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采用绿色乙基化试剂成功探索了乙基-β-环糊精合成的新方法。该方法选用碳酸二乙酯为原料,以DMF为溶剂,在无水碳酸钾催化下,将其与β-环糊精反应选择性地合成了目标产物。并研究了反应温度、反应时间、碳酸二乙酯与β-环糊精物质的量比和溶剂的量对产品的平均取代度的影响。实验结果表明:同等条件下,产品平均取代度随着反应温度升高而升高;平均取代度在开始时随着反应时间的延长而明显增加,然后增加变缓慢直至停止;碳酸二乙酯与β-环糊精物质的量比对平均取代度的影响是随着物质的量比的增加而增加,达到一定最大值后随物质的量比的增加而下降;溶剂的量对平均取代度的影响规律与物质的量比对平均取代度的规律相同。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。质谱和1 H-NMR结果表明乙基-β-环糊精的平均取代度6.5,~(13)C-NMR表明取代度为6.5的乙基-β-环糊精取代位置为2,6位。
A new method for the synthesis of ethyl-β-cyclodextrin was successfully explored using green ethylic reagent. In the method, diethyl carbonate is used as a raw material, and DMF is used as a solvent to synthesize the target product selectively with β-cyclodextrin under the catalysis of anhydrous potassium carbonate. The effects of reaction temperature, reaction time, the molar ratio of diethyl carbonate to β-cyclodextrin and the amount of solvent on the average degree of substitution of the product were investigated. The experimental results show that under the same conditions, the average degree of substitution of the product increases with the increase of the reaction temperature. The average degree of substitution increases with the reaction time at the beginning, then increases slowly and slowly until it stops. The influence of the ratio of β-cyclodextrin to the average degree of substitution is increased with the increase of the ratio of the amount of the substance. When the amount of β-cyclodextrin reaches a certain maximum value, the amount of β-cyclodextrin decreases with the increase of the amount of substance. The law of influence and the ratio of material to the average degree of substitution are the same. The synthesized products were characterized by TLC, FTIR, MS and NMR. Mass spectrometry and 1 H-NMR results showed that the average degree of substitution of ethyl-β-cyclodextrin was 6.5. The ~ (13) C-NMR showed that the substitution position of ethyl-β-cyclodextrin with the substitution degree of 6.5 was 2,6 .