A simple and efficient approach for the sulfonylation of indoles catalyzed by CuI

In this paper, a simple and efficient protocol for the chemoselective sulfonation of indoles using aryl sulfonyl chlorides in the presence of CuI is reported. The reaction proceeds under mild conditions and is applicable to indoles bearing a selection of functional groups without NH protection.     

负载型Ni催化剂上对硝基酚加氢合成对氨基酚的研究

研究了以硅藻土、锐钛型TiO2、Al2O3和高岭土为载体制备的负载型Ni催化剂催化对硝基酚加氢制备对氨基酚的活性。采用XRD与TPR技术表征了催化剂的结构与还原性能。负载型催化剂具有单一的对氨基酚选择性。NiO与载体硅藻土和锐钛型TiO2有弱的相互作用,制备的催化剂还原后有较高的催化活性。Al2O3和高岭土与NiO有较强的相互作用,抑制了还原后金属Ni的催化加氢活性。     

对硝基苯酚催化加氢制备对氨基苯酚的工艺研究

以Pd/C作为催化剂,对对硝基苯酚催化加氢制备对氨基苯酚进行了研究,考察了溶剂的种类、催化剂Pd的含量、反应温度、反应压力、反应时间等因素对反应的影响。结果表明,反应的最适宜条件为:对硝基苯酚40 g,无水乙醇240 mL,反应压力为0.55 MPa,反应温度为95℃,3%Pd/C催化剂1.5 g,反应时间5 h,对氨基苯酚产率在87%左右,质量分数大于99%。     

Imidazolium ion tethered TsDPENs as efficient water-soluble ligands for rhodium catalyzed asymmetric transfer hydrogenation of aromatic ketones

An imidazolium ion tethered TsDPEN has been synthesized readily and used as a water-soluble ligand for [Cp*RhCl₂]₂ catalyzed asymmetric transfer hydrogenation (ATH) of aromatic ketones in water. This process provided the secondary alcohols in moderate to excellent conversions (up to 100%) with high enantioselectivities (up to 98% ee) under mild reaction conditions without adding any surfactants. The catalytic system is highly effective with the substrate to catalyst (S/C) ratio of 500 and low hydride donor loading of 1.5 equiv. of HCO₂Na. The procedure presented is simple and makes this method suitable for practical use.     

The kinetics of ethylene hydrogenation catalyzed by metallic palladium

The activity of Pd(111) for ethylene hydrogenation is measured using a high-pressure reactor incorporated into an ultrahigh vacuum chamber for temperatures between 300 and 475 K, ethylene pressures between 50 and 300 Torr and hydrogen pressures from 45 to 600 Torr. The reaction rate is found to be rapid with turnover frequencies up to 400 reactions/site/s (where rates are referenced to the atom site density on the (111) face of palladium). The measured activation energy is 35 kJ/mol. A hydrogen reaction order of 1.02 was found at a reaction temperature of 300 K and an ethylene pressure of 100 Torr, where the hydrogen reaction order was found to depend on temperature. A negative reaction order of –0.22 was found in ethylene pressure at a reaction temperature of 320 K and a hydrogen pressure of 100 Torr. The reaction rates are in good agreement with values obtained on silica-supported palladium and with other work on palladium single crystals.     

Selective hydrogenation catalyzed by polymeric palladium and platinum complexes

An organic polymer containing a diphenylbenzyl-phosphine functional group, combined with PtCl₂ or PdCl₂, gives a heterogeneous hydrogenation catalyst which is analogous to the homogeneous catalysts PtCl₂(Pø₃)₂ and PdCl₂(Pø₃)₂. In the hydrogenation of soybean methyl ester, this catalyst is highly selective, the products being monoene and diene, with almost no increase in the content of saturated ester.     

Deposition of carbon and its hydrogenation catalyzed by nickel

Formation of carbon on nickel sheet from benzene vapor carried by hydrogen was studied at a temperature range from 520 to 730°C. A maximum rate was observed at about 630°C, above which the deposition rate decreased rapidly. The carbon formed was hydrogenated in situ. Methane was the main gaseous product and a maximum rate was observed at about 670°C. Very high reactivity of deposited carbon toward hydrogenation was ascribed to the catalytic action of nickel particles dispersed in the carbon. The hydrogenation rates were divided into three zones and possible interpretations are discussed. A mechanism which is a reverse process to deposition was suggested. The decrease of the hydrogenation rate at higher temperatures was due to the equilibrium among carbon, hydrogen and methane, where carbon was more reactive than graphite.     

