使用分子氧催化氧化法合成肉桂醛的研究

分子氧(或空气)不但便宜易得,而且也是在化工生产中很受欢迎的“绿色”氧化剂。近几年来,在国外它被广泛地用于催化氧化醇类以合成羰基化合物的研究。目前已发现了多种这类反应的催化剂。这里用Ru／Al2O3载体催化剂,由分子氧氧化肉桂醇制取肉桂醛。此催化剂具有高的催化转化率和很好的选择性。     

以分子氧为氧化剂合成柠檬醛的研究

分子氧(或空气)是化工生产中的“绿色”氧化剂。用分子氧催化氧化醇类以合成不同的羰基化合物的研究已成为近几年来国外有机合成的一个热门研究领域。综述了以分子氧合成柠檬醛的研究。使用的Ru／Al2O3催化剂对醇-OH基的氧化具有高度的选择性并有很高的转化率。     

用分子氧催化氧化法制取苯甲醛的研究简介

用分子氧催化氧化醇类以合成不同的羰基化合物的研究已成为近几年来国外在工业过程和有机合成中的一个热门研究领域。分子氧(或空气)是化工生产中的"绿色"氧化剂。使用的催化剂对醇羟基的氧化具有高度的选择性并有很高的转化率。简要介绍以此类方法对合成苯甲醛的研究。     

以分子氧为氧源催化苯乙烯环氧化催化剂研究进展

环境友好催化烯烃环氧化是催化氧化领域中的一大热点,分子氧作为一种理想的清洁氧源日益受到人们的重视,而分子氧在常温下非常稳定,必须经过适当的催化才能与烯烃发生环氧化反应。本文综述了近年来以分子氧为氧源催化苯乙烯环氧化所用催化剂的主要研究进展,并对其前景进行了展望。     

催化分子氧环氧化环己烯的研究进展

介绍了分子氧的构型、催化烯烃环氧化机理及其催化环氧化环己烯的研究进展,提出以分子氧为氧源,催化环氧化环己烯的关键在于高效催化剂的制备及廉价易得还原剂的筛选。     

烃类氧化新的N-羟基邻苯二甲酰亚胺基催化氧化体系

烃类氧化反应是石油化工中一类重要反应。空气和氧气是容易得到且环境友好的氧化剂,所以以氧为氧化剂的具有高选择性和转化率的催化体系的开发在烃类氧化中具有极其重要意义。本文在对传统的烃类分子氧氧化催化剂进行讨论的基础上,对近年来出现的以N-羟基邻苯二甲酰亚胺为基础的新催化剂体系进行了综述。该催化体系催化的烃类分子氧氧化反应具有反应条件温和、选择性高等优点。     

氧代异佛尔酮的合成

氧代异佛尔酮（KIP）是合成维生素E的重要中间体,目前主要有两条合成路线。本文研究了以α-异佛尔酮为原料,在催化体系作用下,用分子氧氧化制备氧代异佛尔酮的合成工艺。同时采用喷射氧化反应,验证了催化剂用量、反应温度、氧含量等因素对收率的影响。     

一种分子氧催化氧化制备2-硝基-4-甲砜基苯甲酸的方法

<正>本发明提供了一种邻硝基对甲砜基甲苯通过分子氧催化氧化成2-硝基-4-甲砜基苯甲酸的新工艺:以有机极性溶剂作为溶剂,以钴盐和锰盐作为金属催化剂,分子氧作为氧化剂,并在氮氧自由基引发剂和促进剂的作用下,将邻硝基对甲砜基甲催化氧     

分子氧催化氧化在精细化学品合成中的应用

介绍了以分子氧为氧源的催化氧化在精细化学品合成中的应用,如在醛、酮、酸以及环氧类化合物中的合成应用。     

以分子氧为氧源催化丙烯环氧化制环氧丙烷研究进展

环氧丙烷是重要的基础化工原料。主要工业生产方法有氯醇法和Halcon法。氯醇法环境污染严重 ,急待改进 ;Halcon法产生大量联产品 ,且基本建设投资巨大。为了满足环境和经济等方面的要求 ,以分子氧为氧源的丙烯催化环氧化是最理想的生产方法 ,目前正处于研究阶段。文中对近十年来的研究进展做了综述     

