Aerobic Oxidative Iodination of Organic Compounds with Iodide Catalyzed by Sodium Nitrite

Selective and efficient iodinations of organic compounds were achieved by an aerobic oxidative process catalyzed by sodium nitrite using potassium iodide in acidic media. Using the potasasium iodide (KI)/air/sodium nitrite (NaNO₂; cat.)/sulfuric acid (H₂SO₄) iodinating system, activated and moderately deactivated aromatic compounds were exclusively or preferentially iodinated at the para position. In protic solvents ketones and 1,3‐dicarbonyl compounds were iodofunctionalized at the α carbonyl position, while in the case of aryl methyl ketones bearing an activated aromatic ring, the regioselectivity of iodination could be directed by the solvent used. In acetonitrile (MeCN) the aromatic ring was selectively iodinated, while in aqueous rethanol (EtOH) functionalization of the methyl carbon atom took place. Alkenes were transformed to vicinal iodohydrins or vicinal iodoalkoxy derivatives following Markovnikov‐type regioselectivity and anti stereoselectivity, while 1,2‐diiodoalkenes with preferentially E orientation were formed from alkynes.     

Hydroxyl Radical Promotes the Direct Iodination of Aromatic Compounds with Iodine in Water: A Combined Experimental and Theoretical Study

It is still a challenge to develop green, simple and effective approaches to prepare aromatic iodides. Herein, a novel and green strategy for the direct mono‐iodination of aromatic compounds starting with molecular iodine has been developed. The strategy uses ceria nanocrystals to decompose hydrogen peroxide, giving hydroxyl radicals which are demonstrated experimentally and computationally to be crucial to promote the iodinations.     

Tungsten‐ and Molybdenum‐Based Coordination Polymer‐Catalyzed N‐Oxidation of Primary Aromatic Amines with Aqueous Hydrogen Peroxide

Recyclable tungsten‐ and molybdenum‐based coordination polymers efficiently catalyzed the oxidation of primary aromatic amines to the corresponding nitroso derivatives with 30 % aqueous hydrogen peroxide in high yields at room temperature.     

Heterogeneously Catalyzed Oxidative Cyanation of Tertiary Amines with Sodium Cyanide/Hydrogen Peroxide using Polymer‐Supported Iron(II) Phthalocyanines as Catalyst

The first report on heterogeneously catalyzed oxidative cyanation of various tertiary amines to the corresponding α‐amino nitriles with high yields and selectivity by using hydrogen peroxide oxidant in presence of sodium cyanide and Fe(II) phthalocyanine supported on a polymer as catalyst is described. The present method has the added benefits of facile recovery of the catalyst from the reaction mixture and its subsequent use without further activation. Consistent catalytic activity with no metal leaching was observed during this course.     

Hydrocarbon Oxidations with Hydrogen Peroxide Catalyzed by a Soluble Polymer‐Bound Manganese(IV) Complex with 1,4,7‐Triazacyclononane

Soluble manganese(IV) complexes with polymer‐bound 1,4,7‐triazacyclononanes as ligands (compound 2 ) catalyze the oxidation of alkanes by hydrogen peroxide in acetonitrile at room and lower temperatures. The corresponding alkyl hydroperoxides are the main products. The presence of a relatively small amount of acetic acid is obligatory for this reaction. The oxidation of alkanes and olefins exhibits some features (kinetic isotope effect, bond selectivities) that distinguish this system from an analogous one based on the dinuclear Mn(IV) complex 1 .     

用过氧化氢和乙酸对未经氢化处理的煤油进行直接氧化脱硫

The oxidative desulfurization of a real refinery feedstock (i.e., non-hydrotreated kerosene with total sulfur mass content of 0.16%) with a mixture of hydrogen peroxide and acetic acid was studied. The influences of various operating parameters including reaction temperature (T), acid to sulfur molar ratio (nacid/nS), and oxidant to sulfur molar ratio (nO/nS) on the sulfur removal of kerosene were investigated. The results revealed that an increase in the reaction temperature (T) and nacid/nS enhances the sulfur removal. Moreover, there is an optimum nO/nS related to the reaction temperature and the best sulfur removal could be obtained at nO/nS 8 and 23 for the reaction temperatures of 25 and 60C, respectively. The maximum observed sulfur removal in the present oxidative desulfurization system was 83.3%.     

