A. F. M. Kilbinger et al.
and the residue was extracted with dry boiling toluene, which was fil-
tered, giving a clear yellow filtrate and a white solid residue. The white
solid was refluxed in thionyl chloride (600 mL) for 8 h and treated the
same way as described above. The combined filtrates were cooled to
room temperature, then to À208C. A yellow solid crystallized out, which
was recovered by filtration, washed with petroleum ether and dried
under vacuum to give 4 (87.8 g, 65%). From the filtrate more yellow
crystals were obtained by addition of petroleum ether and cooling to
À208C. M.p. 1578C; elemental analysis calcd (%) for C14H8Cl2N2O3: C
52.18, H 2.50, N 8.67; found: C 51.81, H 2.62, N 8.76; MS (FD): m/z (%)
calcd: 322.0 (100). 324.0 (63.9). 326.0 (10.2); found: 322.5 (100), 324.5
(65.7), 326.4 (10.3); 1H NMR (CDCl3): d=7.08 (d, J=8.8 Hz, 2H), 8.19
(d, J=8.8 Hz, 2H), 8.33 (s, 4H); 13C NMR and DEPT: d=120.4 (+),
123.7 (+), 130.2, 130.5 (+), 132.9 (+), 139.9, 143.7, 150.2, 153.1,
167.5 ppm; UV/Vis (CHCl3): lmax (log e)=280 nm (4.51); IR: n˜ =3109,
crystals as well as the study of molecular recognition based
on hydrogen bonding in synthetic materials.
Experimental Section
Materials: Solvents (p. a. quality) were purchased from Fisher Scientific,
those for spectrometric measurements and all chemical reagents from
Acros Organics. Toluene was dried by azeotropic removal of water and
subsequent storage over molecular sieves (4 ꢄ). All other chemicals were
used as received without further purification. Recycling of used thionyl
chloride was performed by reflux over flowers of sulfur followed by two
successive distillations. Deuterated solvents ([D6]DMSO and CDCl3)
were purchased from Deutero GmbH and used as received. Celite was
purchased from Fluka. p-Aminobenzoic acid (1) (Acros) was used as re-
ceived.
3065, 3043, 1741, 1662, 1518, 1343 cmÀ1
.
Compound 5: Compound 1 (21.2 g, 0.155 mol) and N,N-dimethylaniline
(25 mL) were dissolved in dry acetone (140 mL). A solution of 4 (50 g,
0.155 mol) in of acetone (330 mL) was added dropwise to this solution
under stirring and cooling in an ice bath. The reaction mixture was al-
lowed to warm to room temperature and was stirred for a further 30 min.
Water (20 mL) was added to the resulting yellow suspension and the re-
action mixture was stirred for 30 min. The yellow precipitate was collect-
ed by filtration, washed with hydrochloric acid (2n, 300 mL), then
washed neutral with water and dried under vacuum. The resulting solid
was recrystallized from DMF to give 5 (58.3 g, 93%). M.p. >3008C; ele-
mental analysis calcd (%) for C21H15N3O6: C 62.21, H 3.73, N 10.37;
found: C 61.59, H 3.58, N 10.42; MS (FD): m/z calcd: 405.1; found: 405.4
(100) [M]+; 1H NMR ([D6]DMSO): d=7.92–8.03 (m, 8H), 8.20 (d, J=
8.8 Hz, 2H), 8.38 (d, J=8.8 Hz, 2H), 10.46 (s, 1H), 10.83 (s, 1H),
12.73 ppm (brs, <1H); 13C NMR and DEPT: d 119.6 (+), 119.8 (+),
123.7 (+), 125.5, 128.9 (+), 129.5 (+), 129.9, 130.3 (+), 140.4, 142.1,
143.5, 149.4, 164.4, 165.4, 167.1 ppm; UV/Vis (DMAc + 1% LiCl): lmax
1
Physical and analytical methods: Standard H and 13C NMR spectra were
recorded at 300 MHz (75 MHz for 13C) on a Bruker AC300 spectrometer.
