Pt的氧化状态对甲醇氧化活性的影响

采用NaBH4还原法制备了XC-72碳黑负载的Pt电催化剂,并在化学还原后用H2O2处理部分催化剂以改变Pt的氧化状态,以期改善Pt活性中心上水的离解而提高催化活性.X射线光电子能谱结果表明,经H2O2处理的催化剂含有较多的氧化态Pt.通过循环伏安法和记时电流法考察了经处理和未经处理的催化剂在酸性条件下的甲醇氧化的催化...     

Oxidation of methylamine

A detailed chemical kinetic model for oxidation of methylamine has been developed, based on theoretical work and a critical evaluation of data from the literature. The rate coefficients for the reactions of CHNH + O CHNH / CHNH + HO, CHNH + H CH + NH, CHNH CHNH, and CHNH + O CHNH + HO were calculated from ab initio theory. The mechanism was validated against experimental results from batch reactors, flow reactors, shock tubes, and premixed flames. The model predicts satisfactorily explosion limits for CHNH and its oxidation in a flow reactor. However, oxidation in the presence of nitric oxide, which strongly promotes reaction at lower temperatures, is only described qualitatively. Furthermore, calculated flame speeds are higher than reported experimental values; the model does not capture the inhibiting effect of the NH group in CHNH compared to CH. More work is desirable to confirm the products of the CHNH + NO reaction and to look into possible pathways to NH in methylamine oxidation.     

烷基取代蒽的单电子氧化

在无水CHCl3-吡啶中, 烷基取代蒽被碘氧化生成的中间体游离基正离子, 在亲核试剂进攻蒽环使9-, 10-C氧化, 和侧链烷基去质子两种竞争反应中, 若蒽环9-或10-C未取代, 则以9-, 10-C氧化占绝对优势; 若蒽环9-, 10-C均被取代, 则以侧链去质子氧化占优势。甲基去质子速度比乙基和环丙基快得多。     

Oxidation of hexabenzylhexaazaisowurtzitane

Oxidation of hexabenzylhexaazaisowultzitane by different Cr(Ⅵ) reagents has been studied, and a very stable amide product, hexabenzoylhexaazaisowurtzitane, has been obtained.     

有机催化的不对称氧化反应

有机催化剂在不对称氧化反应中显示出巨大应用潜力. 综述了不同类型的有机催化剂催化的α,β-不饱和醛酮、烯烃的不对称环氧化反应及羰基化合物的不对称α-羟基化反应, 并对催化特点及催化机理作了详细的描述.     

Oxidation of perfluoroaromatics

3,4,5,6-Tetrafluoro-2-nitroaniline (I), 2,3,5,6-tetrafluoro-4-nitroaniline (IV) and 2,5,6-trifluoro-4-nitro-1,3-phenylenediamine (VI) react with nitrous acid to give 3,4,5-trifluoro-6-nitro-1,2-diazo-oxide (III), 3,5,6-trifluoro-4-nitro-1,2-diazo-oxide and (V) 5-fluoro-6-nitro-bis-1,2:3,4-diazo-oxide (VII), respectively. Reduction of the diazo-oxide (III) with hypophosphorous acid gives 4,5,6-trifluoro-3-nitrophenol (VIII). Treatment of 2,3,4,6-tetrafluoroacetanilide with nitric acid affords trifluoro-p-benzoquinone (X), the reduction of which gives trifluorohydroquinone (XI). Proton and fluorine chemical shifts and coupling constants of the new compounds are reported.     

Oxidation of nonamethylferrocenylcarbinols

Conclusions The reactions of secondary nonamethylferrocenylcarbinols with BaMnO₄ lead mainly to oxidation of the methyl group of the pentamethylcyclopentadienyl ligand and to the formation of heteroannular aldehyde alcohols.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 431–434, February, 1988.     

Spectral Signatures of Oxidation States in a Manganese-Oxo Cubane Water Oxidation Catalyst

We report IR and UV/Vis spectroscopic signatures that allow discriminating between the oxidation states of the manganese-based water oxidation catalyst [(Mn₄O₄)(V₄O₁₃)(OAc)₃]³⁻. Simulated IR spectra show that V=O stretching vibrations in the 900–1000 cm⁻¹ region shift consistently by about 20 cm⁻¹ per oxidation equivalent. Multiple bands in the 1450–1550 cm⁻¹ region also change systematically upon oxidation/reduction. The computed UV/Vis spectra predict that the spectral range above 350 nm is characteristic of the managanese-oxo cubane oxidation state, whereas transitions at higher energy are due to the vanadate ligand. The presence of absorption signals above 680 nm is indicative of the presence of Mn^III atoms. Spectroelectrochemical measurements of the oxidation from [Mn Mn ] to [Mn ] showed that the change in oxidation state can indeed be tracked by both IR and UV/Vis spectroscopy.     

