Oxidation and Oxidative Bromination Reactions Catalyzed By a Reusable Polymer-Anchored Iron(III) Complex in Water at Room Temperature

A polymer-anchored iron(III) catalyst was synthesized and characterized. Its catalytic activity was evaluated for the oxidation of various alkenes, sulfides, aromatic alcohols and ethylbenzene with 30 % H₂O₂ as the oxidizing agent. The catalyst was also effective for the oxidative bromination reaction with 80–100 % selectivity of monobrominated products with H₂O₂/KBr at room temperature. The above reactions require a minimum amount of H₂O₂ and short reaction time. Most importantly, all the above reactions occur in aqueous medium. The catalyst can be facilely recovered and reused six-atimes without significant decrease in its activity and selectivity.     

Intramolecular Carbonyl Nitroso Ene Reaction Catalyzed by Iron(III) Chloride/Hydrogen Peroxide as an Efficient Tool for Direct Allylic Amination

A mild, simple oxidation protocol employing iron(III) chloride as a catalyst and hydrogen peroxide as a stoichiometric oxidant was found to be compatible with an intramolecular carbonyl nitroso ene reaction and allowed us to efficiently convert hydroxamic acids into a diverse range of 1,2‐ and 1,3‐amino alcohol derivatives in a single operation.     

Molybdenum Catalyzed Reactions Selectivity in Oxidations with Hydrogen Peroxide and Ammonium Molybdate

Hydrogen peroxide in conjunction with ammonium molybdate effects the epoxidation of olefins, the oxidation of secondary alcohols to ketones, and the oxidation of aldehydes to acids. By controlling pH olefin epoxidation can be suppressed in favor of alcohol oxidation. Secondary alcohols are cleanly oxidized in the presence of primary alcohols. Sterically more hindered alcohols are oxidized more rapidly than less hindered alcohols. The latter rate preference permitted selective conversion of a 17-hydroxyl group of several steroids into a.ketone in the presence of a 3-hydroxyl group. The chemoselective oxidation of aldehydes to carboxylic acids is another use of this inexpensive oxidation system. A rate acceleration by addition of the lanthanide salt cerium chloride is noted and attributed to enhanced rates of hydration of the aldehyde. Potential mechanisms are discussed.     

Iron(II, III)-Catalyzed Oxidation of Limonene by Dioxygen

Labile iron(II) and iron(III) complexes {[Fe^II(bpy)₂²⁺]_solv and [Fe^III(bpy)₂³⁺]_solv} in acetonitrile activate dioxygen for the oxidation of limonene to produce mainly carvone, carveol, limonene oxide, and perillaldehyde. Iron(III) complex is reduced by the substrate to iron(II) one, which activates dioxygen. Probably the catalyst interacts with substrate prior to the oxidation process. Perillaldehyde is likely formed directly from oxidation of methyl group (not via alcohol). However, the aldehyde is also reduced to perillyl alcohol by the reduced form of the catalyst.     

Polymerization of Aniline Using Iron(III) Catalyst and Ozone,and Kinetics of Oxidation Reactions in the Catalytic System

The environmentally benign polymerization of aniline provided polyaniline with an emeraldine structure by using iron(III) and ozone which is easily converted from oxygen in air. The influence of the reaction temperature upon the molecular weight of the polyaniline in this system is different from that in the polymerization of aniline using ammonium peroxodisulfate as an oxidant. Although the polyaniline prepared here has low molecular weight, the low molecular weight of the polyaniline does not significantly influence the electrical conductivity of cast films. In contrast, this can provide an advantage for the engineering of polyaniline through solution‐processing. Kinetics of oxidation reactions in the polymerization, systematically investigated here, has revealed that polyaniline is produced catalytically in terms of iron(III) and that an oxidation reaction of iron(II) to iron(III) could be a rate‐determining step in the polymerization.     

Oxidation of Benzene to Phenol with Hydrogen Peroxide Catalyzed by a Modified Titanium Silicalite (TS‐1B)

The hydroxylation of benzene to phenol with hydrogen peroxide was investigated using different solvents and a series of catalysts, obtained by modification of titanium silicalite (TS‐1). The best results were obtained after post‐synthesis treatment of TS‐1 with NH₄HF₂ and H₂O₂. The new catalyst (TS‐1B), used in the presence of a particular co‐solvent (sulfolane) is able to protect the produced phenol from over‐oxidation and dramatically enhanced the selectivity of the reaction.     

The Hydrated Electron,The Hydroxyl Radical,and Hydrogen Peroxide in Radiation Damage in Cells

Spores of Bacillus megaterium, in suspension, are used to study the biological effects of the three principal products of radiolysis of water, i.e., e^?_aq, OH and H₂ O₂. A model is proposed accounting for the action of OH and H₂ O₂. This model involves two reactions: in which RH₂ is a “target” molecule, and \documentclass{article}\pagestyle{empty}\begin{document}$ \[ \underline {\rm R} \] $\end{document} is a lethally damaged molecule. Experimental evidence is given supporting this model. These studies of the effects of radiolysis products of water are extended by studies using sensitizers such as biacetyl, NO^?₃, and Ag⁺ in varying concentrations. Evidence for a possible relationship between peak sensitivities in anoxic conditions and chemical properties of the sensitizers is discussed. These results are also discussed with regard to the oxygen effect, and the general chemical characteristics of an efficient tumor sensitizer are outlined.     

