硒催化羰基化合成苯基吡啶基脲

采用硒粉催化一氧化碳还原羰基化法,由硝基苯衍生物与氨基吡啶类直接合成一系列含取代基的苯基吡啶基脲类化合物。该合成方法简单,操作易行,最高收率可达70%,可取代传统的光气化法。对所得产品进行了熔点测定。对部分产物进行了红外光谱、高效液相色谱、核磁鉴定。

硒催化羰基化反应若干进展

采用廉价的催化剂代替昂贵的金属,低成本的一氧化碳代替氢气乃至光气,一直是人们追求的目标.综述了非金属硒在含碳、氮、氧、硫类有机化合物中的催化羰基化反应,以及在Se/CO/H2 O体系中一些有机化合物的高选择性还原反应,介绍了近期的一些新进展.催化剂量的硒在温和条件下,即可活化一氧化碳而直接进行羰基化和还原反应,特别是发展了将硝基化合物的还原羰基化与胺的氧化羰基化相结合,合成一系列精细化学品和生物化学品.催化剂硒在催化反应中表现出反应过程相转移的特性,兼具了多相催化与均相催化的优点,是反应过程相转移概念中的典型实例.硒催化反应的特点是反应物转化率高,反应选择性专一,原子经济性高,对环境友好。

羰基合成与羰基化催化剂的研究进展及工业化应用

羰基合成反应在催化化学中扮演着重要角色,并通过新合成方法和新物质的多样性创制成为生产多种含氧化合物及高附加值产品的重要途径。而恰当的催化体系是羰基合成工艺和技术的关键,也是羰基化反应实现工业化的研究重点。首先从不同的反应底物、不同的羰基来源以及不同的反应类型等方面对羰基合成反应及研究进展进行概述,然后从以金属和非金属为活性中心的角度对羰基化催化剂的应用及研究进展进行阐述,最后列举了几种典型的羰基合成反应及羰基化催化剂在工业上的应用。

硒催化取代硝基苯的羰基化合成不对称取代脲类除草剂

以硒作催化剂 ,二甲胺为共试剂 ,直接利用一氧化碳进行取代硝基苯的还原羰基化反应合成了非草隆、灭草隆和伏草隆等 3种除草剂 ,并对反应条件如溶剂、温度、压力、物料比等的影响作了详细的考察。此法反应步骤简单 ,反应条件温和 ,不对称取代脲类除草剂选择性为 1 0 0 % ,产率为 30 5 0 % -5 0 5 0 %。

硒催化反应最新研究进展

价廉易得的非金属硒作催化剂不但具有良好的催化活化CO的性能及反应过程相转移催化特性,而且能循环使用.用Se/CO催化体系替代贵金属催化羰基化法及剧毒的光气法进行羰基化反应及用Se/CO/H2O催化体系进行高选择性的还原反应,具有反应条件温和、原子经济性高、成本低、环境友好、路线简短、后处理方便等优点,因而引起人们的广泛关注.概述了近几年来硒催化羰基化反应和硒催化选择性还原反应的最新研究进展,并对硒催化反应的发展趋势进行了展望.

Controlling Reactivity of Palladium Amides for Selective Carbonylation towards Urea and Oxamide Derivatives

Carbonylation reactions,crucial for carbonyl group incorporation,struggle with the inherent complexity of achieving selective mono-or double-carbonylation on single substrates,often due to competing reaction pathways.Herein,our study introduces a strategy employing palladium amides,harnessing their unique reactivity control,to direct the selective carbonylation of amines for the targeted synthesis of urea and oxamide derivatives.The palladium amide structure was elucidated using single-crystal X-ray diffraction.Controlled experiments and cyclic voltammetry studies further elucidate that the oxidation of palladium amide or its insertion into a carbonyl group diverges into distinct pathways.By employing sodium percarbonate as an eco-friendly oxidant and base,we have successfully constructed a switchable carbonylation system co-catalyzed by palladium and iodide under room temperature.The utilizing strategy in this study not only facilitates effective control over reaction selectivity but also mitigates the risk of explosions,a critical safety concern in traditional carbonylation methods.

黄酮化合物的合成新方法

黄酮类化合物具有广泛而重要的生物活性和药理作用 ,其化学合成研究受到普遍重视 .经典的合成方法主要是查耳酮路线和 β 丙二酮路线 .近年来有很多新技术、新方法在黄酮化合物合成中得到了巧妙的应用 .对近年来出现的新的改进的Baker Venkataraman法。

绿色化学和一氧化碳的综合利用

本文阐述了绿色化学的概念 ,并介绍了在多个领域一氧化碳的大量应用实例及其与绿色化学的关系。

Effect of Calcination Temperature on Catalytic Activity and Textual Property of Cu/HMOR Catalysts in Dimethyl Ether Carbonylation Reaction

The effect of calcination temperature on the catalytic activity for the dimethyl ether （DME） carbonylation into methyl acetate （MA） was investigated over mordenite supported copper （Cu/HMOR） prepared by ion-exchange process. The results showed that the catalytic activity was obviously affected by the calcination temperature. The maximal DME conversion of 97.2% and the MA selectivity of 97.9% were obtained over the Cu/HMOR calcined at 430 ℃ under conditions of 210 ℃, 1.5 MPa, and GSHV of 4883 h^-1. The obtained Cu/HMOR catalysts were characterized by powder X-ray diffraction, N2 absorption, NH3 temperature program desorption, CO temperature program desorption, and Raman techniques. Proper calcination temperature was effective to promote copper ions migration and diffusion, and led the support HMOR to possess more acid activity sites, which exhibited the complete decomposing of copper nitrate, large surface area and optimum micropore structure, more amount of CO adsorption site and proper amount of weak acid centers.

