Study On The Synthesis Of Bisphenol Compounds Catalyzed By Acidic Ionic Liquids

Green manufacturing process improvement is a theme in the field of modern chemical research.The traditional synthesis methods of bisphenol compound have many disadvantages,for example the recovery of catalyst is difficult,the dosage is big and the traditional catalyst may etch apparatus seriously,what's more,extra cocatalyst is needed to add into reaction system.The disadvantages mentioned above are not according with the green development principle.As one of the potential friendly and new catalysts whose structure can be designed,ionic liquids(ILs)have been widely studied by many researchers,which provides a new way to select the catalyst of the preparation of bisphenol compound.In the present study,eight kinds of acid functional ILs catalysts are designed and prepared.The cation of these catalysts are benzothiazole and benzeneimidazole,and anion of them respectively are HSO4-,H2PO4-,BF4-and OTs-.The obtained ILs are used in the synthesis of benzylidene bisphenol by condensation of benzaldehyde and phenol,and the ILs are also used in the preparation of bisphenol fluorene by condensation of fluorenone and phenol,respectively.The catalytic effect of ILs is investigated.The acid functional ILs catalysts are prepared by two step method.The structure and acidity of ILs are characterized.The results show that the change of anion type has a big impact on the H0 of obtained ILs.The [(CH2)3SO3HBth][HSO4] is used as the catalyst.Reaction condition is optimized by univariate method.The optimal condition of the condensation reaction of benzaldehyde and phenol is as follows.n(phenol): n(benzaldehyde): n(ionic liquids)=2.5:1:0.375,T=80°C,t=5 h.And the optimal condition of the condensation reaction of fluorenone and phenol is as follows.n(phenol): n(fluorenone): n(ionic liquids)=6:1:0.375,T=110°C,t=6 h.Under the optimal reaction condition,the catalytic effects of obtained ILs in the synthesis of benzylidene bisphenol and bisphenol fluorene are investigated using conversation rate of raw materials and selectivity of products as index.It demonstrates that the prepared ILs has the similar effect on the above two reaction.The acidity of ILs is related to the anion structure of ILs catalyst.The catalytic effect of IL3 and IL7 whose anion is phosphate to the two kinds of biphenols preparation is the worst,the raw materials can't even react.The cation structure will not affect the acidity of ILs.However,the difference of acid site has an effect on the conversation rate of raw materials,it is important to point out that conversation rate of raw materials is obviously higher when use benzothiazolyl ILs catalyst than benzimidazole catalyst.However,the selectivity of bisphenol fluorene has little change when the cation type is the same.The effect of the cocatalyst thioglycolic acid on the synthesis of bisphenol fluorene is researched.It shows that the thioglycolic acid can significantly raise the conversation rate of fluorenone in the catalyst system of IL3 and IL5~IL8,and at the same time,the selectivity of bisphenol fluorene decreases.On the one hand,the acid site changes resulting from thioglycolic acid.on the other hand,thioglycolic acid raises the acidity of reaction system,which demonstrates that benzothiazolyl ILs catalyst could accelerate reaction speed.In addition,the cycle performance of [(CH2)3SO3HBth][HSO4] which has the best catalytic effect is studied.It shows that the catalytic effect of [(CH2)3SO3HBth][HSO4] remains unchanged after 9 times cycles experiments during the condensation reaction of benzaldehyde and phenol.And [(CH2)3SO3HBth][HSO4] can be reused for at least 5 times in the condensation of fluorenone and phenol.In conclution,benzothiazolyl ILs catalyst IL1,IL2 and IL4 show better catalytic effect in the preparation of the two kinds of bisphenol compound.The cocatalyst thioglycolic acid is not needed in the reaction as a result of the structural feature of the ILs mentioned above,and cocatalyst may produce more ortho byproducts and three phenolic byproducts.