4356 Kang et al.
Macromolecules, Vol. 36, No. 12, 2003
eluting with 5:1 ethyl acetate/CH2CH2. Yield: 4.48 g (53%).
1H NMR (300 MHz, CDCl3): δ 4.89 (s, 2H).
was added DPTS (0. 03 g, 0.11 mmol), and the mixture was
stirred at room temperature under nitrogen for 15 min. DCC
(0.07 g, 0.33 mmol) was then added, and the mixture was
stirred for 24 h. The reaction mixture was filtered, precipitated
into methanol, and filtered to yield 0.126 g (84%) of hyper-
branched polymer 11. FTIR (KBr, cm-1): 3375, 3098, 2960,
1762, 1650, 1596, 1498, 1447, 1323, 1291, 1193, 1167, 1131,
2,2,2-Tr ich lor oeth yl 4-Ben zyloxy-2,3,5,6-tetr aflu or oben -
zoa te (4). Cesium carbonate (8.41 g, 25.81 mmol) was added
to a rapidly stirred, cooled mixture of 3 (8.01 g, 23.46 mmol)
and benzyl bromide (3.35 mL, 28.15 mmol) in dry DMF (50
mL). The mixture was allowed to warm to room temperature
and stirred for 36 h. The reaction mixture was evaporated
under vacuum, and the resulting residue was partitioned
between water and ethyl acetate. The aqueous layer was
extracted with ethyl acetate and then dried over magnesium
sulfate. The crude product was purified by flash chromatog-
raphy eluting with 3:1 hexane/CH2CH2 to give 4 as a viscous
oil. Yield: 8.64 g (85%). 1H NMR (300 MHz, CDCl3): δ 7.42
(m, 5H), 5.19 (s, 2H), 4.98 (s, 2H).
1
1097, 1056, 985, 946, 746, 693. H NMR (750 MHz, acetone-
d6): δ 8.30, 8.26, 8.23, 8.19, 7.99, 7.92, 7.85. 13C NMR (188
MHz, acetone-d6): δ 161.68, 159.02, 158.17, 152.58, 152.51,
152.34, 152.25, 148.85, 148.09, 147.46, 146.72, 143.08, 141.75,
140.28, 138.99, 133.73, 130.23, 124.05, 110.25, 100.93. 19F
NMR (282 MHz, acetone-d6): δ -137.10, -139.26, -151.28,
-161.61.
P ostfu n ction a liza tion of P olym er 11. To a solution of
10 (0.85 g, 1.53 mmol) in dry dichloromethane (5 mL) and dry
THF (10 mL) was added DPTS (0. 18 g, 0.61 mmol), and the
mixture was stirred at room temperature under nitrogen for
15 min. DCC (0.38 g, 1.84 mmol) was then added, and the
mixture was stirred for 24 h. To a reaction mixture was added
p-trifluorovinyloxyl benzoic acid (0.40 g, 1.84 mmol) and DPTS
(0.18 g, 0.61 mmol), and DCC (0.38 g, 1.84 mmol) was then
added after 15 min. After 24 h, the precipitated urea was
filtered off, and the polymer was isolated by precipitation into
methanol. Further purification was carried out by repetitive
precipitations from CH2Cl2 into methanol. Yield: 0.91 g.
Polymer 12. FTIR (KBr, cm-1): 3109, 2926, 1834, 1766, 1651,
1604, 1496, 1447, 1418, 1322, 1276, 1252, 1163, 1094, 1026,
1007, 944, 906, 851, 782, 747, 666. 1H NMR (750 MHz, acetone-
d6): δ 8.39, 8.30, 8.03, 7.53. 13C NMR (188 MHz, acetone-d6):
δ 161.36, 160.79, 160.02, 157.35, 151.77, 151.51, 151.45,
151.10, 147.39, 145.92, 142.37, 141.03, 133.91, 123.75, 122.66,
122.22, 116.87, 109.72, 100.00. 19F NMR (282 MHz, acetone-
d6): δ -119.04, -125.61, -136.09, -138.01, -139.37, -151.13.
