Macromolecules
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NMR and APT (75 MHz, CDCl3): δ (ppm) = 58.88 (+), 69.24 (−),
69.44 (−), 70.42 (−), 70.51 (−), 70.92 (−), 71.76 (−), 108.41 (+),
115.10 (+), 115.24 (+), 119.92 (+), 121.44 (+), 125.56 (−), 126.09
(+), 129.35 (+), 129.48 (+), 132.40 (+), 150.53 (−), 150.89 (−),
153.72 (−), 156.15 (−), 158.95 (−), 163.23 (−). HR-MS (ESI+): m/z
calculated for [C20H23NO8Na]+ = 428.13214; found 428.13119. RP-
HPLC: 21.65 min.
(+), 125.16 (+), 128.46 (+), 129.20 (+), 130.18 (−), 139.20 (−),
144.85 (−), 151.36 (−), 157.53 (−), 158.91 (−), 164.03 (−). HR-MS
(ESI+): m/z calculated for [C35H47NO11Na]+ = 680.30468; found
680.30449. RP-HPLC: 20.66 min.
Phenyl 4-((4-Methoxybenzyl)amino)-2-(2-(2-(2-
methoxyethoxy)ethoxy)ethoxy)benzoate (10b). To a solution
of 9b (1.0 g, 2.66 mmol), p-anisaldehyde (360 mg, 2.66 mmol), and
acetic acid (0.76 mL, 13.3 mmol) in dry dichloromethane (67 mL)
was added sodium triacetoxyborohydride (1.13 mg, 5.32 mmol), and
the solution was stirred overnight at room temperature. The reaction
was quenched with saturated NaHCO3 solution and extracted three
times with dichloromethane. The combined organic layers were
washed with water and dried over magnesium sulfate, and the solvent
was removed under reduced pressure. 480 mg of the viscous light
brown product (1.24 g) was purified by recycling HPLC in
acetonitrile/water (75/25) to give 10b (270 mg) as a slightly brown
Phenyl 4-Amino-2,5-bis(2-(2-(2-methoxyethoxy)ethoxy)-
ethoxy)benzoate (9a). Phenyl 2,5-bis(2-(2-(2-methoxyethoxy)-
ethoxy)ethoxy)-4-nitrobenzoate (8a) (1 g, 1.76 mmol) was dissolved
in ethyl acetate, and palladium on activated charcoal (200 mg, 10%)
was added. The reaction was run for 40 h in a hydrogen reactor at 40
°C and 40 bar. After the reaction was complete, the solution was
filtered over Celite and washed with ethyl acetate, and the solvent was
removed under reduced pressure to give 9a as light brown oil (0.9 g,
1.67 mmol, 95%). Phenyl 4-amino-2,5-bis(2-(2-(2-methoxyethoxy)-
ethoxy)ethoxy)benzoate was highly purified via recycling HPLC in
acetonitrile/water (75/25) prior to usage as monomer for
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oil in 53% yield. H NMR (300 MHz, CDCl3): δ (ppm) = 3.35 (s, 3
H), 3.47−3.55 (m, 2 H), 3.56−3.64 (m, 4 H), 3.70−3.76 (m, 2 H),
3.82 (s, 3 H), 3.85−3.90 (m, 2 H), 4.14 (t, 3J = 5.00 Hz, 2 H), 4.32 (d,
3J = 5.29 Hz, 2 H), 4.64 (s, 1 H), 6.18 (d, 4J = 2.08 Hz, 1 H), 6.26 (dd,
3J = 8.69 Hz, 4J = 2.27 Hz, 1 H), 6.87−6.90 (m, 1 H), 6.90−6.93 (m, 1
H), 7.15−7.25 (m, 3 H), 7.26 (s, 1 H), 7.28−7.30 (m, 1 H), 7.34−7.43
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polycondensation. H NMR (300 MHz, CDCl3): δ (ppm) = 3.34
(s, 3 H), 3.38 (s, 3 H), 3.46−3.75 (m, 18 H), 3.77−3.90 (m, 4 H),
4.08−4.20 (m, 4 H), 4.72 (br s, 2 H), 6.33 (s, 1 H), 7.11−7.25 (m, 3
H), 7.32−7.45 (m, 2 H), 7.54 (s, 1 H). 13C NMR and DEPT (75
MHz, CDCl3): δ (ppm) = 58.98 (−), 69.67 (+), 69.71 (+), 69.86 (+),
70.40 (+), 70.49 (+), 70.57 (+), 70.61 (+), 70.87 (+), 71.88 (+), 71.94
(+), 100.66 (−), 106.43, 118.19 (−), 122.09 (−), 125.27 (−), 129.26
(−), 139.40, 144.86, 151.34, 157.18, 163.93. HR-MS (ESI+): m/z
calculated for [C27H39NO10Na]+ = 560.24717; found 560.24711. RP-
HPLC: 17.46 min.
