New Iron Pyridylamino‐Bis(Phenolate) Catalyst for Converting CO₂ into Cyclic Carbonates and Cross‐Linked Polycarbonates

Abstract

The atom-efficient reaction of CO2 with a variety of epoxides has been efficiently achieved employing iron pyridylamino-bis(phenolate) complexes as bifunctional catalysts. The addition of a Lewis base co-catalyst allowed significant reduction in the amount of iron complex needed to achieve high epoxide conversions. The possibility of controlling the selectivity of the reaction towards either cyclic carbonate or polycarbonate was evaluated. An efficient switch in selectivity could be achieved when cyclic epoxides such as cyclohexene oxide and the seldom explored 1,2-epoxy-4-vinylcyclohexane were used as substrates. The obtained poly(vinylcyclohexene carbonate) presents pending vinyl groups, which allowed post-synthetic cross-linking by reaction with 1,3-propanedithiol. The cross-linked polycarbonate displayed a substantial increase in the glass transition temperature and chemical resistance, thus opening new opportunities for the application of these green polymers.

Bimetallic Nickel Complexes that Bear Diamine‐Bis(Benzotriazole Phenolate) Derivatives as Efficient Catalysts for the Copolymerization of Carbon Dioxide with Epoxides

“…As the produced PVCHC is atactic, DSC thermograms revealed no melting endotherm during heating. The glass transition temperature of such a copolymer with the largest M n in this work is approximately 119 °C (Figure S6), which is higher than that reported . This active Ni catalyst 2 is synthesized readily in two steps from commercial reagents, which indicates that 2 might be a promising catalyst in practical applications.…”

“…Encouraged by the catalysis of CO 2 ‐copolymerization from bimetallic catalysts coordinated with a hexadentate BiIBTP ligand, we intend to develop further dinuclear catalysts that bear multidentate diamine‐bis(benzotriazole phenolate) ( DiBTP ) derivatives (Scheme a, right) and to apply these complexes as thermally robust catalysts for the copolymerization of CO 2 with CHO or less studied 4‐vinyl‐1,2‐cyclohexene oxide (VCHO) (Scheme b). We expect that the DiBTP ligand not only behaves as a hexadentate ligand to chelate two metal centers but also provides a flexible framework to make the coordination sphere more open during catalysis.…”

Copolymerization of cyclohexene oxide with CO2catalyzed by tridentate N-heterocyclic carbene titanium(iv) complexes

“…Iron is another potential element as it is the most abundant transition metal. This novel di- [98], corrole 18 and 19 [99] and amino triphenolate 20 [100] complexes.…”

“…A wide range of catalysts has been successfully reported, leading to the production of polycarbonates. Homogeneous catalysts are classified in two broad types, bimetallic (Scheme 1.7) and monometallic (Scheme boxdipy titanium(IV) 15 [96], bimetallic iron(III) macrocyclic reduced "Robson" type ligand 16 [97], pyridylamino-bis(phenolate) 17 [98], iron-corrole 18 and 19 [99] and iron amino triphenolate 20 [100] catalysts.…”

The Role of Water Revisited and Enhanced: A Sustainable Catalytic System for the Conversion of CO2 into Cyclic Carbonates under Mild Conditions

“…[35,36] Among the severalH BD compounds that have been reported for this application, [37][38][39] one of the moste fficient types is represented by aromatic compounds with one or multiple hydroxy groups, such as as phenol, pyrogallol, and gallic acid. [40,41] Herein, we demonstrate that using water as HBDi nc ombination with specific organic halides such as Bu 4 NI and bis(triphenylphosphine)iminium iodide (PPNI) ( Figure 1), and by tuning the reactionconditions carefully,i ti sp ossible to match the performance of state-of-the-art HBDs such as phenol, [27] gallic acid, [14] and ascorbic acid [31] and to achievet he selectivec onversiono fC O 2 into severalc yclic carbonates under mild conditions (25-60 8C, 2-10 bar CO 2 ). [27,29] Another class of highly efficient HBDs is represented by fluorinated alcohols, which in combination with Bu 4 NX (X = I À ,B r À )p romoted the reactiono fC O 2 with epoxides under mild conditions (60-80 8C, 1-20 bar CO 2 )a nd with complete selectivity towards the cyclic carbonate products.T he high activity was attributed to the electron-withdrawing fluorinated groups,w hich increase the acidity of the alcohol groups and thus the strength of the hydrogen bondingw ith the oxygen atom of the epoxide.…”