1-Butyl-3-methylimidazolium bromide

White crystals

General procedure: The ligands (except 3) were all synthesized by adaptation of the methods of Starikova et al. [20]. A typical and generic procedure is described. Spectroscopic and analyses data are presented. N-monosubstituted azole (0.1mmol) and dry toluene were placed in a two-neck flask and stirred until a homogeneous solution was formed; then alkyl halide (0.3mmol) was added drop wise with continuous stirring. After addition of the alkyl halide, the mixture was stirred while heating at 40°C for 24h. The solvent was removed and the ligand was dried under vacuum. 2.2.3 4.89 g of methylimidazole (0.059 mol) and 8.98 g of butyl bromide (0.065 mol) are introduced into a beaker. The beaker is placed under ultrasound, adjusted to have a pulsation of 2 seconds, with an instantaneous power of 15 W. The butylmethylimidazolium bromide is obtained with 100percent yield. This product is then added dropwise at ambient temperature to a mixture containing 50 ml of water and an equimolar quantity of lithium bis(trifluorosulphonyl)imide. The mixture is then maintained for two hours under reflux. The product is then extracted with three times 20 ml of dichloromethane before being evaporated under vacuum at 70° C. for 30 minutes. The overall yield is 94percent.N-methyl imidazole (8.21 g, 0.1 mol) and n-bromobutane (20.55 g, 0.15 mol) were added into the Schlenk tube under nitrogen atmosphere. The reaction mixture was firstly stirred at room temperature for 30 min and followed by heating slowly to 50 General procedure: 1-Butyl-3-methylimidazolium bromide was synthesized. 1-Bromobutane (1.1 mol) was added dropwise into 1-methylimidazole (1 mol) with agitation at 70 °C. The reaction mixture was refluxed for 24 h, and when cooled to room temperature, ethyl acetate was added to the mixture. The ethyl acetate was removed by a separating funnel followed by the addition of fresh ethyl acetate, and this step was repeated four times. The remaining ethyl acetate was removed by rotary evaporation, and the solution was dried under high vacuum at (343–353)K for at least 6 h to get 1-butyl-3-methylimidazolium bromide ([CAn oil bath with a stirred flask containing equimolar amounts of commercially available 1-methylimidazole and 1-bromobutane in toluene was heated at 70 °C for 24 h. After cooling to room temperature, the reaction mixture was separated and the upper toluene phase was recycled. The lower phase was washed with ethyl acetate and chloroform, and the residue was dried under vacuum to give the product (white crystals), yield: 96.3percent, mp: 77-78 °C. A method for preparing 1-butyl-3-methylimidazolium bromide comprises the following steps:(1) take the reaction raw material bromobutane 30Kg 80L reactor was added to the reactor by passing a water bath into the reactor bromine butyl bromide was heated until heated to 55 ~ 60 ° C;(2) After the raw material is heated and stirred in step (1), the water bath is turned off and 16Kg of N-methylimidazole is added dropwise to the reaction vessel, and the dropwise addition is completed within 4 hours;(3) After the addition of N-methylimidazole in step (2), The temperature is controlled at 80 ~ 90 °C and stirring is continued for 50 minutes.Ethyl acetate 16L was added after stirring was completed.The temperature is lowered by passing tap water into the reaction vessel sandwich.And continue to stir until the temperature of the reactor is lowered to 45-55°C to complete the reaction; then the material is discharged from the outlet of the reactor (the discharge temperature is 45-55°C); the discharged material is transported to the cover through the material conveying pipeline. Centrifuge with feed port, and then added ethyl acetate through the feed port on the cover of the centrifuge to wash the discharged material, centrifuge while washing (centrifuge speed is 350r/min), washing is completed (will not be reacted After the raw material is washed, a white solid is obtained;(4) The white solid obtained after rinsing and centrifuging as described in step (3) is vacuum-steamed under the condition of 40-50° C. (vacuum degree in vacuum rotary evaporation is −0.08 MPa) to remove residual ethyl acetate. That is, 1-butyl-3-methylimidazolium bromide white solid particles are obtained. After testing, the yield of the obtained product is 96.23percent; the purity is 99.80percent and its water content is 1660 ppm; that is, the product prepared by this method has a high yield and purity, and the water content is low and meets the requirements.A mixture of 0.04 mol N-methyl imidazole, 0.04 mol butyl bromide, and 25 mL of toluene was reuxed at 60-70C for 2 h. After cooling to room