Synthesis of novel phasmidic, gemini-type bisimidazolium salts

Article abstract of DOI:10.1055/s-0030-1260137

New bisimidazolium salts based on pyrogallol with flexible ethyl and p-xylyl spacers and with a series of different counter-ions were prepared. ¹HNMR studies showed a good linear correlation of the chemical shift with the radius of the anion. G

Full text of DOI:10.1055/s-0030-1260137

3032
PAPER
Synthesis of Novel Phasmidic, Gemini-Type Bisimidazolium Salts
P
hasmidic
a
Bisimidaz
o
lium Salts H. Porada,a,b,1 Markus Mansueto,a,1 Sabine Laschat,*a Cosima Stubenrauch,b Frank Giesselmannb
a
Institut für Organische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
Fax +49(711)68564285; E-mail: sabine.laschat@oc.uni-stuttgart.de
b
Received 31 May 2011; revised 8 June 2011
Dedicated to Prof. Dieter Hoppe on the occasion of his 70th birthday
F
Abstract: New bisimidazolium salts based on pyrogallol with flex-
ible ethyl and p-xylyl spacers and with a series of different counter-
ions were prepared. 1H NMR studies showed a good linear
correlation of the chemical shift with the radius of the anion.
RO
N
N
N
N
OR
F
1
81
33
I
I
Cr
(SmA)
2 NTf2
Key words: ionic liquid, heterocycles, substituent effects, spectros-
copy, halogens
F
R = C12H25
N
N
R
N
N
R
Tethered bisimidazole derivatives have recently received
a good deal of attention from two different scientific com-
munities. Such bisimidazoles with either rigid or flexible
spacers have been employed as bridging ligands for
metal-organic frameworks (MOFs), i.e. novel 3D coordi-
nation polymers,2 or as precursors of N-heterocyclic car-
bene (NHC) complexes for applications in catalysis.3–5
Surprisingly little work has been carried out on the syn-
thesis of the corresponding charged species, although
many groups worldwide have utilized imidazolium salts
as ionic liquid crystals.6,7 Tethered bisimidazolium salts
are expected to combine the properties of liquid crystals
and ionic liquids, i.e. self-assembly into mesophases,
anisotropic physical properties, low volatility, low viscos-
ity, thermal stability, adjustable melting points, and tun-
able polarity.6a,8 Therefore they lend themselves to being
used as electrolytes in polymer light-emitting diodes
(PLEDs), ion-conductive materials, organic reaction me-
dia, or self-assembling nanostructured materials.6 In con-
trast to the classical amphiphilic imidazolium-based ionic
liquid crystals, which mainly form bilayer type (SmA),
columnar or cubic mesophases, the introduction of a sec-
ond imidazolium moiety, which is tethered via a flexible
or rigid spacer to the first one, can lead to novel liquid
crystalline phases. This was indeed observed by Bruce
and Shreeve, who studied a series of tethered bisimidazo-
lium salts,9 where fluorination of the tether or side chain
led to novel mesomorphic properties. For example, com-
pound 1, which contains a rigid spacer between the imida-
zolium units, shows an unusual modulated ribbon SmÃ
phase with c2mm symmetry, whereas the corresponding
nonfluorinated analogue shows only isotropic melting
(Figure 1). Gin reported on gemini ionic liquid crystals 2
and 3 where the two imidazolium moieties are tethered via
a flexible alkyl or oligoethyleneglycol spacer.10
2 X
F
2a
2b
X = Br
X = BF4
75 SmA
31 SmA
150I
69 I
Cr
Cr
F
R = C12H25
N
O
N
R
O
N
N
R
2 X
F
3a X = Br
3b X =
Cr 73 SmA
Cr 29 SmA
93 I
50 I
BF4
R = C12H25
Figure 1 Examples for linked bisimidazolium ionic liquid crystals
If there are three flexible chains on each side of an elon-
gated rigid core, then these molecules are called phasmid-
ic compounds.11–13 Previous work by Judeinstein et al.14
revealed that tethered phasmidic liquid crystals such as
compound 4 form nematic phases as long as they carry
o,m,p-tris(alkyloxy)aryl side chains with a chain length of
between six and ten carbon atoms (Figure 2).
