Selective Oxidation Of Sulfides Research Articles

Oxo-vanadium immobilized on polydopamine coated-magnetic nanoparticles (Fe 3 O 4 ): A heterogeneous nanocatalyst for selective oxidation of sulfides and benzylic alcohols with H 2 O 2

Abstract Polydopamine (PDA)-coated Fe3O4 nanoparticles (Fe3O4@PDA) were synthesized through a simple and green procedure. In this study, for the first time, successful immobilization of oxo-vanadium (V=O) on surface of Fe3O4@PDA as a magnetic adsorbent and stabilizing agent. The structure, morphology and physicochemical properties of the synthesized nanocatalyst [VO(PDA)@Fe3O4] were characterized by different analytical techniques such as high resolution transmission electron microscopy (HRTEM), field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDS), vibrating sample magnetometer (VSM), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma (ICP) and FT–IR spectroscopy. VO(PDA)@Fe3O4 nanoparticles illustrated high catalytic activity as a recyclable nanocatalyst in the chemoselective oxidation of sulfides to sulfoxides and benzylic alcohols to aldehydes using green oxidant of hydrogen peroxide in high-yield. The synthesized catalyst can be used several times with no considerable leaching and change in its activity. Both improvement of catalytic performance and easy separation for the reaction procedure were obtained because of the presence of oxo-vanadium and the magnetic core.

EFFICIENT MOLYBDENUM CATALYZED CHEMOSELECTIVE, SOLVENT-FREE OXIDATION OF SULFIDES TO SULFONES AT ROOM TEMPERATURE

An efficient and reusable molybdenum-based catalyst has been prepared by tethering dioxomolybdenumacetylacetonate complex, MoO 2 (acac) 2 , via post-synthesis modification of zeolite beta. The catalyst has been characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) and inductively coupled plasma (ICP). The catalyst exhibited very high activity for the selective oxidation of sulfides to sulfones at room temperature. The catalyst can be recycled and reused four times without significant loss of activity.

An isotetramolybdate-supported rhenium carbonyl derivative: synthesis, characterization, and use as a catalyst for sulfoxidation.

A novel isotetramolybdate-supported rhenium carbonyl derivative, [(CH3)4N]4[{Re(CO)3}4(Mo4O16)]·H2O (1), has been successfully synthesized and characterized by single crystal X-ray diffraction crystallography, IR and UV spectroscopy, etc. Results showed that, compound 1 is an efficient catalyst for the oxidation of thioanisole into the corresponding sulfoxide in the presence of hydrogen peroxide with good to excellent conversion (99%) and excellent selectivity (93%). Highly efficient oxygenation of thioanisole can also be achieved with 100% selectivity of sulfone and >99% conversion. Furthermore, optimized conditions were applied to a range of sulfides to obtain the corresponding sulfoxides and sulfones.

Sandwich type polyoxometalates encapsulated into the mesoporous material: synthesis, characterization and catalytic application in the selective oxidation of sulfides.

The A-type sandwich polyoxometalates of [(HOSnIVOH)3(PW9O34)2]12− (P2W18Sn3) and [(OCeIVO)3(PW9O34)2]12− (P2W18Ce3) were immobilized for the first time into the porous metal–organic framework MIL-101(Cr). FT-IR, powder X-ray diffraction, SEM-EDX, ICP analysis, N2 adsorption and thermogravimetric analysis collectively confirmed immobilization and good distribution of polyoxometalates into cages of MIL-101(Cr). The catalytic activities of the homogeneous P2W18Sn3 and P2W18Ce3 and the corresponding heterogeneous catalysts were examined in the oxidation of sulfides to sulfones with H2O2 as the oxidant at room temperature. The effects of different dosages of polyoxometalates, type of solvent, reaction time, amount of catalyst and oxidant in this catalytic system were investigated. The new P2W18Sn3@MIL-101 and P2W18Ce3@MIL-101 nanocomposites exhibited good recyclability and reusability in at least five consecutive reaction cycles without significant loss of activity or selectivity.

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.

Green catalysis for the selective oxidation of sulfides with high turnover numbers in water at room temperature

A hybrid catalyst based on monoprotonated divanadium-substituted phosphotungstate ([γ-HPV2W10O40]4−) was synthesized and used for the selective oxidation of sulfides.

