Peralkylated Imidazoles as Ionic Liquids
3J(H,H)=6.6 Hz, 6H; (CH3)2CH,), 1.53–1.65 (m, 2H; NCH2CH2), 2.09
Batch Procedure for the Synthesis of 1-Hexyl-2-Isopropyl-
(s, 3H; CCH3), 2.14 (s, 3H; CCH3), 2.86–2.99 (1H, CH, m), 3.70 ppm
3,4,5-Trimethylimidazolium Iodide ([C6isoC3m3im][I], 6h)
3
(t, J(H,H)=8.0 Hz, 2H; NCH2); 13C NMR (75 MHz, CDCl3, 258C, TMS):
In an oven-dried flask of 100 mL, 1-hexyl-2-isopropyl-4,5-dimethyl-
imidazole (20 mmol, 4.44 g) was dissolved in dry CH3CN (40 mL).
The solution was cooled to 08C and MeI (60 mmol, 8.47 g) was
added dropwise at 08C. The reaction mixture was allowed to stir at
room temperature for 20 h. When the reaction was completed, the
solvent and residual MeI were removed in vacuo. The resulting
yellow oil was dissolved in 20 mL CH3CN and washed 3 times with
20 mL hexanes. The solvent was removed in vacuo, yielding 6.99 g
(96%) of a yellow oil.
d=8.92 (CH3C), 12.73 (CH3C), 13.99 (CH3CH2), 22.28 ((CH3)2CH),
22.57 (CH2), 26.05 (CH2), 26.57 (NCH2CH2), 31.27 (CH2), 31.48 (CH),
43.30 (NCH2), 120.19 (CCH3), 131.32 (CCH3), 150.71 ppm (CCH); IR
(ATR): n˜ =1085, 1312, 1433, 2926, 2960 cmÀ1; MS (ES): m/z [%]:
223.3 (100) [M+H+]; yield: 40%, yellow oil.
Batch Procedure for the Synthesis of 1-Ethyl-2-Isopropyl-
3,4,5-Trimethylimidazolium Iodide ([C2isoC3m3im][I], 6d)
In an oven-dried flask of 100 mL, 1-ethyl-2-isopropyl-4,5-dimethyl-
imidazolium (20 mmol, 3.32 g) was dissolved in dry CH3CN (40 mL).
The solution was cooled to 08C and MeI (60 mmol, 8.47 g) was
added dropwise at 08C. The reaction mixture was allowed to stir at
room temperature for 8 h. When the reaction was completed, the
solvent and residual MeI were removed in vacuo. The resulting
yellow solid was recrystallized in dry acetone to furnish transparent
to white crystals (1st crop: 75%, 2nd crop: 11%). Residual solvent
was removed in a high vacuum.
Characterisation of Products 6e–h
1
1-Hexyl-3,4,5-Trimethylimidazolium Iodide [C6m3im][I] (6e): H NMR
(300 MHz, CDCl3, 258C, TMS): d=0.89 (t, 3J(H,H)=6.6 Hz, 3H;
CH2CH3), 1.32–1.34 (m; 6H; (CH2)3CH3), 1.82–1.92 (m, 2H; NCH2CH2;
m), 2.27 (s, 3H; CCH3), 2.29 (s, 3H; CCH3), 3.95 (s, 3H; NCH3), 4.15
3
(2H, t, J(H,H)=7.4 Hz, 2H; NCH2), 9.96 ppm (s, 1H; C2H); 13C NMR
(75 MHz, CDCl3, 258C, TMS): d=8.90 (CH3C4, CH3C5), 14.00
(CH3(CH2)5), 22.46 (CH2), 26.05 (CH2), 29.93 (NCH2CH2), 31.16 (CH2),
34.54 (NCH3), 47.47 (NCH2), 126.36 (CH3C), 127.38 (CH3C),
Characterisation of Products 6a–d
1-Ethyl-3,4,5-Trimethylimidazolium Iodide [C2m3im][I] (6a): 1H NMR
(300 MHz, CDCl3, 258C, TMS): d=1.59 (t, 3J(H,H)=7.4 Hz, 3H;
NCH2CH3), 2.26 (s, 3H; CH3C), 2.27 (s, 3H; CH3C), 3.94 (s, 3H; NCH3),
4.21 (q, 3J(H,H)=7.4 Hz, 2H; NCH2CH3), 10.13 ppm (s, 1H; CH);
13C NMR (75 MHz, CDCl3, 258C, TMS): d=8.76 (CH3C), 8.79 (CH3C),
15.34 (CH3CH2), 34.41 (NCH3), 42.70 (CH2), 126.30 (CH3C), 127.34
(CH3C), 134.92 ppm (CH); IR (ATR): n˜ =1199, 1241, 1572, 1634,
3032 cmÀ1; MS (ES): m/z [%]: 139.3 (100) [M+H+]; yield: 87%,
transparent crystals.
