One-pot and chemoselective synthesis of bis(4-hydroxycoumarin) derivatives catalyzed by nano silica chloride

Abstract

In this work, MWCNT-COOH-cellulose nanocomposite was prepared with MWCNT-COOH, SOCl2 as leaving group and cellulose as an adsorbent (A1); MgO nanoparticles have been successfully coated on the surface of nanocomposite by directly adding to A1 (MWCNT-COOH-cellulose-MgO; A2), magnesium nitrate was added to A1 and MgO nanoparticles were achieved by coating indirectly on the surfaces (MWCNT-COOH-cellulose-MgO; A3). These nanocomposites (A1, A2, and A3) were used for the removal of methyleneblue (MB) dye from aqueous solution. For characterization of adsorbent surfaces, the FT-IR, TEM, SEM, and XRD analysis were used. The effects of initial concentration of MB dye, contact time, and temperature on the adsorption were studied. According to the results, 55 min was selected as the optimum contact time for the removal process. The equilibrium data of adsorption were well fitted and the Langmuir (type III) model had the best agreement because it possesses high value of linear regression, high value R 2 , and least value of average relative error, ARE (%). Parameters of thermodynamics including enthalpy (∆H°), entropy (∆S°), and Gibbs energy (∆G°) were calculated. Kinetic data had best agreement with pseudo-second-order model. Graphical abstract Schematic synthesis of MWCNT-COOH-cellulose-MgO NP nanocomposite as adsorbent

Choline Hydroxide: An Efficient and Biocompatible Basic Catalyst for the Synthesis of Biscoumarins Under Mild Conditions

“…Biscoumarins are usually synthesized through the Domino Knoevenagel-Michael reactions of aldehydes with two equivalents of 4-hydroxycoumarin in the presence of catalyst. The present catalyst systems such as molecular iodine [5], SO 3 Hfunctionalized ionic liquids [6], ionic liquids with both Lewis acid and bronsted acid sites [7], Zn(Proline) 2 [8], sodium dodecyl sulfate [9], p-dodecylbenzenesulfonic acid/piperidine [10], sulfated titania [11], heteorpoly acid [12], nano silica chloride [13], propane-1,2,3-triyltris (hydrogen sulfate) [14] and Ce 2 (SO 4 )Á4H 2 O [15], are almost acidic and often suffered from drawbacks like low yield, long reaction time, high reaction temperature, necessity of refluxing in organic solvent and use of expensive, toxic and unreusable catalyst. In the aspect of green chemistry and industrial application, a non-toxic, reusable and efficient catalytic system at reduced temperature for the synthesis of biscoumarins is in great necessary.…”

Recent Advances in the Synthesis of Biscoumarin Derivatives

“…Furthermore, nano SiO 2 Cl had good chemoselectivity of aryl aldehydes in the presence of aliphatic ketones and aliphatic aldehydes (Scheme ). Also, 4‐(bis(4‐hydroxy‐2‐oxo‐2 H ‐chromen‐3‐yl)methyl)benzaldehyde was prepared in moderate yield (76%) from the reaction of 1 equiv of terephthaldehyde and 4 equiv of 4‐hydroxycoumarin in the presence of nano SiO 2 Cl within 7 h (Table , entry 19) …”

“…entry 19) 34. Different aldehydes were used in the synthesis of bis(4-hydroxycoumarin) derivatives in the presence of thallium(III) oxide (Tl 2 O 3 ) NPs as catalyst in aqueous EtOH as solvent at room temperature.…”

Tetramethylguanidium-based ionic liquids as efficient and reusable catalysts for the synthesis of biscoumarin at room temperature

“…Actually, this Domino reaction can also be catalyzed by acidic catalysts such as molecular iodine, 26 Zn(Proline) 2 , 27 sodium dodecyl sulfate, 28 heteorpoly acid, 29 nano silica chloride, 30 propane-1,2,3-triyltris (hydrogen sulfate), 31 and SO 3 H-functionalized ionic liquids. Actually, this Domino reaction can also be catalyzed by acidic catalysts such as molecular iodine, 26 Zn(Proline) 2 , 27 sodium dodecyl sulfate, 28 heteorpoly acid, 29 nano silica chloride, 30 propane-1,2,3-triyltris (hydrogen sulfate), 31 and SO 3 H-functionalized ionic liquids.…”