* All experimental methods are cited from the reference, please refer to the original source for details. We do not guarantee the accuracy of the content in the reference.
at 40℃; for 24 h; Schlenk technique; Inert atmosphere
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 1-Methyl-3-butylimidazolium bromide (4) Colorless oil. Yield (1.98 g, 91percent). IR (ATR cm-1): 3077, 2959, 1626, 1570, 1463, 1166, 1109, 752, 619, 460; δH (400 MHz, CDCl3): 0.74 (3H, t, J 7.4 Hz, CH3), 1.18 (2H, m, CH2), 1.70 (2H, m, CH2), 3.92 (3H, s, NCH3), 4.14 (2H, t, J 6.7 Hz, NCH2), 7.42 (1H, s, NCH), 7.53 (1H, s, NCH) and 10.03 ppm (1H, s, CH), δC (100 MHz, CDCl3): 13.41 (CH3), 19.37 (CH2), 32.11 (CH2), 36.65 (NCH3), 49.72 (NCH2), 122.29, 123.83, 136.99 ppm; m/z (ESI) 139.4 (M+-Br-) HRMS (ESI) calcd for C6H11BrN2, 139.12352 (M+-Br-); found, 139.12327 (M+-Br-).
Reference:
[1] Journal of Molecular Catalysis A: Chemical, 2014, vol. 385, p. 98 - 105
[2] Chemical Communications, 2004, # 5, p. 590 - 591
2
[ 616-47-7 ]
[ 109-65-9 ]
[ 85100-77-2 ]
Yield
Reaction Conditions
Operation in experiment
100%
ultrasound
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.
100%
at 50℃; for 12 h; Inert atmosphere
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 oC for another 12 h. After completed, the mixture was washed thrice with redistilled petroleum and ethyl acetate (1:1, 50 mL.x.3). The great amount of white solid was generated during the washing with solvents. Then the product was drained at room temperature under vacuum for 2 h and dried continuously at 50 oC under vacuum for another 6 h. Finally, the white waxy solid BmimBr was obtained in nearly quantitative yield (21.99 g).
99%
for 24 h; Reflux
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 ([C4mim] [Br]) at very high yield (99percent) (Scheme 1).
96.3%
at 70℃; for 24 h;
An 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. 1H NM (D2O, 400 MHz) δ: 1.68 (t, J = 14.8 Hz, 3H, CH3), 2.06 (m, 2H, CH2), 2.61 (m, 2H, CH2), 4.95 (t, J = 14.4 Hz, 2H, NCH2), 5.54 (s, 3H, NCH3), 8.16-8.25 (m, 2H, C3H3N2 4,5-H), 9.48 (s, 1H, C3H3N2 2-H).
96.23%
at 45 - 90℃; for 4.83333 h; Large scale
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.
95%
at 60 - 70℃; for 2 h;
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.
94%
at 90℃; for 24 h; Inert atmosphere
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,
94%
at 40℃; for 12 h;
The ionic liquid [C4mim]Br was prepared according to the procedure described in the literature [30]. 1-Bromobutane (13.7g, 0.1mol) was slowly added to freshly distilled 1-methylimidazole (8.2g, 0.1mol) in a 100mL round-bottom flask fitted with a reflux condenser. This mixture was then stirred with a magnetic stirrer at 40°C for 12h, during a yellowish viscous liquid formed. The liquid was then purified by moderate amount of ethyl acetate, gave the white solid product with a 94percent yield.
94%
for 24 h; Reflux
10 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).
92%
at 70℃; for 24 h;
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 Et2O (3 .x. 30 mL) to remove excess 1-bromobutane, then dried in vacuo (50 °C, 40 mbar) for 2 h. On cooling to room temperature, the colourless, viscous ionic liquid crystallised to form a white solid. Yield: 74.1 g (92percent); 1H NMR (DMSO-d6) δ 0.86 (3H, t, J = 7.2 Hz), 1.23 (2H, m), 1.74 (2H, m), 3.86 (3H, s), 4.19 (2H, t, J = 7.2 Hz), 7.78 (1H, t, J = 1.8 Hz), 7.86 (1H, t, J = 1.8 Hz), 9.36 (1H, t, J = 1.8 Hz); 13C NMR (DMSO-d6) δ 13.4, 18.9, 31.5, 35.9, 48.6, 122.4, 123.7, 136.7 ppm.
87%
at 70℃; for 24 h;
General 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.
86%
at 60 - 70℃; Inert atmosphere
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).
82%
at 0 - 40℃; for 12 h; Inert atmosphere
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. 1H NMR (DMSO-d6, 300 MHz): δ (ppm) = 9.24 (s,1H,Im+), 7.77 (d,2H,Im+), 4.17(t,2H,-CH2Im+), 3.86 (s,3H, CH3Im+),1.76 (m,2H,-CH2-) 1.25 (m,2H,-CH2-), 0.89 (t,3H,-CH3).13C NMR (DMSO-d6, 125 MHz): δ(ppm) = 136.99(Im+); 124.05(Im+); 122.72(Im+);48.91(CH3Im+); 36.23(-CH2Im+);31.82(-CH2-); 19.22(-CH2-); 13.74(-CH3). HR MS(ESI) m/z: [M*+](calcd for C8H15N2+):139.123 found: 139.124. Elementalanalysis: Calcd for C8H15BrN2: N 12.78; C43.85; H 6.90. Found: N 12.73; C 43.91; H 7.02.
50%
at 80℃; Schlenk technique
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)
Reference:
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[2] Patent: US2007/7137, 2007, A1, . Location in patent: Page/Page column 4-5
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3
[ 4316-42-1 ]
[ 149-73-5 ]
[ 85100-77-2 ]
Yield
Reaction Conditions
Operation in experiment
95%
Schlenk technique; Reflux
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
Reference:
[1] Green Chemistry, 2014, vol. 16, # 9, p. 4098 - 4101
[2] Patent: KR2015/79403, 2015, A, . Location in patent: Paragraph 0049-0052
4
[ 85100-77-2 ]
[ 174501-64-5 ]
Yield
Reaction Conditions
Operation in experiment
100%
With potassium hexafluorophosphate In water at 20℃;
The round flask was equipped with the BmimBr (32.85 g, 0.15 mol) and distilled water (50 mL), the solution of KPF6 (27.9 g, 0.15 mol) and H2O (50 mL) was then slowly added. The mixture was stirred at room temperature for overnight. After completed, the reaction system was extracted with CH2Cl2 (100 mL.x.3), combined with the organic phase, dried by anhydrous MgSO4, filtrated and concentrated. The residual was dried at 40-50 oC for 8 h under vacuum and sequentially was dried at 100 oC for another 6 h under vacuum. The colorless liquid was afforded with quantitative yield. 1H NMR (400 MHz, CDCl3): δ ppm 0.84-0.87 (t, 3H), 1.26-1.31 (m, 2H), 1.77-1.81 (t, 2H), 3.84 (s, 3H), 4.07-4.09 (d, 2H), 7.28-7.31 (d, 2H), 8.35 (s, 1H). 31P NMR (400 MHz, CDCl3): δ ppm -157.55, -153.16, -148.76, -144.37, -139.98, -135.58, -131.19.
