JOURNAL OF POLYMER SCIENCE: PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
(COOCH3), 52.54 (CCOOCH3), 51.64 (COOCH3), 44.92
(CCH2C), 32.92 (CH2CH2).
1,3-dimethoxycarbonylcyclopentane. Vacuum distillation (90–
100 C/0.2 mmHg) gave the product as a colorless oil (liquid
ꢀ
and solid mixture, cis- and trans-product), yield, 88%.
Recrystallization from hexane gave a white crystalline solid
(trans-product), yield, 51%. 1H NMR (400 MHz, CDCl3, d,
ppm): 3.63 (s, 6H, COOCH3), 2.07 (d, 4H, J ¼ 10 Hz,
CH2CH2), 1.20 (d, 4H, J ¼ 10 Hz, CH2CH2), 1.13 (s, 6H,
CCH3); 13C NMR (400 MHz, CDCl3, d, ppm): 177.87
(COOCH3), 51.89 (COOCH3), 42.92 (CCH3), 33.05 (CH2CH2),
27.51 (CCH3). mp: 94.5–95.3 ꢀC, MS (m/z): calcd for
Synthesis of Dimethyl bicyclo[2.2.2]octane-1,
4-dicarboxylate (DMCD-2)
DMCD-2 was prepared by a published literature procedure.14
The workup method was modified to improve the purity of
the product. This modification involved vacuum distillation
ꢀ
(130 C/ 0.1–0.2 mmHg) and recrystallization from hexanes.
Finally a whiteꢀ crystalline solid was obtained, yield: 38.5%,
ꢀ
mp: 98.8–99.1 C (literature 92.8 C). The structure was con-
C
12H20O4, 228.14; found, 229.6 [MþH]þ.
1
firmed by NMR measurement. NMR data were as follows: H
NMR (400 MHz, CDCl3, d, ppm): 3.61 (s, 3H, OCH3), 1.75 (s,
6H, CH2); 13C NMR (400 MHz, CDCl3, d, ppm): 177.77
(COOCH3), 51.66 (COOCH3), 38.57 (CCOOCH3), 27.69 (CH2).
Abbreviation of Polyesters
The polymer nomenclature used in this manuscript is based
on a polyester containing 100 mol % of diester and 100
mol % of diol. For example, the polymer designated by
poly[50(DMCD-2)50(DMCD)30(EG)70(CHDM)] means this
targeted polymer containing 50 mol % DMCD-2 and 50 mol
% DMCD as the diester units and 30 mol % EG and 70 mol
% CHDM as the diol units. The letters, stand for various
monomers’ abbreviation and the numbers indicate targeted
mol % of monomers, respectively.
Synthesis of Dimethyl bicyclo[3.2.2]nonane-1,
5-dicarboxylate (DMCD-3)
DMCD-3 was synthesized following a literature procedure.15
The Dieckmann condensation of dimethylmalonate obtained
white solid product dimethyl succinylsuccinate in 72%
1
yield.16 m.p.126–127 C. H NMR (400 MHz, CDCl3, d, ppm):
ꢀ
12.12 (s, 2H, COH), 3.79 (s, 6H, COOCH3), 3.18 (s, 4H,
CH2CCOOCH3); 13C NMR (400 MHz, CDCl3, d, ppm): 171.93
(COOCH3), 168.82 (COH), 93.42 (CCOOCH3), 52.10 (COOCH3),
28.77 (CH2).
Preparation of Catalyst Solution
The Ti catalyst solution was obtained by mixing titanium n-
butoxide with n-BuOH in a dry bottle under nitrogen at a
concentration of 0.06 g/mL based on Ti.
Dimethyl succinylsuccinate was treated with sodium hydride
in dry DME and then reacted with 1,3-dibromopropane to
obtain white product 1,5-biscarbmethoxybicyclo[3.2.2]no-
nane-6,8-dione. Yield: 26%, m.p. 125–126 ꢀC. 1H NMR (400
MHz, CDCl3, d, ppm): 3.77 (s, 6H, COOCH3), 3.39 (s, 1H,
CH2CO), 3.35 (s, 1H, CH2CO), 2.78 (s, 1H, CH2CO), 2.73 (s,
1H, CH2CO), 2.45–2.52 (m, 2H, CH2CH2CH2), 1.92–1.99 (m,
2H, CH2CH2CH2), 1.75–1.82 (m, 2H, CH2CH2CH2).
