270
N.G. Khaligh et al. / Journal of Molecular Liquids 259 (2018) 260–273
Table 4
Comparison of the results obtained for the synthesis of 3a in the presence of BBSI-Cl and BBSI-HSO
4
with those afforded using some of the other ionic liquids.
Entry
Catalyst
Catalyst loading (%)
Temperature (°C)/solvent
Time (min)
Yield (%)
Ref.
1
2
3
4
5
6
(THA)(HSO
4
)
2
r.t./solvent-free
Microwave (560 W)/EtOH
r.t./MeOH
r.t./EtOH
r.t./MeCN
10
5
180
60
45
30
90
95
90
97
96
93
[45]
[46]
[47]
[48]
[42]
[49]
[n-Pr
2
NH
2
][HSO
4
]
10
10
5
5
150
Sulfamic acid
[hmim][HSO
SuSA
4
]
Aminosulfonic acid
Ultrasound (25KHz, 250 W)/
EtOH & H
r.t./solvent-free
r.t./[omim][PF
50/solvent-free
r.t./solvent-free
2 2
O (N atm)
7
8
9
[bmim][BF
In(OTf)
BBSI-Cl
4
] or [bmim][PF
6
]
2 mL
5
2 mL
1.5 mL
270
15
20
87
90
91
95
[49]
[50]
This work
This work
3
6
]
10
BBSI-HSO
4
20
4
(THA)(HSO ) = tris(hydroxymethyl)methane ammonium hydrogen sulfate; SuSA = Succinimide sulfonic acid.
solvent was removed under vacuum evaporation. The resulting color-
less liquid was weighed 0.83 g (98%) after drying and had the following
properties: IR (KBr): νmax = 3401, 3144, 2926, 2854, 1626, 1579, 1548,
phases; the upper phase was decanted and excess of solvent was re-
moved under vacuum evaporation. The resulting yellow viscous liquid
was weighed 1.06 g (97%) after drying and showed the following prop-
erties: IR (KBr): νmax = 3500–3350, 3151, 2878, 1677, 1580, 1548,
−
1 l
1
(
2
1
=
455, 1408, 1116, 1048, 995, 878, 758, 635, 614, 588 cm ; H NMR
600 MHz, DMSO d ) δ = 9.16 (s, 2H), 7.79 (dd, J = 1.5 and 1.5 Hz,
H), 7.68 (dd, J = 1.6 and 1.4 Hz, 2H), 4.26 (t, J = 5.9 Hz, 4H, NCH ),
.81–1.77 (m, 4H, NCH CH ) δ
) ppm; 13C NMR (150 MHz, DMSO d
135.6, 122.4, 120.4, 48.1, 26.7 ppm; MS(ESI) m/z: calcd for
−
1
l
6
1454, 1409, 1143, 1087, 1017, 861, 751, 620, 568 cm ; H NMR
(600 MHz, DMSO d ) δ = 14.32 (br s, 2H), 9.11 (s, 2H), 7.77 (dd, J =
1.6 and 1.5 Hz, 2H), 7.66 (dd, J = 1.6 and 1.4 Hz, 2H), 4.26 (t, J =
5.7 Hz, 4H, NCH ), 1.80–1.77 (m, 4H, NCH CH
–) ppm; 13C NMR
(150 MHz, DMSO d ) δ = 135.8, 122.5, 120.4, 48.1, 26.7 ppm; MS(ESI)
m/z: calcd for C10
calcd for C10
2
6
2
2
6
2
2
2
+
C
C
10
H
15
N
4
O
6
S
2
: 351.0, found: 351.2 and MS(ESI) m/z: calcd for
6
+
+
10
H
17
N
4
O
6
S
2
: 353.0, found: 353.2.
H
15
N
4
O
6
S
2
: 351.0, found: 351.2 and MS(ESI) m/z:
+
17 4 6 2
H N O S : 353.0, found: 353.2.