NO的催化氧化

采用傅里叶变换红外光谱定量分析方法研究了γ－Ａｌ２Ｏ３,ＴｉＯ２和硅胶负载的金属氧化物和贵金属催化剂对ＮＯ催化氧化反应的活性,考察了反应温度、活性组分负载量、空速及预氧化还原处理等因素对催化剂活性的影响,并以ＮＯ的催化氧化机理为基础,对各种因素影响机理进行了分析,实验结果表明,ＭｎＯ,Ｃｒ２Ｏ３和Ｃｏ３Ｏ４催化剂的活性较好：预处理条件对贵金属催化剂Ｐｔ／Ａｌ２Ｏ３的活性影响较大,不同载体及不同的活     

The Oxidation of Pyrrole

The dearomatization of heterocycles has been a powerful means for producing functional molecules in synthesis. In the case of pyrroles, reductive methods (such as the Birch reduction) have been most widely exploited, while oxidative methods are generally dismissed as too difficult or unpredictable to be useful. However, since the early twentieth century considerable research has been carried out on the controlled oxidation of pyrroles to give highly functionalized products, using a variety of oxidants. This review presents a summary of all work up until the present day in the area of pyrrole oxidation, looking at the use of peroxide, singlet oxygen, hypervalent iodine reagents, a range or organic and inorganic oxidants, and electrochemical approaches. It also offers some perspective on the potential future role of pyrrole oxidation in synthesis.     

选择性氧化HMF

近年来,利用储量丰富且可再生的生物质资源制备高附加值化学品和液体燃料是目前化学研究领域的热点之一,同时契合可持续发展的国家战略。5-羟甲基糠醛(HMF)是关键的生物质平台化合物之一,广泛应用于制备精细平台化合物、药物的中间体、聚合物的合成、液体燃料的前驱体等。因此,HMF的选择性氧化逐渐成为生物质领域的研究热点。本文主要介绍了近五年来关于HMF选择氧化制备DFF、FFCA、FDCA等生物质衍生物的研究,以及以HMF为中间体的生物质转化过程。关于对HMF进行选择性氧化,主要聚焦于以热催化和光催化两种途径。其中,以热催化的途径将HMF选择性氧化为DFF和FDCA研究较多,此途径下的催化体系主要介绍了贵金属和非贵金属两类;而在为数不多的光催化途径下,主要研究的催化体系是g-C₃N₄催化剂。最后,指出了目前HMF氧化反应研究存在的不足,并提出了可能解决的方法。     

乙醇电催化氧化

乙醇作为典型的可再生绿色环保型能源,具有易储存和携带、较高的能量密度、易生产等优点而备受关注。本文详细介绍了近年来国内外乙醇电催化氧化研究的重要进展,着重叙述了乙醇电催化氧化的反应机理,不同催化剂材料对乙醇电氧化的优缺点,进一步探讨了影响乙醇电氧化反应活性和选择性的因素,总结了提高乙醇电氧化活性和选择性的策略,最后,对其今后可能的研究方向进行了展望。     

Oxidation State 10 Exists

In a recent paper, Wang et al. found an iridium‐containing compound with a formal oxidation state of 9. ⁵ This is the highest oxidation state ever found in a stable compound. To learn if this is the highest chemical oxidation state possible, Kohn–Sham density functional theory was used to study various compounds, including PdO₄²⁺, PtO₄²⁺, PtO₃F₂²⁺, PtO₄OH⁺, PtO₅, and PtO₄SH⁺, in which the metal has an oxidation state of 10. It was found that PtO₄²⁺ has a metastable state that is kinetically stable with a barrier height for decomposition of 31 kcal mol⁻¹ and a calculated lifetime of 0.9 years. All other compounds studied would readily decompose to lower oxidation states.     

肟的无污染氧化

No2;污染治理;二噁烷;肟的无污染氧化     

甲苯类化合物的选择性氧化

综述了以O2为清洁氧源甲苯类化合物的气相和液相选择性氧化。甲苯类化合物的气相选择性氧化中主要介绍了金属氧化物、分子筛和负载型催化剂并对影响催化剂活性和选择性的因素进行了分析;甲苯类化合物的液相选择性氧化中重点介绍了MC(mid-century)催化体系及其反应机理方面的研究进展,并特别介绍了仿生催化在甲苯类化合物催化氧化中的应用。对各催化氧化体系的应用前景进行了展望。     

钙钛矿型水氧化电催化剂

在全球能源结构“清洁化”转型的背景下,可再生能源的开发与利用能够有效解决能源危机与环境问题,符合我国的可持续发展路线。能源转换与储存技术贯穿着循环能源技术的各个环节,是新型能源框架的核心支撑。 水氧化反应是众多能源体系（例如, 水裂解反应、 二氧化碳还原反应、 氮还原反应和金属-空气电池）的重要半反应, 但其动力学缓慢, 严重限制了设备的能源效率, 阻碍了相应技术的广泛应用。因此, 亟需开发具有低成本、 高活性、 强稳定性的水氧化电催化剂以降低反应能垒,进而推动能源转换与存储设备的工业化发展。钙钛矿型材料的晶体结构包容性强, 元素组成涵盖广泛, 具有丰富而独特的电子特性, 易于实现表面化学与电子结构的精准调控, 因此被公认为理想的催化材料设计平台。本文综述了钙钛矿型水氧化电催化剂的最新研究进展。首先介绍了钙钛矿型材料的晶体结构和电子特性,归纳了制备钙钛矿型氧化物的代表性的合成策略。通过讨论近期钙钛矿型水氧化电催化剂在酸性和碱性介质中的研究进展, 强调了钙钛矿型电催化剂结构与催化性能间的构效关系。 最后, 我们总结了钙钛矿型水氧化电催化剂在实际应用中面临的挑战与机遇, 提出了相应的建议与解决方案, 期望能使读者更清晰地认识到该领域的未来发展方向。