微波强化己糖二酸脱水环合制备2,5-呋喃二甲酸的研究

Synthesis of 2,5-furandicarboxylic acid via microwave-enhanced cyclodehydration of hexaric acids

2,5-呋喃二甲酸(2,5-FDCA)是一种重要的生物质基聚酯单体。针对己糖二酸脱水环合制备2,5-FDCA中存在反应时间长的问题,在传统加热与微波加热的对比实验基础上,开展了HBr-MgBr_(2)催化下微波强化己糖二酸脱水环合制备2,5-FDCA的工艺研究。实验结果证实了微波的引入可在保证2,5-FDCA高收率的前提下显著提高己糖二酸脱水环合制备2,5-FDCA的反应速率,大大缩短反应时间。通过工艺优化,得到较佳的工艺条件:温度为110℃、催化剂质量分数w(HBr)=3%、w(MgBr_(2))=3%、微波强化反应15 min,2,5-FDCA收率可达75.0%。进一步考察了不同己糖二酸原料对微波强化脱水环合制备2,5-FDCA的影响,2,5-FDCA收率从高到低的次序为:葡萄糖二酸单钾盐>葡萄糖二酸钙>半乳糖二酸。研究工作将为己糖二酸路线制备2,5-FDCA的工业化进程起到一定的推动作用。

2,5-Furandicarboxylic acid(2,5-FDCA) is an important monomer for biomass-based polyesters. In order to solve the problem of long reaction time in the preparation of 2,5-FDCA by cyclodehydration of hexaric acid, microwave-enhanced cyclodehydration catalyzed by HBr-MgBr_(2) was studied. Compared with conventional heating, microwave heating ensures high yield and shortens reaction time. The optimized condition are: catalyst concentration of w(HBr)=3%, w(MgBr_(2))=3% at 110 ℃ and 15 min reaction time with yield of 75.0%. Furthermore, the effect of different hexaric acids on microwave-enhanced cyclodehydration was studied and the yield of 2,5-FDCA was: potassium bisaccharate > calcium saccharate > galactaric acid. This work helps the industrialization of 2,5-FDCA produced from hexaric acid.