Carbonate five-membered alkylene

The transesterification of 1,2-diols by reaction with carbonates, both cyclic and linear, produces five-membered alkylene carbonates almost exclusively. A well-known example of this is the reaction of DMC with propene glycol to yield PC [295],... 

The synthesis of five-membered alkylene carbonates (1,3-dioxolan-2-ones) of the structure presented in Scheme 1 has been the subject of considerable research. Two of them, ethylene carbonate (EC) (R = H) and propylene carbonate (PC) (R = H, R" = CH3), have been available commercially for over 45 years. 

Vinyl-functional alkylene carbonates can also be prepared from the corresponding epoxides in a manner similar to the commercial manufacture of ethylene and PCs via CO2 insertion. The most notable examples of this technology are the syntheses of 4-vinyl-1,3-dioxolan-2-one (vinyl ethylene carbonate, VEC) (5, Scheme 24) from 3,4-epoxy-1-butene or 4-phenyl-5-vinyl-l,3-dioxolan-2-one (6, Scheme 24) from analogous aromatic derivative l-phenyl-2-vinyl oxirane. Although the homopolymerization of both vinyl monomers produced polymers in relatively low yield, copolymerizations effectively provided cyclic carbonate-containing copolymers. It was found that VEC can be copolymerized with readily available vinyl monomers, such as styrene, alkyl acrylates and methacrylates, and vinyl esters.With the exception of styrene, the authors found that VEC will undergo free-radical solution or emulsion copolymerization to produce polymeric species with a pendant five-membered alkylene carbonate functionality that can be further cross-linked by reaction with amines. Polymerizations of 4-phenyl-5-vinyl-l,3-dioxolan-2-one also provided cyclic carbonate-containing copolymers. 

Copolymerisation of propylene oxide as well as other oxiranes with carbon dioxide in the presence of zinc-based coordination catalysts is generally accompanied with the formation of a cyclic five-membered carbonate, propylene carbonate or another alkylene carbonate [147,206,207,210,212,230]. The alky-lene carbonate, however, is not the precursor for poly(alkylene carbonate), since it hardly undergoes a polymerisation under the given conditions [142-146],... 

Carbon monoxide is an important industrial C-1 Chemicar. The major derived products are methanol and phosgene. The synthesis of methyl methacrylate from acetylene, carbon monoxide and methanol is another industrially useful reaction. Carbon monoxide is a stable carbene, CO, and therefore I have included many of its cycloaddition reactions. The [2-I-2-I-1] cycloaddition reaction which leads to five-membered ring carbonyl compounds is of considerable synthetic value. Copolymers of alkenes and carbon monoxide are a new class of biodegradable polyketones, which can be readily converted into functional polymers. Also copolymers of alkylene oxides and carbon monoxide are known. 

The alkylene carbonates are easily available through transesterification of dialkyl carbonates (usually dimethyl or diethyl carbonate) or diphenyl carbonate with appropriate 1,2-diols in the presence of alkaline catalysts.This approach for the preparation of five-membered cyclic carbonates also was described in the 1950s by Ludwig and Piech ° and Sarel et al ... 

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