135.21 ppm (CH); IR (ATR): n˜ =1202, 1452, 1570, 1633, 2928 cmÀ1
MS (ES): m/z [%]: 195.3 (100) [M+H+]; yield: 99%, yellow oil.
;
1-Hexyl-2,3,4,5-Tetramethylimidazolium Iodide [C6C1m3im][I] (6 f):
1H NMR (300 MHz, CDCl3, 258C, TMS): d=0.89 (t, 3J(H,H)=6.6 Hz,
3H; CH2CH3), 1.27–1.44 (m; 6H; (CH2)3CH3), 1.67–1.77 (m, 2H;
NCH2CH2; m), 2.27 (s, 3H; CCH3), 2.28 (s, 3H; CCH3), 2.82 (s, 3H;
C2CH3), 3.81 (s, 3H; NCH3), 4.06 ppm (2H, t, 3J(H,H)=7.4 Hz, 2H;
NCH2); 13C NMR (75 MHz, CDCl3, 258C, TMS): d=9.22 (CH3C), 9.47
(CH3C), 12.43 (CH3C2), 14.00 (CH3(CH2)5), 22.41 (CH2), 26.26 (CH2),
29.79 (NCH2CH2), 31.18 (CH2), 33.77 (NCH3), 46.29 (NCH2), 125.03
(CH3C), 126.25 (CH3C), 142.02 ppm (C2CH3); IR (ATR): n˜ =727, 920
1373, 1444, 1533, 1648, 2929 cmÀ1; MS (ES): m/z [%]: 209.3 (100)
[M+H+]; yield: 99%, yellow oil.
1-Ethyl-2,3,4,5-Tetramethylimidazolium Iodide [C2C1m3im][I] (6b):
1H NMR (300 MHz, CDCl3, 258C, TMS): d=1.42 (t, 3J(H,H)=7.4 Hz,
3H; NCH2CH3), 2.27 (s, 6H; CH3C4/5), 2.86 (s, 3H; CH3C2), 3.79 (s, 3H;
NCH3), 4.17 ppm (q, 3J(H,H)=7.4 Hz, 2H; NCH2CH3); 13C NMR
(75 MHz, CDCl3, 258C, TMS): d=9.04 (CH3C4/5), 9.39 (CH3C4/5), 12.44
(CH3C2), 15.33 (CH3CH2), 33.71 (NCH3), 41.52 (CH2), 124.80 (C4/5),
126.25 (C4/5), 142.10 ppm (C2); IR (ATR): n˜ =1198, 1456, 1572, 1634,
2358, 3032 cmÀ1; MS (ES): m/z [%]: 153.3 (100) [M+H+]; yield:
89%, transparent crystals.
2-Ethyl-1-Hexyl-3,4,5-Trimethylimidazolium Iodide [C6C2m3im][I]
(6g): 1H NMR (300 MHz, CDCl3, 258C, TMS): d=0.90 (t, 3J(H,H)=
6.9 Hz, 3H; CH2CH3), 1.26–1.44 (m; 6H; (CH2)3CH3), 1.34 (t, J(H,H)=
3
7.7 Hz, 3H; CCH2CH3), 1.69–1.80 (m, 2H; NCH2CH2; m), 2.27 (s, 3H;
3
1,2-Diethyl-3,4,5-Trimethylimidazolium Iodide [C2C2m3im][I] (6c):
1H NMR (300 MHz, CDCl3, 258C, TMS): d=1.34 (t, 3J(H,H)=7.7 Hz,
CCH3), 2.29 (s, 3H; CCH3), 3.19 (q, J(H,H)=7.7 Hz, 2H; C2CH2CH3),
3.83 (s, 3H; NCH3), 4.04 ppm (2H, t, 3J(H,H)=8.0 Hz, 2H; NCH2);
13C NMR (75 MHz, CDCl3, 258C, TMS): d=9.36 (CH3C), 9.56 (CH3C),
12.35 (CH3CH2C2), 13.94 (CH3(CH2)5), 18.49 (CH3CH2C2), 22.35 (CH2),
26.23 (CH2), 30.38 (NCH2CH2), 31.15 (CH2), 33.64 (NCH3), 46.19
(NCH2), 125.14 (CH3C), 126.57 (CH3C), 145.90 ppm (CCH2); IR (ATR):
n˜ =726, 1081, 1452, 1528, 2929 cmÀ1; MS (ES): m/z [%]: 223.3 (100)
[M+H+]; yield: 99%, yellow oil.