RO
OR
N
OR
RO
N
RO
OR
4
Cr 34 N 64
R = C8H17
I
Figure 2 Example of a phasmidic liquid crystal that forms a ne-
matic phase14
We were curious whether or not this nematogenic motif
could be transferred to gemini-type bisimidazolium salts,
thus leading to ionic liquid crystals with nematic me-
sophases, which are quite rare in this class of com-
pounds.15 Here we report on first results in relation to this
goal.
SYNTHESIS 2011, No. 18, pp 3032–3036
x
x.
x
x
.
2
0
1
1
Advanced online publication: 25.07.2011
DOI: 10.1055/s-0030-1260137; Art ID: Z56311SS
© Georg Thieme Verlag Stuttgart · New York

PAPER
Phasmidic Bisimidazolium Salts
3033
The synthesis of the desired bisimidazolium salts started
with the etherification of pyrogallol 5 with bromooctane
in N,N-dimethylformamide at 60 °C with 97% yield ac-
cording to a procedure by Percec (Scheme 1).16 a-Bromi-
nation of 6 was achieved with N-bromosuccinimide at 60
°C in dichloromethane yielding 85% of 7. The C–N bond
formation was accomplished by an Ullmann reaction of 7
with imidazole in N,N-dimethylformamide at 110 °C in
the presence of copper(I) iodide and cesium carbonate in
79% yield.
2 Br
R
2 X
Ar
Ar
N
N
MX
– 2 MBr
N
N
R
N
N
N
N
Ar
Ar
R
MX
9
10
= Ar
99%a
83%a
81%a
99%b
99%b
99%a
99%a
74%a
99%b
99%b
KBF4
KPF6
KSCN
LiNTf2
KI
b
c
d
e
f
C8H17
O
O
C8H17O
OC8H17
HO
OH
C8H17
i
C8H17O
HO
OC8H17
6
Scheme 3 Anion exchange of compounds 9 and 10. Reagents and
5
conditions: a Method A: MeCN, 90 °C, 4 h; b Method B: MTBE–H2O,
r.t.
ii
OC8H17
OC8H17
ture with the desired potassium or lithium salt in good
yields (Scheme 3).
C8H17
O
OC8H17
Br
OC8H17
In agreement with previous publications17 we also ob-
served significant proton resonance upfield shifts in the
1H NMR spectra upon replacement of bromide by bigger
anions. In contrast to similar NMR studies in our group18
we observed not only a shift of the CH of the imidazolium
group but also a shift of the N–CH2 protons adjacent to the
imidazolium unit. Typical spectra of 9 are shown in
Figure 3. The following tendency of d(CH) and d(CH2) is pre-
served for 9·X and 10·X (X = Br, BF4, PF6, SCN, NTf2, I):
Br > I > SCN > BF4 > NTf2 > PF6. Details of the anion-
iii
N
C8H17O
N
8
7
Scheme 1 Synthesis of the N-arylated wing group 8. Reagents and
conditions: (i) BrC8H17, K2CO3, DMF, 60 °C, 4 h, 97%; (ii) NBS,
CH2Cl2, 60 °C, 12 h, 85%; (iii) imidazole, DMF, CuI, Cs2CO3, 110
°C, 5 d, 79%.
The tethered bisimidazolium salts were obtained by reac-
tion of the N-arylated compound 8 with the desired dibro-
mo central unit at 110 °C with 69% yield for 9 and 87%
yield for 10, respectively (Scheme 2).
1
dependent H NMR shifts of compound 10·X are de-
scribed in the Supporting Information.
Br
Br
Ar
Ar
N
N
N
N
N
N
Ar
i
69%
9a
8
2 Br
Br
C8H17
O
OC8H17
= Ar
Br
C8H17O
i
87%
2 Br
Ar
N
N
Figure 3 Lowfield section of the 1H NMR spectra (500 MHz,
CDCl3, r.t.) of the phasmidic salts 9·X with different anions X. In the
lower field, the C–H resonances of the imidazole proton could be ob-
served, whereas in the higher field the adjacent CH2 groups resonate.