A Rapid and Efficient Synthesis of Quinone Derivatives: Ru(II)‐ or Ir(I)‐Catalyzed Hydrogen Peroxide Oxidation of Phenols and Methoxyarenes

Hydroquinone and methoxybenzene derivatives were catalytically oxidized promptly to the corresponding quinones in up to 99% yield. With a catalyst loading of 0.01 mol %, a maximum TON of 8.4×10³ was attained in the case of Ru(II)‐complex. Ru(II)(pybox‐dh)(pydic) is able to enhance the hydrogen peroxide oxidation of substituted hydroquinones as well as methoxybenzenes, but Ir[(coe)₂Cl]₂ and Ir[(cod)Cl]₂ were found to be effective catalysts only for the former substrates under similar oxidation conditions.     

Non‐Heme Manganese Complexes Catalyzed Asymmetric Epoxidation of Olefins by Peracetic Acid and Hydrogen Peroxide

Chiral non‐heme aminopyridine manganese complexes catalyze the enantioselective epoxidation of olefins with peracetic acid or hydrogen peroxide with moderate to high yields and ee valuess up to 89% (peracetic acid, AcOOH) and 84% (hydrogen peroxide, H₂O₂), performing as many as 1000 turnovers.     

Fe(PyTACN)‐Catalyzed cis‐Dihydroxylation of Olefins with Hydrogen Peroxide

A family of iron complexes with general formula [Fe(II)(^R,Y,XPyTACN)(CF₃SO₃)₂], where ^R,Y,XPyTACN=1‐[2′‐(4‐Y‐6‐X‐pyridyl)methyl]‐4,7‐dialkyl‐1,4,7‐triazacyclononane, X and Y refer to the groups at positions 4 and 6 of the pyridine, respectively, and R refers to the alkyl substitution at N‐4 and N‐7 of the triazacyclononane ring, are shown to be catalysts for efficient and selective alkene oxidation (epoxidation and cis‐dihydroxylation) employing hydrogen peroxide as oxidant. Complex [Fe(II)(^Me,Me,HPyTACN)(CF₃SO₃)₂] ( 7 ), was identified as the most efficient and selective cis‐dihydroxylation catalyst among the family. The high activity of 7 allows the oxidation of alkenes to proceed rapidly (30 min) at room temperature and under conditions where the olefin is not used in large amounts but instead is the limiting reagent. In the presence of 3 mol% of 7 , 2 equiv. of H₂O₂ as oxidant and 15 equiv. of water, in acetonitrile solution, alkenes are cis‐dihydroxylated reaching yields that might be interesting for synthetic purposes. Competition experiments show that 7 exhibits preferential selectivity towards the oxidation of cis olefins over the trans analogues, and also affords better yields and high [syn‐diol]/[epoxide] ratios when cis olefins are oxidized. For aliphatic substrates, reaction yields attained with the present system compare favourably with state of the art Fe‐catalyzed cis‐dihydroxylation systems, and it can be regarded as an attractive complement to the iron and manganese systems described recently and which show optimum activity against electron‐deficient and aromatic olefins.     

Chiral Phosphoric Acid‐Catalyzed Asymmetric Oxidation of Aryl Alkyl Sulfides and Aldehyde‐Derived 1,3‐Dithianes: Using Aqueous Hydrogen Peroxide as the Terminal Oxidant

(R)‐1,1′‐Binaphthyl‐2,2′‐diol (R‐BINOL) derived chiral phosphoric acids have been explored as organocatalysts for the asymmetric oxidation of a series of aryl alkyl sulfides and 1,3‐dithianes derived from aldehydes with aqueous hydrogen peroxide (H₂O₂) as the terminal oxidant. The enantiomerically enriched sulfoxides are obtained in moderate to excellent yield (up to 99%) with excellent diastereoselectivity (up to >99:1 dr) and moderate to good enantioselectivity (up to 91:9 er). In particular, the present protocol stereoselectively provides an efficient access to enantiomerically enriched aryl alkyl sulfoxides and dithioacetal mono‐sulfoxides, which strictly restrains the formation of the undesirable by‐products: sulfones or disulfoxides. The tracking experiments also verify that this approach proceeds via a direct sulfoxidation process, instead of a kinetic resolution route by overoxidation of the resulting sulfoxides.     

Silica‐Supported Vanadium‐Catalyzed N‐Oxidation of Tertiary Amines with Aqueous Hydrogen Peroxide

A recyclable silica supported vanadium 1 catalyzes the oxidation of tertiray amines to the corresponding N‐oxides with 30% H₂O₂ in high yield.     

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.     

