3-Amino-2-cyano-imidoacrylate ligands and their zinc complexes for the copolymerisation of CO2 and epoxides: Living character and temperature optimisation

Alternating Copolymerization of Carbon Dioxide and Cyclohexene Oxide and Their Terpolymerization with Lactide Catalyzed by Zinc Complexes of N,N Ligands

“…Interestingly, such calculations only fitted the experimental findings when the growth of two polymer chains on one active metal center was assumed. [35] This stands contrary to aforementioned findings (like the solid-state structures) [26] that rather support a bimetallic mechanism and thus, further studies are necessary to clarify this remaining question.…”

“…Optimization experiments proved a temperature window between 80 8C and 100 8C to be ideal. [35] At higher temperatures, more and more cyclic carbonate is formed in an unwanted, thermodynamically-favored side reaction. [36] In our experiments at and below 100 8C the formation of cyclic cyclohexyl carbonate did not exceed 10 %.…”

“…This was corroborated by a kinetic study that showed the linear relation between monomer (CHO) conversion and chain length of the resulting polymer. [35] Under the assumption that one polymer chain is growing on one active metal center (like it should do in a living polymerization), the length of the polymer can be calculated for each stage of monomer conversion, if the monomer to catalyst ratio is known. Interestingly, such calculations only fitted the experimental findings when the growth of two polymer chains on one active metal center was assumed.…”

Catalysts for CO2/epoxide copolymerisation

“…In general the carbonate inclusion was low, between 60-80%, and the reactions were carried out under high pressures and temperatures (40 atm, 90-100 1C). 52,53 A similar ligand formed clusters containing 12 zinc sites, and was significantly less active, giving a best TOF of 50 h À1 , with only 34% carbonate linkages and an extremely broad PDI (20), which is not surprising given the aggregated structure. 54 A novel bimetallic BDI ligand structure (Fig.…”

Chemical Technologies for Exploiting and Recycling Carbon Dioxideinto the Value Chain

“…Also the terpolymerization with cyclic acid anhydrides is feasible. [157] Fundamentally, one differentiates between two distinct catalyst classes: in case of cobalt(III)-catalysts, [158][159][160][161] chromium(III)-salen and -salan complexes, [116,163] aluminum(III)-salen complexes [164] or Lewis acidic compounds [117,162] such as zinc glutarate, [165,166] zinc diiminate -ethylsulfinate [167] or rare-earth complexes [168] as catalysts, polyalkylenecarbonates with alternating repetition units are obtained; in contrast, if one uses double metal cyanide (DMC) catalysts, one acquires polyalkylenecarbonates, in which ether units occur besides the carbonate linkages. While alternating polypropylenecarbonate is on the market, the production of non-alternating polypropylenecarbonate is currently being commercialized.…”