Quaternary Ammonium Ionic Liquids as Bi-functional Catalysts
341
1
3.05 (s, 6H), 3.26–3.30 ppm (t, J = 8.4, 4H). C NMR
3
2
.2 Preparation and Characterization of the Quaternary
Ammonium ILs
(D O, 400 MHz) d = 13.37, 19.64, 22.33, 24.44, 25.93,
2
2
6.50, 26.65, 44.32, 51.10, 58.83, 64.39, 64.51 ppm. IR
0
0
Inspired by the synthesis of 6-(N ,N -dimethylamino)-
-(N,N,N-trimethylammonium)hexane iodide ([N111,6N11]I)
(KBr): 2940, 2863, 2822, 2778, 1487, 1468, 1382, 1260,
-
1171, 1100, 1040, 1006, 910, 843, 737, 536 cm .
1
1
1
mentioned in the literature [33, 34], [N112,6N11]Br was
synthesized as follows: TMHDA (40 mmol), bromoeth-
ane (20 mmol) and ethanol (50 mL) were charged into a
sealed reactor with magnetic stirring and reacted at room
temperature for 48 h. Then, the ethanol was removed with
rot-vap and 30 mL acetone was added, and the bi-quater-
nary ammonium salt as a white precipitate formed imme-
diately. After filtration, diethyl ether was added to the
filtrate to precipitate the product of [N112,6N11]Br. The
product was purified by recrystallization from acetone/
diethyl ether (1:2) and a white hygroscopic powder was
obtained.
[N116,6N11]Br, H NMR (CD COCD , 400 MHz): d =
3
3
0.88–0.91 (t, J = 6.8, 3H), 1.34–1.54 (m, 12H), 2.17 (s, 6H),
2.25–2.28 (t, J = 6.8, 2H), 3.41 (s, 6H), 3.67–3.74 ppm (m,
1
4H). C NMR (D O, 400 MHz) d = 13.72, 22.27, 25.63,
25.85, 26.31, 26.55, 30.91, 44.19, 51.07, 58.72, 64.35,
64.51 ppm. IR (KBr): 2933, 2860, 2821, 2778, 1487, 1467,
1379, 1260, 1160, 1100, 1041, 1011, 931, 844, 729,
3
2
-
1
535 cm
.
1
[N114,6N11]Cl, H NMR (D O, 400 MHz): d = 0.97–1.01
2
(t, J = 7.6, 3H), 1.41–1.49 (m, 8H), 1.78–1.86 (m, J = 7.8,
4H), 2.16 (s, 6H), 2.24–2.27 (t, J = 7.0, 2H), 3.45 (s, 6H),
3
3.71–3.77 ppm (m, J = 6.3, 4H).
1
C NMR (D O,
2
[
N114,6N11]Br, [N114,6N11]I, [N116,6N11]Br was prepared
with a similar procedure but processed at 60 °C for 12 h.
N114,6N11]Br and [N114,6N11]I as white hygroscopic pow-
der were obtained. [N116,6N11]Br was a viscous liquid.
N114–C –N ]Br was a white powder and obtained as the
400 MHz) d = 13.37, 19.64, 22.33, 24.43, 25.92, 26.49,
26.66, 44.30, 51.07, 58.81, 64.40, 64.52 ppm. IR (KBr):
2940, 2863, 2822, 2778, 1487, 1468, 1383, 1261, 1160, 1100,
[
-
1
1040, 1005, 910, 843 cm
1
.
[
[N114,6N11]I, H NMR (CD COCD , 400 MHz): d =
6
114
2
3
3
byproduct of [N114,6N11]Br.
N114,6N11]Cl was a viscous liquid and also prepared
0.98–1.01(t, J = 7.2, 3H), 1.41–1.49 (m, 8H), 2.12 (s, 6H),
[
2.18–2.22 (t, J = 6.8, 2H), 3.37 (s, 6H), 3.63–3.69 ppm (m,
3
1
with a similar procedure but processed at 120 °C for 24 h.
4H). C NMR (D O, 400 MHz) d = 13.40, 19.64, 22.34,
2
For the synthesis of [N114,6N11]BF [35], the silver tetra-
24.44, 25.90, 26.51, 26.67, 44.32, 51.14, 58.79, 64.41,
4
fluoroborate solution was titrated with [N114,6N11]Br solution
in water against a silver wire electrode. Precipitated silver
bromide was removed by filtration and water was removed at
64.53 ppm. IR (KBr): 2939, 2862, 2820, 2778, 1482, 1466,
1
-
1380, 1260, 1157, 1099, 1039, 1008, 904, 843, 733 cm
1
.
