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.     

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.     

Mesoporous silica-supported V-substituted heteropoly acid for efficient selective conversion of glycerol to formic acid

V-substituted polymolybdenum phosphoric acid (PV_xMo) supported on mesoporous silica was prepared and investigated as a catalyst for the oxidation of glycerol to formic acid in a batch operation. Different synthetic methods for PV_xMo supported on mesoporous silica were compared. Detailed characterizations of the final products were carried out by N₂ adsorption and desorption, XRD, HR-TEM, SEM, ICP-OES, XANES, NH₃-TPD, and FTIR to identify the chemical properties and the porous structure of silica-supported PV_xMo, as well as the strong interactions between PV_xMo with the silica skeleton. These critical properties explain the bifunctionality of silica-supported PV_xMo as a catalyst for the selective oxidation of glycerol to formic acid with standing stability.     

甲酸为氢源的甘油催化选择氢解

以甲酸作为氢源, 采用铜基复合金属氧化物催化剂, 催化氢解甘油制备1,2-丙二醇, 其中液相甲酸的高选择性分解是实现甘油氢解的必要和关键步骤. 活性测试表明, 高分散的铜和ZrO₂载体间的协同作用对甲酸分解和甘油到1,2-丙二醇的转化至关重要, 20%Cu/ZrO₂催化剂的活性最佳. 由于避免使用相对昂贵的化石燃料氢, 因而该催化体系在生物质的高值利用方面具有潜在的应用前景.     

Poly(4-vinylpyridine-co-divinylbenzene) supported iron(III) catalyst for selective oxidation of toluene to benzoic acid with H2O2

Poly(4-vinylpyridine-co-divinylbenzene) supported iron(III) catalysts were developed for the selective oxidation of toluene to benzoic acid in the presence of H₂O₂. The influence of the DVB content on the capacity of immobilized Fe(III) and on the catalytic activities of the polymeric complexes was investigated. The extent of Fe(III) uptake by the copolymers varied slightly with the concentration of DVB. The catalytic activities generally increase with increasing degree of crosslinker from 2 to 10% and decrease further with increasing the DVB content. Under the optimal conditions (80 °C, 6 h), the catalyst containing 10% DVB was found to be highly efficient in conversion of toluene to benzoic acid with 90% conversion and 96% selectivity.     

Biomimetic oxidation of metribuzin with hydrogen peroxide catalyzed by 5,10,15,20-tetraarylporphyrinatoiron(III) chlorides

The biomimetic oxidation of metribuzin, a pre- and post-emergence herbicide with hydrogen peroxide catalyzed by 5,10,15,20-tetraarylporphyrinatoiron(III) chlorides [TAPFe(III)Cl], has been studied yielding 6-t-butyl-3-methylthio-1,2,4-triazine-5(4H)-one, 4-amino-6-t-butyl-3,5(2H,4H)-dione and 6-t-butyl-1,2,4-triazin-3,5(2H,4H)-dione under various reaction conditions.     

Effective oxidation of alcohols by Iron(III)-Schiff base-triphenylphosphine complexes

Iron(III)-Schiff base-triphenylphosphine complexes catalyze the oxidation of alcohols to their corresponding carbonyl compounds in presence of hydrogen peroxide in good yields.     

离子排斥色谱法测定甘油催化氧化产物中的H2CO3和HCOOH

建立了测定甘油催化氧化产物中H2CO3和HCOOH的离子排斥色谱分析方法。采用离子排斥柱分离,分别用纯水和4 mmol/L HCl作流动相进行H2CO3和HCOOH的分析。检测方式为非抑制电导检测。实验结果显示,H2CO3和HCOOH工作曲线的线性范围为2～100 mg/L和6.23～124.6 mg/L,检出限分别为0.45 mg/L和2.49 mg/L(S/N=3)。H2CO3的保留时间和峰面积的相对标准偏差分别为0.07%和4.0%,HCOOH的保留时间和峰面积的相对标准偏差分别为0.09%和2.2%。方法已用于甘油催化氧化产物中H2CO3和HCOOH的分析。     

Selective oxidation of naphthalene derivatives with ruthenium catalysts using hydrogen peroxide as terminal oxidant

The selective oxidation of naphthalene and its derivatives to give naphthoquinones has been investigated in detail. The reaction can be carried out effectively in the presence of a catalytic amount of Ru complexes (0.2 mol%) and phase transfer catalysts (PTC) using H₂O₂ as the terminal oxidant and water as the solvent. The effect of different ruthenium complexes, phase transfer catalysts, and the concentration of hydrogen peroxide were studied. Compared to previous procedures for this type of reactions, acidic solvents and high concentration of hydrogen peroxide are not necessary, which makes the reaction more environmentally friendly.     