Phenyl 4-Amino-2,5-bis(2-(2-(2-methoxyethoxy)ethoxy)-
ethoxy)benzoate (9b). Phenyl 2-(2-(2-(2-methoxyethoxy)ethoxy)-
ethoxy)-4-nitrobenzoate (8b) (680 mg, 1.67 mmol) was dissolved in
ethyl acetate, and palladium on activated charcoal (130 mg, 10%) was
added. The reaction was run for 40 h in a hydrogen reactor at 40 °C
and 40 bar. The solution was filtered over Celite and washed with
ethyl acetate, and the solvent was removed under reduced pressure to
give 9b as a light brown oil (610 mg, 1.62 mmol, 97%). Before use in
polycondensation the product was purified by column chromatog-
raphy in dichloromethane:methanol (95:5) to give yellow crystals. Rf =
0.3. 1H NMR (300 MHz, CDCl3): δ (ppm) = 3.36 (s, 3 H), 3.49−3.56
(m, 2 H), 3.58−3.63 (m, 4 H), 3.71−3.77 (m, 2 H), 3.85−3.92 (m, 2
H), 4.15 (t, 3J = 5.00 Hz, 2 H), 4.27 (br s, 2 H), 6.23−6.27 (m, 1 H),
6.29 (d, 4J = 2.27 Hz, 1 H), 7.14−7.25 (m, 3 H), 7.34−7.47 (m, 2 H),
7.91 (d, 3J = 8.50 Hz, 1 H). 13C NMR and APT (75 MHz, CDCl3): δ
(ppm) = 58.89 (−), 68.67 (−), 69.48 (−), 70.33 (−), 70.56 (−), 70.85
(−), 71.80 (−), 99.14 (+), 106.83 (+), 108.04 (−), 115.32, 122.02
(+), 125.20 (+), 129.21 (+), 129.43, 134.68 (+), 151.27 (−), 152.91
(−), 161.70 (−), 163.92. HR-MS (ESI+): m/z calculated for
[C20H25NO6Na]+ = 398.15796; found 398.15760. RP-HPLC: 16.50
min.
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(m, 2 H), 7.94 (d, J = 8.69 Hz, 1 H). 13C NMR and APT (75 MHz,
CDCl3): δ (ppm) = 47.02 (−), 55.25 (+), 58.91 (+), 68.65 (−), 69.47
(−), 70.33 (−), 70.54 (−), 70.87 (−), 71.80 (−), 97.05 (+), 104.94
(+), 107.18 (−), 114.12 (+), 122.04 (+), 125.12 (+), 128.66 (+),
129.17 (+), 130.07 (−), 134.58 (+), 144.92, 151.33 (−), 153.48 (−),
159.00, 161.77, 163.90 (−). HR-MS (ESI+): m/z calculated for
[C28H33NO7Na]+ = 518.21547; found 518.21437. RP-HPLC: 23.32
min.
4-Amino-2,5-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-
benzoic Acid (11). 2,5-Bis(triethylene glycol)-4-nitrobenzoic acid
(7a) (910 mg, 1.85 mmol) was dissolved in ethyl acetate, and
palladium on activated charcoal (136 mg) was added. The reaction was
run for 40 h in a hydrogen reactor at 40 °C and 40 bar. After the
reaction was complete, the solution was filtered over Celite and
washed with ethyl acetate, and the solvent was removed in vacuo to
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obtain a colorless liquid (850 mg, 1.84 mmol, 99%). H NMR (360
MHz, CDCl3): δ (ppm) = 3.32 (s, 3 H), 3.34 (s, 3 H), 3.47−3.54 (m,
4 H), 3.55−3.70 (m, 12 H), 3.73−3.78 (m, 2 H), 3.78−3.85 (m, 2 H),
4.08 (t, 3J = 4.54, 4.09 Hz, 2H), 4.17−4.20 (t, 3J = 4.09 Hz, 2H), 6.27
(s, 1 H), 7.45 (s, 1 H). 13C NMR and DEPT (75 MHz, CDCl3): δ
(ppm) = 58.75 (−), 68.65 (+), 69.05 (+), 69.27 (+), 69.38 (+), 70.23
(+), 70.33 (+), 70.35 (+), 70.51 (+), 71.66 (+), 71.73 (+), 98.65 (−),
105.58, 116.63 (−), 140.43, 144.58, 154.09, 166.10. HR-MS (ESI+):
m/z calculated for [C21H36NO10]+ = 462.23392; found 462.23386. RP-
HPLC: 11.34 min.
