Polycarbonates alternating copolymerization

The synthesis of polycarbonates from the alternating copolymerization of epoxides with C02 was first reported in 1969 using a ZnEt2/H20 mixture.954 Subsequent studies have focused upon a... 

It is also possible to desymmetiize a meso epoxide in the alternating copolymerization. Thus, asymmetric alternating copolymerization of cyclohexene oxide with CO2 catalyzed by a dimeric zinc complex provides a polycarbonate in which the diol unit is optically active with 80% ee. (See Scheme 4.24.)... 

An alternative source of polycarbonate derived from C02 involves the alternating copolymerization of oxetane and C02 (Equation 8.1). 

We have found for the first time the alternating copolymerization of carbon dioxide and epoxide catalyzed by some organometallic systems to give an aliphatic polycarbonate of high molecular weight. 

Nozaki, K. Nakano, K. Hiyama, T. Optically active polycarbonates Asymmetric alternating copolymerization of cyclohexene oxide and carbon dioxide. J. Am. Chem. Soc. 1999, 121,... 

Carbon Dioxide as a Renewable Cl Feedstock Synthesis and Characterization of Polycarbonates from the Alternating Copolymerization of Epoxides and CO2... 

The alternating copolymerization of cis/fraws-limonene oxide and carbon dioxide can be achieved with p-diiminate zinc acetate complexes (Scheme 5). The balance between high catalyst activity and selectivity is optimal with catalyst complex 8 (see Scheme 5, right) at 25°C. Catalysts exhibits high selectivity for the trans diasteriomer (% trans in the copolymer is >98%). The biodegradable polycarbonates have MWs in the range of 4.0-10.8 kg/mol, which can be controlled by the [epoxide]/[Zn] ratio, CO2 pressure, and reaction time. They also have narrow... 

Sugimoto, H. Ohshima, H. Inoue, S. Alternating Copolymerization of Carbon Dioxide and Epoxide by Manganese Porphyrin The First Example of Polycarbonate Synthesis from 1-atm Carbon Dioxide. J. Polym. Set, Part A Polym. Chem. 2003, 41,3549-3555. 

Metal-catalyzed reactions of C02 and epoxides that give polycarbonates and/or carbonates have been extensively investigated as a potentially effective C02 fixation (Beckman, 1999 Inoue, 1987). The possible reaction mechanism is illustrated in Figure 3.8 (Darensbourg et al., 1999). The repetition of the reaction sequence in which C02 inserts into a metal-alkoxide bond, followed by ring-opening of the epoxide with the metal carbonate forms the alternating copolymer. In 1969, this copolymerization was first reported by Inoue and Tsuruta who used a Zn catalyst derived from... 

Carbon dioxide is considered to be an interesting alternative to most traditional solvents [17, 18] because of its practical physical and chemical properties it is a solvent for monomers and a non-solvent for polymers, which allows for easy separation. To a somewhat lesser extent, it can also be a sustainable source of carbon [19]. The use of CO2 as a reactant is considered to contribute to the solution of the depletion of fossil fuels and the sequestration of the greenhouse gas CO2. One example in this area is the copolymerization of carbon dioxide with oxiranes to aliphatic polycarbonates [19-22]. 

The carboxylation of epoxides may afford either monomers, as discussed above, or polycarbonates for example, Al-porphyrin complexes [175, 176] or Zn-compounds [177] promote the formation of polycarbonates. The pioneering studies of Inoue [178] and Kuran [179] have opened the route to the investigation of the copolymerization of CO2 and epoxides. The key issue here is to master the alternate insertion epoxide-C02. 

Heitz synthesized polymers with two phenolic end groups by carrying out the polymerization in the presence of a biphenol. Block polyether-polycarbonate and polyether-polyester carbonates were synthesized from these blocks. Percec also prepared a bifunctional PPO by polymerization of 2,6-dimethylphenol in the presence of 2,2 -di(4-hydroxyphenyl-3, 5-dimethylpropane). Etherification of the blocks with chloromethylstyrene gave reactive oligomers that were cross-linkable. When monofunctional PPO was reacted with chloromethyl styrene the resulting styryl-substituted polymers formed comb-like structures on polymerization and could be copolymerized with vinyl monomers. Alternatively, Meijer was able to coredistribute phenol-terminated polymers with PPO to produce block copolymers. ... 

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