Molecular dynamics simulations of HIV-1 protease with peptide substrate

Molecular dynamics simulations of human immunodeficiency virus(HIV)-l protease with a model substrate were used to test ifthere is a stable energy minimum for a proton that is equidistantfrom the four delta oxygen atoms of the two catalytic asparticacids. The crystal structure of HIV-1 protease with a peptidicinhibitor was modified to model the peptide substrate Ser-Gln-Asn-Tyr-Pro-Ile-Val-Glnfor the starting geometry. A proton was positioned between thetwo closest oxygen atoms of the two catalytic aspartic acids,and close to the carbonyl oxygen of the scissile bond in thesubstrate. All crystallographic water molecules were included.Two molecular dynamics simulations were run: 30 ps with united-atompotentials and 40 ps using the more accurate all-atom potentials.The molecular dynamics used a new algorithm that increased thespeed and allowed the elimination of a cut-off for non-bondedinteractions and the inclusion of an 8 shell of water moleculesin the calculations. The overall structure of the protease dimer,including the catalytic aspartic acids, was stable during thecourse of the molecular dynamics simulations. The substrateand a water molecule, that is an important component of thebinding site, were stable during the simulation using all-atompotentials, but more mobile when united-atom potentials wereused. A Poincare map representation showed that the positionsof the proton and its coordinating oxygen atoms were stablefor 93% of both simulations, although many of the buried andpoorly accessible water molecules exchanged with solvent. Theproton has a stable minimum energy position and maintains coordinationwith all four delta oxygen atoms of the two catalytic asparticacids and the carbonyl oxygen of the scissile bond of the substrate.Therefore, a loosely bound hydrogen ion at this position willnot be rapidly exchanged with solvent, and will rebond to eithera catalytic aspartic acid or possibly the substrate. The implicationsfor the reaction mechanism are discussed.     

烃类选择氧化过程中自由基的调控策略与工业氧化应用研究进展

催化烃类氧化是提供合成树脂、合成纤维和合成橡胶等大宗化学品以及各类精细化学品的基本工艺,在化学工业中具有重要的地位。目前工业上的烃类氧化工艺普遍需要高温高压条件,苛刻条件可以使氧气活化及碳氢键断裂产生自由基。本文从均相催化、非均相催化、仿生催化等方面对近年来催化氧化反应的研究进展进行了回顾,梳理了催化氧化中的自由基机理。总结了仿生催化体系中自由基稳定性和定向性调控机制等方面的研究现状,提出了高效催化剂的设计、自由基的传递及调控机制等方面将是催化氧化领域的重要研究方向。     

Overcoming the "oxidant problem": strategies to use O2 as the oxidant in organometallic C-H oxidation reactions catalyzed by Pd (and Cu)

Oxidation reactions are key transformations in organic chemistry because they can increase chemical complexity and incorporate heteroatom substituents into carbon-based molecules. This principle is manifested in the conversion of petrochemical feedstocks into commodity chemicals and in the synthesis of fine chemicals, pharmaceuticals, and other complex organic molecules. The utility and function of these molecules correlate directly with the presence and specific placement of oxygen and nitrogen heteroatoms and other functional groups within the molecules. Methods for selective oxidation of C-H bonds have expanded significantly over the past decade, and their role in the synthesis of organic chemicals will continue to increase. Our group's contributions to this field are linked to our broader interest in the development and mechanistic understanding of aerobic oxidation reactions. Molecular oxygen (O(2)) is the ideal oxidant. Its low cost and lack of toxic byproducts make it a highly appealing reagent that can address key "green chemistry" priorities in industry. With strong economic and environmental incentives to use O(2), the commmodity chemicals industry often uses aerobic oxidation reactions. In contrast, O(2) is seldom used to prepare more-complex smaller-volume chemicals, a limitation that reflects, in part, the limited synthetic scope and utility of existing aerobic reactions. Pd-catalyzed reactions represent some of the most versatile methods for selective C-H oxidation, but they often require stoichiometric transition-metal or organic oxidants, such as Cu(II), Ag(I), or benzoquinone. This Account describes recent strategies that we have identified to use O(2) as the oxidant in these reactions. In Pd-catalyzed C-H oxidation reactions that form carbon-heteroatom bonds, the stoichiometric oxidant is often needed to promote difficult reductive elimination steps in the catalytic mechanism. To address this challenge, we have identified new ancillary ligands for Pd that promote reductive elimination, or replaced Pd with a Cu catalyst that undergoes facile reductive elimination from a Cu(III) intermediate. Both strategies have enabled O(2) to be used as the sole stoichiometric oxidant in the catalytic reactions. C-H oxidation reactions that form the product via β-hydride or C-C reductive elimination steps tend to be more amenable to the use of O(2). The use of new ancillary ligands has also overcome some of the limitations in these methods. Mechanistic studies are providing insights into some (but not yet all) of these advances in catalytic reactivity.     