Iron(III)-catalyzed hydroarylation of propiolic acid with activated arenes

FeCl₃/AgOTf-catalyzed hydroarylation of propiolic acid with electron-rich arenes such as mesitylene, tetramethylbenzene, and pentamethylbenzene in trifluoroacetic acid proceeded to give 3-arylpropenoic acids in moderate to high yields. The same reactions with anisole and 1,4-dimethoxybenzene afforded double hydroarylation products, 3,3-diarylpropionic acids.     

Silver-Cobalt bimetallic nanoparticles to the generation of hydrogen from formic acid decomposition

The fabrication of cost effective heterogeneous catalysts for the release of hydrogen from hydrogen storage materials is the key technological challenge to the fuel-cell based hydrogen economy. Ag-Co bimetallic NPs were fabricated by using sodium dodecyl sulphate (SDS) and sodium borohydride as stabilizing and reducing agents, respectively. Catalytic activity of SDS-Ag-Co was higher than that of SDS free Ag-Co and monometallic (Ag and Co) due to the electron interactions and synergistic effect between the Ag and Co. Ag₁₀-Co₉₀ exhibited the superior catalytic activity, with rate constant of 5.2 × 10^?4 s^?1 at 303 K, activation energy of 46 kJ/mol, activation enthalpy of 44 kJ/mol, activation entropy of ?165 J/K/mol, and turn over frequency of 240 h^?1. The hydrogen generation rate increased and decreased with in increasing temperature, molar concentration of formic acid, presence of sodium formate, and pH, respectively. The kinetic rate equation can be stated as: rate = -d[formic acid]/dt = k_obs[formic acid]^0.99[Ag₅₀Co₅₀]^0.98, k_obs = 2.48 × 10⁷ exp (?5637.96/RT).     

A mild and efficient oxidation of alcohols to aldehydes and ketones with periodic acid catalyzed by chromium(III) acetylacetonate

Chromium(III) acetylacetonate was found to be an efficient catalyst (10 mol%) for the oxidation of alcohols to aldehydes and ketones with periodic acid (1.5 equiv.) in acetonitrile at room temperature.     

Diphenylmethane Oxidation Catalyzed by Mononuclear Mn(III) Complexes

Catalytic property of a series of manganese(III) complexes with tetradentate phenol‐ and pyridinebased ligands on the oxidation of the C‐H bond of diphenylmethane in the presence of hydrogen peroxide as an oxidant at ambient conditions were investigated. In this process, diphenylmethane was oxidized to the corresponding keton and alcohol. The catalytic selectivity of the complexes was evaluated.     

An ultrasensitive iron(III)-complex based hydrogen peroxide electrochemical sensor based on a nonelectrocatalytic mechanism

In this communication, the first nonelectrocatalysis-type hydrogen peroxide electrochemical sensor is reported. The electroactive iron(III) diethylenetriaminepentaacetic acid (DTPA-Fe^III) complex is immobilized on the cysteamine (cys) modified nanoporous gold (NPG) films by covalent method. The immobilized DTPA-Fe^III complex quickly communicates an electron with the electrode. Upon addition of hydrogen peroxide, however, hydrogen peroxide inhibits the direct electron transfer of the DTPA-Fe^III complex due to the generation of nonelectroactive DTPA-Fe^III–H₂O₂ complex. Based on quenching mechanism, the first hydrogen peroxide electrochemical sensor based on a nonelectrocatalytic mechanism is developed. The novel hydrogen peroxide electrochemical sensor has the ultralow detection limit (1.0 × 10^–14 M) and wide linear range (1.0 × 10^–13 to 1.0 × 10^–8 M) with excellent reproducibility and stability.     

Baeyer-Villiger oxidation of ketones with hydrogen peroxide catalyzed by Sn-aniline complex

Sn-aniline complex was prepared by a simple procedure.Cyclic and acyclic ketones were oxidized into lactones or esters with very high selectivity and yield with 30% hydrogen peroxide in the presence of Sn-aniline complex.     