Ter m in a l Mod el Com p ou n d (T). This compound was
prepared from the 9 (1.0 g, 1.39 mmol), pentafluorophenol (0.30
g, 1.60 mmol), DPTS (0.16 g, 0.56 mmol), and DCC (0.33 g,
1.60 mmol) in dry CH2Cl2 (20 mL) following essentially the
method used to prepare 8. The crude product was purified by
flash chromatography eluting with 2:1 CH2CH2/hexane. The
resulting solid (1.11 g, 1.26 mmol) and 10% Pd/C (0.25 g) in
THF (15 mL) was degassed and stirred under H2 at room
temperature for 24 h. The catalyst was removed by filtration
through Celite, the filtrate was evaporated, and the crude
product was purified by flash chromatography eluting with
ethyl acetate. Yield: 0.59 g (67%). FTIR (KBr, cm-1): 3436,
3070, 2958, 2895, 2857, 1698, 1608, 1462, 1428, 1410, 1280,
4-Ben zyloxy-2,3,5,6-tetr a flu or oben zoic Acid (5). To a
solution of 4 (8.52 g, 19.74 mmol) in THF (25 mL) was added
glacial acetic acid (25 mL), and the mixture was stirred at room
temperature under nitrogen. Zinc dust (8.39 g, 128 mmol) was
added, and the mixture was stirred vigorously at room
temperature for 1 h. The reaction mixture was filtered, and
the filtrate was poured into water (150 mL) and extracted with
diethyl ether (200 mL). The combined extracts were washed
with water and dried over magnesium sulfate. The crude
product was purified by flash chromatography eluting with
CH2Cl2 and then increasing polarity to ethyl acetate. Yield:
4.56 g (77%). 1H NMR (300 MHz, CDCl3): δ 7.42 (m, 5H), 5.40
(s, 2H).
2,2,2-Tr ich lor oeth yl 3,5-Dih yd r oxyben zoa te (7). To a
solution of 2,2,2-trichloroethanol (30 mL) was added 3,5-
dihydroxybenzoic acid (5.25 g, 34.1 mmol) followed by concen-
trated sulfuric acid (2 mL), and the mixture was stirred
vigorously and heated at 90 °C for 48 h under nitrogen. The
reaction mixture was cooled and evaporated to dryness. The
crude product was purified by flash chromatography eluting
with CH2Cl2 and then increasing polarity to diethyl ether.
Yield: 5.71 g (59%). 1H NMR (300 MHz, CDCl3): δ 8.12 (s,
2H), 7.07 (d, 2H), 6.69 (t, 1H), 5.03 (s, 2H).
2,2,2-Tr ich lor oet h yl 3,5-Bis(4-b en zyloxy-2,3,5,6-t et -
r a flu or oben zoa te)ben zoa te (8). To a solution of 5 (4.34 g,
14.45 mmol) in dry CH2Cl2 (45 mL) was added 7 (1.92 g, 6.72
mmol) followed by DPTS (0.79 g, 2.69 mmol), and the mixture
was stirred at room temperature under nitrogen for 15 min.
DCC (3.05 g, 14.45 mmol) was then added, and the mixture
was stirred for 12 h. The reaction mixture was filtered, and
the filtrate was evaporated to dryness under reduced pressure.
The crude product was purified by flash chromatography
eluting with 1:1 CH2CH2/hexane. Yield: 4.66 g (82%). 1H NMR
(300 MHz, CDCl3): δ 7.94 (d, 1H), 7.43 (m, 12H), 5.42 (s, 4H),
5.01 (s, 2H). 19F NMR (282 MHz, acetone-d6): δ -139.37,
-156.01.