3
.5. Typical synthesis of 1,1′-butylenebis(3-sulfo-3H-imidazol-1-ium) hy-
3.6. Physical and spectral data of some products
,4-bis(di(1H-indol-3-yl)methyl)benzene (3h): Mp = 245–247 °C,
drogen sulfate (BBSI-HSO
4
)
1
Neat sulfuric acid (0.196 g, 2 mmol) was dropwise added to BBSI-Cl
0.85 g, 2 mmol) in dry CH Cl (2 mL). The reaction mixture was stirred
Lit. Mp = 246.5–248 °C [55]; FTIR (KBr) ν
max
= 3408, 3051, 1615,
1455, 1417, 1337, 1215, 1092, 1010, 738 cm−1; H NMR (400 MHz,
1
(
2
2
at 50 °C for 6 h under a continuous flow of nitrogen to remove the hy-
CDCl ) δ = 7.40 (d, J = 7.6 Hz, 4H),7.18 (s, 4H), 7.15(t, J = 7.6 Hz,
3
drogen chloride gas produced during the reaction which formed two
4H), 7.08–7.05 (m, 8H), 6.67 (s, 4H), 5.79 (s, 4H), 5.69 (s, 2H) ppm;
13
C NMR (100 MHz, CDCl
21.7, 119.9, 119.2, 118.9, 111.4, 39.9 ppm; Anal. Calcd. for C40
C, 84.78; H, 5.34; N, 9.89; Found: C, 84.73; H, 5.39; N, 9.86; HRMS
3
) δ = 141.5, 136.5, 128.6, 127.0, 123.8,
1
30 4
H N :
Table 5
−
1
Comparison of result obtained for the synthesis of 3,3′-(4-chlorophenylmethylene)bis
(ESI): Calcd. For [M − H]
40 29 4
C H N : 565.2398; Found 565.2378. H
NMR and 13C NMR were in agreement with that published in the litera-
ture [38].
(
1H-indole) in the presence of some sulfonic-functionalized ionic liquid containing mono-
a
4
and di- cationic nucleus with BBSI-Cl and BBSI-HSO .
Entry
1
IL as solvent-catalyst
Abbreviation
PiS-Cl
Yield (%)
68
3,3′-((4-methylphenyl)methylene)bis(5-bromo-1H-indole) (3j): Mp
210–212 °C;, Lit. Mp = 212–214 °C [56]; FTIR (KBr) νmax = 3421,
=
3
1
024, 2922, 2864, 1602, 1591, 1514, 1475, 1448, 1342, 1284, 1201,
170, 1110, 835, 752, 732 cm ; H NMR (400 MHz, CDCl ) δ = 7.94
3
−1 1
2
PzS-Cl
62
(
(
s, 2H), 7.46 (d, J = 1.6 Hz, 2H), 7.24 (d, J = 7.6 Hz, 2H), 7.19–7.05
m, 6H), 6.58 (d, J = 1.6 Hz, 2H), 5.68 (s, 1H), 2.31 (s,3H) ppm; 13
) δ = 140.1, 136.0, 135.4, 129.2, 128.8, 128.4,
25.0, 124.9, 122.4, 119.4, 112.8, 39.6, 21.2 ppm; Anal. Calcd. for
C
NMR (100 MHz, CDCl
3
3
4
5
PzPS-Cl
DSI-Cl
74
62
67
1
C
5
24
H
18Br
2 2
N : C, 58.33; H, 3.67; N, 5.67; Found: C, 58.29; H, 3.65; N,
1
13
.61. H NMR and C NMR were in agreement with that published in
the literature [56].
DSI-HSO
DSBI-Cl
4
3,3′-((furan-2-yl)methylene)bis(5-bromo-1H-indole) (3n): Mp =
81–183 °C; FTIR (KBr) νmax = 3410, 2932, 2825, 1625, 1581, 1510,
1
1
7
2
1
1
480, 1451, 1442, 1340, 1290, 1205, 1172, 1105, 1045, 920, 835, 790,
6
64
−1 1
52, 732 cm ; H NMR (400 MHz, CDCl
H), 6.91 (s, 2H), 6.83–6.79 (m, 5H), 6.72 (s, 1H), 6.27 (d, J = 4.0 Hz,
H), 5.81 (s, 1H) ppm; 13C NMR (100 MHz, CDCl
) δ = 160.2, 135.7,
31.0, 128.6, 127.9, 124.2, 113.6, 113.5, 112.8, 110.8, 83.4, 44.4 ppm;
13Br O: C, 48.96; H, 2.54; N, 8.16; Found: C,
8.91; H, 2.50; N, 8.11.
1,4-bis(di(5-bromo-1H-indol-3-yl)methyl)benzene (3p): Mp = 210
C (dec.), Lit. Mp = 210 °C (dec.) [39]; FTIR (KBr) νmax = 3400, 3050,
3
) δ = 7.94 (s, 2H), 7.26 (m,
3
7
8
BBSI-Cl
76
96
Anal. Calcd. for C21
4
H
2 2
N
BBSI-HSO
4
°
−
1
1
2
840, 1679, 1454, 1330, 1217, 1090, 1012, 558 cm
; H NMR
a
(400 MHz, CDCl
7.09 (s, 4H), 6.39 (s, 4H), 5.64 (s, 2H) ppm; C NMR (100 MHz,
) δ = 8.07 (s, 4H), 7.44 (s, 4H), 7.27–7.18 (m, 8H),
Reaction conditions: 4-chlorobenzaldehyde (1d) (2.0 mmol), indole (4.0 mmol), IL
3
13
(
2 mL), reaction time (20 min), room temperature.