For high-temperature measurements a Bruker DRX400 spectrometer
was used, working at 400 MHz (100 MHz for 13C). FD mass spectra were
measured on a Finnigan MAT 95 and ESI mass spectra on a Micromass
Q-TOF Ultima 3. Infrared spectra were recorded on a Nicolet 5DXC
FT-IR spectrometer, and UV-visible spectra on a Shimadzu UV-210 2 PC
scanning spectrophotometer. DSC curves were obtained from a Perkin–
Elmer DSC7 and a Perkin–Elmer Thermal Analysis Controler TAC 7/
DX. For elemental analyses, an Elementar Vario EL2 was used. X-ray
crystal structures were obtained on a Turbo CAD4. For polymeric com-
pounds 9–15 only 1H NMR data corresponding to the modified OPBA
end-group are reported.
4-(4-Nitrobenzamido)benzoic acid (2): Compound 1 (80 g, 0.584 mol) and
N,N-dimethylaniline (100 mL) were dissolved in dry acetone (530 mL). A
solution of 4-nitrobenzoyl chloride (108 g, 0.582 mol) in acetone
(130 mL) was added dropwise to this mixture under stirring and cooling
with an ice bath. The reaction mixture was allowed to warm to room
temperature and was stirred for one further hour. The resulting yellow
precipitate was collected by filtration and washed with hydrochloric acid
(2 N, 400 mL) and then water until the filtrate was neutral. The resulting
solid was dried under vacuum and recrystallized from DMF to give 2
(158.2 g, 95%). M.p. >3008C; elemental analysis calcd (%) for
C14H10N2O5: C 58.73, H 3.52, N, 9.79; found: C 58.23, H 3.28, N 9.84; MS
(FD): m/z calcd: 286.1; found: 286.5 (100) [M]+; 1H NMR ([D6]DMSO):
d=7.93 (m, 4H), 8.18 (d, J=8.5 Hz, 2H), 8.36 (d, J=8.5 Hz, 2H), 10.82
(s, 1H), 12.75 ppm (brs, <1H); 13C NMR and DEPT ([D6]DMSO): d=
119.8 (+), 123.7 (+), 126.2, 129.5 (+), 130.4 (+), 140.4, 142.9, 149.4,
164.4, 167.0 ppm; UV/Vis (DMAc + 1% LiCl): lmax (log e)=268 nm
(log e)=294 nm (4.31); IR: n˜ =3337, 3112, 3070, 1725, 1654, 1347 cmÀ1
.
Compound 6: Compound 5 (56.8 g, 0.14 mol) was refluxed in thionyl
chloride (400 mL) for 90 min. Total dissolution of 5 was achieved after
30 min. The SOCl2 was distilled off and petroleum ether was added to
give a yellow precipitate, which was collected by filtration and recrystal-
lized from dry toluene to give 6 (22.7 g, 35%). From the filtrate of the re-
crystallization further product was obtained by addition of petroleum
ether. M.p. 1698C; elemental analysis calcd (%) for C21H12N3Cl3O3: C
54.90, H 2.63, N 9.15; found: C 54.71, H 2.77, N 9.09; MS (FD): m/z (%)
calcd: 459.0 (100.0), 461.0 (95.8), 463.0 (30.6); found: 459.4 (100.0) [M]+,
461.4 (91.1), 463.4 (35.1); 1H NMR (CDCl3): d=7.06 (d, J=8.8 Hz, 2H),
7.12 (d, J=8.8 Hz, 2H), 8.17 (d, J=8.8 Hz, 2H), 8.25 (d, J=8.8 Hz, 2H),
8.34 ppm (s, 4 Hz); 13C NMR and DEPT (CDCl3): d=120.3 (+), 120.7
(+), 123.7 (+), 129.6, 130.5 (+), 130.7 (+), 131.9, 132.8 (+), 140.2, 143.0,
144.8, 150.1, 150.8, 154.0, 167.6 ppm; UV/Vis (CHCl3): lmax (log e)=
(4.55);. IR: n˜ =3319, 3108, 3075, 1669, 1645, 1524, 1342 cmÀ1
.