For reasons of clarity, only the signals for d(CH) and d(CH2) are shown.
N
N
Ar
10a
Scheme 2 Coupling of the wing group 8 with the central unit.
Reagents and conditions: (i) MeCN, 110 °C, 5 d.
A fairly good relation between the degree of upfield shift
and the anion radius could be observed (Figure 4, SCN
and NTf2 are not included because of the anisotropic
shape of the molecules).19 This suggests that the position
of the anion is close to the CH of the imidazoles and the
bridging atoms next to them.18a
Anion exchange of the phasmidic dibromo compounds
were performed either in acetonitrile at 90 °C or with a
tert-butyl methyl ether–water mixture at room tempera-
Synthesis 2011, No. 18, 3032–3036 © Thieme Stuttgart · New York

3034
J. H. Porada et al.
PAPER
3
1H NMR (500 MHz, CDCl3): d = 7.15 (d, J = 8.9 Hz, 1 H, H6),
6.54 (d, 3J = 9.0 Hz, 1 H, H5), 4.03 (t, 3J = 6.7 Hz, 2 H, OCH2), 3.97
(t, 3J = 6.6 Hz, 2 H, OCH2), 3.93 (t, 3J = 6.5 Hz, 2 H, OCH2), 1.80
(m, 6 H, 3 b-CH2), 1.47 (m, 6 H, 3 g-CH2), 1.38–1.22 (m, 24 H,
CH2), 0.89 (t, 3J = 6.9 Hz, 9 H, CH3).
13C NMR (125 MHz, CDCl3): d = 153.26 (C4), 150.79 (C2), 143.29
(C3), 126.66 (C6), 109.56 (C5), 108.76 (C1), 74.16, 74.04 (C2-
OCH2, C3-OCH2), 69.08 (C4-OCH2), 32.02, 32.01, 31.96, 30.43,
30.39, 29.64, 29.59, 29.50, 29.45, 29.44, 29.41, 26.24, 26.23, 26.20,
22.83, 22.82, 22.81 (CH2), 14.24 (CH3).
+
HRMS (ESI): m/z [M + NH4 ] calcd for C30H57BrNO3: 558.3516;
found: 558.3526.
Anal. Calcd for C30H53BrO3: C, 66.52; H, 9.86. Found: C, 66.23; H,
9.63.
Figure 4 Correlation of the CH (lowfield section) and CH2 (high-
field section) chemical shifts for 9·X and 10·X (d, CDCl3, r.t.) with the
anionic radii.
1-[2,3,4-Tris(octyloxy)phenyl]-1H-imidazole (8)
A suspension of 7 (5.42 g, 10 mmol), imidazole (0.95 g, 14 mmol),
CuI (0.38 g, 2.0 mmol) and Cs2CO3 (3.25 g, 10 mmol) in degassed
DMF (30 mL) was stirred for 5 d at 110 °C under an N2 atmosphere.
After cooling to r.t., MTBE (50 mL) were added and the suspension
was washed with NH4OH soln (3 × 20 mL) and H2O (2 × 50 mL).
The organic layers were dried (MgSO4) and the solvent was re-
moved under reduced pressure. The crude product was purified by
column chromatography (silica gel, CH2Cl2–MTBE, 15:1) yielding
8 (4.15 g, 7.85 mmol, 79%) as a brown oil; Rf = 0.10–0.25 (CH2Cl2–
All compounds 9·X and 10·X were investigated with re-
gard to their mesomorphic properties by differential scan-
ning calorimetry (DSC) and polarizing optical
microscopy (POM), whereas no mesophases could be ob-
served. The rationale for not forming mesophases may be
two fold. Firstly, the C8 chain could be too short to induce MTBE, 15:1).
mesomorphic properties, which is somewhat surprising as
Judeinstein reported a decrease and disappearance of me-
sophases for derivatives with longer alkyl chain lengths.
