Catalytic Synthesis and Characterization of Biodegradable ...
Catalytic Synthesis and Characterization of Biodegradable ...
Catalytic Synthesis and Characterization of Biodegradable ...
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<strong>Synthesis</strong> <strong>and</strong> Electrochemistry <strong>of</strong> Schiff Base Cobalt(III) Complexes <strong>and</strong> Their<br />
<strong>Catalytic</strong> Activity for Copolymerization <strong>of</strong> Epoxide <strong>and</strong> Carbon Dioxide<br />
(2,4-Dinitrophenolato)[(R,R)-N,N�-1,2-diphenylethylenebis(3,5-di-tert-butylsalicylide<br />
neiminato)]cobalt(III) (L 3 -Co III -dnp) was synthesized by a method similar to that <strong>of</strong><br />
L 1 -Co III -dnp. Yield: 90%. IR (KBr): 1625 (s, C=N), 1597 (s, Ar–ring), 1555 (w, N=O), 1525<br />
(s, Ar–ring), 1310 (s, N=O), 1269 (s, C–O), 1056 (w, C–N), 571 cm -1 (w, Co–O).<br />
C50H57N4O7Co (884.9): Calcd. C 67.86, H 6.49, N 6.33; Found C 66.05, H 6.34, N 5.97.<br />
ESI-MS: m/z = 883.8, (C50H57N4O7Co) + , 701.5 (C44H54N2O2Co) + , 183.2 (C6H3N2O5) - .<br />
(2,4-Dinitrophenolato)[N,N�-2,2-dimethyl-1,3-propylenebis(3,5-di-tert-butylsalicylide<br />
neiminato)]cobalt(III) (L 4 -Co III -dnp) was synthesized by a procedure similar to that <strong>of</strong><br />
L 1 -Co III -dnp. Yield: 95%. IR (KBr): 1625 (s, C=N), 1601 (s, Ar–CH), 1568 (s, N=O), 1522 (s,<br />
Ar–ring), 1318 (s, N=O), 1261 (s, C–O), 1061 (w, C–N), 575 cm -1 (w, Co–O). C41H55N4CoO7<br />
(774.8): Calcd. C 63.55, H 7.15, N 7.23; Found C 63.39, H 7.06, N 7.14. ESI-MS: m/z =<br />
774.1 (C41H55N4O7Co) + , 591.4 (C35H52N2O2Co) + , 183.1 (C6H3N2O5) - .<br />
Typical Copolymerization Procedure<br />
A mixture <strong>of</strong> the cobalt complex(0.1 mmol) <strong>and</strong> tetra(n-butyl)ammonium bromide<br />
(Bu4NBr)(0.1 mmol) was dissolved in 3.5 mL <strong>of</strong> racemic propylene oxide (rac-PO) under a<br />
nitrogen atmosphere. The mixture was injected into a high pressure reactor equipped with a<br />
magnetic stirrer under a CO2 atmosphere. The reactor with a 2.5 MPa CO2 pressure was<br />
placed in an oil bath. The mixture was stirred at 40 for the allotted reaction time <strong>and</strong> then<br />
vented in a fume hood. A small aliquot <strong>of</strong> the polymerization mixture was sampled from the<br />
reactor for the 1 H NMR spectroscopic analysis. The remaining polymerization mixture was<br />
then dissolved in CH2Cl2, quenched with 5% HCl in methanol, <strong>and</strong> transferred to a<br />
pre-weighed vial. The product mixture was dried under vacuum to a constant weight. The<br />
crude yield was carefully determined after subtracting the catalyst weight. The product was<br />
then dissolved in CH2Cl2 <strong>and</strong> precipitated from methanol again. The polymer was collected<br />
by filtration <strong>and</strong> dried under vacuum to a constant weight. Analytical data for the typical<br />
product (with the L 1 -Co III -dnp catalyst) was as follows. IR (KBr): 1749 (s, C=O), 1609 (w,<br />
Ar-ring), 1580 (w, N=O), 1531 (w, Ar-ring), 1314 (s, N=O), 1235 cm -1 (s, C-O). 1 H NMR<br />
(500 MHz, CDCl3, ppm): = 1.24 (–CHCH3), 4.19 (–CH2CH–), 4.90 (–CH2CH–). 13 C NMR<br />
(400 MHz, CDCl3, ppm): = 16.1 (–CH3), 72.3 (–CH2–), 69.1 (–CH–), 154.1 (C=O) .<br />
References<br />
1. J. K. Lee, S. W. Park, J. W. Lee, M. R. Kim, Polym. Int. 2006, 55, 849.<br />
2. H. Sugimoto, S. Inoue, J. Polym. Sci., Part A: Polym. Chem. 2004, 42, 5561.<br />
3. D. J. Darensbourg, R. M. Mackiewicz, A. L. Phelps, D. R. Billodeaux, Acc. Chem. Res.<br />
2004, 37, 836.<br />
4. M. Cheng, E. B. Lobkovsky, G. W. Coates, J. Am. Chem. Soc. 1998, 120, 11018.<br />
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