Synthesis and characterization of MCM-41@XA@Ni(II) as versatile and heterogeneous catalyst for efficient oxidation of sulfides and acetylation of alcohols under solvent-free conditions

Herein, Ni(II) immobilized on modified mesoporous silica MCM-41 was designed and synthesized via a facile sequential strategy. The structure of the catalyst was characterized by X-ray diffraction. The thermal property of the as-synthesized materials was studied using thermogravimetric-differential thermal analysis. The average particles size and morphology of MCM-41@XA@Ni(II) were investigated using scanning electron microscopy and transmission electron microscopy. This nanostructure catalyst was effective for the selective oxidation of sulfides and acetylation of alcohols in solvent-free conditions. The easy recyclability of the catalyst and their complete chemoselectivity toward the sulfur group of substrates in the oxidation of sulfides are important “green” attributes of this catalyst.

Aluminum(III) Chloride Promoted Oxygen Transfer: Selective Oxidation of Sulfides to Sulfoxides

An efficient selective oxidation of sulfides to sulfoxides has been developed by means of AlCl3-promoted oxygen transfer from phenyliodine diacetate [PhI(OAc)2]. AlCl3 proved to be the optimal ­Lewis acid for the activation of PhI(OAc)2. Various substituted sulfides were selectively transformed into the corresponding sulfoxides in good to excellent yields (≤99%). The high efficiency, excellent functional-group compatibility, broad substrate scope, and mild conditions render the current transformation useful for the synthesis of sulfoxides.

Two New Sandwich-Type Polyoxomolybdates Functionalized with Diphosphonates: Efficient and Selective Oxidation of Sulfides to Sulfones.

Two sandwich-type polyoxomolybdates Na8[MO2{Mo2O5(O3PCH3C(O)PO3)}2] (M = Ni2+ (1); Co2+ (2)) were synthesized by one-pot reaction of Na2HPMo12O40·14H2O, 1-hydroxy ethidene diphosphonic acid (HEDP=HOC(CH3)(PO3H2)2), and (1) NiCl2/CoCl2 (2). Compounds 1 and 2 were characterized by single crystal X-ray analysis, X-ray powder diffraction (XRPD), IR spectroscopy, 31P NMR spectra, UV-vis spectroscopy, and thermogravimetric analyses (TGA). Structural analysis reveals that 1 and 2 exhibit similar centrosymmetric structure, which consists of one transition metal (TM) ion sandwiched by two same subunits {Mo2O5(O3PCH3C(O)PO3)}. The clusters 1 and 2 show efficient catalytic activities for oxidation of thioanisole. Moreover, they are catalytically selective for oxidizing thioanisole. Both resuable polyoxomolybdates 1 and 2 catalysts show good thermo- and hydrolytic stability. It is noted that compound 1 shows outstanding catalytic activity for oxidation of various sulfides to corresponding sulfones with 93–100% selectivity at 97–100% conversion in one hour under mild conditions, which is potentially valuable to the removal of organic sulfides.

Di(hydroperoxy)alkane Adducts of Phosphine Oxides: Safe, Solid, Stoichiometric, and Soluble Oxidizing Agents

The di(hydroperoxy)alkane adducts of phosphine oxides 1-9, Ph3 PO⋅(HOO)2 CMe2 , Cy3 PO⋅(HOO)2 CMe2 , Ph3 PO⋅ (HOO)2 CMeEt, Cy3 PO⋅(HOO)2 CMeEt, Cy3 PO⋅(HOO)2 CEt2 , Cy3 PO⋅ (HOO)2 C(CH2 )5 , Cy3 PO⋅(HOO)2 CMePh, (Ph2 P(O)CH2 CH2 P(O)Ph2 )⋅ ((HOO)2 CEt2 )2 , and Ph2 P(O)CH2 P(O)Ph2 ⋅(HOO)2 CMe2 , respectively, are synthesized and fully characterized by 1 H, 13 C, and 31 P NMR, and IR spectroscopies. Single crystal X-ray structures are reported for 3-9. Different one-pot synthetic pathways, starting from R3 P, R3 PO, R3 PO⋅H2 O, and R3 PO⋅H2 O2 are explored and discussed and a mechanism for the formation of the di(hydroperoxy)alkane adducts of phosphine oxides is suggested. The longevity of the adducts is tested by monitoring the oxidation of Ph3 P with quantitative NMR. The solubilities of the adducts in organic solvents are presented, and their applicability as stoichiometric oxidizing agents for the selective oxidation of sulfides to sulfoxides is reported.

