Catalytic synthesis of organic cyclic carbonate through CO2 fixation and production of β-amino alcohol via ring opening of epoxides under green condition by polystyrene embedded Al(III) catalyst

Constructing a metal-free 2D covalent organic framework for visible-light-driven photocatalytic reduction of CO2: a sustainable strategy for atmospheric CO2 utilization

A 2D polyimide-linked covalent organic framework (COF) with band gap energy of 2.2 eV is developed as a stable and efficient porous photocatalyst which shows CO2 reduction to formic acid, formaldehyde and methanol.

Efficient imidazolium ionic liquid as a tri-functional robust catalyst for chemical fixation of CO2 into cyclic carbonates

The recent increase in CO₂ levels has had an extensive impact on the environment; hence an effective catalyst for chemical CO₂ fixation into value-added products is demanded. This work demonstrates a simple approach towards the chemical fixation of CO₂ to cyclic carbonates without solvent, metal and additives using one-pot synthesized tri-functional-imidazolium bromide ionic liquid. Herein, synthesized tri-functional-imidazolium-based ionic liquids, namely 3-(2-hydroxyethyl)-1-vinyl-1H-imidazole-3-ium bromide ([VIMEtOH][Br] (24 and 72 h)), 3-(2-hydroxyethyl)-1-vinyl-1H-imidazole-3-ium hydroxyl ([VIMEtOH][OH]) and poly 3-(2-hydroxyethyl)-1-vinyl-1H-imidazole-3-ium bromide (poly [VIMEtOH][Br]), were used for the comprehensive investigation of chemical fixation of CO₂ into cyclic carbonates and their physiochemical properties. In case of [VIMEtOH][Br] ionic liquid, it displayed time-dependent synthesis dissolution in the reaction system. This study found that [VIMEtOH][Br]-72 ionic liquid is not dissolved in the reaction system. The effect on the catalytic efficiency of the presence of functional groups in ionic liquids such as N-vinyl (-CC-N), acidic proton of imidazolium (-C (2)-H) and hydroxyl (-OH) along with bromide anion and the reaction conditions are systematically investigated. For CO₂ fixation, 99.6% conversion of propylene oxide with an excellent selectivity of propylene carbonate (≥99%) over [VIMEtOH][Br]-72 catalyst (at 120 °C, 2 MPa, 2 h) was observed without co-catalyst, metal and solvent. Also, it demonstrated an excellent wide substrates scope of epoxide and all reactions were performed on gram-scalable, which are potential prospects for industrial use.

Mechanistic study on the coupling reaction of CO2 with propylene oxide catalyzed by (CH3 )4 PI·MgCl2

The mechanistic study of CO₂ coupling with propylene oxide (PO) into cyclic carbonate catalyzed by (CH₃ )₄ PI has been investigated using the B₃ LYP/6-311++G (d, p)/B₃ LYP/6-31G (d) level of theory for non-iodine atoms and LANL2DZ was used, together with its associated basis set for the iodine atom. Two hypothetical reaction mechanisms were proposed for the studied reaction and thermodynamic and kinetic parameters were computed for each step to determine the more favorable route. The density functional theory (DFT) study reveals that the reaction prefers to proceed through a three-step mechanism (pathway II) than a tri-molecular intermediate (pathway I) where the CO₂ and the catalyst act simultaneously on the PO ring. The rate-determining step of the catalytic reaction is found to be the ring-opening step with an energy barrier of 27.1 kcal/mol (pathway II) in the gas phase, which is kinetically more favorable than that of non-catalytic CO₂ fixation with a relatively higher barrier of 63.7 kcal/mol. The synergetic effect of MgCl₂ is tested as a cocatalyst for the (CH₃ )₄ PI/MgCl₂ catalyzed reaction and it gave a better result and minimized the activation energy for the reaction and the rate-determining step was the ring closure with the free energy of activation 18.8 kcal/mol in the gas phase. The polarizable continuum model was used to account for the solvent effect, obtaining the best results of 23.1 kcal/mol in water for pathway I and 16.5 kcal/mol and 14.9 kcal/mol in dimethyl sulfoxide for pathway II and binary system, respectively.

Zn(II)-Functionalized COF as a Recyclable Catalyst for the Sustainable Synthesis of Cyclic Carbonates and Cyclic Carbamates from Atmospheric CO2

A simple covalent organic framework (COF) bearing β-ketoenamine units as a potential heterogeneous ligand for ZnII-catalyzed fixation and transformation of CO2 into value-added chemicals is reported. Catalytic investigations convincingly demonstrated...

Mechanistic insights on CO2 utilization using sustainable catalysis

Caffeinium halides were used to catalyse the cycloaddition of CO2 to form cyclic carbonates. The reaction intermediates were isolated and characterized experimentally. The reaction mechanism has been confirmed by DFT calculations.

CO2 coupling with epoxides catalysed by using one-pot synthesised, in situ activated zinc ascorbate under ambient conditions

An in situ generated zinc ascorbate pre-catalyst for cyclic carbonate (CC) synthesis via CO₂ coupling with epoxides under ambient conditions was reported. Spectroscopic measurements indicated that CO₂ was inserted into the zinc ascorbate complex through the formation of an activated zinc carbonate catalyst upon abstracting the enediol protons with sodium hydride. The aliphatic diols were not activated under the applied conditions and did not interfere with either the process of cycloaddition or CO₂ activation. The catalyst was active against different terminal epoxides, with a conversion of 75 and 85%, when propylene oxide and styrene oxide were used at 20 and 50 °C, respectively under 1 atm CO₂ for 17 h, which was considered a good advancement for heterogeneous based catalysis. Moreover, green chemistry principles were applied to ultimately end up with more ecofriendly approaches for the synthesis of CC following a simple balloon technique. Herein, we used zinc as a sustainable metal, together with ascorbic acid as a bio-renewable material in addition to CO₂ as a renewable feed-stock. Furthermore, waste prevention was achieved using the reaction side product, viz., NaBr as a co-catalyst.

DNA intercalative trinuclear Cu(ii) complex with new trans axial nitrato ligation as an efficient catalyst for atmospheric CO2 fixation to epoxides

A trinuclear octahedral Cu^II complex was synthesized and structurally characterized by single crystal X-ray diffraction studies and behaved as a catalyst for CO₂ fixation to epoxide and as a DNA binder.

Macroporous polystyrene degraded and functionalized chromium MPS-Cr(iii)-alen complex as a sustainable porous catalyst for CO2 fixation under atmospheric pressure and selective oxidation of aromatic alkenes

The benign synthesis of porous polystyrene supported chromium(iii) catalyst has been carried out for the production of cyclic carbonates via CO₂ fixation under atm. pressure and for the selective oxidation of aromatic alkenes under mild conditions.

Triazinetriamine-derived porous organic polymer-supported copper nanoparticles (Cu-NPs@TzTa-POP): an efficient catalyst for the synthesis of N-methylated products via CO2 fixation and primary carbamates from alcohols and urea

Copper nanoparticles incorporated triazinetriamine derived porous organic polymer based catalyst was synthesized for catalytic production N-methylated amines and primary carbamates.