Copolymerization of cyclohexene oxide and carbon dioxide using (salen)Co(<scp>iii</scp>) complexes: synthesis and characterization of syndiotactic poly(cyclohexene carbonate)

Cohen, Claire T.; Thomas, Christophe M.; Peretti, Kathryn L.; Lobkovsky, Emil; Coates, Geoffrey W.

doi:10.1039/b513107c

Cited by 145 publications

(146 citation statements)

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“…[13] The determination of various isotactic-enriched or syndiotactic-enriched poly(cyclohexene carbonate)s in subsequent experiments was realized on the basis of previous spectroscopic assignments. [14] More recent, highly stereoregular poly(cyclohexene carbonate)s with a high melting point (T m ) of about 215-230 8C were synthesized and their unique crystallization behavior was revealed. [12b, 15] Nevertheless, these investigations on CO 2 copolymers have been associated with the use of aliphatic terminal epoxides or cyclohexene oxide and its derivatives.…”

Section: H-t and H-h (Dimers (Rr)-t-t (Ss)-t-t And (Rs)-t-t; (Rmentioning

confidence: 99%

Microstructure Analysis of a CO₂ Copolymer from Styrene Oxide at the Diad Level

et al. 2013

Chemistry An Asian Journal

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A large amount of interesting information on the alternating copolymerization of CO2 with terminal epoxides has already been reported, such as the regiochemistry of epoxide ring-opening and the stereochemistry of the carbonate unit sequence in the polymer chain. Moreover, the microstructures of CO2 copolymers from propylene oxide and cyclohexene oxide have also been well-studied. However, the microstructure of the CO2 copolymer from styrene oxide (SO), an epoxide that contains an electron-withdrawing group, has not yet been investigated. Herein, we focus on the spectroscopic assignment of the CO2 copolymer from styrene oxide at the diad level by using three kinds of model dimer compounds, that is, T-T, H-T, and H-H. By comparing the signals in the carbonyl region, we concluded that the signals at δ=154.3, 153.8, and 153.3 ppm in the (13)C NMR spectrum of poly(styrene carbonate) were due to tail-to-tail, head-to-tail, and head-to-head carbonate linkages, respectively. Moreover, various isotactic and syndiotactic model compounds based on T-T, H-T, and H-H (dimers (R,R)-T-T, (S,S)-T-T, and (R,S)-T-T; (R,R)-H-T, (S,S)-H-T, and (R,S)-H-T; (R,R)-H-H, (S,S)-H-H, and (R,S)-H-H) were synthesized for the further spectroscopic assignment of stereospecific poly(styrene carbonate)s. We found that the carbonate carbon signals were sensitive towards the stereocenters on adjacent styrene oxide ring-opening units. These discoveries were found to be well-matched to the microstructures of the stereoregular poly(styrene carbonate)s that were prepared by using a multichiral Co(III)-based catalyst system.

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Section: H-t and H-h (Dimers (Rr)-t-t (Ss)-t-t And (Rs)-t-t; (Rmentioning

confidence: 99%

Microstructure Analysis of a CO₂ Copolymer from Styrene Oxide at the Diad Level

et al. 2013

Chemistry An Asian Journal

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“…Copolymerization of PO with CO 2 was investigated using salphen Co(III)Br complex without any cocatalyst resulting in high selectivity to PPC (99%) but poor activity (23h -1 ) [24]. The same complex was reported as inactive for CHO/CO 2 copolymerization [47]. A monometallic and bimetallic flexibly linked salphen chromium complexes were used in CO 2 /epoxide copolymerization producing selectively PPC with moderate TOF 50-90 h -1 containing 40-90% carbonate linkage and M n up to 32 kg.mol -1 [48].…”

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Salphen-Co(III) complexes catalyzed copolymerization of epoxides with CO2

Hošťálek

Mundil

Cı́sařová

et al. 2015

Polymer

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International audienceThe series of novel symmetric and asymmetric salphen cobalt (III) complexes with different counteranions (trichloroacetate, dinitrophenolate, pentafluorobenzoate and acetate) was synthesized and used as catalysts in copolymerization of CO2 with propylene oxide (PO) and cyclohexene oxide (CHO). Hexacoordinated structure of complexes adducts was found in solid phase. The effect of catalyst structure, temperature, CO2 pressure, catalyst/cocatalyst ratio on overall activity and selectivity was investigated. Synthesized salphen-Co (III) complexes were effective for both PO/CO2 and CHO/CO2 highly alternating copolymerization. Substitution of phenylene framework of salphen ligand by chlorine atom led to decrease of activity in PO/CO2 copolymerization. Complexes with trichloroacetate counteranion were shown to be the most active and selective in PO/CO2 copolymerization leading to poly(propylenecarbonate) with highest molar mass. On contrary, catalytic performance of salphen Co (III) complexes in CHO/CO2 copolymerization was almost independent on ligand structure and counteranion. Excellent selectivity to poly(cyclohexenecarbonate) was achieved even at 0.1 MPa CO2. MALDI-TOF analysis of polycarbonates was used to investigate the initiation step of the copolymerization

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“…Fortunately, we obtained the X-ray crystal structure of a dinuclear Al III complex bridged with a biphenyl group and chlorine as axial group. [17] The complex displays an Al-Al distance of 7.89 and an exo phenyl-phenyl dihedral angle of 45.18. In comparison to complex 4 a (chloride ion as axial group) with a Co-Co distance of 6.45 and an endo naphthyl-naphthyl dihedral angle of 798, [16b] the dinuclear Al III complex has a wider metal-metal separation, consistent with the flexible nature of the biphenyl linker.…”

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confidence: 99%