Selective and green oxidation of sulfides in water using a new iron(III) bis(phenol) amine complex supported on functionalized graphene oxide

A new iron complex of bis(phenol) amine ligand of glycine amino acid derivative, FeLGDC supported on amine-functionalized graphene oxide (GO) nanosheets (FeLGDC -AP@GO) was synthesized. This is the first report of bis(phenol) amine complexes immobilized to a solid support. This novel catalyst was characterized by different techniques such as TEM, SEM, EDX, XRD, FT-IR, TGA, AAS, ICP-AES and Porosimetry. The results show that FeLGDC -AP@GO has layered structure incorporating FeLGDC complex by covalent attachment. FeLGDC-AP@GO was examined as a catalyst for the selective oxidation of sulfides as environmental pollutants to their corresponding sulfoxides. This reaction was performed using hydrogen peroxide as a green oxidant in water at room temperature. The recycling experiment results showed that FeLGDC -AP@GO could be easily recovered by simple filtration and recycled for several times without the loss of activity and selectivity.

A Polyoxovanadate-Resorcin[4]arene-Based Porous Metal-Organic Framework as an Efficient Multifunctional Catalyst for the Cycloaddition of CO2 with Epoxides and the Selective Oxidation of Sulfides.

In this work, we report a new polyoxovanadate-resorcin[4]arene-based metal-organic framework (PMOF), [Co2L0.5V4O12]·3DMF·5H2O (1), assembled with a newly functionalized wheel-like resorcin[4]arene ligand (L). 1 features an elegant porous motif and represents a rare example of PMOFs composed of both a resorcin[4]arene ligand and polyoxovanadate. Remarkably, 1 shows open V sites in the channel, which makes 1 an efficient heterogeneous Lewis acid catalyst for the cycloaddition of carbon dioxide to epoxides with high conversion and selectivity. Strikingly, 1 also exhibits high catalytic activity for the heterogeneous oxidative desulfurization of sulfides. Particularly, the heterogeneous catalyst 1 can be easily separated and reused with good catalytic activity.

Tungstate supported mesoporous silica SBA‐15 with imidazolium framework as a hybrid nanocatalyst for selective oxidation of sulfides in the presence of hydrogen peroxide

In this work, a new heterogeneous catalyst (SBA‐15/Im/WO42−) was prepared, and then its performance in the oxidation of organic sulfides was studied (using 30% H2O2 as green oxidant under neutral reaction conditions). This organic–inorganic hybrid mesoporous material was characterized by various techniques, such as FT‐IR, inductively coupled plasma, X‐ray powder diffraction, high‐resolution‐transmission electron microscopy, N2 adsorption–desorption and thermogravimetric analysis. The catalyst was also applied to the selective oxidation of various sulfides. The hybrid catalyst was easily recovered, and was very stable and retained good activity for at least five successive runs without any additional activation. Moreover, there was no remarkable decrease in the activity and selectivity of the catalyst. The products could be easily isolated by just removing the solvent after filtering the catalyst. The yields of the catalytic productions through this catalyst were in the range from 75% to 97%.

A Mild, Efficient and Highly Selective Oxidation of Sulfides to Sulfoxides Catalyzed by Lewis Acid–Urea–Hydrogen Peroxide Complex at Room Temperature

Alkyl and aryl sulfides were oxidized to the corresponding sulfoxides with urea–hydrogen peroxide (UHP) in the presence of FeCl3 as a Lewis acid catalyst under simple and mild reaction conditions. The protocol is efficient and highly selective and sulfoxides were obtained as the sole oxidation products in high yields at room temperature.

Solvent, metal and halogen-free synthesis of sulfoxides by using a recoverable heterogeneous urea-hydrogen peroxide silica-based oxidative catalytic system

An efficient and green protocol was used for the selective oxidation of sulfides to sulfoxides by using silica sulfuric acid (SSA) as a recoverable heterogeneous solid acid catalyst in the presence of urea-hydrogen peroxide (UHP) under toxic transition metal-, solvent- and halogen-free conditions at room temperature. The present method offers several noteworthy advantages, such as high product yields, easy work-up, non-toxicity, easy preparation and reusability of the catalyst for at least six runs, which make this procedure the most convenient and attractive with low cost of catalyst and oxidant.

Iron oxide on carbon‐based supports as efficient catalysts for organic compounds oxidation

For the first time, iron oxide on carbon aerogel, amine functionalized carbon nanotube, black carbon and carboxylic acid functionalized carbon nanotube in the presence of H2O2 was reported as an efficient and stable catalyst for the selective oxidation of sulfides and alcohols. The catalysts were characterized by scanning electron microscopy, energy‐dispersive spectroscopy, transmission electron microscopy, X‐ray photoelectron spectroscopy, X‐ray diffraction, Fourier transform infrared spectroscopy and atomic absorption spectroscopy. In the next step, catalytic reactivity toward sulfide to sulfoxide and alcohol to aldehyde/ketone oxidation in the presence of H2O2 was studied and discussed.

