Na-promoted aerobic oxidation of alcohols to ketones

Aerobic oxidation of a number of diaryl and arylalkyl carbinols to ketones was promoted by Na in THF at room temperature with up to 99% yield. This new oxidation method is also selective with good efficiency for the oxidation of benzylic secondary alcohols but not for a primary alcohol or nonbenzylic secondary alcohols. Under nitrogen, a catalytic amount of Ni or transition metal halides such as CoCl₃, FeCl₃, and NiCl₃ in combination with Na was also found to conduct a dehydrogenation of a secondary alcohol to the corresponding ketone in high yield at room temperature.     

Oxovanadium complex-catalyzed aerobic oxidation of propargylic alcohols

A catalytic system consisting of vanadium oxyacetylacetonate [VO(acac)(2)] and 3 A molecular sieves (MS3A) in acetonitrile works effectively for the aerobic oxidation of propargylic alcohols [R(1)CH(OH)Ctbd1;CR(2)] to the corresponding carbonyl compounds under an atmospheric pressure of molecular oxygen. Although the reactivity of alpha-acetylenic alkanols (R(1) = alkyl) is lower compared to that of the alcohols of R(1) = aryl, alkenyl, and alkynyl, the use of VO(hfac)(2) as a catalyst and the addition of hexafluoroacetylacetone improve the product yield in these cases. A catalytic cycle involving a vanadium(V) alcoholate species and beta-hydrogen elimination from it has been proposed for this oxidation.     

An efficient and reusable carbon-supported platinum catalyst for aerobic oxidation of alcohols in water

Platinum nanoparticles embedded in a hollow porous carbon shell prepared by a photocatalytic reaction acted as a reusable catalyst for the aerobic oxidation of alcohols under atmospheric pressure of oxygen in water.     

Recent advances in the homogeneous palladium-catalyzed aerobic oxidation of alcohols

The use of palladium catalysts for the oxidation of alcohols to aldehydes and ketones in the presence of various types of reoxidants is well known. Recently, the advantages of using molecular oxygen as the oxidant in the Pd-catalyzed oxidation of alcohols have been explored. The aim of this review is to provide an overview on the most important homogeneous palladium-catalyzed aerobic oxidation of alcohols without a co-catalyst during last decade until the end of 2007.     

Biomimetic aerobic oxidation of amino alcohols to lactams

The right path: N-Protected amino alcohols undergo aerobic and biomimetic oxidation to the corresponding lactams in the presence of a ruthenium catalyst and a combination of electron-transfer mediators under air. The reaction was used for the synthesis of five-, six-, and seven-, membered lactams and showed good tolerance to a number of N-protecting groups.     

Pseudohalide assisted aerobic oxidation of alcohols in the presence of visible-light

Pseudohalides are well known to do similar chemistry like halides. Thiocyanate, a pseudohalide acts like halides in many ways. Thiocyanate radicals (SCN) are generated from readily available thiocyanate salts using Rose Bengal through single electron transfer (SET) in the presence of visible light. Thiocyanate radicals abstract hydrogen like other halide radicals, so this aspect of chemistry was used for the oxidation of alcohols to their corresponding aldehydes using oxygen as the terminal oxidant. This method shows a broad scope and well tolerance towards various functional groups.     

Unique gold chemoselectivity for the aerobic oxidation of allylic alcohols

Gold nanoparticles supported on nanocrystalline ceria has been found to be more active and chemoselective than palladium and gold(core)-palladium(shell) nanoparticles for the aerobic oxidation of allylic alcohols.     

pH-Sensitive gold nanoparticle catalysts for the aerobic oxidation of alcohols

Gold nanoparticles (NPs) stabilized by carboxylate modified polyvinylpyrrolidone have been prepared and fully characterized. The gold NPs efficiently catalyze the aerobic oxidation of benzyl alcohol in water at ambient temperature and are easily separated from the reaction mixture by lowering the pH of the solution, causing the NPs to precipitate. The mechanism of the precipitation process has been studied. Due to the efficiency of this process, the NPs may be reused as catalysts by readjusting their pH.     