[N114,6N11]BF , H NMR (D O, 400 MHz): d = 0.96–
4
2
7
0 °C under reduced pressure. [N114,6N11]BF was checked
1.00 (t, J = 7.4, 3H), 1.40–1.49 (m, 8H), 1.80–1.88 (m, 4H),
4
for residual bromide using aqueous AgNO , and no AgBr
2.15 (s, 6H), 2.21–2.25 (t, J = 6.8, 2H), 3.25 (s, 6H),
3
1
3.47–3.51 ppm (t, J = 8.6, 4H). C NMR (D O, 400 MHz)
3
precipitate was detectable.
2
For the synthesis of [N114,6N11]NTf [36], the CH Cl
2
d = 13.35, 19.66, 22.30, 24.31, 24.44, 25.65, 25.74, 43.16,
51.08, 58.14, 64.38, 64.49 ppm. IR (KBr): 2939, 2863, 2821,
2778, 1635, 1468, 1383, 1115, 1038, 843, 739, 533,
2
2
solution of [N114,6N11]Br is reacted with 1.1 equivalence of
lithium bis(trifluoromethylsulfonyl)imide (LiNTf ) over-
2
-
1
night and the organic layer was repeatedly washed with
water to remove bromide. CH Cl and water are removed
483 cm
.
1
2
2
[N114,6N11]NTf , H NMR (CD COCD , 400 MHz): d =
2
3
3
under vacuum and [N114,6N11]NTf was obtained.
2
0.97–1.01 (t, J = 7.4, 3H), 1.41–1.48 (m, 8H), 1.85–1.93 (m,
4H), 2.15 (s, 6H), 2.21–2.25 (t, J = 6.8, 2H), 3.29 (s, 6H),
13
Before each physicochemical property test, the prepared
2
-
-3
ILs were dried at 85 °C and 10 –10 mbar for 12 h. And
the water content for all the ILs was lower than 200 ppm.
3.49–3.54 ppm (t, J = 8.6, 4H). C NMR (CD COCD ,
3
3
400 MHz) d = 13.76, 20.27, 23.12, 25.08, 26.82, 27.40,
27.98, 45.57, 51.31, 59.99, 64.93, 65.12, 120.89,
206.12 ppm. IR (KBr): 2942, 2866, 2818, 2779, 1486, 1470,
1
[
m, 7H), 1.47–1.51 (m, 2H), 1.74–1.78 (m, 2H), 2.19 (s, 6H),
N112,6N11]Br, H NMR (D O, 400 MHz) d = 1.32–1.39
2
(
2
3
.32–2.36 (t, J = 7.4, 2H), 3.03 (s, 6H), 3.25–3.29 (m, 2H),
1352, 1331, 1226, 1194, 1138, 1057, 789, 740, 654, 617, 571,
-1
514 cm .
1
.35–3.40 ppm (q, J = 7.4, 2H). C NMR (D O, 400 MHz)
3
2
1
d = 8.05, 22.32, 25.97, 26.56, 26.72, 44.33, 50.50, 58.84,
[N114–C –N ]Br , H NMR (D O, 400 MHz): d =
6 114 2
2
6
1
5
0.12, 64.07 ppm. IR (KBr): 2941, 2861, 2823, 2778, 1487,
0.94–0.98 (t, J = 7.4, 6H), 1.36–1.43 (m, 8H), 1.72–1.78 (m,
1
3
467, 1397, 1259, 1172, 1099, 1039, 1023, 928, 843, 815,
-
8H), 3.06 (s, 12H), 3.28–3.32 ppm (t, J = 8.2, 8H).
C
1
13 cm
.
NMR (D O, 400 MHz) d = 13.43, 19.69, 22.42, 24.51,
2
1
[
N114,6N11]Br, H NMR (D O, 400 MHz) d = 0.94–0.98
25.76, 51.16, 64.39, 64.54 ppm. IR (KBr): 3011, 2960, 2865,
2
(
t, J = 7.4, 3H), 1.36–1.41 (m, 6H), 1.48–1.52 (m, 2H),
.71–1.77 (m, 4H), 2.19 (s, 6H), 2.33–2.36 (t, J = 7.6, 2H),
1487, 1465, 1251, 1164, 1067, 965, 935, 910, 809,
-
737 cm .
1
1
123