Sustainable Protocol for the Reduction of Nitroarenes by Heterogeneous Au@SBA-15 with NaBH4 under Flow Conditions

C(sp3 )-H Arylation Promoted by a Heterogeneous Palladium-N-Heterocyclic Carbene Complex in Batch and Continuous Flow

A heterogeneous reusable palladium(II)-bis(N-heterocyclic carbene) catalyst was prepared and shown to catalyze the intramolecular C(sp³ )-H activation/cyclization of N-alkyl-2-bromoanilines furnishing indolines. This new catalytic system was based on a bis-imidazolium ligand immobilized on a spaced cross-linked polystyrene support. The iodide ligands on the catalyst played a central role in the efficiency of the process occurring through a "release and catch" mechanism. The heterogeneous nature of the catalyst was further exploited in the design of a continuous-flow protocol that allowed a more efficient recovery and reuse of the catalyst, as well as a very fast and safe procedure.

Green Synthesis of Pd Nanoparticles for Sustainable and Environmentally Benign Processes

Among transition metal nanoparticles, palladium nanoparticles (PdNPs) are recognized for their high catalytic activity in a wide range of organic transformations that are of academic and industrial importance. The increased interest in environmental issues has led to the development of various green approaches for the preparation of efficient, low-cost and environmentally sustainable Pd-nanocatalysts. Environmentally friendly solvents, non-toxic reducing reagents, biodegradable capping and stabilizing agents and energy-efficient synthetic methods are the main aspects that have been taken into account for the production of Pd nanoparticles in a green approach. This review provides an overview of the fundamental approaches used for the green synthesis of PdNPs and their catalytic application in sustainable processes as cross-coupling reactions and reductions with particular attention afforded to the recovery and reuse of the palladium nanocatalyst, from 2015 to the present.

The effect of hydrothermal temperature on the properties of SBA-15 materials

In present work, ordered mesoporous material SBA-15 was synthesized by using poly (alkylene oxide) block copolymer (Pluronic P123) as template and ethylsilicate as silica source in weak acid environment in a wide range of temperature. The focus of synthesis research was high hydrothermal temperature. The obtained products were characterized by various techniques, including XRD, N₂ sorption isotherms, FTIR spectroscopy and thermogravimetric. The effect of hydrothermal temperature on the specific surface area, pore volume and pore size of SBA-15 products was investigated systematically. As the hydrothermal temperature increases from the 100–120 °C, the specific surface area and the pore volume of the mesoporous molecular sieve increase greatly. When the hydrothermal temperature increase further, the pore volume of the mesoporous molecular sieve increase continually. But the specific surface area decrease significantly. When the hydrothermal temperature is too high (over 140 °C), the order degree begins to decrease, So the specific surface area and pore volume decrease significantly because the pores structure have significant destruction and collapse. Mechanism and structural characteristics of P123 block copolymer could explain in detail the effect of hydrothermal temperature on the property and structure of mesoporous molecular sieve SBA-15.