temperature, the lower phase, which contained the product, was separated from the upper phase. The product was washed a few more times with toluene and yellowish viscous liquid was obtained in 95percent yield.Freshly distilled 1-methylimidazole (8.21g, 0.1mol) and n-butylbromide (13.7g, 0.1mol) were combined in 100 mL round bottom flask equiped with a reflux condenser. The reaction mixture was heated to reflux (90°C) under N2 atmosphere for 24h. The product was washed with ethyl acetate (3×30 mL) to remove starting material. The residual ethyl acetate was removed from product under vacuum pressure. The yellow solid was dissolved in water (50 mL) and decolorizing charcoal (2g) was added. This solution was heated at 70°C for 24h, cooled and filtered. The water was removed using rotavapor. The resulting solid was heated under high vacuum for 48h at 70°C. The product was obtained as a white solid.Yield: 94percent, The ionic liquid [C10 mL (0.13 mol) of 1-methylimidazole, 16 mL (0.15 mol) of 1-bromobutane and 50 mL ofacetonitrile were added to the round-bottomed flask fitted with a reflux condenser and refluxed for24 hours. After removal of the solvent, the residual liquid was diluted with 50 mL of deionizedwater. The solution was washed with 50 mL of ethyl acetate three times. After the water phasewas evaporated, the residual liquid was further dried in vacuo (under 0.1mbar) at 60°C for 24 hours, producing a pale yellow viscous liquid (yield: 25.8g, 94percent).To a clean, dry round-bottomed flask were added 1-methylimidazole (29.4 mL, 0.37 mol) and 1-bromobutane (44.1 mL, 0.41 mol). The reaction mixture was stirred at 70 °C for 24 h. During this time, an emulsion formed, followed by the formation of the colourless ionic liquid. The crude ionic liquid was washed with EtGeneral procedure: C4mimBr was synthesized according to the reported literatures.1 In a 100 mL round-bottom flask, 1-methylimidazole (8.21 g, 0.1 mol) was mixed with n-butyl bromide (16.44 g, 0.12 mol) and allowed to reflux for 24 h at 70 °C. The excess n-butyl bromide was distilled off under reduced pressure and the residue was finally extracted thoroughly 2-3 times (50 mL each) with diethyl ether to remove the traces of unreacted starting materials. A white solid of 1-n-butyl-3-methylimidazolium bromide was obtained in 87percent yield.For the synthesis of IL [bmim][Br], slight excess of 1-bromobutane(10 g, 73 mmol) was added drop wise to 1-methylimidazole (5.7 g, 69 mmol) in a round bottom flask followed by refluxing the solutionat about 60–70 °C for 24 h under N2 atmosphere. It was then cooledto room temperature followed by washing of the product obtainedusing diethyl ether several times. After this slight yellow viscous productis obtained which was dried under vacuum to get 1-butyl-3-methylimidazolium bromide [bmim][Br], with 86percent yield. Karl–Fisherexamination of the IL indicated that the water content reduced tob400 ppm.1H NMR (400 MHz, D2O, δ-ppm): 0.846(t, 3H), 1.241(m, 2H), 1.771(m, 2H), 3.810(s, 3H), 4.116(t, 2H), 7.344(d, 1H), 7.393(d, 1H).8.625(s, 1H).Under inert conditions, 1-methyl-imidazole (1 eq) was addedto neat 1-bromobutane (2 eq) at 0°C. The mixture wasstirred during 12 hours under 40°C. The resulting salt was dried to give yellowoil and a white solid was obtained by several wash with diethyl ether. The final product was dried during 12 hours at roomtemperature. Yield: 82percent. To a 50 mL Schleck tube was added 1-methyl-1H-imidazole (4.1g, 0.05 mol), 1-bromobutane(13.5g, 0.1 mol, 2equiv) and distilled toluene (20 mL), the mixture were heated and stirred at 80 °C oil bath overnight, after reaction, all the versitile were removed under vacuo, the residue red oil were washed with 2-methoxy-2-methylpropane (5 * 20 mL), dried under vacuo, which afforded 3-butyl-1-methyl-1H-imidazol-3-ium bromide ( NHC precursor F ) as colorless oil (50percent, 5g)1-butyl imidazole put 1.82 mmol (0.24 mL) and 2.18 mmol NH4Br (214 mg) and trimethyl ortho formate 9.1mmol (1 mL) in a Schlenk reaction tube and reflux under air or N2. Confirming that the protonated imidazole disappears then removed trimethyl ortho formate remaining under vacuum, and then, a small amount of the protonated imidazole deprotonation was passed through a basic alumina dissolved in ethyl acetate. After having passed through this solution, putting them in a vacuum and the product was confirmed by NMR. Yield: 95percent

Ionic liquid for Heck reaction

Molecular Weight:219.12
Hydrogen Bond Acceptor Count:1
Rotatable Bond Count:3
Exact Mass:218.04186
Monoisotopic Mass:218.04186
Topological Polar Surface Area:8.8
Heavy Atom Count:11
Complexity:93.3
Covalently-Bonded Unit Count:2
Compound Is Canonicalized:Yes