Synthesis and Characterization of Hybrid Mg(OH)2 and CeCO3 OH Composite with Improved Activity Towards Henry Reaction

Development of bioactive 2-substituted benzimidazole derivatives using an MnOx/HT nanocomposite catalyst

Benzimidazole is a vital moiety found in a wide range of naturally and pharmacologically active molecules. We prepared a proficient and facile manganese oxide-supported magnesium and aluminium-based nanocomposite catalytic framework using the deposition-precipitation method and characterised it with XRD, XPS, SEM, TEM, and TGA techniques. Following that, the catalyst was used in the green synthesis of highly functional 2-substituted benzimidazole derivatives in an ethanol-water solvent system at room temperature using various assorted benzaldehydes and o-phenylenediamine as substituents. The synthesised catalyst operates efficiently and is applicable to a wide range of electron-withdrawing and electron-donating substrates, resulting in good to excellent yields. The advantages of this process include the use of a greener solvent, high yield, high conversions, no use of additives or bases, a good TOF, and a shorter reaction time.

Conversion of Limonene over Heterogeneous Catalysis: An Overview

The natural terpene limonene is widely found in nature. The (R)-limonene (the most abundant enantiomer) is present in the essential oils of lemon, orange, and other citrus fruits, while the (S)-limonene is found in peppermint and the racemate in turpentine oil. Limonene is a low-cost, low toxicity biodegradable terpene present in agricultural wastes derived from citrus peels. The products obtained from the conversion of limonene are valuable compounds widely used as additives for food, cosmetics, or pharmaceuticals. The conversion of limonene to produce different products has been the subject of intense research, mainly with the objective to improve catalytic systems. This review focused on the application of heterogeneous catalysts in the catalytic conversion of limonene.

Small-Sized Mg-Al LDH Nanosheets Supported on Silica Aerogel with Large Pore Channels: Textural Properties and Basic Catalytic Performance after Activation

Layered double hydroxides (LDHs) have been widely used as an important subset of solid base catalysts. However, developing low-cost, small-sized LDH nanoparticles with enhanced surface catalytic sites remains a challenge. In this work, silica aerogel (SA)-supported, small-sized Mg-Al LDH nanosheets were successfully prepared by one-pot coprecipitation of Mg and Al ions in an alkaline suspension of crushed silica aerogel. The supported LDH nanosheets were uniformly dispersed in the SA substrate with the smallest average radial diameter of 19.2 nm and the thinnest average thickness of 3.2 nm, both dimensions being significantly less than those of the vast majority of LDH nanoparticles reported. The SA/LDH composites also showed large pore volume (up to 1.3 cm3·g) and pore diameter (>9 nm), and therefore allow efficient access of reactants to the edge catalytic sites of LDH nanosheets. In a base-catalyzed Henry reaction of benzaldehyde with nitromethane, the SA/LDH catalysts showed high reactant conversions and favorable stability in 6 successive cycles of reactions. The low cost of the SA carrier and LDH precursors, easy preparation method, and excellent catalytic properties make these SA/LDH composites a competitive example of solid-base catalysts.