Selective Oxidation Of Sulfides Research Articles

Preparation and characterization of oxovanadium(IV)-glycine imine immobilized on magnetic nanoparticles and its catalytic application for selective oxidation of sulfides to sulfoxides

A novel Fe3O4@VO (salen) complex was designed as an efficient and heterogeneous catalyst for selective oxidation of sulfides to sulfoxides using H2O2 at room temperature. The catalyst was characterized by techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), vibrating-sample magnetometry (VSM), and inductively coupled plasma optical emission spectrometry (ICP-OES) analysis. The simple preparation of the catalyst from commercially available materials, excellent chemoselectivity, easy separation of products, and straightforward recovery and reusability of the catalyst with unaltered activity make our procedure a green and practical method.

Synthesis, characterization and catalytic evaluation of H3PW12O40 included in acrylic acid/acrylamide polymer for the selective oxidation of sulfides

A series of hybrid materials (SAPTPA) based on tungstophosphoric acid H3PW12O40 (TPA) included in acrylic acid/acrylamide polymer (SAP) were synthetized. The samples were characterized by FT-IR, XRD, 31P MAS-NMR, DTA-TGA, and the acidic properties were determined by means of potentiometric titration with n-butylamine. Materials with 10, 20, 30 and 40% (w/w) TPA content in the solid (SAPTPA10, SAPTPA20, SAPTPA30 and SAPTPA40, respectively) were prepared by impregnating the polymer with tungstophosphoric acid water solutions. According to FT-IR and 31P MAS-NMR studies, the main species present in the samples is the [PW12O40]3− anion, which was partially transformed into [P2W21O71]6− and [PW11O39]7− anions during the synthesis and drying steps.Taking into account XRD results, these species are highly dispersed in the polymer matrix or appear as noncrystalline phases. The DTA-TGA results show that SAPTPA materials did not undergo any remarkable chemical changes up to 200°C. Additionally, the SAPTPA materials showed strong acid sites whose number increased as the TPA content in them was higher.The materials obtained by impregnation of TPA onto the polymer matrix present suitable physicochemical properties to be used as catalysts in the selective oxidation of sulfides to the corresponding sulfoxide/sulfone using acetonitrile as solvent and H2O2 35% w/v as a clean oxidant.The SAPTPA40 catalyst was appropriate for the selective sulfide oxidation in heterogeneous conditions and can be reused without significant loss of its catalytic activity. A convenient and selective procedure for oxidizing sulfides to sulfoxides or sulfones by varying the H2O2/substrate ratio and the temperature was found.

Efficient and selective oxidation of sulfides in batch and continuous flow using styrene-based polymer immobilised ionic liquid phase supported peroxotungstates

Good conversion and high selectivity for sulfoxidation have been achieved under segmented and continuous flow using a polystyrene-based polymer immobilised ionic liquid phase (PIILP) peroxotungstate.

Ni-SMTU@boehmite: as an efficient and recyclable nanocatalyst for oxidation reactions

An efficient heterogenized nickel catalyst on boehmite nanoparticles was synthesized and characterized. The catalytic activity of this organometallic catalyst was examined in the selective oxidation of sulfides and oxidative coupling of thiols.

Nonanebis(peroxoic acid) mediated efficient and selective oxidation of sulfide

Metal free, chemoselective oxidation of sulfide using aliphatic diperoxyacid.

Kinetically controlled synthesis of Au102(SPh)44 nanoclusters and catalytic application.

We here explore a kinetically controlled synthetic protocol for preparing solvent-solvable Au102(SPh)44 nanoclusters which are isolated from polydispersed gold nanoclusters by solvent extraction and size exclusion chromatography (SEC). The as-obtained Au102(SPh)44 nanoclusters are determined by matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometry, in conjunction with UV-vis spectroscopy and thermogravimetric analysis (TGA). However, Au99(SPh)42, instead of Au102(SPh)44, is yielded when the polydispersed gold nanoclusters are etched in the presence of excess thiophenol under thermal conditions (e.g., 80 °C). Interestingly, the Au102(SPh)44 nanoclusters also can convert to Au99(SPh)42 with equivalent thiophenol ligands, evidenced by the analyses of UV-vis and MALDI mass spectrometry. Finally, the TiO2-supported Au102(SPh)44 nanocluster catalyst is investigated in the selective oxidation of sulfides into sulfoxides by the PhIO oxidant and gives rise to high catalytic activity (e.g., 80-99% conversion of R-S-R' sulfides with 96-99% selectivity for R-S([double bond, length as m-dash]O)-R' sulfoxides). The Au102(SPh)44/TiO2 catalyst also shows excellent recyclability in the sulfoxidation process.

