Metal- and solvent-free synthesis of aniline- and phenol-based triarylmethanesviaBrönsted acidic ionic liquid catalyzed Friedel-Crafts reaction

Abstract

Brönsted acidic ionic liquid catalyzed the synthesis of aniline- and phenol-based triarylmethanes via Friedel-Crafts reaction under metal- and solvent-free conditions.

Brønsted Acidic Ionic Liquid Catalyzed Three-Component Friedel–Crafts Reaction for the Synthesis of Unsymmetrical Triarylmethanes

“…Zwitter ionic compound: [24] To a solution of 1-methylimdizalole (4.00 mL, 0.050 mol) in acetonitrile (15.0 mL) was added 1,4-butanesultone (5.7 mL, 0.056 mol) in portions at room temperature. The reaction mixture was heated to 80 o C with stirring for 24 h, and then cooled to room temperature resulting in white precipitate.…”

“…with ethyl acetate (3x5 mL) to remove any unreacted starting materials, and then the precipitate was dried in a vacuum to give the zwitter ionic compound as a white solid in 99% yield (10.8189 g); 1-Butylsulfonic-3-methylimidazolium hydrogen sulfate (I): [24] A mixture of zwitter ionic compound (0.10 g, 0.46 mmol) in anhydrous toluene (0.20 mL) was added a stoichiometric amount of sulfuric acid (0.025 mL, 0.46 mmol) in portions at room temperature. The reaction was then stirred at 80 o C for 24 h. After complete the reaction, anhydrous toluene was removed by rotary evaporator to obtain [bsmim][HSO4] (I) as a colorless oil in quantitative yield (0.148 g); [24] A mixture of zwitter ionic compound (0.10 g, 0.46 mmol) in anhydrous toluene (0.20 mL) was added a stoichiometric amount of para-toluene sulfonic acid (0.144 mL, 0.46 mmol) in portions at room temperature.…”

“…with ethyl acetate (3x5 mL) to remove any unreacted starting materials, and then the precipitate was dried in a vacuum to give the zwitter ionic compound as a white solid in 99% yield (10.8189 g); 1-Butylsulfonic-3-methylimidazolium hydrogen sulfate (I): [24] A mixture of zwitter ionic compound (0.10 g, 0.46 mmol) in anhydrous toluene (0.20 mL) was added a stoichiometric amount of sulfuric acid (0.025 mL, 0.46 mmol) in portions at room temperature. The reaction was then stirred at 80 o C for 24 h. After complete the reaction, anhydrous toluene was removed by rotary evaporator to obtain [bsmim][HSO4] (I) as a colorless oil in quantitative yield (0.148 g); [24] A mixture of zwitter ionic compound (0.10 g, 0.46 mmol) in anhydrous toluene (0.20 mL) was added a stoichiometric amount of para-toluene sulfonic acid (0.144 mL, 0.46 mmol) in portions at room temperature. The reaction was then stirred at 80 o C for 24 h. After complete the reaction, anhydrous toluene was removed by rotary evaporator to obtain [bsmim][pTsO] (II) as a colorless oil in quantitative yield (0.180 g); [24] A mixture of zwitter ionic compound (0.10 g, 0.46 mmol) in anhydrous toluene (0.02 mL) was added a stoichiometric amount of trifluoromethanesulfonic acid (0.041 mL, 0.46 mmol) in portions at room temperature.…”

“…The reaction was then stirred at 80 o C for 24 h. After complete the reaction, anhydrous toluene was removed by rotary evaporator to obtain [bsmim][pTsO] (II) as a colorless oil in quantitative yield (0.180 g); [24] A mixture of zwitter ionic compound (0.10 g, 0.46 mmol) in anhydrous toluene (0.02 mL) was added a stoichiometric amount of trifluoromethanesulfonic acid (0.041 mL, 0.46 mmol) in portions at room temperature. The reaction was then stirred at 80 o C for 24 h. After complete the reaction, anhydrous toluene was removed by rotary evaporator to obtain [bsmim][OTf] (III) as a colorless oil in quantitative yield (0.171 g); [24] A mixture of zwitter ionic compound (1.00 g, 4.58 mmol) in anhydrous toluene (2.00 mL) was added a stoichiometric amount of bis(trifluoromethanesulfonyl)imide (1.29 g, 4.58 mmol) in portions at room temperature. The reaction was then stirred at 80 o C for 24 h. After complete the reaction,…”

“…3,3'-(Phenylmethylene)bis(1H-indole) (5h): [8,9,[14][15][16][17][18][19][20][21][26][27][28][29][30][38][39][40]42] [24,31,32,36]…”