75%
With ammonium hexafluorophosphate In water at 20℃; for 2 h;
Into a 25 mL tube was added NHC precursor F 2.18 g (10 mmol ), NH4PF6 (3.2g, 20 mmol), 10 mL distilled water, the mixture was stirred at room temperature for 2 hours. The reaction mixture was then extracted with dichloromethane (3×10 mL). The organic phases were combined and washed with distilled water (3×15 mL). The organic phase dried by magnesium sulfate and was filtered, concentrated under reduced pressure, the residue was dried under vaccum, which afforded 3-butyl-1-methyl-1H-imidazol-3-ium hexafluorophosphate (NHC precursor H) as light yellow oil (2.1 g, 75percent).
Reference:
[1] Tetrahedron Letters, 2011, vol. 52, # 43, p. 5636 - 5639
[2] Chemistry - A European Journal, 2010, vol. 16, # 23, p. 6748 - 6751
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[6] Synthesis (Germany), 2018, vol. 50, # 6, p. 1315 - 1322
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[20] Patent: CN108017657, 2018, A, . Location in patent: Paragraph 0020; 0033; 0034
[21] Patent: CN108017658, 2018, A, . Location in patent: Paragraph 0020; 0029; 0031; 0032; 0038; 0044; 0050
[22] Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 2018, vol. 201, p. 134 - 142
5
[ 85100-77-2 ]
[ 174501-64-5 ]
Yield
Reaction Conditions
Operation in experiment
75%
at 20℃; for 24 h;
First 0.02 mol imidazolium bromide salt and 0.02 mol NH4PF6 were added to 50 mL of dichloromethane. The mixture was then stirred at room temperature for 24 h. At end of the reaction, ammonium bromide was filteredand dichloromethane was evaporated using a rotary evaporator. The yield was calculated as 75percent.
Reference:
[1] Turkish Journal of Chemistry, 2016, vol. 40, # 2, p. 364 - 372
6
[ 85100-77-2 ]
[ 90076-65-6 ]
[ 174899-83-3 ]
Yield
Reaction Conditions
Operation in experiment
60%
at 20℃; for 24 h;
First 0.02 mol imidazolium bromide salt was added to 50 mL of dichloromethane and mixed. Then 0.02 mol bis(trifluoromethanesulfonyl)imide salt of lithium was added to the stirring solution of imidazolium bromide salt. The mixture was left stirring for about 24 h at room temperature. Then the lithium bromide salt was filtered and the concentrated AgNO3 solution was added to the solution. The resulting solution was washed with pure water so that AgBr was allowed to pass into the water phase. Then dichloromethane was evaporated with a rotary evaporator. The yield was calculated as 60percent.
Reference:
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With sodium tetrafluoroborate; In acetone; for 48h;Inert atmosphere; Darkness;
The above synthesized BmimBr (21.9 g, 0.1 mol) and NaBF4 (11.0 g, 0.1 mol) with the solvent of dried acetone (100 mL) were added into a dried 250 mL round bottom flask under nitrogen atmosphere. The mixture was then stirred for 48 h under darkness. The reaction mixture was filtrated to remove off the produced white solid salt NaBr and followed by concentrated, the residual was filtrated again so as to remove off the NaBr as much as possible. The resulted liquid was dried at 40-50 oC for 4 h under vacuum, and then improved the temperature to 100 oC for further dryness under vacuum for another 6 h. The colorless or slightly yellow liquid BmimBF4 was finally obtained with 95% yield (21.77 g). 1H NMR (400 MHz, CDCl3): deltappm 8.53ppm (s, 1H), 7.30 (s, 1H), 7.25 (s, 1H), 4.03 (t, 2H), 3.72 (s, 3H), 1.68 (m, 2H), 1.16 (m, 2H), 0.76 (t, 3H).
95%
With sodium tetrafluoroborate; In acetone; at 20℃; for 24h;Inert atmosphere;
To a solution of [bmim][BF4] (5.47g, 0.25mol) in dry acetone (50 mL), sodium tetrafluoroborate (5.0g) was added and reaction mixture was stirred vigorously at room temperature for 24h. The precipitated solid sodium bromide was filtered off, and the filtrate was evaporated to leave the crude [bmim][BF4] as a viscous liquid. It was washed with diethyl ether (3×30 mL) and dried at 90C for 10 h to afford the pure colorless ionic liquid. Yield: 95 %.
93%
With tetrafluoroboric acid; 1-hexene; dihydrogen peroxide; at 25℃; for 3h;
General procedure: A mixture of the appropriate imidazolium bromide (0.2 mol) and hex-1-ene (30 mL) was stirred in a flask, and a mixture of the appropriate protonic acid (0.2 mol) and H2O2 (0.1 mol) was added dropwise at room temperature (25 C). After the appropriate time (Table 1), the liquid was placed in a separatory funnel and the oil phase was removed. The aqueous phase was washed with portions of CH2Cl2 (50mL) until it was colorless. Residual H2O in the product was removed by azeotropic distillation with cyclohexane. For [BzMim]PF6 (Table 1,entry 18), which has low water solubility, post-processing required only distillation and desiccation of the oil phase.
87%
With tetrafluoroboric acid; silver(l) oxide; In water; at 20℃; for 2h;
Tetrafluoroboric acid (32.8 cm3, 0.232 mol, 48% solution in water) was added slowly to a rapidly stirred slurry of silver (I) oxide (29.1 g, 0.106 mol) in water (50 cm3) over 15 min. The reaction mixture was stirred for further hour until all the silver (I) oxide had completely reacted to give a colourless solution. A solution of 1-butyl-3-methylimidazolium bromide (48 g, 0.219 mol) in water (30 cm3) was added to the reaction mixture and stirred at room temperature for 2 h. The resulting yellow precipitate of silver bromide was removed by filtration and the solvent removed by rotary evaporator. After ionic liquid was passed through a short SiO2 column with acetonitrile: chloroform, the solvents were removed by rotary evaporator to give the tetrafluoroborate salt as pale yellow liquid, which was dried in vacuo for ca. 24 h. Yield 43.2 g, 87%. vmax(film)/cm- 1: 3162-3122 (s., aromatic ?-? stretch); 2964-2877 (m., ?-? aliphatic stretch); 1600-1480 (CN); 1467 (s., sym. ring stretch), 1171 (s., sym. ring stretch), 1054 (br s., BF4 stretch), 624 (amid (III)). delta?(250 MHz; D2O; Me4Si): 0.97 (3H, triplet, J 7.4, -CH3); 1.39 (2H, sextet, J 7.4, CH3-??2-(??2)N); 1.91 (2H, quintet, J 7.4, N-??2-??2); 3.83 (3H, singlet, N-??3); 4.24 (2H, triplet, J 7.3, N-??2-); 7.53 (2H, doublet, J 1.8, N-??-??-N); 8.71 (1H, singlet, N-?(?)-N). deltaC(50.32 MHz; D2O; cyclohexanol): 13.27; 19.42; 31.95; 36.23; 49.92; 122.86; 124.15; 136.49.
