6016 Macromolecules, Vol. 43, No. 14, 2010
Liu et al.
yield 12 g of 4-ethynylbenzoic acid as yellow solids (yield 82%).
1HNMR (400MHz, CDCl3), δ(ppm):8.07 (d, 2H, Ar-Horthoto
COOH), 7.59 (d, 2H, Ar-H meta to COOH), 3.27 (s, 1H, ꢀCH).
(b). Synthesis of 4-[(4-Hydroxyphenyl)oxycarbonyl]phenylac-
etylene. Potassium 4-ethynylbenzoate (2 g) was added to dry
THF with two drops of dimethylformamide (DMF). The mix-
ture was cooled with an ice bath, to which 2 mL of SOCl2 was
added dropwise. The mixture was then refluxed for 1.5 h.
Afterward, the solution was concentrated by a rotary evapora-
tor to give an orange solid of 4-ethynylbenzoyl chloride. Hydro-
quinone (2.5 g) was dissolved in dry THF with a small amount of
pyridine, to which a THF solution of 4-ethynylbenzoyl chloride
was added under stirring via a dropping funnel with a pressure-
equalization arm. The reaction mixture was refluxed for 8 h and
then the solvent was removed by a rotary evaporator. The crude
product was purified by column chromatography using petro-
leum ether/ethyl acetate (3/1, v/v) as the eluent. After recrystal-
lization from ethanol, 4-[(4-hydroxyphenyl)oxycarbonyl]phen-
ylacetylene was obtained as white solids (1.9 g, yield 65%). 1H
NMR (400 MHz, CDCl3), δ (ppm): 8.17-8.14 (d, 2H, Ar-H
ortho to COO), 7.64-7.61 (d, 2H, Ar-H ortho to CtCH),
7.09-7.06 (d, 2H, Ar-H ortho to OOC), 6.88-6.85 (d, 2H,
Ar-H ortho to OH), 4.85 (s, 1H, OH), 3.28 (s, 1H, tCH).
(c). Synthesis of 4-(Pentyloxy)benzoic Acid. 4-Hydroxyben-
zoic acid (14 g, 0.1 mol) and KI (0.1 g) were dissolved in 50 mL of
ethanol, to which 12 g (0.21 mol) of KOH in 10 mL of water was
added dropwise with stirring. After being cooled, the reaction
mixture was titrated dropwise with 0.1 mol of 1-bromopentane.
After refluxing for 24 h, the reaction mixture was poured into a
large amount of water, followed by acidification to pH 3-4 by
HCl. The white precipitate was filtered, washed with water and
recrystallized in ethanol. 4-(Pentyloxy)benzoic acid was ob-
1H, tCH), 1.85-1.82 (m, 2H, OCH2CH2), 1.47-1.40 (m, 4H,
CH2CH2CH3), 0.97-0.94 (t, 3H, CH3). 13C NMR (100 MHz,
CDCl3), δ (ppm): 164.79, 164.38 (COO), 163.63 (aromatic
carbon linked with OC5H11), 148.67, 148.12 (aromatic carbon
linked with OOC), 132.30 (aromatic carbon ortho to HCtC),
132.27 (aromatic carbon ortho to COO and meta to OC5H11),
130.05 (aromatic carbon linked with COO and para to HCtC),
129.40 (aromatic carbon ortho to COO and meta to HCtC),
127.54 (aromatic carbon linked with HCtC), 122.77, 122.47
(aromatic carbon ortho to OOC), 121.35 (aromatic carbon
linked with COO and para to OC5H11), 114.34 (aromatic carbon
ortho to OC5H11), 82.68 (HCtC-), 80.57 (HCtC-), 68.34
(OCH2), 28.79 (OCH2CH2CH2CH2CH3), 28.13 (OCH2CH2-
CH2CH2CH3), 22.42 (OCH2CH2CH2CH2CH3), 13.99 (CH3).
MS: m/z = 428 (Mþ). Anal. Calcd for C27H24O5: C, 75.68; H,
5.65; Found: C, 75.43; H, 5.64.
(f). Synthesis of 4-(Pentyloxy)phenyl 4-Ethynylbenzoate (M2-5).
Monomer M2-5 was synthesized by esterification of 4-ethynylben-
zoic acid with 4-(pentyloxy)phenol. The experimental procedures
were similar to those for the synthesis of M3-5 described above.
Monomer M2-5 was obtained as white solid in a yield of 60%.
1H NMR (400 MHz, CDCl3), δ (ppm): 8.15 (d, 2H, Ar-H
meta to CtCH), 7.61 (d, 2H, Ar-H ortho to CtCH), 7.10 (d,
2H, Ar-H meta to OCH2), 6.93 (d, 2H, Ar-H ortho to OCH2),
3.96 (t, 2H, OCH2), 3.27 (s, ꢀCH), 1.79 (m, 2H, OCH2CH2),
1.47-1.38 (m, 4H, CH2CH2CH3), 0.94 (t, 3H, CH3). 13C NMR
(100 MHz, CDCl3), δ (ppm): 164.79 (COO), 157 (aromatic
carbon linked with OC5H11), 144.13 (aromatic carbon para to
OC5H11), 132.17 (aromatic carbon ortho to CtCH), 129.94
(aromatic carbon meta to CtCH), 129.70 (aromatic carbon
para to CtCH), 127.32 (aromatic carbon linked with CtCH),
122.25 (aromatic carbon meta to OC12H25), 115.13 (aromatic
carbon ortho to OC12H25), 82.72 (HCꢀC-), 80.41 (HCꢀC-),
68.43 (OCH2), 29.67 (OCH2CH2), 29.08 (CH2CH2CH3), 22.42
(CH2CH3), 13.97 (CH3). MS: m/z = 308 (Mþ). Anal. Calcd for
C20H20O3: C, 77.92; H, 6.49; Found: C, 77.96; H, 6.33.