氨基羧酸铁(III)配合物催化分解过氧化氢

用碘量法研究了[Fe（EDTA],[FeⅢ(DCTA)],[FeⅢ(EGTA)]催化分解H2O2反应，提出了反应动力学方程为-d[H2O2]/dt=k[FE(Ⅲ)][H2O2][H ]^-1，认为氨基羧酸铁（Ⅲ）配合物催化分解H2O2反应为键式自由基反应，反应中间体包括过氧铁（Ⅲ）配合物，氨基羧酸铁（Ⅱ）和HO-，HO2-自由基。     

二氧化硅包覆的杂多酸在双氧水存在条件下催化氧化甘油

催化剂的酸性和氧化还原性在催化生物质平台分子转化过程中起着非常重要的作用,杂多酸具有较强的酸性以及优良的氧化还原性,因而杂多酸在生物质催化转化领域备受关注。本文利用溶胶-凝胶法和硅烷化方法将杂多酸催化剂封装在二氧化硅载体内部,随后以傅立叶红外光谱、X-射线衍射仪、热重分析仪、透射电子显微镜、扫描电镜等手段对合成的材料进行了表征。红外光谱表明杂多酸在催化剂中保持了其完整结构,X-射线衍射表明杂多酸高度分散在二氧化硅载体上,电镜表征显示催化剂呈球形纳米颗粒形貌。基于以上表征结果,我们将包覆的杂多酸催化剂应用于甘油氧化,在以过氧化氢为氧化剂,温和反应条件下,合成的材料对甘油氧化具有良好的催化活性,其中对甲酸的选择性大约为70%,对乙醇酸的选择性大约为27%。硅烷化过程对于催化剂循环起着重要的作用,单纯二氧化硅的比表面积为287 m²·g^-1,二氧化硅包覆杂多酸经过硅烷化后,其比表面积降为245 m²·g^-1,而且孔径也有所降低。单纯二氧化硅与水的接触角为0°,而二氧化硅包覆的杂多酸在硅烷化之后的催化剂具有很强的疏水性,与水的接触角为137°。根据这些催化剂表征数据说明硅烷化过程不仅可以显著提高催化剂的疏水性,而且同时限制了载体孔径,阻止杂多酸流失到反应体系中,与传统的浸渍法将杂多酸负载在二氧化硅载体上得到的催化剂相比,催化剂的循环利用性显著提高。反应后的催化剂结构与新鲜催化剂相比,并没有发生明显变化。催化剂经过一次循环后,表面暴露了更多的活性中心,活性稍有提高。催化剂在反应体系中加入强质子酸可以显著提高反应的催化性能,揭示了Bronsted酸在甘油氧化过程中对甘油分子的活化起着重要的作用。     

Cobalt(II)-catalyzed oxidation of alcohols into carboxylic acids and ketones with hydrogen peroxide

The oxidation of aliphatic and aromatic alcohols into the corresponding carboxylic acid analogues and ketones has been carried out using 30% H₂O₂ and cobalt(II) complex 1 in good to high yields. The reaction is safe, clean and functions in the absence of additives.     

Ruthenium(III)-catalyzed oxidation of thallium(i) by 12-tungstocobaltate(III) in hydrochloric acid medium

The reaction between thallium(I) and [Co^IIIW₁₂O₄₀]^5- in the presence of ruthenium(III) as catalyst proceeds viainitial outer-sphere oxidation of the catalyst to ruthenium(VI). The ruthenium(IV) thus generated will oxidize thallium(I) to an unstable thallium(II) which by reacting with oxidant gives the final product, thallium(III). The formation of ruthenium(II) by direct two-electron reduction of the catalyst by thallium(I) is thermodynamically less favorable. The reaction rate is unaffected by the [ H⁺ ], whereas it is catalyzed by chloride ion . The formation of reactive chlorocomplex,TlCl, in a prior equilibrium is the reason for the chloride ion catalysis. Increasing the relative permittivity of the medium increases the rate of the reaction, which is attributed to the formation of an outer-sphere complex between the catalyst and oxidant. This revised version was published online in June 2006 with corrections to the Cover Date.     

Simple one‐pot conversion of organic compounds by hydrogen peroxide activated by ruthenium(III) chloride: organic conversions by hydrogen peroxide in the presence of ruthenium(III)

The aromatic compounds p‐nitrobenzaldehyde, p‐hydroxybenzaldehyde, naphthalene, toluene, catechol, quinol, aniline and toluidine dissolved in aqueous acetic acid or aqueous medium were oxidized in quantitative to good yields by 50% H₂O₂ in the presence of traces of RuCl₃ (～10^?8 mol; substrate/catalyst ratio 1488:1 to 341 250:1). Conditions for highest yields, in the most economical way, were obtained. Higher catalyst concentrations decrease the yield. Oxidation in aromatic aldehydes is selective at the aldehydic group only. In the case of hydrocarbons, oxidation results in the introduction of a hydroxyl group with >85% (in the case of toluene) selectivity for the ortho position. Formation of low‐molecular‐weight polyaniline was reduced to 10%, along with 90% formation of higher molecular weight polyaniline. In this new, simple and economical method, which is environmentally safe and requires less time, oxo‐centered carboxylate species of ruthenium(III) in acetic acid medium and hydrated ruthenium(III) chloride in aqueous medium probably catalyze the oxidation. Copyright © 2005 John Wiley & Sons, Ltd.