Selective hydrogen peroxide oxidation of sulfides to sulfoxides or sulfones with MWW-type titanosilicate zeolite catalyst under organic solvent-free conditions

Selective oxidation of sulfides to sulfoxides and sulfones with hydrogen peroxide under organic solvent-free conditions was demonstrated by the MWW-type titanosilicate zeolite catalyst. Sulfides were oxidized smoothly to give sulfoxides with good selectivities at ambient temperature using 1.0–1.2 equiv of hydrogen peroxide with the MWW-type titanosilicate zeolite catalyst. Especially, the Ti-MWW with an interlayer-expanded structure (Ti-IEZ-MWW) catalyst showed high activity with good chemoselectivity for the oxidation of various sulfides. The catalyst is recyclable for at least five cycles, and the only byproduct is water. Sulfides were directly oxidized to give sulfones in high yields by 2.5 equiv of hydrogen peroxide with the MWW-type titanosilicate zeolite catalyst under organic solvent-free conditions.     

Selective synthesis of sulfoxides and sulfones by tantalum(V) catalyzed oxidation of sulfides with 30% hydrogen peroxide

The reaction of sulfides with 30% hydrogen peroxide catalyzed by tantalum(V) chloride in acetonitrile, i-propanol, or t-butanol selectively provided the corresponding sulfoxides in high yields. On the other hand, the reaction of sulfides with 30% hydrogen peroxide-catalyzed by tantalum(V) chloride or tantalum(V) ethoxide in methanol effectively gave the sulfones.     

Mn(III)-catalyzed oxidation of sulfides to sulfoxides with hydrogen peroxide

Sulfides were selectively oxidized to the corresponding sulfoxides in good yields with hydrogen peroxide using a manganese(III) Schiff-base complex as a catalyst in glacial acetic acid as solvent under mild conditions.     

Synthesis of magnetic CuFe2O4 nanoparticles as green catalyst for toluene oxidation under solvent-free conditions

A green method was developed for the synthesis of CuFe₂O₄ magnetic nanoparticles using a Neem leave extract. The prepared nanoparticles with an average size of 19.7 nm were used as an effective catalyst for the oxidation of various aryl alkanes in moderate to excellent yields under solvent-free conditions. The catalyst was characterized by powder- XRD, SEM and TEM study. The key advantages of this protocol are simple preparation, a recyclable heterogeneous catalytic system, and benign reaction condition with good to excellent yields with high selectivity toward acid (42–87%).     

Highly selective and efficient oxidation of sulfides with hydrogen peroxide catalyzed by a chromium substituted Keggin type polyoxometalate

The catalytic oxidation of sulfides into the corresponding sulfones by a chromium substituted Keggin type polyoxometalate, (TBA)₄[PW₁₁CrO₃₉]·3H₂O, was achieved using mild reaction conditions. Excellent yields were obtained using four equivalents of 30% H₂O₂. Under these reaction conditions, the sulfide group was highly reactive and other functional groups such as hydroxyl or a double bond were unaffected. Using a commercially available, eco-friendly, and cheap oxidant, mild reaction conditions, operational simplicity, practicality, short reaction times, high to excellent yields, and excellent chemoselectivity are some of the advantages of this catalytic system.     

Selective oxidation of sulfides to sulfoxides and sulfones using 30% aqueous hydrogen peroxide and silica-vanadia catalyst

A green, efficient and selective approach for the oxidation of sulfides to sulfoxides and sulfones with stoichiometric amount of 30% aq. H₂O₂ is reported. The reaction is performed in methanol with silica-vanadia as heterogeneous and reusable catalyst.     

Organosulfur oxidation by hydrogen peroxide using a dinuclear Mn-1,4,7-trimethyl-1,4,7-triazacyclononane complex

A mechanistic study of organosulfide oxidation by H₂O₂, using a dinuclear manganese complex as the catalyst, has revealed an unusual switch in the philicity of the oxidant for the first and the second oxygen transfer steps; this switch has been exploited to tune selectivity for each of the products.     

Copper catalyzed oxidation of sulfides to sulfoxides with aqueous hydrogen peroxide

Copper(II) complex 1 catalyzes the oxidation of sulfides to sulfoxides with 30% H₂O₂ in high yields. Addition of a catalytic amount of TEMPO to the reaction mixture enhances the conversion and selectivity. Complex 1 can be recycled without loss of activity.     