4-(4-Aminobenzamido)benzoic acid (3): Compound 2 (15 g, 0.052 mol)
was suspended in DMF (50 mL). Methanol (400 mL) and ammonium for-
mate (33 g, 0.523 mol) were added while stirring and cooling with an ice
bath. Under an N2 atmosphere Pd/C (10%, 1 g) was added, and the re-
sulting suspension was allowed to warm to room temperature and stirred
for 12 h. It was passed through Celite (Aldrich) and the solvent was
evaporated to near dryness. The residue was neutralized with HCl
(conc.), resulting in a white precipitate, which was recovered by filtration.
Further product could be obtained from the filtrate by addition of water.
This precipitate was combined with the first, stirred in water, recovered
by filtration, washed neutral with water and dried under vacuum to give
3 (11.8 g, 89%). M.p. >3008C; MS (FD): m/z calcd for C14H12N2O3:
256.1; found: 256.2 (100) [M]+; 1H NMR ([D6]DMSO): d=6.66 (d, J=
8.8 Hz, 2H), 7.76 (d, J=8.8 Hz, 2H), 7.90 (s, 4H), 10.08 ppm (s, 1H);
13C NMR and DEPT ([D6]DMSO): d=112.7(+), 119.2 (+), 120.7, 124.8,
129.7 (+), 130.3 (+), 144.1, 152.6, 165.7, 167.2 ppm; UV/Vis (DMAc +
1% LiCl): lmax (log e)=317 nm (4.76); IR: n˜ =3384, 3350, 3275, 1683,
292 nm (4.31); IR: n˜ =3109, 3083, 1764, 1641, 1517, 1344 cmÀ1
.
Compound 7: Compound 3 (6 g, 23.4 mmol) and N,N-dimethylaniline
(6 mL) were dissolved in a mixture of dry acetone (15 mL) and dry N-
methylpyrrolidinone (20 mL). A solution of 2 (7.55 g, 23.4 mmol) in dry
acetone (25 mL) was added dropwise to this solution under stirring at
room temperature. After one hour water (15 mL) was added, and the re-
action mixture was stirred for about 6 h. The resulting solid was collected
by filtration, stirred with HCl (1m), washed neutral with water, and fil-
tered, and the filtrate evaporated to dryness under vacuum. Recrystalli-
zation from DMF or a DMF/NMP mixture was not possible, but by stir-
ring in refluxing DMF for several hours colored impurities dissolved,
while the product remained insoluble. After cooling, the solid was fil-
tered, washed with water and acetone, and was dried under vacuum to
give 7 (11.76 g, 96%). M.p. >3008C; MS (FD)m/z calcd for C28H20N4O7:
524.1; found: 524.5 (100) [M]+; 1H NMR ([D6]DMSO): d=7.92–8.05 (m,
12H), 8.20 (d, J=8.8 Hz, 2H), 8.38 (d, J=8.8 Hz, 2H), 10.43 (s, 1H),
10.46 (s, 1H), 10.83 (s, 1H), 12.72 ppm (brs, <1H); 13C NMR and DEPT
([D6]DMSO, T=1308C, 100 MHz): d=120.05 (+), 120.11 (+), 120.42
(+), 123.56 (+), 126.26, 128.65 (+), 128.72 (+), 129.43 (+), 129.96, 130.22
(+), 130.66, 140.83, 142.14, 142.83, 143.66, 150.03, 164.51, 165.50, 165.61,
1653, 1604 cmÀ1
.
Compound 4: Compound 2 (120 g, 0.42 mol) was refluxed in thionyl chlo-
ride (600 mL). After 3 h complete dissolution of 2 was achieved, after 8 h
a turbid suspension was obtained. The thionyl chloride was distilled off,
2174
ꢃ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2005, 11, 2170 – 2176