Halogenated macroporous sulfonic resins as efficient catalysts for the Biginelli reaction

12‐Tungstosilicic Acid H4[W12SiO40] Over Natural Bentonite as a Heterogeneous Catalyst for the Synthesis of 3,4‐dihydropyrimidin‐2(1H)‐Ones

“…Patil et al recently extensively reviewed usage of different kind of supports as a heterogeneous catalyst for this reaction . A notable solid acid catalysts such as silica sulfuric acid, MCM‐41‐SO 3 H, PS‐PEG‐SO 3 H, Al 2 O 3 /MeSO 3 H, bio‐glycerol‐SO 3 H, Fe 3 O 4 @SBA‐15‐COOH, PPF‐SO 3 H, Fe 3 O 4 /PAA‐SO 3 H, BPMO‐IL‐SO 3 H, SiO 2 ‐Pr‐SO 3 H, nano‐γ‐Fe 2 O 3 ‐SO 3 H, perlite‐SO 3 H, nano‐ZrO 2 ‐SO 3 H, Fe 3 O 4 @SiO 2 ‐PhSO 3 H, SiO 2 ‐phosphonicacid, β‐cyclodextrin‐propylsulfonicacid, ZrO 2 ‐SO 3 H, GO‐SO 3 H, halogenated macroporous sulfonic resin and Fe 3 O 4 @meglumine‐SO 3 H that delivered DHPMs in high yields with good reusability. In spite of exploring the different type of material as a catalyst for this one‐pot condensation reaction, there is still scope to find a novel catalyst system which is easily available and can mitigate the above mentioned problems.…”

Deep eutectic solvents (DESs) as powerful and recyclable catalysts and solvents for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones

“…Brønsted acids or Lewis acids, such as HBF 4 [23], H 3 PW 12 O 40 [24], InBr 3 [25], ZrCl 4 [26], Fe(OTs) 3 •6H 2 O [27], and Ce(NO 3 ) 3 •6H 2 O [28], have been traditionally used as catalysts. In recent years, some novel catalysts, including organocatalysts [29,30], biocatalysts [31], immobilized urease [32], PS-PEG-SO 3 H [33], Ti-graftedpolyamidoamine dendritic silica hybrid catalyst [34], halogenated macroporous sulfonic resins [35], polyaniline-supported FeCl 3 [36], cobalt supported on alumina catalyst [37], and ionic liquid [38][39][40][41] have attracted great attention for use in the Biginelli reaction. These catalysts, for their uses in accomplishing the Biginelli reaction, have produced varying degrees of success.…”

Fabrication of a solid superacid with temperature-regulated silica-isolated biochar nanosheets

“…In generally, the thermal stability and acidity of sulfonated materials can be improved by increasing the density and spatial proximity of their SO3H groups [29][30][31], and in particular by introducing halogen substituents on the polyaromatic ring [43][44][45][46]. This is mainly because the C-S bonds can be strengthened by increasing the delocalization of the negative charges of the sulfonate group toward the aromatic ring via the HB interactions of the SO3H groups [29][30][31] and the electron-withdrawing effect of the halogen substituent [43][44][45][46]. The enhanced thermal stability of SIBCSA-1 suggests the existence of strong HB interactions between its SO3H groups, probably created by the migration and rearrangement of its high silica-isolated CNSs with a loose stacking particle structure during sulfonation.…”