General Procedure for Polycondensation. Monomer 9a, 9b,
10a, or 10b (60−100 mg) was dried in a Schlenk tube in high vacuum
and transferred into a glovebox under an argon atmosphere. The
polymerization was started by fast addition of LiHMDS (1 M in THF,
2.1 equiv for monomers 9a/9b, 1.2 equiv for monomers 10a/10b) to a
solution of monomer in dry THF or diglyme (0.5 mol/L). The
polymerization was carried out overnight and quenched by addition of
saturated aqueous ammonium chloride solution, followed by
extraction with dichloromethane. For purification the combined
organic layers were washed three times with 1 N NaOH to remove
cleaved phenol and once with brine. The organic phase was dried over
magnesium sulfate, and the solvent was removed under reduced
pressure to yield polymer 13a, 13b, 14a, or 14b.
Phenyl 4-((4-Methoxybenzyl)amino)-2,5-bis(2-(2-(2-
methoxyethoxy)ethoxy)ethoxy)benzoate (10a). To a solution
of 9a (850 mg, 1.58 mmol), p-anisaldehyde (320 mg, 2.35 mmol), and
acetic acid (0.45 mL, 7.90 mmol) in dry dichloromethane (40 mL)
was added sodium triacetoxyborohydride (670 mg, 3.16 mmol), and
the solution was stirred overnight at room temperature. The reaction
was quenched with saturated NaHCO3 solution and extracted three
times with dichloromethane. The combined organic layers were
washed with water and dried over magnesium sulfate, and the solvent
was removed under reduced pressure. 500 mg of the oily brown
product (1.24 g) was purified by recycling HPLC in acetonitrile/water
(75/25) to give 10a (190 mg) as a slightly brown oil in 46% yield. 1H
NMR (300 MHz, CDCl3): δ (ppm) = 3.35 (d, J = 0.38 Hz, 6 H),
3.46−3.54 (m, 4 H), 3.56−3.64 (m, 8 H), 3.64−3.73 (m, 4 H), 3.78−
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13a: H NMR (400 MHz, CDCl3): δ (ppm) = 3.31 (s, 3 H), 3.34
(s, 3 H), 3.41−3.77 (m, 22 H), 3.79−4.02 (m, 5 H), 4.36 (br. s., 2 H),
4.53 (br s, 2 H), 7.72−7.90 (m, 1 H), 8.54−8.72 (m, 1 H), 10.80 (br s,
1 H). 13C NMR and APT (100 MHz, CDCl3): δ (ppm) = 58.90 (−),
68.96 (+), 69.35 (+), 70.41 (+), 70.45 (+), 70.51 (+), 70.54 (+), 70.61
(+), 71.78 (+), 71.83 (+), 106.52 (−), 114.35 (−), 116.01 (+), 133.98
(+), 142.27 (+), 151.83 (+), 163.52 (+). GPC (CHCl3): Mn 12 100 g/
mol, Mw 25 000 g/mol; PDI 2.5. Yield: 60 mg (81%).
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3.87 (m, 7 H), 4.08 (t, J = 5.10 Hz, 2 H), 4.13−4.21 (m, 2 H), 4.37
(s, 2 H), 6.17 (s, 1 H), 6.86−6.89 (m, 1 H), 6.89−6.92 (m, 1 H),
7.14−7.24 (m, 3 H), 7.27 (s, 1 H), 7.28−7.31 (m, 1 H), 7.34−7.43
(m, 2 H), 7.52 (s, 1 H). 13C NMR and APT (75 MHz, CDCl3): δ
(ppm) = 46.53 (−), 55.25 (+), 58.96 (+), 69.43 (−), 69.54 (−), 69.64
(−), 69.69 (−), 70.36 (−), 70.50 (−), 70.53 (−), 70.57 (−), 70.83
(−), 71.83 (−), 96.59 (+), 104.53 (−), 114.08 (+), 115.97 (+), 122.07
13b: Insoluble in organic solvents (DMSO, DMF, THF) and only
partly soluble in chloroform, making characterization by NMR
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dx.doi.org/10.1021/ma4010023 | Macromolecules 2013, 46, 5520−5530