Precursor state effects in catalysis: Oxidative dehydrogenation of propan-2-ol on Cu(110)

The oxidative dehydrogenation of propan-2-ol has been investigated using a thermal molecular beam system. The main products after predosing the surface with oxygen atoms are the dehydrogenated molecule (acetone), water and hydrogen. The effect of oxygen is to enhance the sticking of propan-2-ol from approximately 0.05 on the clean surface to 0.76 (±0.02). By varying the oxygen predose we have shown unambiguously that precursor state effects dominate the catalytic reaction, since at oxygen coverages as low as 0.008 monolayers the propanol sticking probability remains at 0.76. This is due to the long lifetime and diffusivity of the reactant on the surface enabling it toseek out the active sites (those with oxygen atoms) on the surface.     

含铁模拟酶催化苯羟基化反应

对比测试了多种含铁模拟酶对苯羟基化反应的催化性能,发现能同时提供氮和氧配位原子的乙二胺四乙酸([FeIII(EDTA)]-)表现出非常高的催化活性. 以分子氧为氧化剂,抗坏血酸为还原剂,在[FeIII(EDTA)]-的催化下,苯酚的产率和选择性分别达到了15.8%和100%. 考察了氧气压力、反应温度和反应时间对反应的影响,并对其动力学和机理进行了初步探讨. 氧气和苯对该反应均为一级反应. [FeIII(EDTA)]-在还原剂的作用下,能将分子氧活化为羟基自由基与苯进行羟基化反应.     

Research Note: O3 or O2 and Ag: A New Catalyst Technology for Aqueous Phase Sanitation

Silver deposited on an inert surface with a very large area exhibits a strong catalytic interaction with oxygen which results in strong bactericidal activity. This catalytic process is fundamentally different from other known silver-based approaches which deliver low levels of silver ions into water.

Two factors appear to control the rate of this catalytic reaction process: (1) the size and dispersion of the silver crystals and surface area of the supporting bed; and (2) the volume of oxygen in solution. The source of the oxygen can be atmospheric oxygen dissolved in the water or, for a greatly enhanced reaction rate, dissolved ozone produced by an ozone generator. In this process, oxygen molecules absorbed onto the catalyst surface are subsequently transferred to other oxidizable substrates including bacteria and viruses.

These catalytic oxidizing reactions exhibit two properties of significance in the sanitation of water. First, because oxygen on the catalyst surface reacts with both living and nonliving substrates, bacteria or viruses which are in the water flowing over the catalyst-containing medium are killed or inactivated on contact by the oxidizing reactions (i.e., without requiring the release of metals into water). Second, oxygen also is transferred to oxidizable inorganics (such as bromide ion) to generate readily measurable and relatively stable “residual” oxidizers/disinfectants that continue to sanitize water downstream.

Results of this Author's experiments have been independently replicated by sources from the University of Arizona, and at Herbert V. Shuster, Inc. Laboratories in Massachusetts.     

Continuous generation of lattice oxygen via redox engineering for boosting toluene degradation performances

Excellent performances promoted by lattice oxygen have attracted wide attention for catalytic degradation of volatile organic compounds(VOCs).However,how to control the continuous regeneration of lattice ox-ygen from the support is seldom reported.In this study,we selected sepiolite supported manganese-cobalt oxides(CoxMn100-xOy)as model catalysts by tuning Co/(Co+Mn)mass ratio(x=3％,10％,15％,and 20％)to enhance toluene degradation efficiency,owing to lattice oxygen regeneration by redox cycle existing at the interface and Mn species with high valence state,initiated by cobalt catalytic performance under the role of crystal field stability phase.The results of activity test show that the sepiolite-Co15Mn85Oy catalyst exhibit outperformances at 193℃with 10,000 h-1 GHSV.In addition,the catalyst existed at the bottom of the"vol-cano"curve correlated T50 or T90 with Co/(Co+Mn)weight ratio is sepiolite-Co15Mn85Oy,conforming its outperformance.Further characterized by investigating active sites structural and electronic properties,the essential of superior catalytic activity is attributed to the grands of lattice oxygen continuous formation resulted from redox engineering based on the high atomic ratio of surface lattice oxygen with continuous refilled from the support and that of Mn4+/Mn3+cycle initiated by cobalt catalytic behaviors.All in all,redox engineering,not only promotes grands of active species reversible regeneration,but supplies an al-ternative catalyst design strategy towards the terrific efficiency-to-cost ratio performance.