Structure-induced catalysis enhancement of Cu-amino catalysts for rapidly selective oxidation of sulfides in the presence of H2O2

A Cu-amino coordination polymer promotes rapid sulfoxidation of benzyl phenyl sulfide toward the sulfoxide with high conversion and selectivity.

An organic–inorganic hybrid supramolecular framework material based on a [P2W18O62]6−cluster and Yb & Na complexes of pyridine-2,6-dicarboxylic acid: a catalyst for selective oxidation of sulfides in water with H2O2

A rare-earth-containing polyoxometalate (RECP) hybrid, {(Yb (PDCH2)2(PDCH))·Na(H2O)2·(Na(PDCH)(H2O)2)}2[P2W18O62]·14H2O (1), based on [P2W18O62]6− cluster anions and cationic Yb & Na complex units of pyridine-2,6-dicarboxylic acid (PDCH2) has been synthesized under normal reaction conditions, which exhibited a supramolecular 3-D framework structure in the crystal lattice. Hybrid 1 acts as a green catalyst for the selective oxidation of sulfides in water with H2O2 as the reagent.

Selective Oxidation of Sulfides to Sulfones by H2O2 Catalyzed by Fe-Substituted Sandwich Type Polyoxometalate

Catalytic activity of the sandwich-type heteropolytungstates ([(XW9O39)M4](n−m)−, where X = P, Si, As and M = Mn, Fe, Co, Ni, Cu and Zn) in the selective oxidation of sulfides to corresponding sulfone with aqueous H2O2 have been studied in acetonitrile. In comparison, different sandwich type polyoxometalates with various transition metals substituted and heteroatoms, TBAPWFe was found to be more active to each other’s. This catalyst with 2.5 equivalent of hydrogen peroxide, converted various sulfides to the corresponding sulfone with 96.8–99 % selectivity at 94–97 % conversion. Furthermore, for oxidizing various sulfides to the corresponding sulfone, the sulfide function is highly reactive and other functional groups such as the double bond and hydroxyl group are tolerable. This catalyst indicated very good reusability in the oxidation reaction.

Highly selective and efficient oxidation of sulfide to sulfoxide catalyzed by platinum porphyrins

Two platinum porphyrins, meso-tetramesitylporphyrinatoplatinum and meso-tetrakis(pentaflourophenyl) porphyrinatoplatinum, are explored for catalytic application in the selective oxidation of sulfide to sulfoxide by iodosylbenzene. The obtained overall turnover number of 90,000 in the oxidation of thioanisole in the presence of meso-tetrakis(pentaflourophenyl) porphyrinatoplatinum indicates the pronounced catalytic activity of the platinum porphyrins. Perfect selectivity toward sulfoxide or sulfone also was achieved via stoichiometric control of reactants.

Synthesis and characterization of two binuclear nickel(II) complexes of thiophenol-based “end-off” compartmental ligands and their application as catalysts for selective oxidation of sulfides

Reaction of the binucleating S-protected ligand precursors 2-(N,N-dimethylthiocarbamato)-5-methylisophthalaldehyde di-2′-hydroxy anil (I) and 2-(N,N-dimethylthiocarbamato)-5-methylisophthalaldehyde di-2′-hydroxy 5′-methyl anil (II) with nickel(II) acetate tetrahydrate in the presence of pyrazole afforded the binuclear nickel(II) complexes [LINi2(pz)] (1) and [LIINi2(pz)] (2), respectively. The complexes have been characterized by routine physicochemical studies as well as by X-ray single crystal structure analysis. In both complexes, Ni(II) ions are doubly bridged by the thiophenolic sulfur of the pentadentate Schiff base ligand and a pyrazolate group. Efficient protocols for the oxidation of sulfides to sulfoxides with high selectivities, catalyzed by binuclear μ-thiophenolato-μ-pyrazolatonickel(II) in the presence of urea hydrogen peroxide (UHP) were explored. We obtained predominantly the monooxygenated product. The resulting products are obtained in good to excellent yields within a reasonable time.