Iron‐Catalyzed Oxidation of Cycloalkanes and Alkylarenes with Hydrogen Peroxide

An iron‐catalyzed process for the oxidation of saturated hydrocarbons (cycloalkanes and alkylarenes) to alcohols and ketones with aqueous H₂O₂ in acetonitrile at room temperature is reported. Addition of a carboxylic acid increases the selectivity towards the ketone formation. Best results were obtained with ethylbenzene as substrate and acetic acid as additive, affording acetophenone as the main product.     

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.     

杂多化合物催化过氧化氢氧化烯烃环氧化反应研究进展

烯烃的环氧化反应是化学工业中重要的化学反应之一,其环氧化物是用途极为广泛的有机原料和化学中间体。文章综述了以杂多酸为催化剂,过氧化氢为氧化剂的烯烃环氧化反应研究进展,指出了今后此类环氧化反应催化剂发展方向。     

Osmium‐Catalyzed Selective Oxidations of Methane and Ethane with Hydrogen Peroxide in Aqueous Medium

Various transition metal chlorides including FeCl₃, CoCl₂, RuCl₃, RhCl₃, PdCl₂, OsCl₃, IrCl₃, H₂PtCl₆, CuCl₂ and HAuCl₄ were studied for the selective oxidations of methane and ethane with hydrogen peroxide in aqueous medium. Among the metal chlorides investigated, osmium(III) chloride (OsCl₃) exhibited the highest turnover frequency (TOF) for the formation of organic oxygenates (mainly alcohols and aldehydes) from both methane and ethane. For the OsCl₃‐catalyzed oxidation of methane with hydrgen peroxide, methyl hydroperoxide was also formed together with methanol and formaldehyde. The effects of various kinetic factors on the catalytic behavior of the OsCl₃‐H₂O₂ system were investigated, and TOF values of 12 and 41 h⁻¹ could be obtained for oxygenate formation during the oxidations of methane and ethane, respectively. In the presence of OsCl₃, NaClO, NaClO₄ or NaIO₄ as oxidant was incapable of oxidizing methane and ethane to the corresponding oxygenates, and the use of tert‐butyl hydroperoxide (TBHP) instead of H₂O₂ provided remarkably lower rates of formation of oxygenates. UV‐Vis spectroscopic measurements suggested that OsCl₃ was probably oxidized into an Os(IV) species by H₂O₂ in aqueous medium, and the Os(IV) species might be involved in the oxygenation of methane or ethane. The result that the conversions of both methane and ethane to oxygenates were suppressed by the addition of a radical scavenger suggested that the reactions proceeded via a radical pathway.     

3,5‐Dimethylpyrazolium Fluorochromate(VI)‐Catalysed Oxidation of Organic Substrates by Hydrogen Peroxide under Solvent‐Free Conditions

3,5‐Dimethylpyrazolium fluorochromate (VI), C₅H₈N₂H[CrO₃F], DmpzHFC , serves as an efficient catalyst for oxidation of primary, secondary and allylic alcohols to the corresponding carbonyl compounds using H₂O₂ at room temperature under solvent‐free conditions. Oxidation of methyl phenyl sulfides and triphenylphosphine were also carried out successfully.     

蒽醌法制H2O2工艺过程强化

在蒽醌法工艺全流程模试装置上,采用含四丁基脲工作液、富氧空气在筛板氧化塔氧化及带聚凝板筛板塔萃取等技术,对蒽醌法氧化、萃取工艺过程进行了强化研究。结果显示:氧化塔H2O2生产能力提高至32kg/(m3.h);萃取液中过氧化氢质量分数可达50%。与空气鼓泡塔氧化相比,采用筛板塔和富氧空气进行氧化,均可提高氧化塔生产能力;在萃取塔内添加聚凝板,可增强萃取效果。     

双氧水催化氧化法合成邻苯二酚的研究进展

评述了邻苯二酚传统合成方法的优缺点,重点综述了双氧水催化氧化法合成邻苯二酚的研究进展,总结出此法的四类催化剂:无机酸或有机酸催化剂;无机盐或复合金属氧化物催化剂;分子筛催化剂;杂多酸或杂多酸盐催化剂.     

Brønsted Acid‐Catalyzed Dihydroxylation of Olefins in Aqueous Medium

The trans‐dihydroxylation of olefins occurs efficiently by aqueous hydrogen peroxide catalyzed by p‐toluenesulfonic acid at 50 °C, allowing the catalyst reuse and an outstanding substrate functional group tolerance such as tert‐butoxycarbonylamino (BocNH), benzyloxycarbonylamino (CbzNH), benzyloxy (OBn), tosyloxy (OTs), hindered ketal, (2‐trimethylsilyl)ethoxymethoxy (OSEM), benzylamino (NBz), benzyloxy (OBz) and free amino acid.