With sodium tetrafluoroborate; In acetone; at 20℃; for 24h;
To a solution of C4mimBr (2.1912 g, 10 mmol) in acetone (10 mL) at room temperature was added sodium tetrafluoroborate (1.0979 g, 10 mmol). Afer 24 h stirring, the reaction mixture was filtered and the volatiles were removed under reduced pressure. Drying in vacuo for 10 h afforded 1-butyl-3-methylimidazolium tetrafluoroborate as a light yellow liquid.
With ammonium tetrafluoroborate; In acetonitrile; for 24h;Reflux;
General procedure: The second step of synthesis of [C4mim][BF4] is the substitution of the bromide ion with the BF4- ion. Tetrafluoroborate salt was synthesized by metathesis reactions from the corresponding bromide. [C4mim][Br] (0.1 mol) was dissolved in acetonitrile (50 mL), and ammonium tertrafluoroborate (0.11 mol) was added. The mixture was refluxed for at least 24 h. When it was cooled to room temperature, NH4Br precipitate was removed by filtration. Any remaining precipitate was removed by further filtration at this step. The remaining acetonitrile was removed by rotary evaporation to get crude 1-butyl-3-methylimidazolium tetrafluorobarate. Crude [C4mim][BF4] was dissolved in dichloromethane (50 mL) and cooled below 278 K. Deionized water and a separation funnel were also cooled to below 278 K. The dichloromethane solution was washed with cooled deionized water (30 mL) five times until the aqueous solution did not form any precipitate with 0.1 mol L-1 AgNO3 solution. The solvent dichloromethane was removed by rotary evaporation, and the [C4mim][BF4] was dried under high vacuum at (323-333)K for at least 6 h (Scheme 2).
With sodium tetrafluoroborate; In water;
A series of IBILs were prepared using standard methods [28-36]. Briefly, N-methylimidazole was reacted with a little excess of 1- bromobutane in a round-bottom flask at room temperature for 5 h to produce [Bmim]Br. The halide-based ionic liquids were purified by recrystallization and dried overnight under vacuum conditions at room temperature. For [Bmim][BF4] or [Bmim][PF6], [Bmim]Br was ion-exchanged with equal mole of sodium tetrafluoroborate (NaBF4) or sodium hexafluorophosphate (NaPF6) in aqueous solution. The obtained IBILs were extracted using dichloromethane, and the amount of halide impurities in the ionic liquids were qualitatively determined by adding silver nitrate. Then IBILs were dried under vacuum conditions at 343 K for two to three days before use.
With sodium tetrafluoroborate;
The ionic liquids [bmim][BF4] and [bmim][PF6] have been prepared from [bmim][Br] by treatment with NaBF4 and KPF6 respectively.
2.2.3 1-Butyl-3-methyl-1H-imidazolium dicyanamide ([BMIM]N(CN) 2 ) (3)
Compound 1 (10 g) and sodium dicyanamide (1.0 equiv) were stirred at room temperature in dry distilled acetone (20 mL) for 2 h. The resulting suspension was filtered, and the filtrate was dried under vacuum. The obtained oil was dissolved in dry dichloromethane (20 mL), and the formed solid was eliminated by filtration. The title compound was obtained as a slightly yellowish oil in quantitative yield by drying under reduced pressure. 1 H-NMR and 13 C-NMR data are in accordance with those reported in the literature [31] .
Stage #1: sodium dicyanamide With silver nitrate
Stage #2: 1-n-butyl-3-methylimidazolim bromide In water
35 g (0.16 mol) of [C4mim][Br] was diluted with 100 mL of deionized water and 45.7 g (0.16 mol)of Li(Tf2N) was added. After mixing, the reaction mixture was separated into two layers. Thebottom layer was [C4mim] [Tf2N] and the top layer was aqueous LiCl. After decanting the toplayer, 100 mL of fresh deionized water was added and the solution was thoroughly mixed. Thisprocedure was repeated twice. The ionic liquid was dried in vacuo (under 0.1mbar) at 60C for 24hours, producing a colorless liquid (yield: 61.5 g, 87.5%).
60%
In dichloromethane; at 20℃; for 24h;
First 0.02 mol imidazolium bromide salt was added to 50 mL of dichloromethane and mixed. Then 0.02 mol bis(trifluoromethanesulfonyl)imide salt of lithium was added to the stirring solution of imidazolium bromide salt. The mixture was left stirring for about 24 h at room temperature. Then the lithium bromide salt was filtered and the concentrated AgNO3 solution was added to the solution. The resulting solution was washed with pure water so that AgBr was allowed to pass into the water phase. Then dichloromethane was evaporated with a rotary evaporator. The yield was calculated as 60%.