Preparation and characterization of nanocomposite of graphitic carbon nitride and TiO2 as a porous support for nano catalyst for desulfurization process

A novel heterogeneous nanocatalyst H3PW12O40/TiO2/g-C3N4 (PW/TiO2/CN) was successfully synthesized by immobilization of PW on TiO2/CN nanocomposite, and characterized by SEM, BET, FT-IR, XRD, EDX, TEM and ICP. Catalytic performance of the as-prepared catalyst was investigated for the selective oxidation of sulfides to sulfoxides and sulfones in the presence of H2O2 as oxidant with good conversion and high selectivity. The main factors influencing the ability for selective oxidation of sulfides were studied, including reaction temperature, amounts of the catalyst, H2O2 and type of the reaction solvent. Catalytic oxidation of the different model oils containing dibenzothiophene (DBT), benzothiophene (BT) and thiophene (T) into corresponding sulfone was also studied. Effects of different extractive solvents, aromatics, alkenes and nitrogen compounds on the oxidative desulfurization processes (ODS) were also studied. In addition, reducing the level of sulfur content in real oil was investigated. The recyclability of the PW/TiO2/CN nanocatalyst for various cycles without a significant loss of activity was proved. The heterogeneity of the as-prepared catalyst was confirmed by leaching tests.

Organic-inorganic hybrid polyionic liquid based polyoxometalate as nano porous material for selective oxidation of sulfides

Organic-inorganic hybrid nano porous materials based on poly(ionic liquid)-polyoxometalate (PIL-POM) were reported. These hybrid materials were synthesized by the reaction of 4-vinyl pyridine with 1,3-propanesultone, followed by the polymerization and also sulfonate-functionalized cross-linked poly(4-vinylpyridine) and combining these polymers with H5PMo10V2O40 (PMo10V2). Activity of prepared PIL-PMo10V2 hybrids were investigated as catalysts for oxidation of sulfides with H2O2 as oxidant. For understanding catalytic activities of the PIL-PMo10V2 hybrids in oxidation of sulfides, effect of catalyst composition, substrate, and reaction conditions were studied. The results show that the PIL-PMo10V2 hybrids are active as selective heterogeneous catalysts for oxidation of sulfides and can be recovered and reused. The catalyst was characterized by FT-IR, TGA-DSC, XRD, SEM/EDX, BET, CV and zeta potential measurement. Also, average molecular weight of prepared catalysts were measured.

Cytochrome P450 Enzyme‐Copper Phosphate Hybrid Nano‐Flowers with Superior Catalytic Performances for Selective Oxidation of Sulfides

AbstractCytochrome P450 enzyme‐copper phosphate hybrid materials with flower‐like shape were prepared with a simple but efficient coprecipitation method. The growth process of the hybrid flowers can be divided into three successive steps: coordination/nucleation, growth, and further ripen. The concentration of enzymes in the mother liquor exerted great influence on the morphology and surface enzyme content of the nano‐composites. The catalytic performance in the reaction of selective oxidation of sulfide to sulfoxide was also investigated. The hybrid flowers exhibited superior catalytic performance: satisfied thioanisole conversion and selectivity to methyl phenyl sulfoxide (both above 97%) with H2O2 as oxidant under mild reaction conditions, excellent stability and recyclability, and wide scope of substrates. Such results indicate that the hybrid materials are potentially good candidates in the industrial enzyme catalysis.

Oxidative desulfurization of diesel by potato based-carbon as green support for H5PMo10V2O40: Efficient composite nanorod catalyst

The C@POM (carbon@polyoxometalate) containing H3PMo12O40 (PMo12), H5PMo10V2O40 (PMo10V2), H6PMo9V3O40 (PMo9V3), H7PMo8V4O40 (PMo8V4), H3PW12O40 (PW), and H4SiW12O40 (SiW) were prepared from natural potato as green, and cheap catalyst support source. The C@PMo10V2 was found to be a unique, effective, and eco-friendly catalyst for selective oxidation of sulfides, using 30% aq. H2O2. C@PMo10V2 composite was characterized by X-ray diffraction spectroscopy (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), Fourier transform infrared (FT-IR) spectrophotometry, zeta sizer, and zeta potential. The XRD results show that during immobilization PMo10V2 on the carbon catalyst support (CCS), the crystallite structure of PMo10V2 and CCS was not changed. The SEM results show that PMo10V2 crystals deposited on the surface CCS rods as composite nanorod structure. A variety of sulfides, sulfur-containing model and real oil were oxidized with the C@PMo10V2/H2O2 at room temperature. Recovered catalyst show excellent activity for at least four repeating cycles.