玉米淀粉为原料,醋酸酐为酯化剂,甲烷磺酸为催化剂,制备高取代度淀粉醋酸酯。研究了反应条件对产品取代度和结构的影响。结果表明:在n(淀粉葡萄糖基)∶n(醋酸酐)=1∶5.18,甲烷磺酸0.003 5 mol,反应温度75℃的条件下反应3 h,合成了取代度2.83的淀粉醋酸酯。用FTIR和1HNMR方法研究了淀粉醋酸酯的化学结构。FTIR分析表明,随着取代度的增加淀粉醋酸酯的特征峰逐渐增强;根据1HNMR谱峰的变化计算了淀粉醋酸酯的取代度,与化学滴定法测定的取代度一致;通过X射线衍射、偏光显微镜分析表明,酯化反应过程中破坏了原淀粉的结晶结构,生成了具有非晶态结构的淀粉醋酸酯。该淀粉酯已经过扩大生产,性能良好。

Synthesis and Characterization of Acetylated Corn Starch with High Degree of Substitution

Acetylated starches with high degree of substitution were synthesized from cornstarch with acetic anhydride as esterifying agent and methanesulphonic acid as catalyst.The influence of reaction conditions on the degree of substitution of acetylated starche was investigated.Under the conditions of n(glucosyl group)∶n(acetic anhydride)=1∶5.18,catalyst(0.003 5) mol,reaction temperature 75 ℃ and reaction time 3 h,degree of substitution of the product was 2.83.FTIR results indicated that with increasing degree of substitution,characteristic peaks of pure starch weakened and those of acetylated starches were enhanced.The degree of substitution calculated by chemical titration was consistent with that by ~1HNMR method.The results of X-ray diffraction and polarizing microscope indicated that the crystalline structure of pure starch was destroyed and disordered structure of acetylated starch formed.The acetylated starch has been produced on a large scale,and the performance is superior.