Study Of Acylation And Esterification In Ionic Liquids

In recent years, with the attention to the environmental quality, we need to developecologically friendly alternatives for clean technologies. The functional ionic liquids, as a newtype of environmentally friendly solvents and catalyst, possess many unique properties, such asgood solvating ability, negligible vapor pressure, non-volatility, adjustable acidity and so on, andcan be used as an alternative for traditional acid catalysts.At first,1-emtyl-3-methylimidazolium bromide （[Emim]Br）,1-Butyl-3-methylimidazoliumchloride （[Bmim]Cl） were prepared. Then,[Emim]Br-AlCl₃,[Emim]Br-FeCl₃,[Emim]Br-ZnCl₂,[Emim]Br-CuCl,[Bmim]HSO₄,[Bmim]BF₄,[Bmim]PF₆were synthesized by two step method.These samples were characterized by IR and H-NMR spectra.Four derivatives of acetophone were obtained by Friedel-Crafts acylation, in whichLewis acidic ionic liquids were used as solvent and catalyst, acetic anhydride as acylating agent.The impacts of factors on the reaction were explored when [Emim]Br-AlCl₃was chosen as thecatalyst and solvent. Under the conditions of80℃, x（AlCl₃）=0.67and n（[Emim]Br-AlCl₃）:n（1,3,5-trimethylbenzene）:n（acetic anhydride）=1:3:1, the yield of the product could reach73.4%after6h reaction. And the o/p ratio could reach1:85in the acylation of anisole with aceticanhydride.The catalytic activities for esterification of acetic acid and alcohols were measured in threekinds of Bronsted acid ionic liquids. The influences of various reaction conditions werestudied when [Bmim]HSO₄was chosen as the catalyst and solvent. Under the conditions of110℃, n（[Bmim]HSO₄）: n（acetic acid）:n（n-butanol）=0.35:1:1, the yield of the product couldreach78.05%after2h reaction. We also studied the recycle ability of catalyst and find that itscatalytic activity is constant after used several times.