Cyclic carbonate synthesis

Co(OAr)-salen complex [Ar = 2,4-(N02)2CeH3] with tetrabutylammonium chloride under neat propylene oxide, quite similar to the conditions for the cyclic carbonate synthesis, give polycarbonate with fe ei of 3.5. ° Without any additives, the use of Co(OAc)-salen provides the polycaronate with fe ei of 2.8. ... 

Later, Srivastava et al. [74] reported the catalytic activities of several Cu and Mn aza complexes for cyclic carbonate synthesis from C02 and epoxides. These authors showed that the reaction of C02 with the catalyst system generated two new IR bands... 

Figure 4.8 Possible reaction mechanism for cyclic carbonate synthesis from C02 and epoxides on Cu aza complexes [74].

A better AE value (59wt%) is obtained with the coproduction of ethylene glycol from the methanolysis of ethylene carbonate (entry 2). The AE value is higher when water is coproduced (83 wt %, entries 4—5). The use of urea as a feedstock (entry 3) may also lead to AE = 83 wt%, by coupling the urea synthesis equation. The complete use of feedstock atoms (AE = 100 wl%) has been demonstrated commercially for cyclic carbonate synthesis, but as yet no real case has been reported for unstrained ethers (entry 6). 

North M, Pasquale R (2009) Mechanism of cyclic carbonate synthesis from epoxides and C02. Angew Chem Int Ed 48(16) 2946-2948... 

Cyclic carbonate synthesis from epoxide and CO2 is one of the few industrial processes that use CO2 as a feedstock. The reaction proceeds in the presence of catalysts that are typically metal halides or tetraalkylammonium halides. The products (e.g. ethylene carbonate, which is an important intermediate of dimethyl carbonate) are utilized for polycarbonate synthesis via a non-phosgene, melt polymerization process. 

Catalyst/product separation for cyclic carbonate synthesis from SCCO2... 

The wide variety of ILs and reaction conditions makes it difficult to extract a trend, but clearly the presence of both acid and base sites are crucial for the cyclic carbonate synthesis. Outstanding results were reported by Takahashi et al. [78] using phosphoniiun quaternary salts as phospho-niiun halides immobilized on SiO (e.g. CO SiO -CjHg-Pfn-BuljBr)) for the synthesis of PC from PO and CO using a continuous fixed-bed reactor. As far as we know it is best catalytic performance ever reported for the synthesis of PC using a continuous flow reactor with a PO conversion... 

Honda M, Tamura M, Nakao K, Suzuki K, Nakagawa Y, Tranishige K (2014) Direct cyclic carbonate synthesis from CO2 and diol over carboxylatimi/hydration cascade catalyst CeOa with 2-cyano-pyridine. ACS Catal 4 1893-1896... 

Clegg W, Harrington RW, North M, Pasquale R (2010) Cyclic carbonate synthesis catalysed by bimetallic aluminium-salen complexes. Chem Eur J 16 6828-6843... 

The reaction of CO2 with aziridine producing 2-oxazolidinone is analogous one to the cyclic carbonate synthesis from CO2 and epoxide. If an alkyl or aryl group is attached to the aziridine ring, two oxazolidinone products could come from the ring ofjening across N-CH2... 

Matsuo et al. have revealed another universal method of cyclic carbonate synthesis from PPDs and ethyl chloroformate in the presence of a stoichiometric amount of triethylamine. The formation of a specific ammonium salt as an intermediate seems to be the driving force for the reaction proceeding at low temperatures favoring six-membered cycles (yields up to 60%) (Scheme 11). 

Takahashi, T., Watahiki, T., Kitazume, S., Yasuda, H., and Sakakura, T. (2006) Synergistic hybrid catalyst for cyclic carbonate synthesis remarkable acceleration caused by immobilization of homogeneous catalyst on sihca. Chem. Commuit, 1664-1666. 

FIGURE 8 Organocatalytic approaches toward cyclic carbonate synthesis [66-69]. MEK, methyl ethyl ketone DMF, dimethylformamide MBS, N-bromo-succinimide. 

For a recent example see C. Beattie, M. North, R ViUuendas, C. Young, Influence of temperature and pressure on cyclic carbonate synthesis catalyzed by bimetallic aluminum complexes and application to overall syn-Bis-hydroxylation of alkenes, J. Org. Chem. 78 (2013) 419-426. 

Y. Yang, Y. Hayashi, Y. Fujii, T. Nagano, Y. Kita, T. Ohshima, J. Okuda, K. Mashima, Efficient cyclic carbonate synthesis catalyzed by zinc cluster systems imder mild conditions, Catal. Sci. Technol. 2 (2012) 509-513. 

M. North, B. Wang, C. Yotmg, Influence of flue gas on the catalytic activity of an immobilized aluminium(salen) complex for cyclic carbonate synthesis. Energy Environ. Sci. 4 (2011) 4163-4170. 

L. Han, H.-J. Choi, S.-J. Choi, B. Liub, D.-W. Park, Microwave synthesized quaternized celluloses for cyclic carbonate synthesis from carbon dioxide and epoxides. Green Chem. 13 (2011) 1023-1028. 

TABLE 5.5 Cyclic carbonate synthesis from epoxide and CO... 

Yang, Y Hayashi, a, Y Fujii, Y Nagano, T. Kita, Y Ohshima, T. Okuda, I Mashima, K. Efficient Cyclic Carbonate Synthesis Catalyzed by Zinc Cluster Systems Under Mild Conditions. Catal. Sci. Technol. 2012,2, 509-513. 

Baia, D. Jing, H. Wang, G. Cyclic Carbonate Synthesis from Epoxides and CO over Cyanocobalamin/n-Bu NI.zl/J/j/. Organometal. Chem. 2012,26, 600-603. 

Yasuda, H. He, L.- N. Sakakura, T. Cyclic Carbonate Synthesis from Supercritical Carbon Dioxide and Epoxide over Lanthanide Oxychloride. J. Catal. 2002, 209, 547-550. 

The above studies [8-10] strongly indicate the participation of silanol groups as acid sites in the amine-catalyzed reactions. The synergistic catalysis of immobilized organic bases and silanol groups has been highlighted by the cyclic carbonate synthesis from carbon dioxide and epoxide. Acid-base dual activation mechanism of the cyclic carbonate synthesis is widely accepted. Sakakura and coworkers [11] reported silica-supported phosphonium salts as highly active catalysts for the cyclic carbonate synthesis. The results for propylene carbonate synthesis are summarized... 

Table 1.5 Cyclic carbonate synthesis from COj and propylene oxide."...

Scheme 1.6 Proposed reaction pathway of the silica-supported phosphonium halide-catalyzed cyclic carbonate synthesis from CO and epoxide.

Catalytic Activation of COj Carbon dioxide activation in or by IL is one of the most successful discoveries of IL catalysis [100]. The potential for carbon dioxide activation in or by IL might be derived from the high solubility of carbon dioxide in IL and its special properties. As a typical reaction, the cyclic carbonate synthesis from dioxide and epoxide has been studied extensively from homogeneous to supported IL catalyst, Scheme 2.25. 

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