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TABLE 1 Conditions and Results of Polyadditions of 4,40-Bis(2-oxazolin-2-yl)biphenyl (BiBOX) with Different Dicarboxylic Acids
Amount
(mmol)
Solvent
(mL)
Temp.
(ꢀC)
Time
(h)
Yield
(%)
Mn
Tm
(ꢀC)
No.
1
Diacid
(VPO)
Note
Sebacic
0.5
–
155
5
90
–
270–273
Acid did not
dissolved BiBOX
2
3
4
5
6
7
8
Sebacic
0.5
0.5
0.5
0.5
0.5
0.5
0.5
DMF/0.3
TMS/0.5
DMSO/0.5
TMS/1
170
180
180
180
180
180
155
5
5
5
5
5
5
8
95
–
–
Phase separation
Sebacic
97
Sebacic
100
95
Suberic
8,330
275–292
303–306
258–265
300–307
Adipic
TMS/1
100
95
22,000
Dodecanedioic
Succinic
TMS/1
TMS/0.5
91
biphenyl (BiBOX), were prepared as monomers of AB- and
AA–BB-types for polyaddition reactions.
Synthesis of 4,40-Bis(2-oxazolin-2-yl)biphenyl (BiBOX)
4,40-Biphenyldicarboxylic acid (BiDAc, 4.84 g, 0.02 mol) and
thionyl chloride (7.3 mL, 0.1 mol) were heated under reflux
for 3 hours. The excess SOCl2 was removed and colorless
crystals of biphenyl-4,40-dicarbonylchloride (BiDCl) were
obtained. Yield: ꢁ100%. mp ¼ 186–188ꢀC.
BiDCl (5.6 g, 0.02 mol) and 2-chloroethylamine hydrochlor-
ide (4.64 g, 0.04 mol) were dispersed in a mixture of aque-
ous NaOH (4.5 g, 0.08 mol) and dichloromethane (70 mL). A
white precipitate was formed immediately. The solid was
then separated, washed with water, and dried. A white pow-
der of N, N0-Bis(2-chloroethyl)biphenyl-4,40-dicarboxamide
(BiDAm) was obtained. Yield: 99.5%. mp >300ꢀC.
EXPERIMENTAL
Materials
The starting materials including 40-hydroxy-4-biphenylcar-
boxylic acid (HBiAc) and 4,40-biphenyldicarboxylic acid
(BiDAc) were purchased from Aldrich. All other available
reagents (Aldrich) were used as received. All solvents used
for polymerizations and subsequent measurements were dis-
tilled and dried over molecular sieves before the use.
Synthesis of 40-Hydroxy-4-(2-oxazolin-2-yl)
biphenyl (HBiOX)
BiDAm (5.48 g, 0.015 mol) was dissolved in methanolic KOH
(0.03 mol), and the solution was heated under reflux for 3
hours. After cooling, the precipitate was separated and the
residue was concentrated. A white solid of BiBOX was
The ester (HBiEs) was prepared from 40-hydroxy-4-biphenyl-
carboxylic acid (HBiAc) (5 g, 0.023 mol) by heating under
reflux in methanol (50 mL) in the presence of a catalytic
amount of sulfuric acid (0.11 mL, 0.002 mol) for 5 hours.
The reaction yield was 97%. mp 226–229ꢀC. 1H NMR
(DMSO-d6): 3,86 (s, OCH3, 3H), 6,88 (d, ar, 2H), 7,59 (d, ar,
2H), 7,74 (d, ar, 2H), 7,98 (d, ar, 2H), 9,74 (s, Ar-OH, 1H).
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obtained. Yield: 87%. mp ¼ 320ꢀC, sublimation at 250ꢀC. H
NMR (DMSO-d6): 3.99 (t, CH2N, 4H), 4.43 (t, CH2O, 4H), 7.83
(d, ar, 4H), 7.97 (d, ar, 4H).
Polymerization in Melt
The hydroxyamide HBiAm was prepared by the reaction of
HBiEs (2.97 g, 0.013 mol) with 2-aminoethanol (6.35 g,
0.104 mol) at 150ꢀC for 3 hours. The excess of 2-aminoetha-
nol was removed with suction and the residue was poured
into water. A white crystalline compound was obtained. The
yield: 98%. mp 240–242ꢀC. 1H NMR (DMSO-d6): 3,35 (q,
CH2N, 2H), 3,52 (d, CH2O, 2H), 4,75 (s, RAOH, 1H), 6,86 (d,
ar, 2H), 7,57 (d, ar, 2H), 7,67 (d, ar, 2H), 7,91 (d, ar, 2H),
8,44 (t, NH, 1H), 9,57 (broad s, ArAOH, 1H).
Calculated amounts of comonomers were weighed in a dry
ampoule, which was evacuated and filled with argon several
times before sealing. The tube was then immersed in a pre-
heated oil bath. After finishing polymerization, the ampoule
was opened; the polymer was dissolved in hot DMF, precipi-
tated in nonsolvent, separated, washed, and dried under
vacuum. Detailed polymerization conditions and results are
listed in Table 1.
HBiOX was prepared by cyclization of HBiAm (3.01 g, 0.012
mol) in dichloromethane (70 mL). Thionyl chloride (4.4 mL,
0.06 mol) was added dropwise in an ice bath, and the reac-
tion mixture was stirred for 20 hours at an ambient temper-
ature. The white solid of hydrochloride was isolated, dried,
and neutralized with saturated aqueous NaHCO3. A white
precipitate was isolated and recrystallized from ethanol.
Yield: 79%. mp 238–240ꢀC. 1H NMR (DMSO-d6): 3,97 (t,
CH2N, 2H), 4,41 (t, CH2O, 2H), 6,89 (d, ar, 2H), 7,58 (d, ar,
2H), 7,79 (d, ar, 2H), 7,91 (d, ar, 2H), 9,67 (broad s, ArAOH,
1H), UV (CH3OH): 220 nm (log e ¼ 4,17), 297 (log e ¼ 4,38).
Polymerization in Solution
Calculated amounts of comonomers were weighed in a dry
ampoule, solvent was added, and the mixture was bubbled
with argon for 5 min and then sealed. The ampoule was
immersed in an oil bath preheated to the desired tempera-
ture and withdrawn after the desired time. The liquid or vis-
cous product was precipitated in a nonsolvent (methanol,
water). The solid product was dissolved in the solvent used
during polymerization and precipitated in nonsolvent.
Detailed polymerization conditions and results are listed in
Table 1.
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JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY 2012, 000, 000–000