8
2
H. Song et al.
1
3
ILs
ILs
2H), 7.387 (d, J = 4.4, 2H), 8.691 (s, 1H). C-NMR
100 MHz, D O): d 12.497, 18.657, 20.846, 27.997,
31.088, 48.771, 49.270, 49.943, 117.964 (JC–F =
HCHO + CO + H O
HOCH COOH
2
2
(
2
HOCH COOH + CH OH
HOCH COOCH + H O
2
3
2
3
2
ionic liquid:
R
(CH2)n
315.1 Hz), 122.177, 122.396, 135.093. Anal. calcd for
C H N O S F : C, 35.12; H, 5.16; N, 6.83. Found: C,
N
N
SO H
3
12 21 2 6 2 3
X
3
5.32; H, 5.33; N, 6.81.
1
IL1: R=CH3,
IL2: R=CH3,
n=3, X=CF SO
3
3
3
IL4: H-NMR (400 MHz, D O): d 1.577 (h, J = 4.8 Hz,
2
n=4, X=CF SO
3
2
H), 1.852 (h, J = 7.8 Hz, 2H), 2.775 (t, J = 7.6 Hz, 2H),
3.718 (s, 3H), 4.076 (t, J = 7.0 Hz, 2H), 7.264 (d,
J = 3.6 Hz, 1H), 7.324 (d, J = 3.6 Hz, 1H), 8.573 (s, 1H).
IL3: R=(CH ) CH , n=4, X=CF SO
2
3
3
3
3
IL4: R=CH3,
IL5: R=CH3,
n=4, X=HSO4
n=4, X=p-(CH )C H SO
3 6 4 3
1
3
C-NMR (100 MHz, D O): d 20.858, 28.041, 35.615,
2
Scheme 1 Carbonylation of HCHO with CO catalyzed by acidic
ionic liquids
48.846, 55.357, 122.079, 123.671, 135.940. Anal. calcd for
C H N O S : C, 30.37; H, 5.10; N, 8.86. Found: C, 29.53;
8 16 2 7 2
H, 5.20; N, 8.78.
1
2
Experimental
IL5: H-NMR (400 MHz, D O): d 1.561 (h, J = 7.7 Hz,
2
2
H), 1.835 (h, J = 7.5 Hz, 2H), 2.227 (s, 3H), 2.774 (t,
J = 7.6 Hz, 2H), 3.703 (s, 3H), 4.050 (t, J = 7.0 Hz, 2H),
.192 (d, J = 6.4 Hz, 2H), 7.244 (d, J = 3.6 Hz, 1H),
7.304 (d, J = 3.6 Hz, 1H), 7.508 (d, J = 8.4 Hz, 2H),
2
.1 Ionic Liquids Preparation
7
The BAILs were prepared according to the similar proce-
dure [16]. A stoichiometric amount of 1,4-butane or 1,3-
propane sultone was added dropwise to a solution of
N-alkyl imidazole in toluene, and then the mixture was
stirred at 60 °C for 8 h. The obtained white powdery solid
was filtered, washed with toluene and dried in vacuo to
afford pure 1-alkyl-3-(alkyl-4 or 3-sulfonate) imidazolium
betaine. Then the zwitterion and corresponding acid were
mixed in a molar ratio of 1:1 in anhydrous toluene, and
stirred magnetically at 60 °C for 8 h, followed by washing
1
3
8.543 (s, 1H). C-NMR (100 MHz, D O): d 20.386,
2
20.823, 27.991, 35.534, 48.790, 49.952, 122.031, 123.528,
125.232, 129.341, 135.787, 139.342, 142.353. Anal. calcd
for C H N O S : C, 46.02; H, 5.66; N, 7.16. Found: C,
1
5 22 2 6 2
45.96; H, 5.72; N, 7.15.
2.2 Catalytic Reactions
1
with toluene and drying in vacuo to obtain the final ILs. H
The carbonylation of HCHO with CO was carried out using
a 100 mL autoclave with a Teflon liner and a magnetic
stirrer. 1,3,5-trioxone was used as a source of HCHO. In a
typical experiment, 1,3,5-trioxane (22.3 mmol), BAILs
(26.8 mmol), water (134.0 mmol) and solvent (20 mL)
were charged into the reactor, and then CO ([99.95%) was
introduced with initial pressure of 3.0–8.0 MPa at room
temperature after flushed three times with CO. The reac-
tions were performed at 100–180 °C for 2–10 h. After
reaction, the autoclave was cooled to room temperature and
depressurized. For the esterification, excess methanol
(67 mmol) was added into the autoclave and refluxed for
2 h at 80 °C to esterify the glycolic acid into MG. The final
products were identified and quantitatively analyzed by gas
chromatography/mass spectrometry (GC/MS) (Agilent
7890A/5975C) and GC (Agilent 6890 equipped with a SE-
54 capillary column), respectively. A known amount of n-
hexane was added as an internal standard to the product
mixture before the GC analysis. Unconverted HCHO was
detected as dimethoxymethane. For the recycling of cata-
lyst, dimethoxymethane, methanol and products were
separated from the reaction system by distillation under
vacuo of 10 mmHg at 90 °C after carbonylation and
esterification, the IL and sulfolane was recovered and
reused directly for a new batch reaction.
1
NMR spectra and C NMR spectra in D O were recorded
3
2
on an Inova-400 MHz instrument using tetramethylsilane
(
TMS) as internal standard. Elementary analyses were
obtained with an elementar Vario EL cube instrument.
1
IL1: H-NMR (400 MHz, D O): d 2.231 (h, J = 7.3 Hz,
2
2
H), 2.837 (t, J = 7.6 Hz, 2H), 3.806 (s, 3H), 4.277 (t,
J = 7.0 Hz, 2H), 7.358 (d, J = 3.6 Hz, 1H), 7.434 (d,
1
3
J = 3.6 Hz, 1H), 8.667 (s, 1H). C-NMR (100 MHz,
D O): 24.991, 35.601, 47.099, 47.630, 117.970
JC–F = 315.1 Hz), 122.097, 123.673, 136.090. Anal. calcd
for C H N O S F : C, 27.12; H, 3.70; N, 7.91. Found: C,
d
2
(
8
13 2 6 2 3
2
7.46; H, 3.08; N, 7.92.
1
IL2: H-NMR (400 MHz, D O): d 1.293 (h, J = 7.8 Hz,
2
2
H), 1.564 (h, J = 7.5 Hz, 2H), 2.482 (t, J = 7.6 Hz, 2H),
.433 (s, 3H), 3.781 (t, J = 7.2 Hz, 2H), 6.980 (d,
3
J = 3.6 Hz, 1H), 7.032 (d, J = 4.0 Hz, 1H), 8.255 (s, 1H).
3
1
C-NMR (100 MHz, D O): d 20.912, 28.077, 35.616,
2
4
1
2
8.847, 50.060, 118.046 (JC–F = 315.1 Hz), 122.113,
23.608, 135.825. Anal. calcd for C H N O S F : C,
9
15 2 6 2 3
9.35; H, 4.10; N, 7.61. Found: C, 29.32; H, 4.21; N, 7.56.
1
IL3: H-NMR (400 MHz, D O): d 0.797 (t, J = 7.4 Hz,
2
3
1
H), 1.180 (m, J = 7.4 Hz, 2H), 1.640 (h, J = 7.8, 2H),
.733 (h, J = 7.3, 2H), 1.909 (h, J = 7.4, 2H), 2.822 (t,
J = 7.8, 2H), 4.079 (t, J = 7.0, 2H), 4.128 (t, J = 7.0,
1
23