Poly(4-vinylpyridinium tribromide) as metal-free, green and recoverable oxidizing polymer for the chemoselective oxidation of sulfides into sulfoxides

Poly(4-vinylpyridinium tribromide) was prepared from poly(4-vinylpyridin) and used for the selective oxidation of a variety of sulfides to the corresponding sulfoxides.The oxidation reaction was carried out heterogeneously in acetone/water,as green solvent, at room temperature.     

An efficient solvent free catalytic oxidation of sulfides to sulfoxides with hydrogen peroxide catalyzed by a binaphthyl-bridged Schiff base titanium complex

A titanium binaphthyl-bridged Schiff base complex proved to be an efficient catalyst for the hydrogen peroxide oxidation of aromatic and aliphatic sulfides to the corresponding sulfoxides in satisfactory yields under solvent-free conditions.     

Effective oxidation of benzylic and aliphatic alcohols with hydrogen peroxide catalyzed by a manganese(III) Schiff-base complex under solvent-free conditions

A variety of alcohols were oxidized efficiently into the corresponding ketones and carboxylic acids in excellent yields with hydrogen peroxide using a manganese(III) Schiff-base complex as a catalyst under solvent-free and mild conditions. The oxidation procedure is very simple and the products are easily isolated in excellent yields.     

Activation of superoxide by boron trifluoride: chemoselective and efficient oxidation of sulfides to sulfoxides via tetrafluorodiboronperoxide

Activation of superoxide with boron trifluoride in dry acetonitrile can facilitate highly chemoselective and efficient oxidation of sulfides to corresponding sulfoxides at ice-water bath in excellent yields without any interference in the presence of ketone, olefin, ether, and hydroxyl functionalities. This new method also offers further advantages of a short reaction time, no overoxidation to sulfones, and none of complex catalysts and toxic metallic compounds used. A tetrafluorodiboronperoxide intermediate formed in situ from this new process is proposed.     

Selective and mild oxidation of sulfides to sulfoxides or sulfones using H2O2 and Cp′Mo(CO)3Cl as catalysts

Dialkyl, aryl-alkyl, benzylic, and benzothiophenic sulfides are selectively oxidized to sulfoxides or sulfones, with stoichiometric amounts of H₂O₂ (aq) or TBHP, in the presence of complexes Cp′Mo(CO)₃Cl, CpMoO₂Cl and the mesoporous material MCM-41-2 as catalysts. The use of the thianthrene 5-oxide (SSO) probe shows that CpMo(CO)₃Cl/H₂O₂ or TBHP are electrophilic oxidants (Xso ? 15). The same conclusion is drawn from competition experiments with a mixture of p-ClC₆H₄SCH₃ and C₆H₅SOCH₃.     

钒掺杂的钛酸钠纳米管作为多相催化剂用于室温下硫化物的氧化

合成了一种含有TiO2, Na和V的多相纳米管催化剂,采用红外光谱、X射线衍射、扫描电镜、透射电镜和N2吸附-脱附法对该催化剂的结构和织构性质进行了表征,并用于水中30%H2O2选择性氧化硫化物制备对应的亚砜。该法具有产率极高、多相体系和简便等优点,可用于含一系列官能团底物的氧化,产物分离简便。     

A highly efficient reusable homogeneous copper catalyst for the selective aerobic oxygenation sulfides to sulfoxides

Readily available copper showed efficient activity and great selectivity for the homogeneous catalysis of oxidation of sulfides to sulfoxides using molecular oxygen as the oxidant. The reaction proceeds under mild conditions in the presence of a catalytic amount of TEMPO. Importantly, the catalysts could be conveniently recovered and reused. And this methodology was proved to be applicable for the transformation of various aromatic and aliphatic sulfides into the corresponding sulfoxides with high conversion and high selectivity.     