In water; at 20℃; for 3h;Electrochemical reaction;Product distribution / selectivity;
An embodiment of a reversible mirror of the invention was fabricated as follows: two electrodes were prepared using 6×8 cm single-side planar ITO coated glass plates having a sheet resistivity of 7 Omega/square. Each plate was provided with a bus bar by attaching a copper electrical contact approximately 1 cm wide along the entire edge of the 6 cm end of each plate. The electrodes were then washed with water, methanol and acetone, and dried in a stream of warm air to remove any dust or grease. An o-ring (2 cm internal diameter (ID) vycor rubber donut-shaped o-ring, 0.3 cm thick) was used as a gasket to seal one electrode to the other. A silver wire (5 cm long, 0.25 mm diameter, 99.9% metal purity) was inserted through the o-ring by first piercing a hollow needle through the o-ring, placing one end of the silver wire through the hollow needle, and then withdrawing the hollow needle from the o-ring. Approximately 0.4 mm of the silver wire protruded through the o-ring. The o-ring was then placed between the two electrodes with the conducting ITO coating in contact with the o-ring (see FIGS. 1 and 2) with the bus bars at opposite ends of the device. Two spring-loaded clips were used to hold the device together and provide a tight seal. A digital ohmmeter was used to ensure that the three electrodes (working, counter and pseudo-reference electrodes) were in electrical isolation of each other. Butylmethylimidazolium bis(trifluoromethylsulfonyl)imide was synthesized as follows: Butylmethylimidazolium bromide (50 g) was dissolved deionized water (100 mL). Decolorizing charcoal or activated carbon (3 g) was added to the solution, which was boiled for 3 minutes and filtered. The filtrate was added to a solution of lithium bis(trifluoromethylsulfonyl)imide (65.5 g) in 100 mL of deionized water. After stirring at room temperature for 3 hrs, two layers formed. The bottom layer containing butylmethylimidazolium bis(trifluoromethylsulfonyl)imide was separated, washed deionized water (3×50 mL), heated at 100 C. under vacuum (0.1 mbar) for 48 hrs, and then filtered through activated alumina to give anhydrous, highly pure, molten butylmethylimidazolium bis(trifluoromethylsulfonyl)imide. The purity of the molten salt was assayed by cyclic voltammetry, absorbance spectroscopy or fluorescence measurements. A solution of 3-butyl-1-methylimadazolium bis(trifluoromethylsulfonyl)imide containing less than 1 ppm water and 0.035 mol/L of bismuth (III) bis(trifluoromethylsulfonyl)imide was prepared in a helium atmosphere drybox. The solution was introduced into the chamber of the device by inserting two hollow needles through the o-ring (one needle for introducing the solution, the other needle for removing displaced gas). Afterward, the needles were removed and the o-ring was checked for leaks. Wire connectors were attached to the bus bars and to a potentiostat that provided the voltage for electrodeposition. A bismuth mirror was deposited at a potential of -0.65 Volts versus the silver reference electrode. The bismuth mirror was deplated at a potential of +0.1 Volts versus the silver reference electrode. Overall, this reversible mirror device exhibited good optical reflectance in the reflective state and good transparency in the non-mirrored state, and was switched repetitively between these two states without degradation of performance.
In water; at 70℃; for 24h;pH 6.0;
General procedure: The respective halide IL was dissolved in deionized water (pH =6) and after an equimolar amount of LiNTf2 in water had been added dropwise, the reaction mixture was stirred for 1 day at 70 C. Then CH2Cl2 was added and the aqueous phase was removed. The organic phase was washed halide-free with deionized water (AgNO3 test). The solution was filtered over a column filled with neutral Al2O3 and activated charcoal. The organic solvent was removed under reduced pressure and the reaction product finally dried under dynamic vacuum for 1-2 days at 80-90 C.
for 24h;Inert atmosphere;
Ionic liquid [bmim]Br was heated gently at 80C. The lithiumsalt LiTFSI was added to the melt under N2and stirred for 24 h.Adding CH2Cl2, LiBr was precipitated and separated by filtration.The filtrate was evaporated to dryness then the [bmim][TFSI]obtained.
In water; at 20℃; for 24h;
Then, the dried precursor BmimBr (0. 05 mmol, 10.5 g) and equimolar LiN (S02) 2 (CF3) 2 (0. 05 mmol, 13.7 g) were each dissolved in 20 mL H20 and mixed at room temperature 24h, After adding 50mL CH2Cl2, the water was removed and the aqueous phase was removed. After 5 times, CH2C12 was removed and dried at 80 C for 12 h to obtain ionic liquid [Bmim] [Tf2N].
With potassium hexafluorophosphate; In water; at 20℃;
The round flask was equipped with the BmimBr (32.85 g, 0.15 mol) and distilled water (50 mL), the solution of KPF6 (27.9 g, 0.15 mol) and H2O (50 mL) was then slowly added. The mixture was stirred at room temperature for overnight. After completed, the reaction system was extracted with CH2Cl2 (100 mL×3), combined with the organic phase, dried by anhydrous MgSO4, filtrated and concentrated. The residual was dried at 40-50 oC for 8 h under vacuum and sequentially was dried at 100 oC for another 6 h under vacuum. The colorless liquid was afforded with quantitative yield. 1H NMR (400 MHz, CDCl3): delta ppm 0.84-0.87 (t, 3H), 1.26-1.31 (m, 2H), 1.77-1.81 (t, 2H), 3.84 (s, 3H), 4.07-4.09 (d, 2H), 7.28-7.31 (d, 2H), 8.35 (s, 1H). 31P NMR (400 MHz, CDCl3): delta ppm -157.55, -153.16, -148.76, -144.37, -139.98, -135.58, -131.19.
75%
With ammonium hexafluorophosphate; In water; at 20℃; for 2h;
Into a 25 mL tube was added NHC precursor F 2.18 g (10 mmol ), NH4PF6 (3.2g, 20 mmol), 10 mL distilled water, the mixture was stirred at room temperature for 2 hours. The reaction mixture was then extracted with dichloromethane (3×10 mL). The organic phases were combined and washed with distilled water (3×15 mL). The organic phase dried by magnesium sulfate and was filtered, concentrated under reduced pressure, the residue was dried under vaccum, which afforded 3-butyl-1-methyl-1H-imidazol-3-ium hexafluorophosphate (NHC precursor H) as light yellow oil (2.1 g, 75%).
With sodium hexaflorophosphate; In water;
A series of IBILs were prepared using standard methods [28-36]. Briefly, N-methylimidazole was reacted with a little excess of 1- bromobutane in a round-bottom flask at room temperature for 5 h to produce [Bmim]Br. The halide-based ionic liquids were purified by recrystallization and dried overnight under vacuum conditions at room temperature. For [Bmim][BF4] or [Bmim][PF6], [Bmim]Br was ion-exchanged with equal mole of sodium tetrafluoroborate (NaBF4) or sodium hexafluorophosphate (NaPF6) in aqueous solution. The obtained IBILs were extracted using dichloromethane, and the amount of halide impurities in the ionic liquids were qualitatively determined by adding silver nitrate. Then IBILs were dried under vacuum conditions at 343 K for two to three days before use.
With potassium hexafluorophosphate;
The ionic liquids [bmim][BF4] and [bmim][PF6] have been prepared from [bmim][Br] by treatment with NaBF4 and KPF6 respectively.
With potassium hexafluorophosphate; In acetone; at 20℃; for 2h;
A solution of 6.896g of KPF6 in 50mL of acetone was placed in a 250mL three-necked flask, and then 10mL of acetone solution containing 5.47g of [C4MIm]Br was added dropwise. Immediately, a white precipitate appeared. After stirring for 2h at room temperature, the precipitated solid KBr was removed by suction filtration. The acetone was removed by rotary evaporation and the temperature was lowered to room temperature to give a yellow liquid crude product. After treatment with 3-5 times of 30 mL of CH2Cl2 until the complete removal of KBr solids, the ionic liquid in dichloromethane was dried over anhydrous magnesium sulfate overnight, filtered, and the dichloromethane was removed by rotary evaporation to give a pale yellow viscous liquid product [C4MIm] PF6.