Secondly, the flexibility, or rather rigidity, of the spacer
may not be optimal, meaning mesophases may not form.
IR (ATR): 2923, 2854, 1966, 1599, 1505, 1456, 1370, 1281, 1243,
1198, 1138, 1091, 1064, 977, 902, 797, 725, 659 cm–1.
1H NMR (500 MHz, CDCl3): d = 7.78 (br s, 1 H, H8), 7.26 (br s, 2
H, H10, H11), 6.93 (d, 3J = 8.8 Hz, 1 H, H6), 6.67 (d, 3J = 8.8 Hz,
1 H, H5), 4.03 (t, 3J = 6.6 Hz, 2 H, C3-OCH2), 3.99 (t, 3J = 6.5 Hz,
2 H, C4-OCH2), 3.79 (t, 3J = 6.6 Hz, 2 H, C2-OCH2), 1.81 (m, 4 H,
C3-OCH2CH2, C4-OCH2CH2), 1.49 (m, 6 H, g-CH2), 1.42–1.11 (m,
26 H, C2-OCH2CH2, CH2), 0.88 (m, 9 H, CH3).
13C NMR (125 MHz, CDCl3): d = 153.42 (C4), 147.50 (C2), 142.84
(C3), 125.26 (C1), 119.74 (C6), 107.99 (C5), 74.45 (C2-OCH2),
74.05 (C3-OCH2), 69.12 (C4-OCH2), 32.01, 31.95, 31.94, 30.48,
30.11, 29.64, 29.48, 29.41, 29.32, 26.23, 25.85, 22.81, 22.79, 22.77
(CH2), 14.22 (CH3).
In conclusion, phasmidic compounds with different spac-
ers are easily accessible by the described route and the an-
ion exchange is possible with good yields. The most
promising strategy to generate derivatives with mesomor-
phic properties seems to be the introduction of longer
alkyl chains and/or different spacers.
HRMS (ESI): m/z [M + H+] calcd for C33H57N2O3: 529.4364; found:
529.4367.
Melting points were measured on a Stuart SMP10 apparatus and are
uncorrected. IR spectra were recorded with a Bruker Vector 22 FT-
IR spectrophotometer. 1H and 13C NMR spectra were recorded with
a Bruker Avance 500 spectrometer with TMS as an internal stan-
dard. Mass spectra were recorded with a Bruker Daltonics mi-
croTOF-Q (ESI) spectrometer with N2 as carrier gas. Flash
chromatography was performed using Kieselgel 60 silica powder,
40–63 mm (Fluka). All solvents were dried, and reactions were per-
formed in dried glassware using standard Schlenk techniques unless
stated otherwise. The following compounds were prepared accord-
ing to literature procedures: 6.16
Anal. Calcd for C33H56N2O3: C, 74.95; H, 10.67; N, 5.30. Found: C,
74.74; H, 10.52; N, 5.23.
3,3¢-(Ethane-1,2-diyl)bis{1-[2,3,4-tris(octyloxy)phenyl]-1H-imi-
dazolium} Bromide (9a); Typical Procedure
A soln of 8 (1.058 g, 2.0 mmol) and 1,2-dibromoethane (188 mg,
1.0 mmol) in MeCN (7 mL) was stirred for 5 d at 110 °C. The sol-
vent was removed and the crude product was dissolved in Et2O (5
mL). The product was precipitated from Et2O by addition of MeCN
and cooling to –20 °C yielding 9a (861 mg, 0.69 mmol, 69%) as a
colorless solid; mp 207 °C.
General experimental procedure for compounds 7, 8, 9a,b,e, and
10a are provided here; experimental data for the other salts of 9 and
10 are provided in the Supporting Information.
IR (ATR): 2924, 2855, 2364, 2189, 1965, 1549, 1494, 1465, 1379,
1343, 1303, 1235, 1183, 1119, 1084, 966, 921, 908, 799, 725, 641
cm–1.