Polycondensation of DMCD-2, EG, and CHDM
The detailed procedure is as follows: 3.62 g (16 mmol)
DMCD-2, 1.10 g (17.6 mmol) of EG (120% excess), 1.15 g (8
mmol) CHDM, and 0.05 mL (100 ppm) of a titanium n-butox-
ide solution (0.06 g/mL in butanol) was added to a 50 mL
single-necked, round-bottom glass flask. The reaction flask
was immersed into a molten Belmont metal bath that was
preheated to 190 ꢀC. A multistep temperature procedure
was used for ꢀthe reaction, i.ꢀe. the reaction mixture was
stirred at 190 C for 2 h, 220 C for 2 h. Then the tempera-
The thiane was prepared from the diketone using the litera-
ture procedure16 in 83% yield. 1H NMR (400 MHz, CDCl3, d,
ppm): 3.64 (s, 6H, COOCH3), 3.57 (s, 1H, CH2CS), 3.54 (s, 1H,
CH2CS), 3.40–3.36 (m, 4H, SCH2CH2S), 3.26–3.21 (m, 4H,
SCH2CH2S), 2.96 (s, 1H, CH2CS), 2.93 (s, 1H, CH2CS), 2.56–
2.53 (m, 2H, CH2CH2CH2), 1.89–1.86 (m, 4H, CH2CH2CH2);
13C NMR (400 MHz, CDCl3, d, ppm): 174.05 (COOCH3), 70.20
(CSCH2), 55.97 (COOCH3), 55.07 (CCOOCH3), 52.24 (CH2CS),
40.89 (SCH2CH2S), 40.75 (SCH2CH2S), 37.19 (CH2CH2CH2),
22.01 (CH2CH2CH2).
ꢀ
ture was increased to 275 C and held for 30 min. The pres-
sure then was gradually reduced and the temperature was
raised to 275 ꢀC. The final stage involved applying a high
vacuum (up to 0.1 mmHg) for an additional 2 h at 275 ꢀC
and the highly viscous copolyester was obtained. Some copo-
lyesters started to take on yellow color due to the titanium
catalyst and the long reaction time. The vacuum was stopped
and nitrogen was bled into the flask. The polymer was
cooled to room temperature, dissolved in chloroform, and
precipitated into methanol. The solid precipitate was
obtained by vacuum filtration and dried at 60 ꢀC in vacuo
overnight. The same procedure was employed to prepare
poly[w(DMCD)x(DMCD-2)y(EG)z(CHDM)] (where w and x, y,
and z add up to 100, respectively) (Scheme 2).
Desulfurization of the thioketal by Raney nickel slurry
occurred in ethanol, which was refluxed for 3 days. The
product was purified by distillation under high vacuum (110
ꢀC/0.08 mmHg) to give colorless solid DMCD-3. Yield: 70%,
m.p. 34–35 ꢀC. 1H NMR (400 MHz, CDCl3, d, ppm): 3.63 (s,
6H, COOCH3), 1.94–1.67 (m, 14H, CH2CH2). 13C NMR (400
MHz, CDCl3, d, ppm): 178.81 (COOCH3), 51.87 (COOCH3),
42.68 (CCOOCH3), 37.38 (CH2CH2CH2), 27.95 (CH2CH2),
21.36 (CH2CH2CH2).
Synthesis of All Aliphatic Polyester Poly[50(DMCD-M)50
(DMCD)30(EG)70(CHDM)]
Synthesis of 1,4-Dimethoxycarbonyl-1,4-
dimethylcyclohexane (DMCD-M)
DMCD-M was prepared from the DMCD by following a proce-
dure described by Weagley et al.17 for the dialkylation of
Copolyester was prepared by the same procedure as the
above copolymer except that DMCD-M was used in place of
DMCD-1.
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