T.F. Al-Azemi, A.A. Mohamod / Polymer 52 (2011) 5431e5438
5433
2.03e1.94 (m, 2 H), 1.89e1.83 (m, 1 H), 1.73e1.68 (m, 2 H); 13C NMR
(100 MHz, CDCl3)
d
205.6 (d, Jc,F ¼ 15 Hz, C]O), 6 91.8 (d,
JC,F ¼ 189 Hz, CHF), 40.28(CH,), 34.1 (d, JC,F ¼ 18 Hz, CH2CHF), 26.9
(CH2), 22.7 (d, JC,F ¼ 10 Hz, CH2).
2.5. Synthesis of
a
-&-
3
-fluoro- -caprolactones (3a, and 3b)
3
Scheme 2. Poly(
a-fluoro- 3 -caprolactone) obtained by Sn(Oct)2-catalyzed ROP in bulk
To a solution of 5 g (42.9 mmol) of 2-fluorocyclohexanone in
60 ml dried dichloromethane, m-CPBA (14.4 g, 83.5 mmol) was
added at room temperature and the reaction was stirred for 24 h.
The reaction mixture was cooled in an ice bath to precipitate the m-
chlorobenzoic acid. After filtration, the solid was washed with
additional 100 ml cold dichloromethane. The dichloromethane was
extracted with saturated solution of Na2S2O3 (three times), solution
of NaHCO3 (three times), and finally with water. After drying over
anhydrous Na2SO4, the organic layer was concentrated under
reduced pressure. The two isomeric lactones were separated by
at 120 ꢀC for 12 h.
gel column chromatography eluting 25% ethyl acetate/petroleum
ether. Compound 1 was obtained a yellow liquid (0.078 mol, 9.2 g;
yield 76.4%). HRMS m/z [M]þ. Calcd for C6H11FO: 118.0794. Found
118.0788.1H NMR (400 MHz, CDCl3)
d
4.17 (ddt, JH,F ¼ 51.6 Hz,
J ¼ 7.3 Hz, 1 H, CHF), 3.59 (m, 1 H, CHOH), 3.05 (br, 1 H, OH),
2.10e1.90 (m, 2 H, CH2), 1.75e1.69 (m, 2 H, CH2), 1.48e1.10 (m, 4 H,
CH2CH2); 13C NMR (100 MHz, CDC13)
d
96.17 (d, JC,F ¼ 114 Hz, CHF),
73.26 (d, JC,F ¼ 12 Hz, CHOH), 31.67 (d, JC,F ¼ 4 Hz, CH2, 30.24 (d,
JC,F ¼ 11 Hz, CH2), 23.52 (d, JC,F ¼ 5 Hz, CH2), 23.51 (d, JC,F ¼ 4 Hz,
CH2).
silica gel column chromatography eluting chloroform. The
3
was eluted first ( Rf ¼ 0.58, 2.1 g, 36.9%) and
a
a
second (Rf ¼ 0.57, 2.5 g, 44%). Compound (3a,
[M]þ. Calcd for C6H9FO2: 132.0587. Found 132.0581.1H NMR
2.4. Synthesis of 2-fluorocyclohexanone (2) [12,13]
(400 MHz, CDCl3)
4.08 (m, 1H, eCH2eOe), 4.41 (m, 1H, eCH2eOe), 2.17e1.92 (m, 4H),
1.82e1.75 (m, 2H). 13C NMR (150 MHz, CDCl3)
6170.9 (d,
d
5.15 (ddd, 1H, JH, F ¼ 47.4, 10.8, 2.4 Hz, eCHFe),
Fluorocyclohexanol 1 (9 g, 75.9 mmol) was dissolved in dried
dichloromethane, and PCC (24.5 g, 113.8 mmol) was added to the
mixture, and the solution was stirred over night. The reaction
mixture was filtered and the filtrate was concentrated under
reduced pressure. The crude product was purified by silica gel
column chromatography eluting dichloromethane. Compound 2
was obtained as yellow liquid (8.7 g, 74.6 mmol; yield 98.3%). HRMS
m/z [M]þ. Calcd for C6H9FO: 116.0637. Found 116.0631.1H NMR
d
Jc,F ¼ 22.5 Hz, C]OO), 87.9 (d, JC,F ¼ 186 Hz, CHF), 68.9 (CH2eO),
29.9 (d, JC,F ¼ 22.5 Hz, CH2CHF), 28.4 (CH2), 24.1 (d, JC,F ¼ 9 Hz, CH2).
Compound (3b,
3
132.0587. Found 132.0583.1H NMR (400 MHz, CDCl3)
JH, F ¼ 49.6, 5.6 Hz, eCHFe), 2.72e2.69 (m, 2H, eCH2CO), 2.32e2.25
(m, 1H), 1.97e1.80 (m, 4H), 1.69e1.62 (m, 1H). 13C NMR (150 MHz,
CDCl3)
d
6172.0 (C]OO), 106. 3 (d, JC,F ¼ 228 Hz, CHF), 36.5 (d,
(400 MHz, CDCl3)
2.59e2.54 (m,1 H) 2.43e2.41 (m, 1 H), 2.37e2.32 (m, 1 H),
d
4.82 (ddd, JH,F ¼ 44 Hz, J ¼ 13.6 Hz, 1 H, CHF),
Jc,F ¼ 3.0 Hz,), 32.8 (d, JC,F ¼ 22.5 Hz,), 22.5, 22.1 (d, JC,F ¼ 4.5 Hz,
CH2).
Fig. 2. NMR spectra of poly(a
-fluoro- 3 -caprolactone) obtained by Sn(Oct)2-catalyzed ROP in bulk at 120 ꢀC for 12 h: (a) 1H NMR spectrum (600 MHz, CDCl3); (b) 13C NMR spectrum
(150 MHz, CDCl3).