Catalytic conversion of CO2 and shale gas-derived substrates into saturated carbonates and derivatives: Catalyst design, performances and reaction mechanism

Organocatalytic Polymers from Affordable and Readily Available Building Blocks for the Cycloaddition of CO2 to Epoxides

The catalytic cycloaddition of CO₂ to epoxides to afford cyclic carbonates as useful monomers, intermediates, solvents, and additives is a continuously growing field of investigation as a way to carry out the atom-economic conversion of CO₂ to value-added products. Metal-free organocatalytic compounds are attractive systems among various catalysts for such transformations because they are inexpensive, nontoxic, and readily available. Herein, we highlight and discuss key advances in the development of polymer-based organocatalytic materials that match these requirements of affordability and availability by considering their synthetic routes, the monomers, and the supports employed. The discussion is organized according to the number (monofunctional versus bifunctional materials) and type of catalytically active moieties, including both halide-based and halide-free systems. Two general synthetic approaches are identified based on the postsynthetic functionalization of polymeric supports or the copolymerization of monomers bearing catalytically active moieties. After a review of the material syntheses and catalytic activities, the chemical and structural features affecting catalytic performance are discussed. Based on such analysis, some strategies for the future design of affordable and readily available polymer-based organocatalysts with enhanced catalytic activity under mild conditions are considered.

Bifunctional zinc and magnesium Schiff-base complexes containing quaternary ammonium side-arms for epoxide/CO2 coupling reactions

Novel bifunctional zinc and magnesium Schiff-base complexes containing quaternary ammonium halide side-arms were developed. Zinc complex 1Et-I (0.02 mol%) having an iodide anion has shown the highest TOF for the propylene oxide/CO2 coupling reaction of up to 459 h-1. This TOF value was maintained even when the catalyst loading was reduced to 0.005 mol%.

Dataset for the synthesis and application of single-component heterogeneous catalysts based on zinc and tin for the cycloaddition of pure, diluted, and impure CO2 to epoxides under mild conditions

The cycloaddition of CO₂ to epoxides under mild conditions is a growing field of research and a viable strategy to recycle CO₂ in the form of cyclic carbonates as useful intermediates, solvents, and additives. This target requires readily accessible and recyclable catalysts whose synthesis does not involve expensive monomers, multistep procedures, coupling reagents, etc. Additionally, the catalysts should be active under atmospheric pressure and tolerate impurities such as methane and H₂S. In a recent manuscript (Rational engineering of single-component heterogeneous catalysts based on abundant metal centers for the mild conversion of pure and impure CO₂ to cyclic carbonates;Chemical Engineering Journal 422 (2021) 129930) we have developed strategies to prepare efficient heterogeneous catalysts for the cycloaddition reaction of CO₂ to epoxides. Such materials consist of dispersions of metal halides (ZnCl₂ or SnCl₄) on silica support that is further functionalized with ionic liquids bearing nucleophilic halide moieties for cooperative epoxide activation and ring-opening. Herein, we provide useful complementary data for the characterization of the prepared materials in the form of: SEM images of materials (SEM: scanning electron microscope), SEM-EDS images of materials (EDS: Energy-dispersive X-ray spectroscopy), TEM images of materials (TEM: transmission electron microscope); XPS (X-ray photoelectron spectroscopy) survey spectra of most active catalysts and related high-resolution spectra in spectral regions of interest, BET (Brunauer–Emmett–Teller) physisorption isotherms of materials, raw ¹H NMR spectra of catalytic reactions to verify the reproducibility of the reaction outcome and identify the reaction products.

Efficient Synthesis of Cyclic Carbonates from Unsaturated Acids and Carbon Dioxide and their Application in the Synthesis of Biobased Polyurethanes

Bio-derived furan- and diacid-derived cyclic carbonates have been synthesized in high yields from terminal epoxides and CO₂ . Furthermore, four highly substituted terpene-derived cyclic carbonates were isolated in good yields with excellent diastereoselectivity in some cases. Eleven new cyclic carbonates derived from 10-undecenoic acid under mild reaction conditions were prepared, providing the corresponding carbonate products in excellent yields. The catalyst system also performed the conversion of an epoxidized fatty acid n-pentyl ester into a cyclic carbonate under relatively mild reaction conditions (80 °C, 20 bar, 24 h). This bis(cyclic carbonate) was obtained in high yields and with different cis/trans ratios depending on the co-catalyst used. An allyl alcohol by-product was only observed as a minor product when bis(triphenylphosphine)iminium chloride was used as co-catalyst. Finally, two cyclic carbonates were used as building blocks for the preparation of non-isocyanate poly(hydroxy)urethanes by reaction with 1,4-diaminobutane.

Cycloaddition of carbon dioxide to epoxides by highly active constrained aluminum chloride complexes

Novel constrained aluminum inden complexes were developed revealing high activities and excellent selectivity for cyclic carbonates in epoxides/CO2 coupling reactions.

Synthesis, Characterization, and In Vitro Cytotoxicity of Platinum(II) Complexes Bearing Chiral Tetradentate Salicylaldimine Ligands

A series of platinum(II) complexes with chiral Schiff base ligands derived from various salicylaldehydes with (R,R′)- and (S,S′)-cyclohexanediamine were synthesized and characterized by ESI-MS, IR, and NMR. Obtained spectra with typical signals were in agreement with suggested molecular formulae of the complexes. Their photophysical properties were studied by UV-visible and emission spectroscopies. The UV-Vis showed the typical band with low energy at visible range 400–500 nm for MLCT, and this band can emit the luminescent band with emission maximum wavelengths at 529–595 nm. The in vitro cytotoxicity of obtained platinum(II) complexes was screened for KB and MCF-7 human cancer cell lines. The results showed that (S)-enantiomers were more active than (R)-enantiomers and the different positions of methoxy group in salicyl ring gave different cytotoxicities.