Copper–Schiff base complex catalyzed oxidation of sulfides with hydrogen peroxide

The Selective Oxidation of Sulfides to Sulfoxides or Sulfones with Hydrogen Peroxide Catalyzed by a Dendritic Phosphomolybdate Hybrid

The oxidation of sulfides to their corresponding sulfoxides or sulfones has been achieved using a low-cost poly(amidoamine) with a first-generation coupled phosphomolybdate hybrid as the catalyst and aqueous hydrogen peroxide as the oxidant. The reusability of the catalyst was revealed in extensive experiments. The practice of this method in the preparation of a smart drug Modafinil has proved its good applicability.

Synthesis of a new series of Ni(ii), Cu(ii), Co(ii) and Pd(ii) complexes with an ONS donor Schiff base: crystal structure, DFT study and catalytic investigation of palladium and nickel complexes towards deacylative sulfenylation of active methylenes and regioselective 3-sulfenylation of indoles via thiouronium salt formation

A series of Ni(ii), Cu(ii), Co(ii), and Pd(ii) complexes have been synthesized with a chelating Schiff base ligand coordinated to a metal center with ONS donor atoms. The ligand and complexes are characterized by elemental analysis and spectroscopic techniques like FT-IR, 1H-NMR, and UV-Visible spectroscopy. The single crystal structure of the Pd(ii) complex is obtained by X-ray diffraction analysis and exhibits slightly distorted square planar geometry. The structure is optimized by DFT, TD-DFT calculation to elaborate the electronic structure and NBO for the charge distribution analysis of the Pd(ii) complex. The synthesized Pd(ii) and Ni(ii) complexes as catalysts have been investigated in the C-S cross-coupling of indoles and active methylenes. The metal propelled regioselective transformation afforded 3-sulfenylated indoles while β-diketones favored deacylated monosulfenyl ketones in an excellent yield via thiouronium salt formation. The Pd(ii) complex displays slightly better reactivity whereas the Ni(ii) complex is cost-efficient. The method is fast, easy to handle and cost effective in terms of high reactivity of catalysts, use of non-toxic solvents, and cheaper aryl halides and thiourea replace conventional sulfur sources, providing a practical access to organic transformations.

Schiff base Mn(iii) and Co(ii) complexes coated on Co nanoparticles: an efficient and recyclable magnetic nanocatalyst for H2O2 oxidation of sulfides to sulfoxides

In this paper, an effective and selective heterogeneous catalyst was produced by immobilization of manganese and cobalt Schiff base-complexes on Co magnetite nanoparticles (MNP). The catalysts Co@SiO₂[(EtO)₃Si–L³]/M (M = Mn(iii) and Co(ii)) were synthesized using Co@SiO₂ core–shell nanoparticles and amino-functionalized Co@SiO₂. The Schiff base ligand Co@SiO₂[(EtO)₃Si–L³] was synthesized by reacting Co@SiO₂ core–shell nanoparticles with 2-hydroxy 1-naphthaldehyde for the synthesis of Co@SiO₂[(EtO)₃Si–L³]/M. The catalysts were characterized by several techniques, such as FT-IR, TEM, XRD, TGA and VSM. The catalytic activities of the prepared catalysts were studied by oxidation of sulfides to the sulfoxides under different conditions. These catalysts can be easily recovered and reused in at least seven sequential cycles without considerable leaching and loss of reactivity.

In this paper, an effective and selective heterogeneous catalyst was produced by immobilization of manganese and cobalt Schiff base-complexes on Co magnetite nanoparticles (MNP).

Fe3O4/PEG-SO3H as a heterogeneous and magnetically-recyclable nanocatalyst for the oxidation of sulfides to sulfones or sulfoxides

We present below a sulfonated-polyethylene glycol-coated Fe₃O₄ nanocomposite (Fe₃O₄/PEG-SO₃H) as a greatly effective and ecological nanocatalyst for the selective oxidation of sulfides to sulfoxides or sulfones with brilliant yields under solvent-free conditions by employing 30% hydrogen peroxide as the oxidant.

Graphene Oxide Foam Supported Titanium(IV): Recoverable Heterogeneous Catalyst for Efficient, Selective Oxidation of Arylalkyl Sulfides to Sulfoxides Under Mild Conditions

An efficient and environmentally friendly method was designed for the oxidation of sulfides to sulfoxides with a recyclable, carbon-skeleton-based heterogeneous catalyst developed by titanium sulfate [Ti(SO₄)₂] mineralization on the surface of graphene oxide foam [Ti(SO₄)₂@GOF] by using 30 wt% H₂O₂ as oxidant. Several different substituted sulfides were examined to explore the scope of substrates of the selective oxidation. The excellent reusability and durability of Ti(SO₄)₂@GOF was demonstrated by recycling experiments and the catalyst was further applied in the preparation of pantoprazole sodium in a one-pot process.

Visible light catalyzed methylsulfoxidation of (het)aryl diazonium salts using DMSO

The visible light catalyzed methylsulfoxidation of (het)aryl diazonium salts using DMSO is illustrated.

Metal-free chemoselective oxidation of sulfides to sulfoxides catalyzed by immobilized l-aspartic acid and l-glutamic acid in an aqueous phase at room temperature

Immobilized l-aspartic and l-glutamic acid were employed in the oxidation of sulfides, and 99% conversion and 97% selectivity were achieved.

pH-Dependence of the Aqueous Phase Room Temperature Brønsted Acid-Catalyzed Chemoselective Oxidation of Sulfides with H₂O₂

A pH-dependence of the Brønsted acid-catalyzed oxidation of sulfides to the corresponding sulfoxides with H₂O₂ is reported for the first time based on our systematic investigation of the catalytic performance of a series of Brønsted acids. For all of the Brønsted acids investigated, the catalytic performances do not depend on the catalyst loading (mol ratio of Brønsted acid to substrate), but rather depend on the pH value of the aqueous reaction solution. All of them can give more than 98% conversion and selectivity in their aqueous solution at pH 1.30, no matter how much the catalyst loading is and what the Brønsted acid is. This pH-dependence principle is a very novel perspective to understand the Brønsted-acid catalysis system compared with our common understanding of the subject.