基于小分子空间位阻效应协同酸性离子液体催化高选择性合成4,4′-双酚F

Lower 4,4 '-isomer bisphenol F content synthesized by ordinary chemical synthesis methods is unable to meet the high performance and processing molding requirements of the synthesied bisphenol F epoxy resin as a body material for large-scale wind turbine blades，so it is badly in need to develop a highly selective synthesis method of 4,4'-bisphenol F with independent intellectual property.This project researces on a green chemical synthesis method of highly selective catalytic synthesis of 4,4'-bisphenol F from phenol and formaldehyde, based on the acidic ionic liquid catalysis cooperated with the steric hindrance of small molecules. An urea-formaldehyde resin of small molecules is used as an introductory group combined with formaldehyde to increase the ortho position steric structure hindrance of phenol and make formaldehyde combine with phenol at the para position of smaller steric structure hindrance, when formaldehyde combines with phenol. After the reaction is completed, the introductory group is drew off. The acidic effect of imidazole ionic liquid which have both functions of catalysis and solvent on the stability of electrophilic groups in the synthesis process of bisphenol F were researched to determine the favorable selective conditions of electrophilic groups combining with phenol at the para position.The synergy action of highly selective synthesis of 4,4′-bisphenol F was researched, which is a promoted effect of the steric structure hindrance of small molecule urea-formaldehyde resin by changing ionic liquid acidity so as to change the bonding force between small molecule urea-formaldehyde resin and formaldehyde. The method proposed in this project has important significance for highly selective synthesis of 4,4 '-bisphenol compounds in fine organic synthesis.

普通合成方法所得4,4′-双酚F含量偏低，难以满足合成大型风电叶片双酚F环氧树脂基材的高性能与加工成型要求，急需研发具有自主知识产权的4,4′-双酚F的高选择合成方法。本项目研究以苯酚和甲醛为原料，基于小分子空间位阻协同离子液体催化高选择性合成4,4′-双酚F的绿色化学合成新方法。研究引入小分子脲醛树脂引导基与甲醛结合，增大甲醛与苯酚邻位空间位阻而使其主要与空间位阻较小的苯酚对位结合，反应后再脱去引导基的方法。研究兼具溶剂与催化双功能的咪唑类离子液体酸性对双酚F合成反应中亲电基团的稳定性影响，确定有利于亲电基团与苯酚对位结合的选择性反应条件。研究改变离子液体酸性对调控小分子脲醛树脂与甲醛结合力，促进小分子脲醛树脂空间位阻作用，高选择性合成4,4′-双酚F的协同作用。本研究对精细有机合成中4,4′-双酚类化合物的高选择性合成方法等共性问题亦具有一定的普遍意义。

针对以前合成双酚F方法所得4,4′-异构体含量不高，难以满足大型风电叶片双酚F环氧树脂基材性能要求，研发合成高4,4′-异构体含量双酚F新催化方法。原以小分子脲醛树脂引导基与甲醛结合以增大其与苯酚邻位空间位阻而使其与苯酚对位反应最后脱去引导基提高对位异构体双酚F含量的协同酸性离子液体催化方法，效果不佳，究其原因是酸性条件下小分子脲醛树脂易与甲醛聚合成不溶性脲醛树脂难以脱落而无法起到引导基作用。因此调整研发多功能巯基离子液体，通过巯基与甲醛氢键作用，以增大甲醛与苯酚邻位空间位阻而提高对位选择性，同时引入双咪唑核，咪唑环二位碳强亲电基团易与苯酚羟基发生氢键作用而起到保护苯酚邻位而使甲醛进攻苯酚对位。设计合成磺酸功能化双核离子液体双-(3-磺酸丙基-1-咪唑）亚丁基硫酸氢盐催化合成双酚F收率达94%，4,4’-异构体含量达45%。但离子液体仍存在一定粘度与腐蚀性、需水洗分离、重复使用欠佳，基于甲醛氢键作用，将酸性咪唑离子液体扩展到磺酸功能化双核咪唑与磷钨酸结合可水热调控离子液体、羟基磷灰石、金属有机框架、SBA-15介孔分子筛载体等酸性基团设计、合成及负载方法，催化苯酚甲醛合成双酚F及获得高4,4′-异构体选择性的构效关系及调控规律研究。将以前文献报道甲醛与苯酚酸催化合成4,4′-双酚F 含量45%左右提高到69%或双酚F收率达到90%以上、反应酚醛比由15～20降到10以下，并发现4,4′-双酚F反应初期处于反应动力学控制并最终受到反应热力学平衡限制，对所制备酸性介孔分子筛M(Al,Zr,Al-Zr)-SBA-15分子筛催化剂，调节Al/Zr比可调控双酚F三种异构体分布，增加Zr含量可得到90%含量的高邻位双酚F异构体。研究成果在CEJ、IECR、CST、MChemCatChem 、Mater Lett、RSC adv、Cata Commun、CJCE、化工学报等发表论文14篇，申请发明专利16项，授权11项，发明专利技术转让1项，为工业化生产提供应用基础研究成果，对选择性合成对位双酚类化合物具有一定指导作用。