A Novel Brønsted-Lewis acidic catalyst based on heteropoly phosphotungstates: Synthesis and catalysis in benzylation of p-xylene with benzyl alcohol

A Green and Efficient Solvent- and Catalyst-Free Ultrasonic Dibenzylation Procedure

A greener improvement was achieved for the synthesis of diverse N,N-dibenzylated compounds from the reaction of various aromatic amines with benzyl bromide using the ultrasound irradiation in solvent- and catalyst-free conditions. The dibenzylation reactions were carried out in different solvents and solvent-free conditions under ultrasound irradiation at various temperatures. The yields were very low in all applied solvents, while in the solvent-free condition and at room temperature, the yields were excellent. Due to obtaining the high reaction yields, the catalyst was not used.

Molecular design and experimental study of cellulose conversion to 5-hydroxymethylfurfural catalyzed by different ratios of Brønsted/Lewis acid ionic liquids

Cellulose conversion into 5-hydroxymethylfurfural (5-HMF) is difficult because of the strong hydrogen bonding existed in cellulose chains. Brønsted/Lewis (B/L) biacidic functionalized ionic liquids (ILs) have great advantages in acid-catalyzed tandem reactions, but the catalytic effect of ILs differs considerably depending on B/L acid ratios. Therefore, this work designed a series of reactions with different proportions of biacidic ILs for the preparation of 5-HMF from cellulose. The tandem reaction is often performed in the presence of a solvent, and the activity of the catalyst is also affected by the solvent. Therefore, in this work, the solvation model density(SMD) model was introduced into the quantum chemical calculation method for molecular design to predict the catalytic effect and explore the catalytic mechanism. The calculation results and experiments jointly showed that [(HSO₃-P)₂im]Cl·ZnCl₂ had the highest efficiency, with a 5-HMF yield of 65.66%. This study facilitates the directional optimization design of the catalyst.

Pluronic F127-assisted partial decomposition of ammonium phosphomolybdate and its application as an efficient and recyclable catalyst for the alkylation of toluene with benzyl alcohol

The thermal decomposition of ammonium phosphomolybdate was adjusted by F127 to obtain an efficient and recyclable catalyst for liquid-phase alkylation.

The Steric Effect in Green Benzylation of Arenes with Benzyl Alcohol Catalyzed by Hierarchical H-beta Zeolite

For decades the steric effect was still ambiguously understood in catalytic benzylation reactions of arenes with benzyl alcohol, which limited the green synthesis of phenylmethane derivates in industrial scale. This research applies a series of silica–alumina beta zeolites to systematically evaluate factors like catalyst porosity, reactants molecule size, and reaction temperature on catalytic benzylation. First, a suitable hierarchical beta zeolite catalyst was screened out by X-ray powder diffraction, N2 adsorption−desorption, and probe benzylation with p-xylene. In the following substrates expanding study, for a typical benzylation of benzene, it showed extraordinary performance among literature reported ones that the conversion was 98% while selectivity was 90% at 353 K only after 10 min. The steric effect of aromatics with different molecular sizes on benzylation was observed. The reaction activities of four different aromatics followed the order: benzene > toluene > p-xylene > mesitylene. Combined with macroscopic kinetic analysis, this comprehensive study points out for the first time that the nature of this steric effect was dominated by the relative adsorption efficiency of different guest aromatic molecules on the host zeolite surface.

Hafnium-Doped Mesoporous Silica as Efficient Lewis Acidic Catalyst for Friedel-Crafts Alkylation Reactions

The development of an efficient solid catalyst for Friedel–Crafts (FC) reactions is of great importance to organic synthetic chemistry. Herein, we reported the hafnium-doped mesoporous silica catalyst Hf/SBA-15 and its first use for Friedel–Crafts alkylation reactions. Catalysts with different Si/Hf ratios were prepared and characterized, among which Hf/SBA-15(20) (Si/Hf = 20:1) was the most active catalyst, offering up to 99.1% benzylated product under mild reaction conditions. The influences of reaction conditions on the product were systematically investigated and compared. Pyridine-IR characterization of the catalyst showed that Lewis acid formed the primary active sites for the Friedel–Crafts alkylation reaction. X-ray photoelectron spectroscopy (XPS) characterization revealed that the electron shift from the Hf center to the silica framework resulted in a more active Lewis metal center for FC reactions. Moreover, the catalyst was successfully applied to the alkylation reaction with different alcohols and aromatic compounds. Finally, the Hf/SBA-15(20) catalyst also showed good recyclability in the recycling runs, demonstrating its high potential of being used for large scale FC reactions in the industry.