Catalytic copolymerization, carbon dioxide

In our previous work [8], we rqjorted the synthesis of (2-oxo-l,3-dioxolan-4-yl)methacrylate (DOMA) finrn carbon dioxide and glycidyl methacrylate (GMA) using quaternary salt catalysts. In the present work, we studied the catalytic pra rmance of alkyhnethyl imidazolium salt ionic liquid in the synthesis of polycarbonate from the copolyraerization of CO2 with GMA. The influences of copolymerization variable like catalyst structure and reaction tenperature on the conversion of GMA and the yield of the polycarbonate have been discussed. 

Palladium(II) complexes possessing bidentate ligands are known to efficiently catalyze the copolymerization of olefins with carbon monoxide to form polyketones.594-596 Sulfur dioxide is an attractive monomer for catalytic copolymerizations with olefins since S02, like CO, is known to undergo facile insertion reactions into a variety of transition metal-alkyl bonds. Indeed, Drent has patented alternating copolymerization of ethylene with S02 using various palladium(II) complexes.597 In 1998, Sen and coworkers also reported that [(dppp)PdMe(NCMe)]BF4 was an effective catalyst for the copolymerization of S02 with ethylene, propylene, and cyclopentene.598 There is a report of the insertion reactions of S02 into PdII-methyl bonds and the attempted spectroscopic detection of the copolymerization of ethylene and S02.599... 

Darensbourg DJ, Holtcamp MW (1995) Catalytic activity of zinc(II) phenoxides which possess readily accessible coordination sites. Copolymerization and terpolymerization of epoxides and carbon dioxide. Macromolecules 28 7577-7579... 

Besides zinc catalysts, other transition metal compounds (cobalt, chromium or nickel compounds,etc.) also show catalytic activity (267.268), and aziridines and carbon dioxide can also be copolymerized (240, 241.243,269-275]. The resulting copolymer has urethane linkages. 

I g Catalytic Polymerization of Ol ns in Supercritical Carbon Dioxide Table 8.11 Results of copolymerizations of ethylene and methyl acrylate in compressed carbon dioxide. 

Supercritical carbon dioxide represents an inexpensive, environmentally benign alternative to conventional solvents for chemical synthesis. In this chapter, we delineate the range of reactions for which supercritical CO2 represents a potentially viable replacement solvent based on solubility considerations and describe the reactors and associated equipment used to explore catalytic and other synthetic reactions in this medium. Three examples of homogeneous catalytic reactions in supercritical CC are presented the copolymerization of CO2 with epoxides, ruthenium>mediated phase transfer oxidation of olefins in a supercritical COa/aqueous system, and the catalyic asymmetric hydrogenation of enamides. The first two classes of reactions proceed in supercritical CO2, but no improvement in reactivity over conventional solvents was observed. Hythogenation reactions, however, exhibit enantioselectivities superior to conventional solvents for several substrates. 

Zevaco and co-workers reported the use of aluminum isopropoxide in RO copolymerization of cyclohexene oxide (CHO) with carbon dioxide [4]. Their results showed that the optimum condition was at 70°C and CO pressures of 114 bar with a substrate to catalyst molar ratio of 300 1 and a CO to substrate molar ratio of 2 1. Zevaco et at claimed that their catalytic... 

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... 

Darensbourg DJ, Holtcamp MW, Struck GE, Zimmer MS, Niezgoda SA, Rainey P, Robertson JB, Draper JD, Reibenspies JH (1999) Catalytic activity of a series of Zn(II) phenoxides for the copolymerization of epoxides and carbon dioxide. J Am Chem Soc 121 107-116... 

Naphthaleneytterbium demonstrates a high activity not only in stoichiometric reactions but also in many catalytic processes. It catalyzes at room temperature the polymerization of styrene, methylmetacrylate, ethylacrylate, isoprene, ethylene oxide, the copolymerization of ethylene oxide with styrene, piperilene and carbon dioxide [65], the hydrogenation of alkenes, alkynes, ketones, aldehydes [78], the formation of alkylenecarbonates from epoxides and CO2 [65]. 

Schiff base catalyst was also active in TMC polymerization. Moreover, chromium(III) salen derivatives in the presence of anionic initiators have been shown to be very effective catalytic systems for the alternating copolymerization of oxetane and carbon dioxide to provide the corresponding PC with a minimal amount of ether linkages. The best results were achieved for the salen ligand with tert-butyl groups in the 3,5-positions of the phenolate rings and a cyclohexylene backbone for the diimine along with an azide ion initiator (Scheme 57). 

A novel catalytic system based on aluminum porphyrins has been developed. It is particularly effective for the living ring-opening polymerization of epoxides and lactones and for the copolymerization of epoxides with carbon dioxide and with cyclic anhydrides. HNMR has demonstrated that the growing species of this initiating system is that shown in (3). 

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