With potassium hexafluorophosphate; In acetone; at 20℃; for 2h;
Preparation of [C4MIm]PF6 Ionic Liquids: A solution of 6.896g of KPF6 in 50mL of acetone was placed in a 250mL three-necked flask, and then 10mL of acetone solution containing 5.47g of [C4MIm]Br was added dropwise. Immediately, a white precipitate appeared. After stirring for 2h at room temperature, the precipitated solid KBr was removed by suction filtration. The acetone was removed by rotary evaporation and the temperature was lowered to room temperature to give a yellow liquid crude product. After treatment with 3-5 times with 30 mL of CH2Cl2 until the complete removal of KBr solids, the ionic liquid in dichloromethane was dried over anhydrous magnesium sulfate overnight, filtered, and the dichloromethane was removed by rotary evaporation to give a light yellow viscous liquid product [C4MIm ]PF6.
With hexafluorophosphoric acid; In acetone; at 20℃; for 24h;
General procedure: To a solution of the crude 1-butyl-3-methylimidazoliumbromide, obtained from the above reactions,in acetone (70 mL) was added hexafluorophosphoric acid (10.90 g,100.0 mmol). The reaction mixture was stirred for 24 h at room temperature. The resulting mixture was filtered. Evaporation of the solvent under reduced pressure afforded the corresponding 1-Butyl-3-methylimidazolium hexafluorophosphate. Same procedure was used except that trifluoro methane sulphonic acid (15.08 g,100.0 mmol) was used instead of hexafluorophosphoric acid. The resulting mixture was filtered. Evaporation of the solvent under reduced pressure afforded the corresponding imidazolium trifluromethanesulphonate.1-Butyl-3-methylimidazolium tetrafluoroborate was also prepared using the same procedure as above except that tetrafluoro boric acid (15.08 g, 100.0 mmol) was used in place of hexafluorophosphoric acid. Progress of the reaction was measured by TLC. Completion of the reaction was confirmed by 1HNMR.
General procedure: To a solution of the crude 1-butyl-3-methylimidazoliumbromide, obtained from the above reactions,in acetone (70 mL) was added hexafluorophosphoric acid (10.90 g,100.0 mmol). The reaction mixture was stirred for 24 h at room temperature. The resulting mixture was filtered. Evaporation of the solvent under reduced pressure afforded the corresponding 1-Butyl-3-methylimidazolium hexafluorophosphate. Same procedure was used except that trifluoro methane sulphonic acid (15.08 g,100.0 mmol) was used instead of hexafluorophosphoric acid. The resulting mixture was filtered. Evaporation of the solvent under reduced pressure afforded the corresponding imidazolium trifluromethanesulphonate.1-Butyl-3-methylimidazolium tetrafluoroborate was also prepared using the same procedure as above except that tetrafluoro boric acid (15.08 g, 100.0 mmol) was used in place of hexafluorophosphoric acid. Progress of the reaction was measured by TLC. Completion of the reaction was confirmed by 1HNMR.
With 1-hexene; dihydrogen peroxide at 25℃; for 3h;
Ionic liquids (Table 1, Entries 1-19, 21); General Procedure
General procedure: A mixture of the appropriate imidazolium bromide (0.2 mol) and hex-1-ene (30 mL) was stirred in a flask, and a mixture of the appropriate protonic acid (0.2 mol) and H2O2 (0.1 mol) was added dropwise at room temperature (25 °C). After the appropriate time (Table 1), the liquid was placed in a separatory funnel and the oil phase was removed. The aqueous phase was washed with portions of CH2Cl2 (50mL) until it was colorless. Residual H2O in the product was removed by azeotropic distillation with cyclohexane. For [BzMim]PF6 (Table 1,entry 18), which has low water solubility, post-processing required only distillation and desiccation of the oil phase.
With 1-hexene; sulfuric acid; dihydrogen peroxide at 25℃; for 3h;
Ionic liquids (Table 1, Entries 1-19, 21); General Procedure
General procedure: A mixture of the appropriate imidazolium bromide (0.2 mol) and hex-1-ene (30 mL) was stirred in a flask, and a mixture of the appropriate protonic acid (0.2 mol) and H2O2 (0.1 mol) was added dropwise at room temperature (25 °C). After the appropriate time (Table 1), the liquid was placed in a separatory funnel and the oil phase was removed. The aqueous phase was washed with portions of CH2Cl2 (50mL) until it was colorless. Residual H2O in the product was removed by azeotropic distillation with cyclohexane. For [BzMim]PF6 (Table 1,entry 18), which has low water solubility, post-processing required only distillation and desiccation of the oil phase.
75%
With sulfuric acid; silver sulfate In ethanol at 50℃; for 2h;
75%
With sulfuric acid; silver sulfate In ethanol; water at 50℃; for 2h;
1.3 2.1.3 1-Butyl-3-methylimidazolium hydrogen sulfate
To solution of AgSO4 (4.08 g, 0.013 mol) in 40% H2SO4 solution in water (20 cm3) was added dropwise to a cooled, rapidly stirring solution of 1-butyl-3-methylimidazolium bromide (4.05 g, 0.018 mol) in ethanol (50 cm3). The reaction mixture was stirred at 50 °C for 2 h. The resulting yellow precipitate of silver bromide was removed by filtration and the solvents were removed by rotary evaporator. The remaining extremely viscous oil was recrystallized from acetonitrile/diethyl ether (1:5) to yield colorless crystals. Yield 7.75 g, 75%. Found, %: С 39.31; H 7.43; N 11.86; S 13.16; O 28.23 С8Н16N2O4S. Calc. for %: С 40.43; H 7.39; N 11.79; S 13.47; O 26.92. vmax(film)/cm- 1: 3150-3108 (s., aromatic С-Н stretch); 2962-2875 (m., С-Н aliphatic stretch); 1600-1480 (CN); 1466 (s., sym. ring stretch), 1171 (s., sym. ring stretch), 1046 (s., NO3 stretch), 583 (s., SO4 stretch), 624 (amid (III)). δН(250 MHz; D2O; Me4Si): 0.75 (3H, triplet, J 7.4, -CH3); 1.66 (2H, sextet, J 7.3, CH3-СН2-(СН2)N); 1.68 (2H, quintet, J 7.4, N-СН2-СН2); 3.73 (3H, singlet, N-СН3); 3.99 (1H, singlet, HSO4); 4.06 (2H, triplet, J 7.3, N-СН2-); 7.3 (2H, doublet, J 5.2, N-СН-СН-N); 8.53 (1H, singlet, N-С(Н)-N). δC(50.32 MHz; D2O; cyclohexanol): 13.31; 19.46; 31.96; 36.3; 49.93; 122.88; 124.16; 136.52. m/z: Calc. for М 237; found 235 [М]+.
