Synthesis Of The SO₃H-functionalized Ionic Liquids And Their Catalytic Performance

Ionic liquids as environmentally-friendly green solvention and new catalytic materials have been paid attention all over the world.Over the past decade,chloroaluminate ionic liquids take the place of conventional acid and solid acid because of their low vapour pressure, outstanding acidity and tunable solubility for some organic species.Nevertheless, chloroaluminate ionic liquids are very sensitive to hydrolysis.As a result,it is difficult to control the acidity of these ionic liquids.Therefore,the development of water-and air-stable acidic ionic liquids is highly desirable。In 2002,Forbes et al.synthesized SO₃H-functionalized ionic liquids,which have advantage of easy separation of solid acid and high activity of liquid acid.But,their cost is high,it is difficult to achieve in industrial production.Moreover,it is applied rarely.To economize cost of S03H-functionalized ionic liquids,extend their range of application in chemistry reaction,fifteen of ionic liquids have been synthesized by using methylimidazole,tri-alkylamine,pyridine with industrial materials 1,4-butane-sultone and 1,3-propane sultone as source in this paper.The ionic liquids were synthesized by tri-alkylamine have not been reported and yields are higher than 98%.Their structure,thermal stability and acidity were characterized and evaluation using NMR,Q-TOF,TG-DTG,UV respectively.The results exhibit that ionic liquids are in good agreement with those expected and display higher thermal stability,decomposition temperature higher over 300℃,vapour pressure is vety low.Environmental pollution of SO₃H-functionlized ionicliquids is less than organic solvent.The cost of the materials was reduced.It have wide industrial application prospect.Alkylation of phenol,p-cresol,m-cresol and hydroquinone with(TBA)in SO₃H-functionlized ionic liquids were investigated.Conversion of phenol,p-cresol,m-cresol were 53%,95%,90%and selectivity of 2-tert-butyl-phenol,2-tert-butyl-5-methyl-phenol and 2-tert-4-methyl-phenol were 53%,95%and 90%respectively;Conversion of hydroquinone was 70%and selectivity of 2-tert-butyl-hydroquinone under optimized reaction conditions. Moreover,comparative with solid acid:reaction temperature decrease and reaction can carry on under without sovent.The ionic liquids were recycled six times,and no change in activity. The experimental data is useful to its industrialization,and it has important leading meaning.