1
tained as white solids. H NMR (400 MHz, CDCl3), δ (ppm):
12.62 (s, 1H, COOH), 7.90-7.86 (d, 2H, Ar-H ortho to COOH),
7.04-7.00 (d, 2H, Ar-H ortho to OCH2), 4.05-4.03 (t, 2H,
OCH2), 1.85-1.81 (m, 2H, OCH2CH2), 1.47-1.41 (m, 4H,
CH2CH2CH3), 0.97-0.93 (t, 3H, CH3).
(g). Synthesis of Rh(nbd)[B(C6H5)4] Catalyst. Synthesis of this
catalyst was carried out according to the method reported by
(d). Synthesis of 4-(Pentyloxy)phenol. The compound was
prepared according to the literature method with some modifi-
cation.32 Hydroquinone (11 g, 0.1 mol) was dissolved in 100 mL
of dimethyl sulfoxide (DMSO), to which 16.8 g (0.3 mol) of
powdered KOH was added under stirring. Within 0.5 h, 0.1 mol
of 1-bromopentane was added to the above mixture under
stirring via a dropping funnel with a pressure-equalization
arm. The reaction mixture was kept in 40 °C water bath with
vigorous stirring for 3 h and the course of reaction was followed
by TLC. When completed, the reaction mixture was poured into
400 mL cold water followed by acidification to pH 1. The crude
product was filtered out and washed with cold water. After
purified by column chromatography using dichloromethane
(DCM) as the eluent, 4-(pentyloxy)phenol was obtained as
white solid in a yield of ca. 20%. 1H NMR (400 MHz, CDCl3),
δ (ppm): 6.80-6.73 (m, 4H, Ar-H), 4.53 (s, 1H, OH), 3.90 (t,
2H, OCH2), 1.76 (m, 2H, OCH2CH2), 1.43-1.36 (m, 4H,
CH2CH2CH3), 0.92 (t, 3H, CH3).
Schrock et al.33 RhCl3 3H2O (250 mg) was dissolved in water
3
(1 mL), and Na[B(C6H5)4] (1 g) in methanol (20 mL) was added.
2,5-Norbornadiene (nbd; 1 mL) was then added and the solution
was allowed to stand until crystals were deposited. The yellow
crystalline products were filtered and air-dried. The desired
complex was obtained in a yield of ca. 70%. Anal. Calcd for
C31H28RhB: C, 72.40; H, 5.49; Found: C, 70.14; H, 5.41.
Polymerization. Using Rh(nbd)[B(C6H5)4] as catalyst and dry
toluene as solvent, a typical procedure for the polymerization of
M3-5 is as follows: Into a polymerization tube was added 7 ꢁ
10-3 mmol (3 mg) of monomer M3-5, and then 3 mL of dry
toluene with 0.2 mg of Rh(nbd)[B(C6H5)4] was put into the tube.
After 24 h reaction at room temperature, the red suspension of
polymer product was directly filtered out. After being washed
three times with acetone, the product was dried under vacuum to
a constant weight. The yield was over 80%.
Instruments and Measurements. Elemental analysis was per-
formed with an Elementar Vario EL instrument. Mass spectra
were recorded on a Finnigan-MAT ZAB-HS spectrometer. FT-
IR and Raman measurements were carried out using a Magna-
IR750 (Nicolet) FT-IR spectrometer and an IFS-106 (Bruker)
Raman spectrometer, respectively. Differential scanning calo-
rimetry (DSC, PerkinElmer Pyris I with a mechanical refriger-
ator) was utilized to study the phase transitions of the monomers
and the polymers. Thermogravimetric analysis (TGA) was per-
formed with a TA SDT 2960 instrument at a heating rate of
10 °C/min in nitrogen or air atmosphere. Gel permeation chro-
matography (GPC) was carried out on a Waters 515 GPC
instrument using THF as an eluent at 35 °C. The GPC calibra-
tion curve was obtained with linear polystyrene standards.
UV-vis absorption and turbidity measurements were perfor-
med with a Lambda 35 (Perkin-Elmer) UV-vis spectrometer.
(e). Synthesis of 4-[4-(Pentyloxy)benzoyloxy]phenyl 4-Ethy-
nylbenzoate (M3-5). First, 0.5 g (2.1 mmol) of 4-[(4-hydroxy-
phenyl)oxycarbonyl]phenylacetylene, 1.0 g (4.8 mmol) of 4-
(pentyloxy)benzoic acid, 0.15 g (1.3 mmol) of DMAP, 0.23 g
(1.2 mmol) of TsOH were dissolved in 100 mL of dry DCM, to
which the DCM solution of 1.5 g (7.3 mmol) of DCC was added
dropwise with stirring. The reaction mixture was stirred for 24 h
at room temperature. After the solvent was removed, the crude
product was purified by a silica gel column using petroleum
ether/DCM (1:1 by volume) as eluent. M3-5 was obtained as
white solid in a yield of ca. 60%.
1H NMR (400 MHz, CDCl3), δ (ppm): 8.18-8.13 (t, 4H,
Ar-H meta to CtCH or OCH2), 7.64-7.61 (d, 2H, Ar-H
ortho to CtCH), 7.26 (s, 4H, Ar-H ortho to OOC), 6.99-6.97
(d,2H, Ar-H ortho to OCH2), 4.07-4.03 (t, 2H, OCH2), 3.28 (s,