Unprecedented cooperative DBU-CuCl2 catalysis for the incorporation of carbon dioxide into homopropargylic amines leading to 6-methylene-1,3-oxazin-2-ones

Highly Efficient Conversion of Aziridines and CO2 Catalyzed by Microporous [Cu12] Nanocages

The conversion of CO₂ as a C1 source into value-added products is an attractive alternative in view of the green synthesis. Among the reported approaches, the cyclization reaction of aziridines with CO₂ is of great significance since the generated N-containing cyclic skeletons are extensively found in pharmaceutical chemistry and industrial production. However, a low turnover number (TON) and homogeneous catalysts are often involved in this catalytic system. Herein, one novel copper-organic framework {[Cu₂(L^4-)(H₂O)₂]·3DMF·2H₂O}_n (1) (H₄L = 2'-fluoro-[1,1':4',1″-Terphenyl]-3,3″,5,5″-tetracarboxylic acid) assembled by nanosized [Cu₁₂] cages was successfully synthesized and structurally characterized, which exhibits high CO₂/N₂ selectivity due to the strong interactions between CO₂ and open Cu(II) sites and ligands in the framework. Catalytic investigations suggest that 1 as a heterogeneous catalyst can effectively catalyze the cyclization of aziridines with CO₂, and the TON can reach a record value of 90.5. Importantly, 1 displays excellent chemical stability, which can be recycled at least five times. The combination explorations of nuclear magnetic resonance (NMR), ¹³C-isotope labeling experiments, and density functional theory (DFT) clearly uncover the mechanism of this aziridine/CO₂ coupling reaction system, in which 1 and tetrabutylammonium bromide (TBAB) can highly activate the substrate molecule, and the synergistic catalytic effect between them can greatly reduce the reaction energy barrier from 51.7 to 36.2 kcal/mol.

Synthesis of 4-(organoselenyl) oxazolones via cyclization of N-alkynyl ethylcarbamates promoted by organoselenium

Organoselenyl iodide promoted the intramolecular nucleophilic cyclization of N-alkynyl ethylcarbamates in the synthesis of 4-(organoselenyl) oxazolones. The reaction was regioselective, giving the five-membered oxazolone products as the unique regioisomer via an initial activation of the carbon-carbon triple bond through a seleniranium intermediate, followed by an intramolecular 5-endo-dig cyclization mode. The generality of the methodology has been proven by applying the optimized reaction conditions to different organoselenyl iodides and N-alkynyl ethylcarbamates having different substituents directly bonded to the nitrogen atom and in the terminal position of the alkyne.

A review of gas chromatographic techniques for identification of aqueous amine degradation products in carbonated environments

Degradation of amines is a significant issue allied to amine-based carbon dioxide (CO₂) absorption in post-combustion CO₂ capture. It becomes essential to have a detailed understanding of degradation products for advanced post-combustion CO₂ capture technology. Identification and quantification of degradation products of amines help in practicability and environmental assessment of amine-based technology. Gas, liquid, and ion chromatographic techniques are the benchmark tools for qualitative and quantitative analyses of the amines and their derivatives. Among others, gas chromatography has been more in use for this specific application, especially for the identification of degradation products of amines. This review focuses on the critical elucidation of gas chromatographic analysis and development of methods to determine the amine degradation products, highlighting preparation methods for samples and selecting columns and detectors. The choice of detector, column, sample preparation, and method development are reviewed in this manuscript, keeping in view the industry and research applications. Furthermore, obtained results on the quantitative and qualitative analyses using gas chromatography are summarized with future perspectives.

Synergetic activation of CO2 by the DBU-organocatalyst and amine substrates towards stable carbamate salts for synthesis of oxazolidinones

The development of an efficient methodology to transform CO2 into valuable chemicals has attracted increasing attention concerning the challenging issues of CO2-utitlization.

Tuning acid–base cooperativity to create bifunctional fiber catalysts for one-pot tandem reactions in water

A simple and straightforward route to create acid–base bifunctional fiber catalysts for efficient one-pot tandem deprotection-Knoevenagel reactions in water.

A new 3D luminescent Ba-organic framework with high open metal sites: CO2 fixation, luminescence sensing, and dye sorption

A new synthesized 3D luminescent Ba-organic framework (1) may be used as a recyclable heterogeneous catalyst for fixation of CO₂ and has excellent response and sensitivity for pollutant ions. Moreover, 1 exhibits the particular selective sorption towards Congo red (CR) dye.