3
3H; CCH2CH3), 1.46 (t, J(H,H)=7.4 Hz, 3H; NCH2CH3), 2.28 (s, 6H;
CH3C), 3.22 (q, 3J(H,H)=7.7 Hz, 2H; CCH2CH3), 3.81 (s, 3H; NCH3),
4.16 ppm (q, 3J(H,H)=7.4 Hz, 2H; NCH2CH3); 13C NMR (75 MHz,
CDCl3, 258C, TMS): d=6.99 (CH3C), 7.33 (CH3C), 10.32 (CH3CH2C),
13.80 (NCH2CH3), 16.47 (CH2C), 31.33 (NCH3), 39.30 (NCH2), 122.86
(CH3C), 124.47 (CH3C), 143.89 ppm (CCH2); IR (ATR): n˜ =1090, 1259,
1448, 1529, 1648, 2975 cmÀ1; MS (ES): m/z [%]: 167.3 (100) [M+H+
]; yield: 99%, reddish oil.
1-Hexyl-2-Isopropyl-3,4,5-Trimethylimidazolium
Iodide
[C6isoC3m3im][I] (6h): 1H NMR (300 MHz, CDCl3, 258C, TMS): d=
0.87–0.89 (m, 3H; CH2CH3), 1.28–1.48 (m; 6H; (CH2)3CH3), 1.52–1.77
1-Ethyl-2-Isopropyl-3,4,5-Trimethylimidazolium Iodide [C2isoC3m3im]
1
3
3
[I] (6d): H NMR (300 MHz, CDCl3, 258C, TMS): d=1.43 (t, J(H,H)=
(m, 2H; NCH2CH2), 1.55 (d, J(H,H)=7.2 Hz, 6H; (CH3)2CH), 2.28 (s,
3
7.2 Hz, 3H; NCH2CH3), 1.55 (d, J(H,H)=7.2 Hz, 6H; (CH3)2CH), 2.30
3H; CCH3), 2.31 (s, 3H; CCH3), 3.60–3.72 (m, 1H; (CH3)2CH), 3.87 (s,
3H; NCH3), 4.10 ppm (2H, t, 3J(H,H)=7.4 Hz, 2H; NCH2); 13C NMR
(75 MHz, CDCl3, 258C, TMS): d=9.50 (CH3C), 9.73 (CH3C), 13.96
(CH3(CH2)5), 19.88 ((CH3)2CH), 22.44 (CH2), 25.36 (CH2), 26.28
(NCH2CH2), 30.61 (CH2), 31.24 (NCH3), 34.29 (CH), 46.18 (CH2),
125.34 (CH3C), 127.24 (CH3C), 147.72 ppm (CCH); IR (ATR): n˜ =746,
1239, 1334, 1454, 1520, 2928 cmÀ1; MS (ES): m/z [%]: 237.3 (100)
[M+H+]; yield: 99%, yellow oil.
(s, 6H; CH3C), 3.66–3.81 (m, 1H; CH), 3.87 (s, 3H; NCH3), 4.26 ppm
(q, 3J(H,H)=7.2 Hz, 2H; NCH2CH3); 13C NMR (75 MHz, CDCl3, 258C,
TMS): d=9.26 (CH3C), 9.63 (CH3C), 15.94 (CH3CH2), 19.91 ((CH3)2CH),
25.35 (CH), 34.06 (NCH3), 41.65 (CH2), 125.18 (CH3C), 127.17 (CH3C),
147.72 ppm (CCH); IR (ATR): n˜ =1088, 1331, 1448, 1521, 1651,
2971 cmÀ1; MS (ES): m/z [%]: 181.3 (100) [M+H+]; yield: 86%,
transparent crystals.
ChemPhysChem 0000, 00, 1 – 13
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