Surface Functionalization of Magnetite Nanoparticles with Sulfonic Acid and Heteropoly Acid: Efficient Magnetically Recoverable Solid Acid Catalysts

Abstract

New magnetically recoverable solid acid catalysts for acid‐catalyzed reactions were designed via the surface chemical functionalization of silica‐coated magnetite nanoparticles (SCMNPs) with sulfonic acid groups. First, the SCMNPs were covalently functionalized with 3‐aminopropyl groups to achieve Amp‐SCMNPs. Then, reaction of the Amp‐SCMNPs with 1,4‐butane sultone followed by acidification with phosphotungstic acid (HPW) or diluted sulfuric acid produced magnetically recoverable solid acid catalysts, HPW‐ampsul‐SCMNPs and H‐ampsul‐SCMNPs, respectively. Both catalysts were characterized by various physicochemical analyses such as Fourier transform infrared (FT‐IR) and inductively coupled plasma‐optical emission (ICP‐OES) spectroscopies, vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), and energy‐dispersive X‐ray (EDX) analyses. Finally, the catalytic activities of the prepared catalysts were examined in the esterification of acetic acid with butanol and acetalization of benzaldehyde with ethylene glycol. Excellent catalytic efficiencies were obtained in both cases. The catalysts were consecutively recovered and reused five times without significant loss of their activities.

Green synthesis of CuO nanoparticles using Lantana camara flower extract and their potential catalytic activity towards the aza-Michael reaction

“…1 The great interest in catalysis using nanomaterials has prompted the synthesis and investigation of a diverse range of highly functionalized nanoparticles (NPs), including metal oxide nanostructures. [3][4][5][6][7] Cu based nanomaterials which are cheap and environmentally friendly are especially attractive in this context due to the high abundance of Cu in nature and the available simple and straightforward techniques to synthesize these nanomaterials. 8 Also, Cu based materials can promote and undergo a variety of reactions due to the wide range of accessible oxidation states of Cu such as Cu(0), Cu(I), Cu(II), and Cu(III) which enable reactivity via multiple pathways.…”

Preparation of Functionalized Carbon‐Coated Cobalt Nanoparticles with Sulfonated Arene Derivatives, a Study on Surface Functionalization and Stability

“…This is in comparison to the classical functionalization with compound 3 substantially higher( 60 % increase) andi nc omparison to other in literature well reported loadings on nanoparticles similar in sulfonate loading, but synthesized in am uch simpler way. [20] Scanningt ransmission electron microscopy of unfunctionalized CCo nanoparticles and functionalized particles 3 and 8 was performed. Even though, the particles are vastly different functionalized, no significant optical difference was observed in the dried state of the investigated particles (Figure 4).…”

“…[18,19] Direct sulfonica cid functionalization on iron oxide for use in catalysis hasalso been reported. [20] Scheme1.Schematicdescription of the radical reaction pathwaywith aminon aphthalene sulfonic acidsf or the covalent anchoring on CCo nanoparticles.…”

A new nanocomposite catalyst based on clay‐supported heteropolyacid for the green synthesis of 2,4,5‐trisubstituted imidazoles

“…Among the solid acids, POMs have attracted great interest as environment‐friendly, efficient, and highly selective acid catalysts for organic transformations. [ 1–5 ] Some of these applications include selective oxidation of light alkanes, [ 6 ] epoxidation of olefins, [ 7 ] oxidation of alcohols, [ 8 ] acetalization reactions, [ 9 ] esterification of carboxylic acids, [ 10 ] and heterocyclic synthesis. [ 11 ] Keggin‐type phosphomolybdic acid (H 3 PMo 12 O 40 ) has been broadly studied as a catalyst for many organic synthesis reactions and is used in various processes.…”