分步法合成藜芦醚工艺的研究

以氢氧化钠水溶液为缩合剂、邻苯二酚和硫酸二甲酯为原料,在氮气保护下,采用两步升温法合成藜芦醚。考察了水和甲醇溶剂对氢氧化钠反应活性的影响。实验结果表明,反应在水溶剂中进行时,产物的纯度和收率均高于在甲醇溶剂中产物的纯度和收率。通过正交实验考察了物料配比、氢氧化钠水溶液的含量、第二步反应温度和保温时间对合成反应的影响,得出最佳的反应条件:n(邻苯二酚)∶n(硫酸二甲酯)∶n(氢氧化钠)=1.00∶2.45∶2.57,氢氧化钠水溶液的含量16.67%(w),第二步反应温度80℃,保温时间3 h。在此条件下,藜芦醚的总收率达95%左右。采用1H NMR方法对产物进行了表征。

A Two-Step Synthesis Method for o-Dimethoxy Benzene

The synthesis of o-dimethoxy benzene from catechol(CA) and dimethyl sulfate(DMS) by a two-step methylation process with NaOH aqueous solution as the condensation agent under nitrogen protection which prevented catechol from being oxidated in air was investigated.The effects of water and methanol as the solvents of NaOH on the synthesis were observed,and the results revealed that the product with higher yield and purity were achieved in the NaOH aqueous solution.The influences of the mole ratio of DMS to CA,mass fraction of NaOH solution,reaction time and temperature of the second step reaction on the yield of o-dimethoxy benzene were investigated by orthogonal design.Under the optimal reaction conditions:n(CA)∶n(DMS)∶n(NaOH) 1.00∶2.45∶2.57,the mass fraction of NaOH 16.67%,temperature 80 ℃ and reaction time 3 h in the second step,the total yield of the product o-dimethoxy benzene could reach 95%.The product was characterized by means of1H NMR.