With sodium hydrogen sulfate at 20℃; for 72h;
With sulfuric acid at 20℃; for 24h;
With sodium hydrogen sulfate In acetone at 20℃; for 24h;
With sulfuric acid In dichloromethane at 40℃;
With sulfuric acid In dichloromethane at 20℃; for 24h;
With sulfuric acid In dichloromethane at 0℃; for 26h; Reflux;
Synthesis of ionic liquid [bmim]HSO4
The ionic liquid [bmim]HSO4 was synthesized and characterized according to the literature procedure reported elsewhere1,2. Briefly, n-butyl bromide was treated with methylimidazole in an equimolar ratio for 36 h at ambient temperature under nitrogen atmosphere to yield a dense oily liquid which was washed with ethyl acetate followed by ether and dried under high vacuum. The product butyl-methyl-imidazolium bromide was dissolved into anhydrous dichloromethane and equimolar amount of 97% sulphuric acid was added dropwise at 0 °C over aperiod of few minutes. The reaction mixture was stirred vigorously for 2 h, and then refluxed for 24 h, after completion of reaction, the mixture was cooled at room temperature and evaporated in vacuum to remove dichloromethane. The ionic liquid was further dried under reduced pressure at 70 °C for 6 h before use for the desired reaction.
With sodium hydrogen sulfate In methanol at 20℃; for 24h;
2
The obtained 1-methyl-3-butylimidazolium bromide was dissolved in methanol, and 1 mol of NaHSO4 was added to the solution. The mixture was stirred at room temperature for 24 hours and then suction-filtered. The filtered supernatant was removed of methanol and vacuum-dried. The ionic liquid 1-methyl-3-butylimidazolium sulphide is obtained.
With sodium hydrogen sulfate In methanol; water at 20℃; for 24h;
2
The obtained 1-methyl-3-butylimidazolium bromide salt was dissolved in methanol, and an aqueous solution having a NaHS04 content of 1 mol was added thereto, and the reaction was stirred at normal temperature for 24 hours. Then, it was suction filtered, and the filtered supernatant was evaporated to remove methanol, followed by vacuum drying to obtain an ionic liquid 1-methyl-3-butylimidazolium hydrosulfide
4.58 g
With sulfuric acid In dichloromethane for 48h; Reflux;
Preparation of 1-Butyl-3-methylimidazolium hydrogen sulfate [bmim][HSO4]
As per the reported procedure, [bmim][HSO4] was obtained by dropwise addition of conc. H2SO4 (98%, 22.8 mmol, 1.24 mL) to a cooled solution of [bmim][Br] (22.8 mmol, 5 g) in dry CH2Cl2 (15 mL), and subsequent reflux of the mixture for 48 h. HBr generated as by-product in the reaction was evaporated under a stream of dry nitrogen, and the residual solution was concentrated under vacuum using a rotary evaporator. The ionic liquid was finally dried under vacuum at 60 °C for 6 h. (Yield 4.58 g, 85%). brown viscous liquid; 1H NMR (500 MHz, D2O, DMSO-d6) δ 0.86 (3H, t, J = 7.5 Hz), 1.19-1.24 (2H, m), 1.70-1.76 (2H, m), 3.83 (3H, s), 4.15 (2H, t, J = 7.0 Hz), 7.69 (1H, s), 7.77 (1H, s), 9.17 (1H, s); 13C NMR (125 MHz, DMSO-d6) δ 18.4, 23.9, 36.5, 40.9, 53.7, 127.5, 128.8, 141.7. Anal. Calcd. for C8H16N2O4S: C, 40.66; H, 6.83; N, 11.86, S, 13.57%. Found: C, 40.78; H, 6.69; N, 11.79, 13.13%.
With sodium hydrogen sulfate In methanol at 68℃; for 72h;
Preparation of 1-butyl-3-methylimidazolium dicyanamide ([C4-mim][N(CN)2])
37.6 g (0.22 mol) of Ag[N(CN)2] and 23.8 g (0.11 mol) [C4-mim][Br] were dissolved in 80 mL ofdeionized water. The resulting suspension was stirrer overnight in the dark at RT and filtered toremove any trace of AgI and unreacted Ag[N(CN)2]. After the water phase was evaporated, theresidual liquid was further dried in vacuo (under 0.1mbar) at 60°C for 24 hours, producing a paleyellow liquid (yield: 20.3 g, 91.0%).
83%
In dichloromethane for 48h;
In water at 60℃; for 2h;
1-Butyl-3-methylimidazolium bromide was dissolved in deionized water and a slight molar excess of silver dicyanamide suspended in deionized water was added. The mixture was stirred for 2 h at 60 °C, then filtered and dried. The crude product was dissolved in CH2Cl2, upon cooling to 5 °C most of the silver bromide precipitated. After separation from silver halide by filtration, the remaining solution was filtered over a column filled with neutral Al2O3 and activated charcoal. The solvent was removed under reduced pressure and the IL dried under dynamic vacuum for 1-2 days at 80-90 °C.
In water Darkness;
In acetone at 20℃;
2.1g Preparation of [BMIM][N(CN)2]:
In a roundbottom flask, a mixture of 1-methyl imidazole (4 g; 48.78mmol) and n-butyl bromide (6.7 g; 48.78 mmol) was stirredat 80 °C in neat condition for 10 h. After that, neutral ionicliquid [BMIM][Br] was obtained as white solid. The reactionmixture was washed with ethyl acetate four times forcomplete removal of n-butyl bromide and other organic compounds.It was then subjected to vacuum to obtain the puresolid [BMIM][Br]. On the other hand, silver dicyanamide(AgN[CN]2) was prepared by mixing equimolar amount ofsilver nitrate (7.72 g, 45.66 mmol) and sodium dicyanamide(4.07 g, 45.66 mmol) in water. Freshly prepared silverdicyanamide was added to the [BMIM][Br] in acetone andstirred overnight at room temperature. The solution was filteredand acetone was removed in vacuum to obtain the pure[BMIM][N(CN)2] as colourless liquid.
[Bmim]Br (0.03 mol) and potassium acetate were weighed at the molar ratio of 1:1 and dissolvedin methanol. The reaction lasted for 8 h at 25 °C, 10 mL ether was added after reaction and thewhite precipitate was removed by filtration. The filtrate was evaporated for 1 h at 55 °C and driedin the vacuum oven at 70 °C for 24 h to obtain ionic liquid [Bmim][CH3COO]. [Bmim][HCOO] and[Bmim]OH can be prepared by changing the above-mentioned potassium acetate into potassiumformate and sodium hydroxide, respectively.
