Preparation and characterization of Cu based on 5,5'-bistetrazole as a recyclable metal-organic framework and application in synthesis of diaryl ether by the Ullmann coupling reaction

Efficient base- and ligand-free palladium catalysed O-arylation of phenols in choline chloride:triethanolamine as a reusable deep eutectic solvent

In this paper, we present a novel and sustainable approach using choline chloride:triethanolamine as a green, efficient and reusable deep eutectic solvent (DES) for Pd-catalysed O-arylation reactions with Pd/BaSO4 (10%). By using the unique properties of DESs, we successfully achieved C-O bond formation without the need for additional solvents, bases and ligands. This solvent/catalyst system ([ChCl][TEA]2) functioned as a dual catalyst and solvent system, enabling fast and environmentally friendly C-O bond formation from phenol derivatives and electron-deficient aryl halides, leading to remarkable yields under mild reaction conditions. To identify and characterize this DES, we employed differential scanning calorimetry, thermogravimetric analysis, Fourier-transform infrared spectroscopy, refractive index, viscosity, the potential of hydrogen (pH) and conductivity measurements. One of the remarkable advantages of this DES system is its exceptional stability. This solvent/catalyst system exhibited high stability throughout the reaction cycles, showing no significant loss of activity. As a result, this DES and catalyst (Pd/BaSO4 (10%)) can be easily recycled and re-used for up to three consecutive cycles, making it an economically and environmentally attractive option for organic reactions. Our approach offers several key benefits, including simple catalyst preparation, quick reaction times and excellent production efficiency.

Fe3O4 supported [Cu(ii)(met)(pro-H)2] complex as a novel nanomagnetic catalytic system for room temperature C-O coupling reactions

In this study, a newly-designed copper(ii) complex of metformin and l-proline which was immobilized on Fe₃O₄ MNPs was developed. The structure of the catalyst platform was fully characterized using spectroscopic analyses. Moreover, the catalytic activity of [Fe₃O₄@Cu(ii)(Met)(Pro-H)₂] was investigated in a one-pot synthesis of a variety of functionalized ethers in reasonable to excellent yields through Ullman reaction in an aqueous environment using various aryl halides, phenol, and Cs₂CO₃ and without using any external Cu-reducing agents. Notably, gentle catalytic conditions, quick reaction times, applicability, low cost, and preventing dangerous chemicals and solvents during synthesis and catalytic application are some of the superior properties of the [Fe₃O₄@Cu(ii)(Met)(Pro-H)₂] complex. Furthermore, the catalyst can be reused for several runs (at least eight times) without remarkable loss in efficiency.