1-Bromo-2,3,4-tris(octyloxy)benzene (7)
A soln of 1,2,3-tris(octyloxy)benzene (6, 9.25 g, 20 mmol) and NBS
(3.92 g, 22 mmol) in CH2Cl2 (40 mL) was heated at reflux for 12 h.
After cooling to r.t. the resulting soln was filtered and the solvent
was evaporated. The crude product was purified by column chroma-
tography (silica gel, cyclohexane) yielding 7 (9.02 g, 17.0 mmol,
85%) as a viscous, pale yellow oil; Rf = 0.05 (cyclohexane).
1H NMR (500 MHz, CDCl3): d = 10.39 (s, 2 H, H8), 9.05 (s, 2 H,
3
H10), 7.42 (s, 2 H, H11), 7.20 (d, J = 8.9 Hz, 2 H, H6), 6.74 (d,
3J = 9.1 Hz, 2 H, H5), 5.49 (s, 4 H, H12), 4.08 (t, 3J = 6.9 Hz, 4 H,
C2-OCH2), 4.02 (t, 3J = 6.6 Hz, 8 H, C3-OCH2, C4-OCH2), 1.86 (m,
4 H, C4-OCH2CH2), 1.78 (m, 4 H, C3-OCH2CH2), 1.53 (m, 4 H, g-
CH2), 1.49 (m, 8 H, g-CH2), 1.42–1.20 (m, 52 H, C2-OCH2CH2,
CH2), 0.90 (m, 18 H, CH3).
IR (ATR): 2923, 2854, 1967, 1573, 1463, 1443, 1378, 1295, 1267,
1210, 1125, 1087, 1011, 960, 911, 868, 788, 723, 639 cm–1.
Synthesis 2011, No. 18, 3032–3036 © Thieme Stuttgart · New York

PAPER
Phasmidic Bisimidazolium Salts
3035
13C NMR (125 MHz, CDCl3): d = 155.68 (C4), 146.68 (C2), 142.36
(C3), 136.80 (C8), 124.15 (C10), 123.23 (C11), 120.91 (C1),
119.72 (C6), 108.07 (C5), 74.94 (C2-OCH2), 74.20 (C3-OCH2),
69.22 (C3-OCH2), 48.09 (C12), 31.90, 31.85, 31.82, 30.31, 30.12,
29.51, 29.37, 29.35, 29.30, 29.26, 29.17, 26.09, 25.70, 22.72, 22.70,
22.66 (CH2), 14.14 (CH3).
29.47, 29.33, 29.31, 29.26, 29.24, 29.22, 29.13, 26.05, 25.66, 22.68,
22.66, 22.61 (CH2), 14.10, 14.09 (CH3).
–
–
MS (ESI): m/z = 1172 [M – BF4 ], 581, 542 [M – 2 BF4 ].
–
HRMS (ESI): m/z [M – BF4 ] calcd for C68H116BF4N4O6:
1171.8930; found: 1171.8911.
MS (ESI): m/z = 1166 [M – Br–], 543 [M – 2 Br–].
HRMS (ESI): m/z [M – Br–] calcd for C68H116N4O6Br: 1163.8073;
Anal. Calcd for: C68H116B2F8N4O6: C, 64.86; H, 9.28; N, 4.45.
Found: C, 64.78; H, 9.35; N, 4.34.
Method B: Phasmidic compound 9a or 10a (0.1 mmol) was dis-
solved in MTBE (10 mL) and was shaken for 1 min in a separatory
funnel with a soln of the respective salt [2 mL, salt (2 g) in H2O (10
mL)]. The procedure was repeated four times and the organic layer
was washed with H2O (3 × 10 mL). Subsequently, the organic layer
was dried (MgSO4) and the solvent was removed under reduced
pressure.
found: 1163.8091.
Anal. Calcd for C68H116Br2N4O6: C, 65.58; H, 9.39; N, 4.50. Found:
C, 65.05; H, 9.34; N, 4.34.