In neat (no solvent); at 100℃; for 0.333333h;Microwave irradiation;
General procedure: a mixture of 1-methylimidazole (0.4105 g, 5 mmol), 1-bromobutane (0.6850 g, 5 mmol) was heated under microwave irradiation (or conventional heating) in a 10 mL pressurized glass tube fitted with a Teflon-coated septum at 80 C for 20 min. Then, LiOTf (0.78 g, 5 mmol) was added and the mixture was irradiated at 100 C for 20 min. After cooling, the mixture was diluted with MeCN (5 mL), and after removal of the precipitated salt LiBr, the filtrate was then filtered through Celite. The crude product was washed with Et2O and concentrated to give a colorless to pale yellow liquid (1.382 g, 96 % yield). The [BMIM]OTf was dried under reduced pressure. The purity and authenticity of the ionic liquids were confirmed by 1H and 13C NMR spectroscopy.
In acetone; acetonitrile; at 60℃; for 24h;
1-Butyl-3-methylimidazolium bromide was dissolved in acetone/acetonitrile (50:50) and an equimolar amount of LiTfO in acetone was added. The mixture was stirred for 1 day at 60 C and then filtered. The solvent was removed under reduced pressure and the crude product dissolved in CH2Cl2. Upon cooling to 5 C most of the Li halide precipitated and the precipitate was filtered off. The remaining solution was washed halide-free with deionized water (AgNO3 test) and filtered over a column filled with neutral Al2O3 and activated charcoal. The residual organic phase was freed from solvent under reduced pressure and dried under dynamic vacuum for 1-2 days at 80-90 C.
In dichloromethane at 25℃; for 0.166667h; Darkness;
Improved procedure for the synthesis of 1a-7a
General procedure: To a mixture of equimolar amounts of Ag[B(C6F5)4] and [WCC]X dry CH2Cl2 (20 mL) was added. The mixture was stirred under exclusion of light at room temperature for 10 min. The precipitate was removed by filtration, and the filtrate was dried for 4 h under high vacuum. The product was washed several times with n-hexane and dried under vacuum for one day.
In dichloromethane at 25℃; for 0.166667h; Darkness; Schlenk technique;
General procedure for the synthesis of 1b-7b
General procedure: In a Schlenk flask, to a mixture of equimolar amounts of Ag[B(C6H3-3,5-(CF3)2)4] and [WCC]X dry CH2Cl2 (20 mL) was added. The mixture was stirred under exclusion of light at room temperature for 10 min. The precipitate was removed by filtration, and the filtrate was dried in high vacuum for 4 h. The product was washed several times with n-hexane and dried under vacuum for one day.
In methanol; at 50℃; for 0.333333h;Microwave irradiation;
Synthesis of 1-Butyl-3-methylimidazolium tetrafluoroborate ([Bmim] BF4) in a two-step process Step 1: Synthesis of 1-butyl-3-methylimidazolium bromide salt ([Bmim] Br)To a 2000 ml round bottom flask was added 2.1 mol of bromo-n-butane, Further, 2 mol of N-methylimidazole was added to the constant-pressure dropping funnel, and the reaction was carried out in an ultrasonic-microwave combination reactor, The knob of the constant-pressure dropping funnel was controlled so that 2 mol of N-methylimidazole was dropped in two minutes, Set the ultrasonic power of 1200W, Microwave heating power of 1500W, The reaction was carried out at 100 C for 20 minutes. The content of [Bmim] Br in the reaction mixture was 98% by NMR and LC-MS. The second step: Synthesis of the target product [Bmim] BF4 To the above synthesized [Bmim] Br, 2 mol of sodium fluoroborate was added, Then add 500ml of methanol as solvent, In the 1000W ultrasound, 1200W microwave, 50 deg C for 20 minutes.The content of [Bmim] BF4 in the reaction mixture was determined to be up to 95% by nuclear magnetic resonance and liquid chromatography-mass spectrometry.
In acetone; at 20℃;
In a round bottomflask, a mixture of 1-methyl imidazole (4 g; 48.78 mmol)and n-butyl bromide (6.7 g; 48.78 mmol) was stirred at 80 Cin neat condition for 10 h. After that, neutral ionic liquid[BMIM][Br] was obtained as white solid. The reaction mixturewas washed with ethyl acetate four times for completeremoval of n-butyl bromide and other organic compounds.It was then subjected to vacuum to obtain the pure solid[BMIM][Br]. After that, sodium tetrafluoroborate (5 g, 45.66mmol) was added to the [BMIM][Br] in acetone and stirredovernight at room temperature to obtain [BMIM][BF4]. Thesolution was filtered and and acetone was removed in vacuumto obtain the pure [BMIM][BF4] as colorless liquid.
In dichloromethane; water; at 20℃; for 24h;
The obtained 1-methyl-3-butylimidazolium bromide was dissolved in methylene chloride, and an aqueous solution having a NaBF4 with content of 1 mol was added thereto, and the reaction was stirred at room temperature for 24 hours. After completion of the reaction, the methylene chloride phase was washed with a small amount of water for several times, and then the methylene chloride was removed by a rotary evaporator and vacuum dried to give an ionic liquid 1-methyl-3-butylimidazolium tetrafluoroborate
In dichloromethane; water; at 20℃; for 24h;
The obtained 1-methyl-3-butylimidazolium bromide was dissolved in methylene chloride, an aqueous solution having a NaBF4 content of 1 mol was added to the solution, and the reaction was stirred at room temperature for 24 hours. After completion of the reaction, the methylene chloride phase was washed with a small amount of water to remove ions, and methylene chloride was removed and dried in vacuo to obtain 1-methyl-3-butylimidazolium tetrafluoroborate salt as an ionic liquid.
In methanol; at 20℃; for 24h;
General procedure: Another anion exchange reaction was carried out to achieve IL with boron tetrafluorides as a counter anion (IL-BF4) by metathesis reaction as per reported literature with minor modifications (Scheme 2). A demonstrative example for the synthesis of [RMIM]BF4 (i.e., [EMIM]BF4, [BMIM]BF4, [HMIM]BF4, [OMIM]BF4, [DMIM]BF4) and [RBZMIM]BF4 (i.e., [EBZMIM]BF4, [BBZMIM]BF4, [HBZMIM]BF4, [OBZMIM]BF4, [DBZMIM]BF4) in Scheme 2 (step-3) derivatives are as follows: 1:2 ratio of the 1-methyl-3-alkylimidazolium bromide or 1-methyl-3-alkylbenzimidazolium bromide ([RBZMIM]Br) and NaBF4 were added distinctly in to the round bottom flask containing 25mL of methanol and stirred at room temperature for 24h. Afterward, the salt was removed by filtering the reaction mixture using Whatman filter paper. Further, the filtrate was centrifuged for 10min at 3000rpm to isolate the residual salts. Solvent was evaporated under reduced pressure, vacuum dried and characterized (using 1H and 13C NMR and mass spectroscopy). The spectral details of the synthesized ILs are provided in the supplementary information Figs. S1 to S30.