Recyclable,green and efficient epoxidation of olefins in water with hydrogen peroxide catalyzed by polyoxometalate nanocapsule

A practical method for the selective epoxidation of alkenes was discovered using H_xPMo₁₂O₄₀ ⊂ H₄Mo₇₂Fe₃₀(CH₃COO)₁₅O₂₅₄ as a catalyst in the presence of H₂O₂ as a green oxidant. However, the simple catalyst system involving polyoxometalates and H₂O₂ exercised the most successful system in obtaining high to excellent yields of epoxide products for different alkenes, including aromatic and aliphatic alkenes at room temperature in water. The effectiveness of this catalyst is evidenced by 99% selectivity to epoxide and 97–99% efficiency of H₂O₂ utilization. The stability of PMo ⊂ Mo₇₂Fe₃₀ under a catalytic reaction has been confirmed by XRD, FT-IR and Raman spectroscopies.     

温控相分离纳米Pd催化α, β-不饱和酮的选择加氢

以Pd(OAc)2、[CH3(OCH2CH2)22N+Et3][CH3SO3–](ILPEG1000)为原料,制得温控相分离Pd纳米催化剂,对其进行了UV-Vis和TEM表征.常压氢气条件下在α,β-不饱和酮的选择加氢反应中,Pd纳米催化剂显示了优异的催化性能.在最佳的反应条件下〔n(查尔酮):n(Pd)=500:1,n(ILPEG1000):n(Pd)=100:1,90℃,20 min,p=1.01×105 Pa(H2气球)〕,查尔酮的转化率和C==C双键加氢产物的选择性均>99％.Pd纳米催化剂易于与产物分离并可以循环使用6次,循环使用6次后转化率和选择性均>99％.转化频率(TOF)可达1470 h–1,高于目前文献中报道的常压氢气条件下过渡金属纳米催化剂催化查尔酮选择加氢反应的最高值(870 h–1).     

Effects of porous oxide layer on performance of Pd-based monolithic catalysts for 2-ethylanthraquinone hydrogenation

Pd/oxide/cordierite monolithic catalysts(oxide = Al_2O_3, SiO_2 and SiO_2\\Al_2O_3) were prepared by the impregnation method. The results of ICP, XRD, SEM–EDX, XPS and N_2 adsorption–desorption measurements revealed that the Pd penetration depth increased with increasing the thickness of oxide layer, and the catalysts with Al_2O_3 layers had the larger pore size than those with SiO_2 and SiO_2\\Al_2O_3 layers. Catalytic hydrogenation of 2-ethylanthraquinone(eA Q), a key step of the H_2O_2 production by the anthraquinone process, over the various monolithic catalysts(60 °C, atmosphere pressure) showed that the monolithic catalyst with the moderate thickness of Al_2O_3 layer(about 6 μm) exhibited the highest conversion of e AQ(99.1%) and hydrogenation efficiency(10.0 g·L~(-1)). This could be ascribed to the suitable Pd penetration depth and the larger pore size, which provides a balance between the distribution of Pd and accessibility of active sites by the reactants.     

铑催化剂催化烯烃不对称加氢反应研究进展

不对称催化氢化反应具有完美的原子经济性和清洁高效等特点,是最受青睐的不对称合成方法之一。C=C、C=O、C=N的不对称加氢反应仍主要依赖过渡金属催化剂。过渡金属催化剂,尤其是铑催化剂,催化碳碳双键的不对称加氢反应仍是一个不断发展的领域。本文对近年来利用铑催化剂催化烯烃进行不对称氢化反应的研究进展进行了综述,着重介绍了铑-双膦配体催化体系催化烯烃不对称加氢反应的催化机理,以及铑催化剂在烯胺、不饱和羧酸及衍生物、烯醇酯和非官能团烯烃不对称氢化中的应用,并通过对现有文献的总结指出了今后铑催化剂催化烯烃氢化反应的研究重点,即:①铑-单膦配体催化烯烃不对称氢化反应的作用机理须待提出;②非官能化底物不对称催化氢化反应的手性配体亟待拓宽。     

用金属间化合物催化的丁腈橡胶溶液加氢动力学

在利用金属间化合物作为催化剂实现了常压丁腈橡胶溶液加氢的基础上,对丁腈橡胶在ＴＨＦ溶液中加氢的动力学进行了研究。     

手性铝化合物催化不对称氢转移反应的研究

以手性铝化合物为催化剂，异丙醇为氢源，进行芳香酮的不对称氢转移反应。在考察的酮类底物中，大部分具有较高收率，产物光学收率ee最高为83%。当配体和催化剂物质的量比为1时，反应效果最好。又考察一些手性二醇配体，其中，茚衍生的配体有着较好的手性诱导性能。     