Fe3O4 as a magnetically reusable Fenton nanocatalyst for the oxidation of thiols to sulfonic acid and sulfides to sulfoxides and sulfones

In this study, the oxidation of thiols to sulfonic acids and sulfides to sulfoxides and sulfones was carried out in the presence of Fe₃O₄/H₂O₂ as an efficient heterogeneous Fenton system. The products were obtained in good to excellent yields and short reaction times. Further results showed that the heterogeneous catalyst could be recovered easily using an external magnetic field and reused several times without any loss of its catalytic activity.     

Synthesis and characterization of insoluble cobalt(II), nickel(II), zinc(II) and palladium(II) Schiff base complexes: Heterogeneous catalysts for oxidation of sulfides with hydrogen peroxide

The condensation reaction of 1,2-bis(2′-aminophenoxy)benzene with 2-pyridinecarbaldehyde in a mole ratio of 1:2 gives a new Schiff base ligand (L). Four Schiff base complexes, CoL(NO₃)₂ (1), NiLCl₂ (2), ZnL(NO₃)₂ (3) and Pd₂LCl₄ (4) have been prepared by direct reaction of the ligand (L) and appropriate metal salts. The Schiff base ligand (L) has been characterized by IR, ¹H NMR and ¹³C NMR spectroscopy and elemental analysis. Also, all complexes have been characterized by IR and XRD spectroscopy techniques and elemental analysis. The synthesized complexes have very poor solubility in all polar and non-polar solvents such as: H₂O, MeOH, EtOH, CH₃CN, DMSO, DMF, CHCl₃, CH₂Cl₂, THF, etc; therefore, they have been used as heterogeneous catalysts. Catalytic performance of the complexes was studied in oxidation of thioanisole using hydrogen peroxide (H₂O₂) as the oxidant. Various factors including the reaction temperature, amount of oxidant and catalyst amount were optimized. The palladium Schiff base complex, Pd₂LCl₄ (4), shows better catalytic activity than other complexes. Therefore, the Pd(II) Schiff base complex has been used as a catalyst for oxidation of different sulfides to their corresponding sulfones in acetonitrile with hydrogen peroxide as the oxidant. The palladium Schiff base complex, Pd₂LCl₄ (4), has shown a very good recyclability, up to five times, without any appreciable decreases in catalytic activity and selectivity.     

A novel tridentate Schiff base dioxo-molybdenum(VI) complex: Synthesis,crystal structure and catalytic performance in green oxidation of sulfides by urea hydrogen peroxide

A new dioxo-molybdenum(VI) complex [MoO₂(L)(CH₃OH)] has been synthesized, using 2-[(2-hydroxypropylimino)methyl]phenol as tridentate ONO donor Schiff base ligand (H₂L) and MoO₂(acac)₂. A monoclinic space group P2₁/c was determined by X-ray crystallography from single-crystal data of this complex. The high catalytic activity of this new Schiff base complex has been observed in the oxidation of various sulfides by urea hydrogen peroxide in ethanol affording sulfoxides and sulfones using different molar ratio of oxidant/sulfide in high/excellent yields and selectivity under mild and eco-friendly conditions. The relative high stability and desired turnover numbers have been observed for this Mo-catalyst in the oxidation reactions.     

有序介孔锰氧化物催化过氧化氢降解水中诺氟沙星

采用硬模板法制备了有序介孔氧化锰,并用过氧化氢氧化诺氟沙星的降解率及其抗菌活性变化评价了其催化活性.研究发现,有序介孔锰氧化物表现出较高的催化活性;低pH有利于提高其催化活性.与单独过氧化氢氧化过程相比,有序介孔锰氧化物的存在明显减弱了诺氟沙星的抗菌活性.叔丁醇对催化体系的抑制作用表明有序介孔锰氧化物促进了过氧化氢分解生成羟基自由基.通过对诺氟沙星在催化过程中的分解产物鉴定,提出了可能的分解途径.     

Boric acid as an efficient catalyst for the synthesis of 1,1-diacetate under solvent-free condition

Boric acid (BO₃H₃) is an inexpensive, efficient and mild catalyst for the synthesis of 1,1-diacetate (acylal) from the various aromatic and heteroaryl aldehydes with acetic anhydride at room temperature under solvent-free condition. The present method does not involve any hazardous organic solvents or catalysts. This method gives notable advantages such as excellent chemoselectivity, mild reaction condition, short reaction times and excellent yield.