Catalytic behavior of an iron(III) complex containing an N,O-type bidentate oxazoline ligand for selective oxidation of sulfides

The reaction of Fe(acac)3 and 2-(2′-hydroxyphenyl)oxazoline (Hphox) as a bidentate O,N donor ligand afforded a six-coordinated iron(III) complex [Fe(phox)2(acac)] with distorted octahedral configuration. The complex was isolated as an air-stable crystalline solid and characterized by elemental analysis, FTIR, solution electrical conductivity, and by single-crystal X-ray structure analysis. The structure, electronic properties, and vibrational normal modes of the complex were investigated by DFT. The use of this complex as a catalyst for the oxidation of sulfides to their corresponding sulfoxides using urea hydrogen peroxide as the primary oxidant was investigated. The catalyst shows very efficient reactivity, giving high yields and selectivities at room temperature under air.

Efficient preparation of Zr(IV)-salen grafted mesoporous MCM-41 catalyst for chemoselective oxidation of sulfides to sulfoxides and Knoevenagel condensation reactions

Zr(IV)-salen-MCM-41 was prepared by reaction of NH2-MCM-41 with salicylaldehyde to afford Schiff base ligands. Thereafter, ZrOCl2·8H2O was reacted with the Schiff base ligands for complex formation. The structural properties of the synthesized materials were investigated by a number of analytical techniques including X-ray diffraction, N2 sorption-desorption, thermogravimetric analysis, Fourier transform infrared spectroscopy, inductively coupled plasma atomic emission spectroscpopy, and energy dispersive X-ray spectroscopy. Catalytic studies of the mesoporous materials functionalized with Zr(IV)-Schiff base complexes were investigated and extended to selective oxidation of sulfides to sulfoxides and the Knoevenagel condensation reactions of aldehydes with malononitriles and ethyl cyanoacetate. Additionally, catalyst recycling of the Zr-salen-MCM-41 materials was also studied.

Selective oxidation of sulfides on Pt/BiVO4 photocatalyst under visible light irradiation using water as the oxygen source and dioxygen as the electron acceptor

Photocatalytic selective oxidation represents an environment-friendly strategy for chemical transformation. Herein, we report the oxidation of sulfides into sulfoxides with high selectivity (up to 99%) on Pt/BiVO4 photocatalyst in water under visible light illumination. The system exhibited excellent performance for the oxidation of sulfides in water compared with organic solvents. Isotopic oxygen (H218O) experiments clearly revealed that the oxygen atoms in the sulfoxide were mainly from water. Electron paramagnetic resonance demonstrated that the reactive oxygen species were the peroxy species, which were generated from water oxidation on BiVO4 via the two-electron pathway. Dioxygen was reduced to water through proton-coupled electron transfer.

Selective oxidation of sulfides to sulfoxides using hydrogen peroxide over Au/CTN–silica catalyst

Chitosan (CTN) can be used as potential support to create environmentally friendly catalysts; however, chitosan's poor diffusion properties and low surface area limit its application. Direct deposition method on inorganic supports might be a feasible and simple solution, using core (silica nanosphere)–shell (chitosan) material as support, a series of Au/CTN–silica catalysts were prepared by inverse microemulsion system. These catalysts were active in catalyzing the oxidation of sulfides to sulfoxides with relative good conversion and high selectivity. This study confirms that the key factor governing catalytic performance of this catalyst should be the interaction between gold nanoparticles and N atoms.

