共查询到20条相似文献,搜索用时 15 毫秒
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Dr. Yogesh Somasundar Iris C. Lu Dr. Matthew R. Mills Lisa Y. Qian Ximena Olivares Prof. Dr. Alexander D. Ryabov Prof. Dr. Terrence J. Collins 《Chemphyschem》2020,21(11):1083-1086
Understanding the catalysis of oxidative reactions by TAML activators of peroxides, i. e. iron(III) complexes of tetraamide macrocyclic ligands, advocated a spectrophotometric procedure for quantifying the catalytic activity of TAMLs for colorless targets (kII′, M−1 s−1), which is incomparably more advantageous in terms of time, cost, energy, and ecology than NMR, HPLC, UPLC, GC-MS and other similar techniques. Dyes Orange II or Safranin O (S) are catalytically bleached by non-excessive amount of H2O2 in the presence of colorless substrates (S1) according to the rate law: −d[S]/dt=kIkII[H2O2][S][TAML]/(kI[H2O2]+kII[S]+kII′[S1]). The bleaching rate is thus a descending hyperbolic function of S1 : v=ab/(b+[S1]). Values of kII′ found from a and b for phenol and propranolol with commonly used TAML [FeIII{o,o′-C6H4(NCONMe2CO)2CMe2}2(OH2)]+ are consistent with those for S1 (phenol, propranolol) obtained directly by UPLC. The study sends vital messages to enzymologists and environmentalists. 相似文献
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1,3-二羟基丙酮(DHA)是一种重要的化工原料,广泛应用于医药、化妆品及食品等领域.通过催化选择性氧化甘油制备DHA是一条高效、经济的工艺路线,而催化剂的种类及反应方式被证明对DHA的产率有较大影响.因此,结合近些年来相关文献,系统阐述了热、光和电这3种催化反应方式在甘油氧化制取DHA上的研究进展,并重点介绍了热催化路径中所选用的催化剂、相关研究实例及反应机理.最后,对甘油制备DHA的多路径选择性氧化的研究前景进行了展望. 相似文献
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VPO催化氧化正丁烷制顺酐是目前唯一实现工业化的低碳烷烃选择氧化反应。本文介绍了VPO催化机理和主要的反应网络,综述了国内外反应动力学的研究进展情况。根据人们对正丁烷氧化反应机理的不断认知及动力学模型的完整性,首次将正丁烷氧化制顺酐反应动力学的发展分为探索期、成型期和拓展期三个时期,并阐释了每个时期的特征和典型模型。探索期特征是仅考虑反应物在催化剂表面的吸附行为,成型期特征是充分考虑了产物对反应的抑制作用,拓展期特征是考虑了催化剂氧化度不断变化的动态过程并将不同氧气形式之间的相互变化引入动态模型中。从时空多尺度角度研究动力学和传递之间的相互作用是正丁烷选择氧化反应动力学下一步的研究重点,也是未来动力学研究的发展方向。 相似文献
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Lobachev V. L. Savelova V. A. Prokop'eva T. M. 《Theoretical and Experimental Chemistry》2004,40(3):161-166
The kinetics of the oxidation of diethyl sulfide (Et2S) with hydrogen peroxide, catalyzed by hydrogen carbonate and silicate anions, agree with the assumption that peroxymonocarbonate (HCO–
4) and peroxymonosilicate (HSiO–
4) anions are formed as intermediates. The rate of reaction of Et2S with HCO–
4 is about 100 times as fast as with H2O2. Transfer to aqueous–alcoholic solutions leads to an increase in the solubility of Et2S while retaining the catalytic effects. 相似文献
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Monica Bhatt Pradeep K. Sharma Kalyan K. Banerji 《Reaction Kinetics and Catalysis Letters》2000,69(2):247-252
The oxidation of lower phosphorus oxyacids by benzyltrimethylammonium chlorobromate (BTMACB) proceeds by a mechanism involving a hydride-ion transfer from oxyacids to the oxidant in the rate-determining step. 相似文献
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Andrew J. Ingram Dr. Diego Solis‐Ibarra Prof. Richard N. Zare Prof. Robert M. Waymouth 《Angewandte Chemie (International ed. in English)》2014,53(22):5648-5652
The activation of O2 is a key step in selective catalytic aerobic oxidation reactions mediated by transition metals. The bridging trinuclear palladium species, [(LPdII)3(μ3‐O)2]2+ (L=2,9‐dimethylphenanthroline), was identified during the [LPd(OAc)]2(OTf)2‐catalyzed aerobic oxidation of 1,2‐propanediol. Independent synthesis, structural characterization, and catalytic studies of the trinuclear compound show that it is a product of oxygen activation by reduced palladium species and is a competent intermediate in the catalytic aerobic oxidation of alcohols. The formation and catalytic activity of the trinuclear Pd3O2 species illuminates a multinuclear pathway for aerobic oxidation reactions catalyzed by Pd complexes. 相似文献