Engineering of a monodisperse core-shell magnetic Ti-O-Si oxidation nanocatalyst

There has been limited development in catalyst carriers for magnetic separations where superparamagnetic nanoparticles of a high saturation magnetization with no coercivity are required to isolate expensive catalyst reagent that are subjected to repeated magnetic cycles. By using simple stepwise layer-by-layer nanochemistry techniques, we show that an fcc FePt nanomagnet can be created inside each silica particle with tailored dimensions to great precision. Subsequent engineering of the external surface with Ti-O-Si species in an optimum structure to create a unique interface gives high activity and excellent selectivity of the composite material for the trans-stilbene oxidation to the corresponding epoxide in the presence of tert-butyl hydroperoxide. Thus, a new magnetic separable epoxidation catalyst is described. This work clearly demonstrates the significance of nanoengineering of a single catalyst particle by a bottom-up construction approach in modern catalyst design, which could lead to new catalytic properties.     

Promoting gold nanocatalysts in solvent-free selective aerobic oxidation of alcohols

A trace amount of metal carbonate, acetate or borate significantly boosts gold nanocatalysts in selective aerobic oxidation of alcohols under mild solvent-free conditions.     

Cesium hydroxide-promoted aerobic oxidation of sec-aromatic alcohols

A CsOH-promoted aerobic oxidation of sec-aromatic alcohols has been developed, using air as a free and clean oxidant, and providing aryl ketones in good to excellent yields.     

Heterocycle-substituted tetrazole ligands for copper-catalysed aerobic oxidation of alcohols

An efficient copper-catalysed aerobic oxidation of alcohols has been established, which employed heterocycle-substituted tetrazoles as ligands. The commercially available (S)-5-(pyrrolidin-2-yl)-1H-tetrazole proved as the best ligand for this oxidation. Under optimized conditions, the substrate scope was broadened. A plausible mechanism was also proposed.     

Cu(II) Schiff base complex supported on Fe3O4 nanoparticles as an efficient nanocatalyst for the selective aerobic oxidation of alcohols

Herein, we have prepared a new Cu(II) Schiff base complex supported onto the surface of modified Fe₃O₄ nanoparticles as highly stable, heterogeneous and magnetically recyclable nanocatalyst for the selective aerobic oxidation of different alcohols. The structure, morphology, chemical composition and magnetic property of the nanocatalyst and its precursors were characterized using FT‐IR, TGA, AAS, ICP‐AES, XRD, SEM, EDS, VSM and N₂ adsorption–desorption analyses. Characterization results exhibited the uniform spherical morphology for nanocatalyst and its precursors. A promising eco‐friendly method with short reaction time and high conversion and selectivity for oxidation of various primary and secondary alcohols under O₂ atmosphere condition was achieved. The synthesized nanocatalyst could be recovered easily by applying an external magnetic field and reused for least eight subsequent reaction cycles with only negligible deterioration in catalytic performance.     

聚多巴胺功能化硅胶沉积单分散Pd纳米粒子的简易原位合成及用作醇需氧氧化反应的多相可循环使用的纳米催化剂（英文）

本文报道了一种不使用任何稳定剂或还原剂,原位合成硅胶/聚多巴胺复合物(SiO_2/PDA)负载的Pd纳米颗粒(Pd NPs)的简易方法.该方法先将PDA涂覆的SiO_2颗粒浸在Pd镀液中,然后利用PDA中含N基团的还原能力将Pd物种原位还原为纳米簇合物.并采用高分辨透射电镜、前场扫描电镜、能量散射谱、X射线衍射、X射线光电子能谱、诱导耦合等离子体和红外光谱等手段对所得纳米复合物的结构、形貌和物化性质进行了表征.被PDA基团锚合的Pd NPs具有显著的小颗粒(30–40 nm)特性.作为一个可循环使用的纳米催化剂,SiO_2/PDA/Pd NPs在醇的需氧氧化反应中表现出高活性.另外,催化剂经回收和多次重复使用时未出现明显的失活.     

A convenient palladium-catalyzed aerobic oxidation of alcohols at room temperature

A simple Pd-catalyzed aerobic oxidation of benzylic and aliphatic alcohols to the corresponding aldehydes and ketones at room temperature is described.     

Binuclear complexes for aerobic oxidation of primary alcohols and carbohydrates

The influence of electron-donating and electron-accepting properties of three pentadentate ligands was determined in connection with the aerobic oxidation ability of the corresponding binuclear copper(II) complexes for benzyl and allyl alcohols; additionally, the catalytic performance of their palladium and platinum analogs was characterized under comparable conditions. Quantitative aerobic oxidation of benzyl alcohol at 40 °C was achieved with a binuclear copper(II) complex—TEMPO catalyst in 2.5 h, while the regioselective aerobic oxidation of underivatized methyl-β-d-glucopyranoside was accomplished in about 35% yield at 60 °C after 24 h.