A green procedure for the protection of carbonyls catalyzed by novel task-specific room-temperature ionic liquid

A cheap and recyclable task-specific ionic liquid N,N,N-trimethyl-N-propanesulfonic acid ammonium hydrogen sulfate [TMPSA]HSO₄ was synthesized as dual solvent–catalyst for the protection of carbonyls via formation of acetals or ketals. The satisfactory results were obtained for the protection of carbonyls as cycloacetals or ketals with diols under the mild conditions. The products could be separated from the catalyst simply by decantation and the catalyst could be recycled and reused for several times without noticeably decreasing the catalytic activity after removal of the water.     

HY沸石分子筛催化合成青叶(噁)烷

研究了以异丁醛和2,2,4-三甲基-1,3-戊二醇(TMPD)为原料,HY沸石分子筛为催化剂合成了青叶口恶烷的反应,考察了醛醇比、反应时间、带水剂、催化剂用量与其循环使用性对该反应的影响。结果表明:与传统催化体系相比,该体系不仅具有相当的转化率和选择性,而且具有催化剂分离简单、可循环使用的优点。     

LaCl3/nano-SiO2: A novel nanocatalyst for efficient synthesis of functionalized 2,3-dihydroquinazolinones

The novel LaCl₃/nano-SiO₂ catalyst was synthesized by adsorption of LaCl₃ on nano-SiO₂ and characterized by powder XRD, FE-SEM, TEM, EDX, FT-IR spectra, BET surface area, TPD of ammonia and ICP-AES analyses. It was found as an efficient catalyst for the one-pot synthesis of 2,3-dihydroquinazolinones. All reactions proceeded with high efficacy under solvent-free conditions and gave excellent yields avoiding tedious workup and purification of products.     

负载型双金属催化剂催化间苯二甲腈加氢制备间苯二甲胺

采用浸渍法制备活性炭负载Ni、Ru、Rh单金属及Ni-Ru、Ru-Rh双金属催化剂,考察反应温度、反应压力和m(催化剂)∶m(间苯二甲腈)对间苯二甲腈加氢制备间苯二甲胺的影响。结果表明,Ni-Ru/C催化活性高于Ru/C和Ni/C,通过分步浸渍法制备的Ni-Ru/C催化活性优于一步浸渍法。以甲醇和甲苯为混合溶剂,在m(催化剂)∶m(间苯二甲腈)=1∶20、反应温度120℃、反应压力4.0 MPa和1 000 r·min-1条件下,无需加入碱性抑制剂,间苯二甲胺收率最高可达97.78%。     

载体对镍系催化剂催化对硝基苯酚加氢制对氨基苯酚的影响

采用浸渍法制备了Ni/Al2O3、Ni/TiO2、Ni/活性炭和Ni/硅藻土等一系列镍系催化剂,研究了其催化对硝基苯酚加氢制备对氨基苯酚的活性.负载型镍系催化剂具有单一的对氨基苯酚选择性.不同载体负载的催化剂上对硝基苯酚的转化率顺序为:Ni/活性炭>Ni/硅藻土>Ni/TiO2Ni/Al2O3.高比表面积以及金属镍在活性炭上的良好分散性使得Ni/活性炭催化活性最高;NiO与硅藻土间弱相互作用,有助于提高活性;而NiO与Al2O3之间存在相互作用抑制了还原后金属镍的催化加氧活性.     

Pt-Fe/CNTs催化对氯硝基苯选择加氢的研究

基于乙醇分子易被碳纳米管容纳,分别用H_2PtCl_6和Fe(NO_3)_3的乙醇溶液和先乙醇吸附饱和后再用H_2PtCl_6和Fe(NO_3)_3水溶液浸渍碳纳米管,将0.3%Pt-4%Fe负载于碳纳米管内和管外,考察了其催化对氯硝基苯选择加氢制备对氯苯胺性能,并采用TEM、XRD、XPS等对其结构进行了表征。结果表明,碳纳米管内负载0.3%Pt-4%Fe(0.3%Pt-4%Fe/in-CNTs)对催化对氯硝基苯加氢制备对氯苯胺具有优异性能。乙醇为溶剂、较高的H_2压力和反应温度对0.3%Pt-4%Fe/in-CNTs催化对氯硝基苯加氢制备对氯苯胺有利。催化剂与对氯硝基苯质量比1∶50,30℃和1 MPa H_2条件下反应50 min,p-CAN收率达100%,并且催化剂重复使用3次,活性无明显下降。