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Junjun Wu Lu Gem Gao Zoltan Varga Xuefei Xu Wei Ren Donald G. Truhlar 《Angewandte Chemie (International ed. in English)》2020,59(27):10826-10830
Faced with the contradictory results of two recent experimental studies [Jara‐Toro et al., Angew. Chem. Int. Ed. 2017 , 56, 2166 and Chao et al., Angew. Chem. Int. Ed. 2019 , 58, 5013] of the possible catalytic effect of water vapor on CH3OH + OH reaction, we report calculations that corroborate the conclusion made by Chao et al. and extend the rate constant evaluation down to 200 K. The rate constants of the CH3OH + OH reaction catalyzed by a water molecule are computed as functions of temperature and relative humidity using high‐level electronic structure and kinetics calculations. The Wuhan–Minnesota Scaling (WMS) method is used to provide accurate energetics to benchmark a density functional for direct dynamics. Both high‐frequency and low‐frequency anharmonicities are included. Variational and tunneling effects are treated by canonical variational transition state theory with multidimensional small‐curvature tunneling. And, most significantly, we include multistructural effects in the rate constant calculations. Our calculations show that the catalytic effect of water vapor is not observable at 200–400 K. 相似文献
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Asim Maity Sung‐Min Hyun Alan K. Wortman Prof. David C. Powers 《Angewandte Chemie (International ed. in English)》2018,57(24):7205-7209
Hypervalent iodine(V) reagents, such as Dess–Martin periodinane (DMP) and 2‐iodoxybenzoic acid (IBX), are broadly useful oxidants in chemical synthesis. Development of strategies to generate these reagents from dioxygen (O2) would immediately enable use of O2 as a terminal oxidant in a broad array of substrate oxidation reactions. Recently we disclosed the aerobic synthesis of I(III) reagents by intercepting reactive oxidants generated during aldehyde autoxidation. In this work, aerobic oxidation of iodobenzenes is coupled with disproportionation of the initially generated I(III) compounds to generate I(V) reagents. The aerobically generated I(V) reagents exhibit substrate oxidation chemistry analogous to that of DMP. The developed aerobic generation of I(V) has enabled the first application of I(V) intermediates in aerobic oxidation catalysis. 相似文献
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The paper presents shortly some of the important elements of the theory and of the practical applications of the kinetics of heterogeneous catalytic reactions. Discussed are some of the most important concepts of the kinetics of complex heterogeneous catalytic reactions,methodology of building kinetic models and mathematical treatment of experimental data,influence of heat and mass transfer,types of laboratory reactors,kinetics and nanosized catalysts and others. Examples for use of the kinetic studies for the development and application of industrial catalysts and modeling of industrial reactors are presented. 相似文献
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The bell-shaped relations between the rate constants for the oxidation of hydrocarbons by peroxynitrous acid (HOONO) and the ratio of the volumes of the aqueous and gas phases in the reactor are explained quantitatively on the assumption that the HOONO and the substrate are distributed between the gas and the solution and that OH radicals are formed in the two phases and interact with the hydrocarbon. The distribution coefficient of the HOONO between the gas and aqueous phases is determined [ = (0.4-2)·10–6]. 相似文献
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Yu-Qi Yang Wei Zhang Ming-Shuai Deng Xiu-Mei Pan Feng-Yang Bai Lei Tan 《International journal of quantum chemistry》2020,120(15):e26250