Some Iron(III) Catalyzed Michael Reactions of Chiral Donors,bis‐Donors,and a bis‐Acceptor

Michael reactions of β‐keto esters 1a—1h with methyl vinyl ketone ( 2a ) catalyzed by FeCl₃ · 6 H₂O (5 mol%) proceed with up to 99% yield. Conversion of β‐keto esters 1a—1e derived from chiral alcohols with 2a result in only very low diastereoselectivities (max. de 20%). A bis‐β‐keto ester 1i and a bis‐vinyl ketone 2b — both valuable monomers for poly‐Michael reactions — are synthesized from common starting materials in up to gram quantities.     

铁酸镁催化剂催化苯酚羟化作用的研究

采用共沉淀法合成了一种新的用于苯酚羟基化反应的催化剂铁酸镁( Mg Fe2 O4 ) ,用 XRD、IR进行了表征。考察了溶剂、氧化剂对苯酚羟基化反应的影响。研究结果表明 ,以水为溶剂、过氧化氢为氧化剂 ,铁酸镁催化剂催化苯酚羟基化反应有较高的催化活性 ,并初步提出了反应机理。     

Iron(III)‐Catalyzed Halogenations by Substitution of Sulfonate Esters

A novel halogenation reaction from sulfonates catalyzed by iron(III) is described. The reaction can be performed as a stoichiometric or a catalytic version. This reaction provides a convenient strategy for the efficient access to structurally diverse secondary chlorides, bromides and iodides. The stereochemical course of the reaction is governed by the substrate and the experimental conditions. Secondary alcohols modified as quisylates or pysylates are substantially more reactive. Aliphatic quisylates proceed with overall inversion of configuration under catalytic conditions. Chemoselectivity in bismesylates was observed in favour of the secondary mesylate. Additionally, based on the experimental results, a possible catalytic cycle for the halogenation has been proposed.     

Fe~(3+)和漆酚催化过氧化氢对单取代苯的氧化

本文研究了 Fe~(3+)和漆酚催化 H_2O_2氧化单取代苯的产物。结果表明,硝基苯、苯酚和苯甲酸已被氧化成相应的酚;而在甲苯、氯代苯和溴代苯的反应体系中未检测到酚产物。     

Iodine(I) Reagents in Hydrochloric Acid‐Catalyzed Oxidative Iodination of Aromatic Compounds by Hydrogen Peroxide and Iodine

Hydrochloric acid activates the oxidative iodination of aromatic compounds with the iodine‐ hydrogen peroxide system through the formation of an iodine(I) compound as the iodinating reagent. Activation with hydrochloric acid is more powerful than that with sulfuric acid. The formation of dichloroiodic(I) acid (HICl₂) with various forms of hydrogen peroxide was followed using UV spectroscopy. The HICl₂ was used as the iodinating reagent. In the preparative oxidative iodinaton of various aromatic compounds, hydrochloric acid was used in a catalytic amount and the iodine(I) reagent was formed in situ with 0.5 equiv. hydrogen peroxide and 0.5 equiv. molecular iodine. Two types of reactivity were observed in oxidative iodination with iodine(I) species catalyzed by hydrochloric acid: in the iodination of anisole 1a better yields of iodination were observed with a smaller amount of hydrochloric acid, while on the contrary 4‐tert‐butyltoluene 1b gave better yields of iodination upon increasing the amount of hydrochloric acid. Reactivity was further manipulated by the choice of the solvent (MeCN, trifluoroethanol, hexafluoro‐2‐propanol).     

Oxidation of Methyl tert-Butyl Ether (MTBE) and Ethyl tert-Butyl Ether (ETBE) by Ozone and Combined Ozone/Hydrogen Peroxide

The aim of this work was to study the reaction of ozone and combined ozone/hydrogen peroxide on oxygenated additives such as methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE) in dilute aqueous solution using controlled experimental conditions. Experiments conducted in a semi-continuous reactor with MTBE and ETBE in combination (initial concentration: 2 mmol/L of each) showed that ETBE was better eliminated than MTBE with both ozone and combined O₃/H₂O₂. Batch experiments led to the determination of the ratio of the kinetic constants for the reaction of OH°-radical with MTBE and ETBE [k_OH°/ETBE/k_OH°/MTBE = 1.7). Tert-butyl formate and tert-butyl acetate were identified as the ozonation byproducts of MTBE and ETBE, respectively, while tert-butyl alcohol was found to be produced during the ozonation of both compounds.     

Oxidation of N,N‐Disubstituted Hydroxylamines to Nitrones with Hydrogen Peroxide Catalyzed by Polymer‐Supported Methylrhenium Trioxide Systems

Poly(4‐vinylpyridine)/methylrhenium trioxide (MTO) compounds I III and microencapsulated polystyrene/MTO systems IV V are efficient catalysts for the oxidation of secondary hydroxylamines to the corresponding nitrones with H₂O₂. Complete conversions of substrates and quantitative yields of products are obtained under environmentally friendly experimental conditions and with the use of simple work‐up procedures. Symmetrically substituted hydroxylamines, and non‐symmetrical 3‐substituted and 2‐substituted hydroxypyrrolidines, precursors of nitrones applied in the synthesis of alkaloids and biologically active congeners, have been considered as substrates. The heterogeneous catalysts are stable under the reaction conditions and can be recovered and recycled for at least five times without any appreciable loss in efficiency.     

Oxidation of polycyclic aromatic hydrocarbons with hydrogen peroxide catalyzed by Iron(III)porphyrins

A variety of iron-metallated functional porphyrins have been synthesized and their catalytic activity to oxidize polycyclic aromatic hydrocarbons, (PAHs) using hydrogen peroxide as oxidant was investigated. It was found that iron-metallated porphyrins bearing strong electronegative groups at β-pyrrolic positions show an exceptionally high catalytic efficiency.