己糖二酸脱水环合制备2,5-呋喃二甲酸反应路径探究

A study on reaction pathways for the cyclodehydration of hexedioic acids to 2,5-furandicarboxylic acid

2,5-呋喃二甲酸(2,5-FDCA)是生物可降解聚呋喃二甲酸乙二醇酯(PEF)的单体,目前尚未形成廉价的制备技术,其中用己糖二酸脱水环合制备2,5-FDCA是一条具有发展潜力的路线。针对此路线中副产物定性不准确、反应路径研究不完善等问题,通过高效液相色谱、高分辨质谱、核磁共振和傅里叶变换红外光谱分析,开展了副产物定性工作,确定反应体系中的2个主要副产物为糠酸和3-羟基-6-羧基-2-吡喃酮(HOCA)。在硫酸催化下不同己糖二酸脱水环合的反应路径相似,半乳糖二酸易生成副产物HOCA,而葡萄糖二酸钙易生成主产物2,5-FDCA。结合文献报道,提出了己糖二酸脱水环合制备2,5-FDCA可能的完整反应路径。研究工作可为己糖二酸脱水环合制备2,5-FDCA的高效催化体系开发和工业化生产提供指导。

2,5-furandicarboxylic acid(2,5-FDCA)is a monomer of biodegradable polyethylene 2,5-furandicarboxylate(PEF),however,its cost is high.Production of 2,5-FDCA from the cyclodehydration of hexedioic acids(HAs)is one of promising pathways,but facing the problems that it is difficult to detect the side-products and the reaction pathways is unclear.In this work,the side-products of HAs cyclodehydration were qualitative analyzed by high performance liquid chromatography(HPLC),high-resolution mass spectrometry(HRMS),nuclear magnetic resonance(NMR)and Fourier transform infrared spectroscopy(FTIR).The 2-furoic acid and 3-hydroxy-2-oxopyran-6-carboxylic acid(HOCA)were determined as the two main side-products.The reaction pathways for the cyclodehydration of different hexedioic acids are similar when using H;SO;as catalysts:the Galactaric acid is tended to be converted to HOCA,while calcium saccharate is more likely to be converted to 2,5-FDCA.Combined with the works already reported and the results obtained in this work,the possible reaction pathways for the preparation of 2,5-FDCA by cyclodehydration of hexedioic acid are proposed.This work will provide solid foundation for the constructing the catalytic system and industrialization of 2,5-FDCA from cyclodehydration of hexedioic acid.