First 0.02 mol imidazolium bromide salt, 0.02 mol NH4BF4 , and 50 mL of dichloromethane solvent were mixed at room temperature for 24 h. Then ammonium bromide was filtered and the solvent was evaporated using arotary evaporator. The yield was calculated as 75%.
First 0.02 mol imidazolium bromide salt and 0.02 mol NH4PF6 were added to 50 mL of dichloromethane. The mixture was then stirred at room temperature for 24 h. At end of the reaction, ammonium bromide was filteredand dichloromethane was evaporated using a rotary evaporator. The yield was calculated as 75%.
1-butyl-3-methyl-3H-imidazolium salicylate[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
at 20℃; for 72h;
General procedure: Fig. 1 illustrates the general synthesis of salicylate and thiosalicylatebased ILs [39-41]. Firstly, 20 mmol of 1-bromobutane, 1-bromohexane,or 1-bromooctane was added to 20 mmol of N-methylimidazole, andthe mixture was refluxed while being stirred at 140 C for 30 minuntil a yellow liquid with high viscosity was obtained. The preparedILs ([BMIM][Br], [HMIM][Br], or [OMIM][Br]) were extracted with10 mL diethyl ether and washed with DDW, respectively, dried overanhydrous sodium sulfate and evaporated under vacuum. Secondly, becausethe halide salts underwent metathesis reaction to give the desiredionic liquid, 20 mmol of <strong>[54-21-7]sodium salicylate</strong> was added to the obtained ILinwater, and the mixturewas stirred at roomtemperature for 72 h untilthe anion-exchange process was done. The water was removed withrotary evaporator and the by-product salt of NaBr was removed byfiltration after addition of methanol. Finally, salicylate based IL as ayellow liquid was dried under vacuum
1-butyl-3-methylimidazolium 1-aminocyclopentanecarboxylate[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
In water; at 40℃; for 2h;
Synthesis of 1-butyl-3-methylimidazole 1-aminocyclopentanecarboxylate.In a round bottom flask, 52.56 g (0.24 mol) of 1-butyl-3-methylimidazole bromide was added,34.8 g (0.27 mol) of an aqueous solution of <strong>[52-52-8]1-aminocyclopentanecarboxylic acid</strong> was added, stirred at 40 C for 2 hours, extracted three times with dichloromethane,The methylene chloride solution was washed three times with distilled water, then dried over anhydrous magnesium sulfate overnight, the solvent was distilled off under reduced pressure,And then under reduced pressure at 100 C / 0.1 mmHg for 1 hour to obtain the target product.
With 1-hexene; dihydrogen peroxide; at 25℃; for 4h;
General procedure: A mixture of the appropriate imidazolium bromide (0.2 mol) and hex-1-ene (30 mL) was stirred in a flask, and a mixture of the appropriate protonic acid (0.2 mol) and H2O2 (0.1 mol) was added dropwise at room temperature (25 C). After the appropriate time (Table 1), the liquid was placed in a separatory funnel and the oil phase was removed. The aqueous phase was washed with portions of CH2Cl2 (50mL) until it was colorless. Residual H2O in the product was removed by azeotropic distillation with cyclohexane. For [BzMim]PF6 (Table 1,entry 18), which has low water solubility, post-processing required only distillation and desiccation of the oil phase.
The 1.0 muM of 1 - butyl -3 - methyl imidazole pressure concentrated water for 500 ml dissolved in water, added under mixing 1.0 muM four ammonium borofluoride, stirring at room temperature the reaction 24 hours.The obtained mixed solution is added into the 400 ml of dichloromethane, transferred to a separatory funnel, adding 100g sodium nitrate, shock, static, layered is in the upper layer of the organic phase, the aqueous phase is lower; will be discharged from the lower aqueous phase, the organic phase again by adding 500 ml of water and 150g sodium nitrate, shock, static, layered, the lower aqueous phase discharge, repeat the cleaning operation 1 time; at this moment detecting organic non-bromine ion and ammonium ions, by vacuum and steaming and get to the colorless transparent liquid product, yield 92.0%.
General procedure: To a solution of the crude 1-butyl-3-methylimidazoliumbromide, obtained from the above reactions,in acetone (70 mL) was added hexafluorophosphoric acid (10.90 g,100.0 mmol). The reaction mixture was stirred for 24 h at room temperature. The resulting mixture was filtered. Evaporation of the solvent under reduced pressure afforded the corresponding 1-Butyl-3-methylimidazolium hexafluorophosphate. Same procedure was used except that trifluoro methane sulphonic acid (15.08 g,100.0 mmol) was used instead of hexafluorophosphoric acid. The resulting mixture was filtered. Evaporation of the solvent under reduced pressure afforded the corresponding imidazolium trifluromethanesulphonate.1-Butyl-3-methylimidazolium tetrafluoroborate was also prepared using the same procedure as above except that tetrafluoro boric acid (15.08 g, 100.0 mmol) was used in place of hexafluorophosphoric acid. Progress of the reaction was measured by TLC. Completion of the reaction was confirmed by 1HNMR.
[Bmim]Br (0.03 mol) and potassium acetate were weighed at the molar ratio of 1:1 and dissolvedin methanol. The reaction lasted for 8 h at 25 °C, 10 mL ether was added after reaction and thewhite precipitate was removed by filtration. The filtrate was evaporated for 1 h at 55 °C and driedin the vacuum oven at 70 °C for 24 h to obtain ionic liquid [Bmim][CH3COO]. [Bmim][HCOO] and[Bmim]OH can be prepared by changing the above-mentioned potassium acetate into potassiumformate and sodium hydroxide, respectively.
With hydrogenchloride In 1,4-dioxane; lithium hydroxide monohydrate; N,N-dimethyl-formamide at 120℃; for 72h; Sealed tube;
2.2. Synthesis of [BMI]2[H2TBAPy] (1)
In detail, a mixture of H4TBAPy (0.015 mmol) and [BMI]Br (1 mL)was dissolved in 3.75 mL of DMF/dioxane/H2O/(1/1/1) and 10 μL ofconcentrated HCl (0.116 mmol) and then sealed in a 25 mL Teflonlinedstainless steel vessel. The vial was heated at 120 C for 72 h and thencooled to room temperature at a rate of 5 Ch 1. Yellow block crystals of1 were obtained in high yields (~95%). Elemental analysis calcd (%) forC60H54O8N4 (959.09): C 75.14, H 5.68, N 5.84. found: C 77.36, H 6.75, N6.48.