Effect of NH_4^+ exchange on CuY catalyst for oxidative carbonylation of methanol

NaY and ion exchanged NaNH4Y zeolite with NH4NO3 were used as the support to prepare CuY cata‐lysts by a high temperature anhydrous interaction between the support and copper （II） acety‐lacetonate Cu（acac）2. The catalysts were used for the oxidative carbonylation of methanol to dime‐thyl carbonate （DMC） at atmospheric pressure. The textural and acidic properties of NaNH4Y zeolite and the CuY catalysts were investigated by X‐ray diffraction, scanning electron microscopy, N2 ad‐sorption‐desorption, temperature programmed reduction of H2, X‐ray photoelectron spectroscopy and temperature programmed desorption of NH3. With increasing NH4NO3 concentration, the NH4＋exchange degree increased while the crystallinity of the zeolite remained intact. Crystalline CuO was formed when the NH4＋exchange degree of NaNH4Y was low, and the corresponding CuY catalyst showed low catalytic activity. With increasing of the NH4＋exchange degree of NaNH4Y, the content of surface bound Cu＋active centers increased and the catalytic activity of the corresponding CuY catalyst also increased. The surface bound Cu＋content reached its maximum when the NH4＋ex‐change degree of NaNH4Y reached towards saturation. The CuY exhibited optimal catalytic activity with 267.3 mg/（g·h） space time yield of DMC, 6.9%conversion of methanol, 68.5%selectivity of DMC.

Synthesis of Methyl Acetate by Dimethyl Ether Carbonylation over Cu/HMOR： Effect of Catalyst Preparation Method

Dimethyl ether carbonylation to methyl acetate was comparatively investigated over mor- denite supported copper （Cu/HMOR） catalysts prepared by different methods including evaporation, urea hydrolysis, incipient wetness impregnation and ion-exchange. The results showed that Cu/HMOR prepared via iron-exchange method exhibited the highest catalytic activity due to the synergistic effect of active-site metal and acidic molecular sieve support. Conversion of 95.3% and methyl acetate selectivity of 94.9% were achieved under conditions of 210℃, 1.5 MPa, and GSHV of 4883 h-1. The catalysts were characterized by nitrogen absorption, X-ray diffraction, NH3 temperature program desorption, and CO temperature program desorption techniques. It was found that Cu/HMOR prepared by ion-exchange method possessed high surface area, moderate strong acid centers, and CO adsorption centers, which improved catalytic performance for the reaction of CO insertion to dimethyl ether.

国外专利文献

MOR型沸石选择性去铝酸化MOR型沸石选择性去铝酸化的制备方法如下:沸石加载单价金属,接着用蒸汽处理,去铝酸化的沸石再转换成氢型和/或加载金属,这样制备的沸石适用于催化羰基化过程生产醋酸/或醋酸甲酯。

Ni-mediated Liquid Phase Reduction of Carbonyl Compounds in the Presence of Atmospheric Hydrogen

An efficient reduction system of benzaldehyde with hydrogen under ambient pressure was developed using facile NiO catalyst. The non-aromatic solvents such as cyclohexane, tetrahydrofuran (THF) and n-hexane, and the addi-tive with strong basicity e.g. KOH, were necessary for smooth conversion of the substrate. That the catalyst can be recov-ered and reused for nine times without loss of catalytic activity indicates that this catalyst is a recyclable one for benzal-dehyde reduction.

Study on Direct Synthesis of Diphenyl Carbonate with Heterogeneous Catalytic Reaction (V) Screening Catalysts and Optimizing Synthesis Conditions

Pd/LaxPbyMnOz, Pd/C, Pd/molecular sieve and Pd-heteropoly acid catalysts for direct synthesis of diphenyl carbonate (DPC) by heterogeneous catalytic reaction were compared and the results of DPC synthesis indicated that the catalyst Pd/LaxPbyMnOz had higher activity. The Pd/LaxPbyMnOz catalyst and the support was characterized by XRD, SEM and TEM, the main phase was Lao.szPbo.asMnOa and the average diameter could be about 25.4nm. The optimuna conditions for synthesis of DPC with Pd/LasPbyMnOz were determined by orthogonal experiments and the experimental results showed that reaction temperature was the first factor of effect on the selectivity and yield of DPC, and the concentration of O2 in gas phase also had significant effect on selectivity of DPC. The optimum reaction conditions were catalyst/phenol mass ratio l to 50, pressure 4.5MPa, volume concentration of O2 25%, reaction temperature 60℃ and reaction time 4 h. The maximum yield and average selectivity could reach 13% and 97% respectively in the batch operation.

Lewis base-assisted Lewis acid-catalyzed selective alkene formation via alcohol dehydration and synthesis of 2-cinnamyl-1,3-dicarbonyl compounds from 2-aryl-3,4-dihydropyrans

Acid-catalyzed dehydration of alcohols has been widely employed for the synthesis of alkenes. However, activated alcohols when employed as substrates in dehydration reactions are often pla-gued by the lack of alkene selectivity. In this work, the reaction system can be significantly improved through enhancing the performance of Lewis acid catalysts in the dehydration of activated alcohols by combining with a Lewis base. Observations of the reaction mechanism revealed that the Lewis base component might have changed the reaction rate order. Although both the principal and side reaction rates decreased, the effect was markedly more observed on the latter reaction. Therefore, the selectivity of the dehydration reaction was improved. On the basis of this observation, a new route to synthesize 2-cinnamyl-1,3-dicarbonyl compounds was developed by using 2-aryl-3,4- di-hydropyran as a starting substrate in the presence of a Lewis acid/Lewis base combined catalyst system.