Iron-Oxide-Supported Ultrasmall ZnO Nanoparticles: Applications for Transesterification, Amidation, and O-Acylation Reactions

Abstract

An efficient maghemite–ZnO nanocatalyst has been synthesized via a simple coprecipitation method, where ZnO nanoparticles are uniformly decorated on the maghemite core and characterized by XRD, SEM-EDS, ICP-AES, XPS, TEM, HRTEM, and Mössbauer spectroscopy; maghemite nanoparticles are in the typical size range 10–30 nm with ultrasmall (3–5 nm) ZnO nanoparticles. A competent and benign protocol is reported for various organic transformations, namely, transesterification, amidation, and O-acylation reaction in good to excellent yields (75–97%) using magnetically separable and reusable maghemite–ZnO nanocatalyst.

Iron Oxide-Cobalt Nanocatalyst for O-tert-Boc Protection and O-Arylation of Phenols

“…In continuation of our efforts to develop sustainable, greener, and catalytic organic transformation methods [ 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ], in this paper we report an efficient protocol for the O - tert -butoxycarbonylation and O -arylation of phenols using magnetically separable Fe 3 O 4 -Co 3 O 4 MNPs (magnetic nanoparticles), as depicted in Figure 1 .…”

Metal‐ and Solvent‐Free Transesterification and Aldol Condensation Reactions by a Homogenous Recyclable Basic Ionic Liquid Based on the 1,3,5‐Triazine Framework

“…Aldol condensation and transesterification, are two examples of the most practical reactions in industry, especially in the field of fuel and energy, which are usually catalyzed by a basic reagent in the presence of a catalyst. [ 1 , 2 , 3 , 4 ] Aldol condensation has a wide range of application in fine chemicals synthesis; and includes two steps: [5] (i) the intermediate formation of enols by a basic reagent, and (ii) the formation of a C−C bond between the enols and the carbonyl group that can be takes place via the reaction of an adsorbed molecule and a molecule in the fluid (Ely‐Rideal model) or occurs through a two‐molecular surface reaction (Langmuir‐Hinshelwood model) for heterogeneous catalysts. [6] The next two steps of the re‐protonation and dehydration lead to the desired product.…”

“…Recently, Tanaka et al used an epoxide as a pre-catalyst for metal-free catalytic transesterification reaction. [9] N-heterocyclic carbine, [13] organic methyl carbonate salts, [14,15] maghemite-ZnO, [3] M 2 CO 3 of MI (M=K, Na, Li, Cs), [10] organic and inorganic bases, [16] Lewis acids, [12] and nano CuFe 2 O 4 [11] were used as a catalyst for transesterification of esters.…”

Acetylation of Alcohols, Amines, Phenols, Thiols under Catalyst and Solvent-Free Conditions

“…Subsequently, a wide range of homogeneous transition-metal-based or organocatalysts have been developed for the acetylation of alcohols using RuCl 3 [18], CeCl 3 [19], ZrCl 4 [20], La(NO 3 )•6H 2 O [21], Al(OTf) 3 [22], AgOTf [23], Co(II)salen-complex [24], NiCl 2 [25], CoCl 2 [26], iodine [27], Ph 3 P + CH 2 COMeBr − [28], Cp 2 ZrCl 2 [29], Mg(NTf 2 ) 2 [30], H 3 [P(Mo 3 O 10 ) 4 ]•nH 2 O [31], 3-nitrobenzeneboronic acid [32], (4-dimethylaminopyridine) [33], (4-(N,N -dimethylamino)pyridine hydrochloride) [34], CuZr(PO 4 ) 2 NPs [35], melamine trisulfonic acid [36], tin(IV)porphyrin-hexamolybdate [37], and NaOAc•3H 2 O [38]. Furthermore, acetylation has also been reported with a series of heterogeneous catalysts, such as ionic liquids [39], ZnO [40,41], CuO-ZnO [42], nano γ-Fe 2 O 3 [43], Fe 3 O 4 @PDA-SO 3 H [44], polymer-supported Gd(OTf) 3 [45], silica-sulfamic acid [46], borated zirconia [47], ZnAl 2 O 4 [48], P 2 O 5 /Al 2 O 3 [49], poly(N-vinylimidazole) [50], CMK-5-SO 3 H [51], 4-dimethylaminopyridine-microporous organic nanotube networks [52], maghemite-ZnO [53], and graphene-grafted N-methyl-4-pyridinamine [54]. These methods exhibit some obvious advantages like low reaction temperature, higher conversions of substrates a...…”