Copolymerization of carbon dioxide and epoxide

Inoue S, Koinuma H, Tsumta T (1969) Copolymerization of carbon dioxide and epoxide. J Polym Sci Part B Polym Lett 7 287-292... 

Carbon dioxide is an interesting synthetic feedstock, it can be copolymerized with heterocycles, such as epoxides, aziridines, and episulfides. In 1969, Inoue reported the zinc catalyzed sequential copolymerization of carbon dioxide and epoxides as a new route to polycarbonates (5,15). The reaction is shown in Figure 1.1. 

COPOLYMERIZATION OF CARBON DIOXIDE AND EPOXIDE AND RELATED REACTIONS... 

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. 

The reaction has been studied intensively, and earlier results including the mechanistic aspects of the reaction as well as the fundamental properties of the copolymer were reviewedThe most effective catalyst systems for this copolymerization so far examined are those based on organozinc and related compounds ). The catalyst systems so far reported, from several groups, for the copolymerization of carbon dioxide and epoxide (mainly propylene oxide) are summarized in Table 1. Diethylzinc-water system is applicable to the copolymerization of carbon dioxide and various epoxides (Table 2). 

Table 1. Catalyst Systems for the Copolymerization of Carbon Dioxide and Epoxide...

Cheng M, Lobkovsky EB, Coates GW (1998) Catalytic reactions involving Cl feedstocks new high-activity Zn(II)-based catalysts for the alternating copolymerization of carbon dioxide and epoxides. J Am Chem Soc 120 11018-11019... 

Inoue, S. Komuma,R Tsuruta,T. Copolymerization of Carbon Dioxide and Epoxide J. Polym. Sci., PartB 1969, 7,287-292. 

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. 

It is of particular interest to note that this block copolymer has a very narrow molecular weight distribution, as shown in Fig, 9, which also indicates the absence of the prepol3mier in the final procuct. Therefore, the copolymerization of carbon dioxide and propylene oxide actually takes places from the growing end of the epoxide pol3nneri-zation, an aluminum alkoxide. 

Darensbourg DJ, Yarbrough JC (2002) Mechanistic aspects of the copolymerization reaction of carbon dioxide and epoxides, using a chiral salen chromium chloride catalyst. J Am Chem Soc 124 6335-6342... 

Darensbourg, D. J. Yarbrough, J. C. Mechanistic Aspects of the Copolymerization Reaction of Carbon Dioxide and Epoxides, Using a Chiral Salen Chromium Chloride Catalyst. J. Am. Chem. Soc. 2002,124, 6335-6342. 

Hsu T, Tan C (2002) Block copolymerization of carbon dioxide with cyclohexene oxide and 4-vinyl-1-cyclohexene-1,2-epoxide in based poly(propylene carbonate) by yttrium-metal... 

Copolymerization of carbon dioxide possibly also belongs to this class of polymerizations. Carbon dioxide copolymerizes with epoxides to polyanhydrides, with aziridines to polyurethanes, and with vinyl ethers to poly-ketoethers, i.e.. 

An alternative method for generating enriched 1,2-diols from meso-epoxides consists of asymmetric copolymerization with carbon dioxide. Nozaki demonstrated that a zinc complex formed in situ from diethylzinc and diphenylprolinol catalyzed the copolymerization with cyclohexene oxide in high yield. Alkaline hydrolysis of the isotactic polymer then liberated the trans diol in 94% yield and 70% ee (Scheme 7.20) [40]. Coates later found that other zinc complexes such as 12 are also effective in forming isotactic polymers [41-42]. 

Equations 1 to 3 show some of fixation reactions of carbon dioxide. Equations la and lb present coupling reactions of CO2 with diene, triene, and alkyne affording lactone and similar molecules [2], in a process catalyzed by low valent transition metal compounds such as nickel(O) and palladium(O) complexes. Another interesting CO2 fixation reaction is copolymerization of CO2 and epoxide yielding polycarbonate (equation 2). This reaction is catalyzed by aluminum porphyrin and zinc diphenoxide [3],... 

Some copolymerizations have been studied where one of the reactants is a compound not usually considered as a monomer. These include copolymerizations of epoxides and higher cyclic ethers with carbon dioxide, episulhdes with carbon dioxide and carbon disulhde, and epoxides with sulfur dioxide [Aida et al., 1986 Baran et al., 1984 Chisholm et al., 2002 Inoue and Aida, 1989 Soga et al., 1977]. The copolymers are reported to be either 1 1 alternating copolymers or contain 1 1 alternating sequences together with blocks of the cyclic monomer. 

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