3,3¢-[1,4-Phenylenebis(methylene)]bis{1-[2,3,4-tris(octyl-
oxy)phenyl]-1H-imidazolium} Bromide (10a)
Following the typical procedure for 9a using 8 (1.058 g, 2.0 mmol)
and 1,4-bis(bromomethyl)benzene (0.264 g, 1.0 mmol) gave 10a
(1.145 g, 0.87 mmol, 87%) as a colorless solid; mp 194 °C.
3,3¢-(Ethane-1,2-diyl)bis{1-[2,3,4-tris(octyloxy)phenyl]-1H-imi-
dazolium} Bis(triflatimide) (9e)
IR (ATR): 3039, 2922, 2853, 1966, 1597, 1553, 1496, 1466, 1379,
1345, 1302, 1281, 1233, 1191, 1123, 1082, 955, 814, 749, 724, 636
cm–1.
1H NMR (500 MHz, CDCl3): d = 10.53 (s, 2 H, H8), 7.97 (s, 2 H,
H10), 7.73 (s, 4 H, H14, H14¢), 7.51 (s, 2 H, H11), 7.38 (d, 3J = 9.0
Hz, 2 H, H6), 6.75 (d, 3J = 9.1 Hz, 2 H, H5), 5.97 (s, 4 H, H12), 4.04
(t, 3J = 6.9 Hz, 4 H, C2-OCH2), 4.00 (t, 3J = 6.6 Hz, 8 H, C3-OCH2,
C4-OCH2), 1.84 (m, 4 H, C4-OCH2CH2), 1.77 (m, 4 H, C3-
OCH2CH2), 1.56 (m, 4 H, g-CH2), 1.47 (m, 8 H, g-CH2), 1.40–1.20
(m, 52 H, C2-OCH2CH2, CH2), 0.88 (m, 18 H, CH3).
13C NMR (125 MHz, CDCl3): d = 155.32 (C4), 146.42 (C2), 142.23
(C3), 136.77 (C8), 134.74 (C14, C14´), 130.17 (C13), 123.58
(C11), 122.34 (C10), 121.10 (C1), 120.09 (C6), 108.29 (C5), 74.83
(C2-OCH2), 74.11 (C3-OCH2), 69.14 (C3-OCH2), 52.38 (C12),
31.90, 31.85, 31.83, 30.32, 30.08, 29.53, 29.37, 29.29, 29.20, 26.11,
26.10, 25.73, 22.71, 22.70, 22.68 (CH2), 14.16, 14.13 (CH3).
Pale-yellow oil; yield: 164 mg (0.099 mmol, 99%).
IR (ATR): 3147, 2953, 2856, 2360, 1556, 1495, 1467, 1347, 1229,
1186, 1134, 1086, 1057, 968, 906, 790, 737, 651, 616, 600, 570, 500
cm–1.
1H NMR (500 MHz, CDCl3): d = 9.15 (s, 2 H, H8), 8.04 (s, 2 H,
3
H10), 7.55 (s, 2 H, H11), 7.15 (d, J = 8.9 Hz, 2 H, H6), 6.76 (d,
3J = 9.1 Hz, 2 H, H5), 4.96 (s, 4 H, H12), 4.08 (t, 3J = 6.9 Hz, 4 H,
C2-OCH2), 4.03 (t, 3J = 6.6 Hz, 8 H, C3-OCH2, C4-OCH2), 1.86 (m,
4 H, C4-OCH2CH2), 1.78 (m, 4 H, C3-OCH2CH2), 1.55 (m, 4 H, g-
CH2), 1.49 (m, 8 H, g-CH2), 1.42–1.20 (m, 52 H, C2-OCH2CH2,
CH2), 0.88 (m, 18 H, CH3).
13C NMR (125 MHz, CDCl3): d = 155.93 (C4), 146.46 (C2), 142.22
(C3), 136. 92 (C8), 124.59 (C10), 122.91 (C11), 120.40 (C1),
119.64 (q, 1JC,F = 321.62 Hz, CF3), 119.44 (C6), 107.95 (C5), 74.86
(C2-OCH2), 74.16 (C3-OCH2), 69.19 (C3-OCH2), 47.84 (C12),
31.86, 31.81, 31.73, 30.24, 29.94, 29.46, 29.33, 29.26, 29.20, 29.17,
29.14, 26.07, 26.04, 25.61, 22.68, 22.67, 22.58 (CH2), 14.10, 14.03
(CH3).