2,2,2-Tr ich lor oeth yl-3,5-bis(4-ben zyloxy-2,3,5,6-tetr aflu -
or oben zoa te)ben zoic Acid (9). This compound was prepared
from the 8 (4.56 g, 5.37 mmol) and zinc dust (2.19 g, 33.53
mmol) in THF (20 mL) and glacial acetic acid (20 mL) following
essentially the method used to prepare 5. The crude product
was purified by flash chromatography eluting with 5:1 CH2-
CH2/hexane. Yield: 3.84 g (91%). 1H NMR (300 MHz, CDCl3):
δ 8.76 (s, 1H), 8.33 (d, 2H), 7.57 (m, 4H), 7.37 (m, 10H), 7.04
(d, 4H), 5.29 (s, 4H), 4.80 (s, 2H), 1.01 (m, 9H). 19F NMR (282
MHz, acetone-d6): δ -139.46, -156.03.
1
1223, 1112, 1092, 908, 821, 700. H NMR (750 MHz, acetone-
d6): δ 8.30 (m, 6H), 7.99 (t, 1H), 7.89 (m, 2H), 7.73 (m, 4H).
13C NMR (188 MHz, acetone-d6): δ 161.19, 158.19, 151.51,
147.92, 146.49, 142.38, 141.91, 141.03, 139.34, 138.03, 129.46,
125.47, 122.73, 122.08, 100.33. 19F NMR (282 MHz, acetone-
d6): δ -138.78, -151.54, -153.33, -158.26.
Den d r itic Mod el Com p ou n d (D). This compound was
prepared from the terminal model compound (T) (0.49 g, 0.69
mmol), benzoic acid (0.79 g, 0.83 mmol), DPTS (0.08 g, 0.28
mmol), and DCC (0.17 g, 0.83 mmol) in dry dichloromethane
(2 mL) and dry THF (4 mL) following essentially the method
used to prepare 8. The crude product was purified by flash
chromatography eluting with 2:1 CH2CH2/hexane. Yield: 0.53
g (84%). FTIR (KBr, cm-1): 2927, 2856, 1764, 1652, 1600, 1522,
1496, 1442, 1418, 1323, 1288, 1242, 1175, 1090, 1008, 935, 794,
703, 667, 617. 1H NMR (750 MHz, acetone-d6): δ 8.16 (d, 2H),
7.84 (t, 1H). 13C NMR (188 MHz, acetone-d6): δ 162.30, 162.28,
158.56, 152.64, 147.08, 145.70, 142.39, 141.05, 139.11, 136.82,
133.51, 132.09, 130.83, 128.03, 124.06, 123.60, 110.23. 19F
NMR (282 MHz, acetone-d6): δ -139.57, -153.14, -158.28,
-161.83.
P r ep a r a tion of P olym er F ilm s. Polymer 12 was dissolved
in cyclopentanone at concentration of 30 wt %. A 1 wt % dye,
DCM (4-dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-
4H-pyran), was added to the formulation to aid in photother-
mal deflection spectroscopy (PDS) calibration. The solution
was filtered through 0.2 µm Teflon membrane filters. The
filtered solution was spin-coated on 1 in. diameter × 0.020 in.
3,5-Bis(4-h yd r oxy-2,3,5,6-t et r a flu or ob en zoa t e)b en zo-
ic Acid (10). A mixture of 9 (2.76 g, 3.84 mmol) and 10% Pd/C
(0.50 g) in THF (50 mL) was degassed and stirred under H2
at room temperature for 24 h. The catalyst was removed by
filtration through Celite, the filtrate was evaporated, and the
residue was washed with CH2Cl2. Yield: 1.91 g (93%). FTIR
(KBr, cm-1): 3499, 3073, 2933, 2895, 2860, 1767, 1720, 1650,
1495, 1427, 1318, 1246, 1185, 1109, 1004, 922, 824, 736, 703.
1H NMR (750 MHz, acetone-d6): δ 7.77 (d, 2H), 7.61 (d, 1H).
13C NMR (188 MHz, acetone-d6): δ 165.59, 158.07, 150.36,
148.40, 145.00, 142.09, 139.94, 136.74, 133.55, 121.08, 98.51.
19F NMR (282 MHz, acetone-d6): δ -140.19, -161.52.
P olym er iza tion of 10. To a solution of 10 (0.15 g, 0.27
mmol) in dry dichloromethane (2 mL) and dry THF (4 mL)