Various 2-arylbenzimidazoles were synthesized from phenylenediamines and aromatic aldehydes via a one-step process in the presence of a catalytic amount of a cobalt-salen complex supported on activated carbon [CoxO-CoA C H T U N G T R E N N U N G (salen) 11] at room temperature. The salient features of this method include mild conditions, short reaction times, high yields, easy purification, recyclable catalyst, largescale synthesis and simple procedure. The reactions were performed in ethanol and the catalyst could be reused for several cycles without a decrease in activity. The heterogeneous catalyst was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic forced microscopy (AFM), thermogravimetric (TG) methods for analysis of nitrogen adsorption and FT-IR spectroscopy. Leaching experiments showed that the catalyst is most strongly anchored to the activated support after 10 cycles of reuse.

The synthesis, characterization and catalytic activity of a Cu(II) complex derived from 2‐oxoquinoline‐3‐carbaldehyde Schiff base supported on amino‐functionalized silica are reported. 3‐(1H‐Benzo[d]imidazol‐2‐yl)quinolines containing piperidine, morpholine and phenylpiperazine skeletons at the C‐2 position were formed in good to excellent yields via the one‐pot reaction of 2‐chloroquinoline‐3‐carbaldehyde, benzene‐1,2‐diamines and secondary amines in the presence of the nanocatalyst under mild conditions. Moreover, the nanocatalyst was found to be recyclable for up to seven runs without significant loss of activity. Also, a series of 2H‐indazoles were synthesized by the catalytic condensation of 2‐bromobenzaldehyde, sodium azide and primary amines.

This review article discusses the progress related to the synthesis and catalytic applications of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials for industrial and laboratory products. These catalysts are widely used in acid-catalyzed processes. Most of these acid catalysts are eco-friendly, reusable, and stable. Moreover, the discovery of unique catalysts is vital for developing new, efficient, and reusable catalysts for industrial and laboratory applications. The aim of this review article is to review the recent studies (2014–2018) in the field of the utility of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials for developing acidic catalysts.

The nano magnetic Fe3O4 (NM−Fe3O4) was applied for the synthesis of benzoxazoles via a C(aryl)−OH functionalization of catechol derivatives and amines in ethanol at room temperature. In the next step, amino acids have been applied as nontoxic and cheap alternatives for amines. The obtained products were similar with the regular amines case. This is the first report about the application of amino acids as alternatives for primary amines in organic synthesis. Furthermore, the presented method was successfully applied toward the synthesis of desired products in large scales.

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