A new oxovanadium(IV) complex containing an O,N-bidentate Schiff base ligand: Synthesis at ambient temperature, characterization, crystal structure and catalytic performance in selective oxidation of sulfides to sulfones using H2O2 under solvent-free conditions

A new bidentate ON Schiff base ligand, HL, was synthesized by simple condensation reaction of isopropylamine and salicylaldehyde. Then by reaction of HL and VO(acac)2 in the ratio of 2:1 at ambient temperature, a new oxovanadium(IV) Schiff base complex, VOL2, was synthesized. The Schiff base ligand and its oxovanadium(IV) complex were characterized by elemental analyses, FT-IR, 1H NMR, 13C NMR and UV–visible spectroscopies. The crystal structure of oxovanadium(IV) complex, VOL2, was also determined by single crystal X-ray analysis. The vanadium center in this structure is coordinated to two bidentate Schiff base ligands with the two nitrogen and two phenolate oxygen atoms in equatorial positions and one oxo oxygen in the axial position to complete the distorted trigonal bipyramidal N2O3 coordination sphere.Catalytic performance of the VOL2 complex was studied in the selective oxidation of thioanisole with the green oxidant 35% aqueous H2O2 under solvent-free conditions and under organic solvents (EtOH, CHCl3, CH2Cl2, DMF, CH3CN, EtOAc) as a model. Due to better catalytic performance of the VOL2 complex under solvent-free conditions, this complex used for the oxidation of the different sulfides to the corresponding sulfones under solvent-free conditions. The use of hydrogen peroxide as oxidant and the absence of solvent makes these reactions interesting from environmental and economic points of view.

ChemInform Abstract: Fe(NO3)3·9H2O‐Catalyzed Aerobic Oxidation of Sulfides to Sulfoxides under Mild Conditions with the Aid of Trifluoroethanol.

Abstract Selective oxidation of sulfides to sulfoxides was successfully performed by employing readily available Fe(NO 3 ) 3 ·9H 2 O as the active catalyst with oxygen as the oxidant in 2,2,2-trifluoroethanol (TFE) without the formation of sulfones. Nitrate anion could play a crucial role in promoting the reaction due to the oxidation capacity under acidic media. High yields of sulfoxides were exclusively obtained from the corresponding sulfides. Furthermore, both aromatic and aliphatic sulfides gave moderate to high yields of sulfoxides with this protocol.

Synthesis and characterization of Copper (II) Schiff base complex containing MCM-41 as robust and clean nano reactor catalyst for the selective oxidation of sulfides to sulfoxides using H2O2

An efficient and versatile procedure has been introduced for the preparation of copper supported on functionalized mesoporous silica (MCM-41) containing chelating Schiff base salen (the structure of this functionalized silica complex was studied by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, thermo gravimetric analysis and N2 adsorption and desorption), which has been applied as catalyst for the conversion of various sulfides into sulfoxides with aqueous hydrogen peroxide. Also this heterogeneous catalyst can be recovered easily and reused many times for the oxidation of sulfides without significant loss of activity and selectivity.

Highly Selective Oxidation of Sulfides to Sulfones by H2O2 Catalyzed by Porous Capsules

In this study, selective oxidation of different sulfides to the corresponding sulfone with hydrogen peroxide in the presence of W72Fe30 is reported. W72Fe30 is as an efficient catalyst for the selective oxidation of sulfides to sulfones, in high to excellent yields using 30 % hydrogen peroxide as an oxidant under optimum reaction conditions. Various sulfides containing functional groups such as double bond and hydroxyl group are successfully and selectively oxidized without affecting sensitive functionalities. Oxidation of sulfides to corresponding sulfone by H2O2 in the presence of W72Fe30

Preparation and Characterization of Organically Modified MCM-48 as Heterogonous Catalyst for Oxidation of Sulfides and Thiols

MCM-48 mesoporous synthesized and grafted with aminopropyl triethoxysilane (APTES) and subsequently reacted by isatin to obtain the imine of MCM-48. Addition of ZrOCl2·8H2O, leading to form the complex of Zr(IV)/isatin-MCM-48 as new Schiff base complex of zirconium(IV)-modified-MCM-48. The synthesized catalyst was characterized by XRD, TGA, FT-IR and BET. The resulting catalyst was efficient for selective oxidation of sulfides to sulfoxides and oxidation of thiols to disulfides with hydrogen peroxide. In this method isolation and reusability of catalyst have been investigated