Exploration Of Friedel-Crafts Acylation In Ionic Liquids

These days, lots of toxic, volatile organic solvents and catalysts areused in chemical industries and result serious environmental problem.The functional ionic liquids are made of functional organic cations andfunctional inorganic anions with unique properties, such as nonvolatility,homogeneous active sites, good solvating ability and so on. They haveshown excellent catalytic activity and can be used as dual catalyst andsolvent,socanreplacetraditionalacidcatalyst.1-Butyl-3-methylimidazolium chloride ([Bmim]Cl) was preparedand used to synthesis [Bmim]Cl-AlCl₃, [Bmim]Cl-FeCl₃, [Bmim]Cl-ZnCl2 and [Bmim]BF4 by two step method. Their structures werecharacterized. Acidic sites and the strength of Lewis ionic liquids havebeenstudiedbyIRtechniqueusingacetonitrileasaprobemolecule.Eight derivatives of acetophone were obtained by Friedel-Craftsacylation, in which Lewis acidic ionic liquids were used as solvent andcatalyst. The influences of various reaction conditions on the yieldwere studied. The optimum conditions of the Friedel-Crafts acylationreaction were determined as follow: n([Bmim]Cl-FeCl₃)/n(toluene)/ n(acetyl chloride)=1/3/1, 4h, 80℃, x(FeCl3)=0.67. Under the optimumcondition the total yield was 93.7% with aratio of o: m: p=11:3:86. Theionic liquid [Bmim]Cl-FeCl3 can be reused five times without obviousdeactivation.4-Methoxybenzophenone was obtained by Friedel-Crafts acylation,in which ionic liquid [Bmim]BF₄ was used as solvent and Cu(oft)₂ascatalyst. The optimumreaction conditionsof the Friedel-Crafts acylationreaction were determined as follow: n(benzoyl chloride)/n(anisole)/n([Bmim]BF₄)/n(Cu(otf)₂=1/4/1/0.12, 1h, 80℃. Under the optimumcondition the total yield was 86.5% with a ratio of o: m: p=8: 3: 89. Theionic liquid [Bmim]BF₄ can be reused six times without obviousdeactivation.1,4-Dimethyl-2-(phenylsulfonyl)benzene, 1,3,5-trimethyl-2-(phenylsulfonyl)benzene, 1-chloro-4-(phenylsulfonyl)benzene andsulfonyldibenzene were obtained in which Lewis acidic ionic liquidwasusedascatalyst. Theoptimumreactionconditionsof1,3,5-trimethyl-2-(phenylsulfonyl)benzene were determined as follow: n(mesitylene)/n(benzenesulfonyl chloride)/n([Bmim]Cl-FeCl3)=2/1/0.1, 1h, 30℃,x(FeCl3)=0.6.Undertheoptimumconditiontheyieldwas94.0%.