MS (ESI): m/z = 1241 [M – Br–], 581 [M – 2 Br–].
HRMS (ESI): m/z [M – Br–] calcd for C74H120N4O6Br: 1239.8386;
–
–
found: 1239.8367.
MS (ESI): m/z 1365 [M – NTf2 ], 543 [M – 2 NTf2 ].
–
Anal. Calcd for C74H120Br2N4O6: C, 67.25; H, 9.15; N, 4.24. Found:
C, 67.37; H, 9.07, N; 4.25.
HRMS (ESI): m/z [M – NTf2 ] calcd for C70H116F6N5O10S2:
1364.8062; found: 1364.8060.
Anal. Calcd for C74H120F12N6O14S2: C, 52.54; H, 7.10; N, 5.11.
Found: C, 52.72; H 7.11; N 5.24.
Anion Exchange
Method A: Bromide of the phasmidic compound 9a or 10a (0.1
mmol) was dissolved in MeCN (10 mL) and the respective salt
(2 mmol) was added. The soln was stirred for 4 h at 90 °C. The hot
soln was filtered and the solvent was removed under reduced pres-
sure. CHCl3 (10 mL) was added, the suspension was filtered and the
solvent was removed under vacuum.
Supporting Information for this article is available online at
http://www.thieme-connect.com/ejournals/toc/synthesis.
Acknowledgment
3,3¢-(Ethane-1,2-diyl)bis{1-[2,3,4-tris(octyloxy)phenyl]-1H-imi-
dazolium} Tetrafluoroborate (9b)
Colorless solid; yield: 124 mg (0.099 mmol, 99%); mp 200 °C.
Generous financial support by the Deutsche Forschungsgemein-
schaft, the Ministerium für Wissenschaft, Forschung und Kunst des
Landes Baden-Württemberg, the Bundesministerium für Bildung
und Forschung (shared instrumentation grant) and the Fonds der
Chemischen Industrie is gratefully acknowledged.
IR (ATR): 3422, 2923, 2854, 1594, 1555, 1495, 1466, 1381, 1348,
1304, 1281, 1232, 1190, 1123, 1084, 814, 733, 640 cm–1.
1H NMR (500 MHz, CDCl3): d = 9.89 (s, 2 H, H8), 8.68 (s, 2 H,
3
H10), 7.44 (s, 2 H, H11), 7.17 (d, J = 9.0 Hz, 2 H, H6), 6.74 (d,
References
3J = 9.1 Hz, 2 H, H5), 5.22 (s, 4 H, H12), 4.07 (t, 3J = 6.9 Hz, 4 H,
C2-OCH2), 4.02 (t, 3J = 6.6 Hz, 8 H, C3-OCH2, C4-OCH2), 1.85 (m,
4 H, C4-OCH2CH2), 1.78 (m, 4 H, C3-OCH2CH2), 1.56 (m, 4 H, g-
CH2), 1.48 (m, 8 H, g-CH2), 1.40–1.20 (m, 52 H, C2-OCH2CH2,
CH2), 0.87 (m, 18 H, CH3).
(1) These authors contributed equally to this manuscript.
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13C NMR (125 MHz, CDCl3): d = 155.71 (C4), 146.59 (C2), 142.30
(C3), 136.66 (C8), 123.86 (C10), 123.64 (C11), 120.74 (C1),
119.60 (C6), 108.05 (C5), 74.89 (C2-OCH2), 74.17 (C3-OCH2),
69.18 (C3-OCH2), 48.04 (C12), 31.86, 31.81, 31.77, 30.27, 30.04,
Synthesis 2011, No. 18, 3032–3036 © Thieme Stuttgart · New York

3036
J. H. Porada et al.
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Synthesis 2011, No. 18, 3032–3036 © Thieme Stuttgart · New York