Synthesis Of Ethylene Glycol Oligomer Functionalized Alkali Ionic Liquid Polymers And Their Application In Knoevenagel Condensationas Catalysts

Functionalized ionic liquids exhibit some unique properties,such as acidity,alkalinity,chirality,thermo-sensitive,selective solubility,bifunctionality and so on,due to the presence of the special functional groups.With the ongoing research,functionalized ionic liquids have been more and more widely used in the application of catalysis and considered as the focus of attention.Introducing the polyether chains into the ionic liquids,we can obtain the polyether-based functionalized ionic liquids,of which the ethylene oxide being the hydrophilic group could improve the hydrophilic property of the ionic liquids.When applied in the catalytic reaction and compared with traditional catalyst,the polyether-based functionalized ionic liquids could not only improve the catalytic efficiency,but also solve the problem to some extent that the traditional catalyst encounters in the difficult process of the separation,recycling and reusing.In the present work,polymerizable ionic liquids monomer,comb-shaped ionic liquid polymer and basic ionic liquid polymer catalyst were successively synthesized,and then a systematic research of the catalyst was conducted between the relationship of structure and its property.The details are as follows:In this work,firstly,the monomer of（[VB（EG）_n-Im]Cl）was synthesized from the starting material Vinylbenzyl chloride,based on the corresponding reactions:Williamson reaction,chloration and quaternization.Then,the comb-shaped ionic liquid polymers P（[VB（EG）_n-Im]Cl,n=0,2,3,4）were successfully synthesized by a free radical polymerization with（[VB（EG）_n-Im]Cl,n=0,2,3,4）as raw meterials and azodiisobutyronitrile as initiator.All the polymers were characterizedby using a set of technical means,such as fourier transform infrared,nuclear magnetic resonance,electron spray ionization mass infrared and thermogravimetric.The results showed that the thermal stability of the polymermoderately decrease with the increment of the EG polymerization degree of[VB（EG）_n-Im]Cl.Besides,the viscosity property possessed asimilar trend.Secondly,basic ionic liquid polymers（P[VB（EG）_n-Im][OH],n=0,2,3,4）were prepared by ion exchange,whose thermal stability and surface activity were assessed.The results indicated that the thermal stability of P[VB（EG）_n-Im][OH]will decrease,and simultaneously the lower critical micelle concentration and the better surface activity,when the degree of polymerization of ethylene oxide increases.Finally,the catalytic property of basic ionic liquid polymers（[VB（EG）_n-Im]Cl）was evaluated via the Knoevenagel condensation reaction with benzaldehyde and ethyl cyanoacetate as the substrates.The results indicated that（P[VB（EG）_n-Im][OH]）had a high catalytic activity,which increased with thepolymerization degree of the side chain of（[VB（EG）_n-Im]Cl）,that is,P[VB（EG）₄-Im][OH]>P[VB（EG）₃-Im][OH]>P[VB（EG）₂-Im][OH]>P[VB-Im][OH].The catalytic activity also had a close relationship with the surface activity.Besides,the solvent had an effect on the catalytic activity,which was best in dimethyl sulfoxide.Taking P[VB（EG）₄-Im][OH]as an example to probe the recycling property,it was found that the catalytic activity reduced sharply after recycling for 5 times due to the loss of the catalyst.