甲基化-β-环糊精新型合成工艺研究

A Novel Synthesis Technology of Methyl-β-Cyclodextrin

研究了甲基化-β-环糊精的绿色合成新工艺。选用绿色的碳酸二甲酯为原料,以DMF为溶剂,在无水碳酸钾催化下,将其与β-环糊精反应合成了甲基化-β-环糊精。通过正交实验考察了反应时间、β-环糊精和碳酸二甲酯摩尔比、反应温度和催化剂的量对产品的平均取代度的影响。实验结果表明:产品平均取代度的影响因素主要是反应温度和β-环糊精与碳酸二甲酯摩尔比;最佳合成工艺条件是反应时间为24h、β-环糊精和碳酸二甲酯摩尔比是1:28、反应温度85℃和β-环糊精和催化剂摩尔比为1:14,该条件下,产品的平均取代度达到14.2。采用薄层色谱、红外光谱、质谱和核磁共振技术对所合成的产品进行了表征,结果发现与用硫酸二甲酯或碘甲烷合成的甲基化-β-环糊精基本一致。该甲基化-β-环糊精合成工艺具有合成工艺简单、方便和无毒等特点。

A novel green synthesis process of methyl-β-cyclodextrin was investigated through the reaction betweenβ-cyclodextrin and dimethyl carbonate in DMF （dimethyl formamide） with anhydrous potassium carbonate as catalyst. The influences of factors including reaction time and temperature, molar ratio of β-cyclodextrin to dimethyl carbonate and dosage of anhydrous potassium carbonate on the average degree of substitution of methyl-β-cyclodextrin were studied via orthogonal experiments. The results show that the average degree of methyl-β-cyclodextrin depends on the reaction temperature and the molar ratio of raw material primarily. The optimal maximum average degree of substitution of methyl-β-cyclodextrin can reach 14.2 when the molar ratio of β-cyclodextrin to dimethyl carbonate, reaction temperature, reaction time and molar ratio of β-cyclodextrin to catalyst are 1：28, 85℃, 24 h and 1：14, respectively. The structures of the synthesized methyl- β -cyclodextrin were characterized by TLC, IR, MS, ^1H-NMR and ^13C-NMR, respectively. All the results are concordant with those of methyl-β-cyclodextrin synthesized by dimethyl sulfate or methyl iodide. It should be pointed out that the methyl-β-cyclodextrin synthesis technology proposed is a simple and green one.