Fe3O4@SiO2@CSH+VO3- as a novel recyclable heterogeneous catalyst with core-shell structure for oxidation of sulfides

Iron nanoparticles, with low toxicity and many active sites, are among the materials that not only reduce waste along with green chemistry but also increase the separation power and recover the catalyst from the reaction environment. In this study, first, the surface of iron nanoparticles was silanized, and in the next step, the complex of chitosan HCl.VO3 was placed on the surface of Fe3O4 (Fe3O4@SiO2@CSH+VO3-). This nanocatalyst is a novel, recoverable, and potent nanocatalyst with high selectivity for the oxidation of sulfides to sulfoxides. Various physicochemical techniques such as IR, XRD, TGA, SEM, EDX, mapping, TEM, and VSM were used to affirm the well synthesis of the catalyst. Oxidation of sulfides in the presence of hydrogen peroxide as a green oxidant and in ethanol was catalyzed by the Fe3O4@SiO2@CSH+VO3-. All sulfoxides were achieved with high efficiency and in a short time. The notable privileges of this method include facile and economic catalyst synthesis, proper catalyst durability, great performance, simple catalyst isolation, good recovery capability, at least up to 5 times without an index drop in catalytic power.

Tuning Selectivity in the Visible-Light-Promoted Coupling of Thiols with Alkenes by EDA vs TOCO Complex Formation

The visible-light-promoted catalyst-free condition has been demonstrated for self- and cross-coupling reactions of thiols in an ambient atmosphere. Further, synthesis of β-hydroxysulfides is accomplished under very mild conditions involving the formation of an electron donor-acceptor (EDA) complex between a disulfide and an alkene. However, the direct reaction of thiol with alkene via the formation of a thiol-oxygen co-oxidation (TOCO) complex failed to produce the desired compounds in high yields. The protocol was successful with several aryl and alkyl thiols for the formation of disulfides. However, the formation of β-hydroxysulfides required an aromatic unit on the disulfide fragment, which supports the formation of the EDA complex during the course of the reaction. The approaches presented in this paper for the coupling reaction of thiols and the synthesis of β-hydroxysulfides are unique and do not require toxic organic or metal catalysts.

Diethyl phosphite-mediated switchable synthesis of bis(imidazoheterocycles) derived disulfanes and sulfanes using imidazoheterocycles and octasulfur

A unique diethyl phosphite-mediated switchable synthesis of bis(imidazoheterocycle)-derived disulfanes and sulfanes using imidazoheterocycles with sulfur is reported. Moreover, imidazo[1,2-a]pyridine-indole derived thioethers were also realized.

A nickel nanoparticle engineered CoFe2O4/SiO2-NH2@carboxamide composite as a novel scaffold for the oxidation of sulfides and oxidative coupling of thiols

The purpose of this work was to prepare a new Ni-carboxamide complex supported on CoFe2O4 nanoparticles (CoFe2O4/SiO2-NH2@carboxamide-Ni). The carboxamide host material unit generated cavities that stabilized the nickel nanoparticles effectively and prevented the aggregation and separation of these particles on the surface. This compound was appropriately characterized using FT-IR spectroscopy, FE-SEM, ICP-OES, EDX, XRD, TGA analysis, VSM, and X-ray atomic mapping. The catalytic oxidation of sulfides and oxidative coupling of thiols in the presence of the designed catalyst was explored as a highly selective catalyst using hydrogen peroxide (H2O2) as a green oxidant. The easy separation, simple workup, excellent stability of the nanocatalyst, short reaction times, non-explosive materials as well as appropriate yields of the products are some outstanding advantages of this protocol.

Gold nanoparticles decorated biguanidine modified mesoporous silica KIT-5 as recoverable heterogeneous catalyst for the reductive degradation of environmental contaminants

This current study involves the novel synthesis of Au nanoparticles (Au NPs) decorated biguanidine modified mesoporous silica KIT-5 following post-functionalization approach. The tiny Au NPs were being stabilized over the in situ prepared biguanidine ligand. The high surface area material was characterized using analytical techniques like Fourier Transformed infrared (FT-IR) spectroscopy, N2-adsorption-desorption isotherm, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDS), and X-ray Diffraction study (XRD). Our material was found to be an efficient catalyst in the reductive degradation of harmful water contaminating organic dyes like Methylene blue (MB), Methyl Orange (MO) and Rhodamin B (RhB) in presence of NaBH4 at room temperature. The whole procedure was followed up with the help of time dependant UV-Vis spectroscopy. All the reactions followed pseudo-unimolecular kinetics and corresponding rate constant were determined. The reduction rate becomes high in presence of higher load of catalysts.

A competent green methodology for the synthesis of aryl thioethers and 1H-tetrazole over magnetically retrievable novel CoFe2O4@l-asparagine anchored Cu, Ni nanocatalyst

The current work describes the successful synthesis of a magnetic CoFe₂O₄ centered asparagine functionalized noble metal (M = Cu, Ni) anchored nanocomposite. The novel materials, synthesized by post-functionalization approach, have been characterized by XRD, SEM, EDX, X-ray elemental mapping, FT-IR and VSM studies. The materials are proved to be efficient heterogeneous catalyst in the synthesis of diarylthioethers by C-S cross coupling reaction and 5-substituted 1H-tetrazoles by azide-alkyne cycloaddition reaction under green conditions. The current methodology is advantageous in terms of simplicity of procedure, facile synthesis, high yield in short reaction time, easy magnetic isolation and reusability of catalysts in consecutive runs with insignificant change in catalytic activity.