The transformation mechanism and kinetics of 2-chloro-1,1,2-trifluoroethyl-difluoromethyl-ether (CTDE, CHF2OCF2CHFCl) triggered by OH radicals are studied by density-functional theory methods and canonical variational transition state theory. The computational rate constant including small-curvature tunneling correction is found to be in commendable agreement with the experimental data. Two hydrogen abstraction channels to form the alkyl radicals of C·F2OCF2CHFCl and CHF2OCF2C·FCl are observed, and the formation of CHF2OCF2C·FCl is found to be more favorable than C·F2OCF2CHFCl kinetically and thermodynamically. Subsequent evolution of CHF2OCF2C·FCl in the presence of NO and O2 indicates that the organic nitrate (CHF2OCF2CONO2FCl) is the stable product. The dechlorinate of alkoxy radical (CHF2OCF2C(O·)FCl) is the most favorable degradation channel, and the estimated ozone depletion potential for CTDE relative to chlorofluorocarbon-11 is 0.0204, which could lead to ozone depletion as a consequence. The computed atmospheric lifetime for CTDE is found to be 3.69 years by considering the combined contributions from OH radicals and Cl atoms. The total radiative forcing and global warming potential of CTDE are, respectively, 0.547 W m−2 ppbv and 628.58 (100 years) at 298 K, suggesting that the contribution of CTDE to the greenhouse effect is moderate. 相似文献
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St. Christoskova M. Stoyanova M. Georgieva 《Reaction Kinetics and Catalysis Letters》2000,70(1):139-145
Catalytic oxidation of sulfide ions in aqueous solutions by air oxygen has been investigated using a Ni-oxide system as a catalyst. The kinetics and the selectivity of the oxidation process were studied by varying the pH, catalyst amount and reaction temperature. A reduction/oxidation mechanism of the reaction has been supposed comprising interaction between the surface active oxygen of the catalyst and HS– and reoxidizing of the reduced catalyst by the dissolved oxygen. The results obtained show that the Ni-oxide system is a promising catalyst for practical application. 相似文献
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湿法脱硫中亚硫酸盐非催化氧化本征动力学 总被引:1,自引:0,他引:1
亚硫酸盐的氧化是湿法烟气脱硫工艺中的重要过程. 利用间歇式反应装置, 研究了亚硫酸盐非催化氧化的本征反应动力学. 结果表明, 该反应分为两个阶段进行, 即富氧区的快速反应和贫氧区的慢速反应. 在富氧区, 亚硫酸盐和溶解氧的分级数分别为1.0和1.0, 反应的表观活化能为49.3 kJ•mol-1; 在贫氧区, 亚硫酸盐和溶解氧的分级数分别为2.0和0, 反应的表观活化能为122.6 kJ•mol-1. 对反应的机理进行了预测, 结果与实验现象有较好的吻合. 相似文献
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Monica Bhatt Seema Kothari Kalyan K. Banerji 《Reaction Kinetics and Catalysis Letters》2001,72(1):101-105
The oxidation of thioglycollic, thiolactic and thiomalic acids bybenzyltrimethylammonium tribromide proceeds through the formation of asulfenium cation in the slow step. 相似文献
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Control over Electrochemical Water Oxidation Catalysis by Preorganization of Molecular Ruthenium Catalysts in Self‐Assembled Nanospheres 下载免费PDF全文
Dr. Fengshou Yu David Poole III Dr. Simon Mathew Dr. Ning Yan Joeri Hessels Nicole Orth Prof. Ivana Ivanović‐Burmazović Prof. Joost N. H. Reek 《Angewandte Chemie (International ed. in English)》2018,57(35):11247-11251
Oxygen formation through water oxidation catalysis is a key reaction in the context of fuel generation from renewable energies. The number of homogeneous catalysts that catalyze water oxidation at high rate with low overpotential is limited. Ruthenium complexes can be particularly active, especially if they facilitate a dinuclear pathway for oxygen bond formation step. A supramolecular encapsulation strategy is reported that involves preorganization of dilute solutions (10?5 m ) of ruthenium complexes to yield high local catalyst concentrations (up to 0.54 m ). The preorganization strategy enhances the water oxidation rate by two‐orders of magnitude to 125 s?1, as it facilitates the diffusion‐controlled rate‐limiting dinuclear coupling step. Moreover, it modulates reaction rates, enabling comprehensive elucidation of electrocatalytic reaction mechanisms. 相似文献