Hydrogenation of Benzene at Presence of Rhodium Support Catalyst

In this article, hydrogenation of benzene in liquid phase at presence rhodium support catalyst is considered, where as carrier is used pillar structural montmorillonite obtaining from bentonite clay. The degree of using an internal surface of porous system is depended of the size particles.

Hydrosilylation of olefins over rhodium complex anchored over thioether-functionalized MCM-41

The hydrosilylation of alkenes with triethoxysilane has been achieved at 120 C in the presence of 0.01 mol%of thioetherfunctionalized MCM-41 anchored rhodium complex,affording the corresponding addition products in 68-91%yields.This supported rhodium complex can be reused several times without noticeable loss of activity.Our system not only solves the basic problems of catalyst separation and recovery,but also avoids the use of phosphine ligands.

Biphasic Catalytic Hydroformylation of 1-Dodecene in Micellar System with Cationic Gemini Surfactants

The promotion effect of cationic gemini surfactants for the hydroformylation of 1-dodecene in the organic/aqueous biphasic catalytic system is reported. The hydroformylation reaction in the presence of gemini surfactant occurred with higher turnover frequency and higher selectivity for linear aldehyde than using conventional monomeric surfactant CTAB.

Methane oxybromination over Rh-based catalysts:Effect of supports

Bromine mediation has been regarded as one of the most efficient ways to activate and convert methane to useful organics.This article reports the effects of active components(Rh,Ru,Pd and Pt)and supports(SiO2,Mg O and Al2O3)on the catalysis of methane oxybromination.Among the prepared catalysts,Rh/SiO2 is the best in performance(CH4 conversion of ca.20%and CH3Br selectivity exceeding 70%).The results reveal that support type has a notable influence on the catalytic performance of Rh,especially on product distribution.The high selectivity to CH3 Br over Rh/SiO2 is attributed to its low propensity for CH3Br oxidation.It was found that Rh small in particle size shows high catalytic activity and CH3Br selectivity.Although silicalite-1 zeolite suffers from a certain degree of structural damage due to the presence of high temperature steam,the use of silicalite-1 as support results in a performance comparable to that of Rh/SiO2.

Mechanistic Investigation on Rhodium(III)-Catalyzed Cycloaddition of 2-Vinylphenol Derivatives with Ethyne or Carbon Monoxide by DFT Study

Rhodium-catalyzed cycloaddition reaction was calculated by density functional theory M06-2X method to directly synthesize benzoxepine and coumarin derivatives.In this work,we conducted a computational study of two competitive mechanisms in which the carbon atom of acetylene or carbon monoxide attacked and inserted from two different directions of the six-membered ring reactant to clarify the principle characteristics of this transformation.The calculation results reveal that:(i)the insertion process of alkyne or carbon monoxide is the key step of the reaction;(ii)for the(5+2)cycloaddition reaction of acetylene,higher energy is required to break the Rh−O bond of the reactant,and the reaction tends to complete the insertion from the side of the Rh−C bond;(iii)for the(5+1)cycloaddition of carbon monoxide,both reaction paths have lower activation free energy,and the two will generate a competition mechanism.

Atomically Adjustable Rhodium Catalyst Synthesis with Outstanding Mass Activity via Surface-Li mi ted Cation Exchange

Rh has been widely studied as a catalyst for the promising hydrazine oxidation reaction that can replace oxygen evolution reactions for boosting hydrogen production from hydrazine-containing wastewater.Despite Rh being expensive,only a few studies have examined its electrocatalytic mass activity.Herein,surface-limited cation exchange and electrochemical activation processes are designed to remarkably enhance the mass activity of Rh.Rh atoms were readily replaced at the Ni sites on the surface of NiOOH electrodes by cation exchange,and the resulting RhOOH compounds were activated by the electrochemical reduction process.The cation exchange-derived Rh catalysts exhibited particle sizes not exceeding 2 nm without agglomeration,indicating a decrease in the number of inactive inner Rh atoms.Consequently,an improved mass activity of 30 A mg_(Rh)^(-1)was achieved at 0.4 V versus reversible hydrogen electrode.Furthermore,the two-electrode system employing the same CE-derived Rh electrodes achieved overall hydrazine splitting over 36 h at a stable low voltage.The proposed surface-limited CE process is an effective method for reducing inactive atoms of expensive noble metal catalysts.

烯烃氢甲酰化反应的催化技术进展

综述了烯烃氢甲酰化反应工业化的不同催化体系,分析了各自的技术特点,阐述了其新进展情况,并对催化剂的今后发展进行了展望。

甲醇羰基化制醋酸催化剂体系的研究

介绍了均相钴基催化剂、铑基催化剂、铱基催化剂和多相体系催化剂的研究应用及不同催化剂的优缺点,分析了甲醇羰基化催化剂的研究发展方向。

新型表面活性膦在长链烯烃氢甲酰化反应中的助催化作用

考察了新型表面活性膦配体DPPTS(对-十二烷基苯基二苯基膦的磺酸钠盐)和OPPTS(对-辛基苯基二苯基膦的磺酸钠盐)在铑络合物催化的水/有机两相长链烯烃氢甲酰化反应中的助催化作用.在催化烯烃氢甲酰化反应时,观察到烯烃与膦配体之间有一定的链长匹配效应;含DPPTS的催化剂体系在低膦/铑比条件下表现出比含表面活性剂十六烷基三甲基溴化铵和水溶性配体三苯基膦三磺酸钠的催化剂体系高得多的催化活性,而且铑流失到有机相极少,仅为加入总铑量的0.8%.这种亲水基团和磷原子处于碳链同一端的表面活性膦配体比文献报道的亲水基团和磷原子分别处于碳链两端的表面活性膦配体具有更好的助催化活性.

烯烃氢甲酰化反应研究进展

本文综述了烯烃氢甲酰化反应的催化剂从钴配合物到铑配合物和从均相催化体系到两相催化体系的发展过程。比较了三种催化剂和两个催化体系的特点、应用情况及研究工作进展.

The influence of different monodentate P-ligand mixtures on Rh-catalyzed 1-butene hydroformylation

Four monodentate P-ligands and their mixtures（six groups of double-ligand systems,four groups of triple-ligand systems and one group of tetra-ligand system）were used with Rh（acac）（CO）2（acac=acetylacetonate）or Rh（acac）CO（PPh3）as the catalyst in the hydroformylation reaction of 1-butene.It was found that different Rh catalysts showed little difference in the catalysis performance.The general order of catalysis performance is doubleligand system 〉 single-ligand system〉triple-ligand system 〉 tetra-ligand system.Some synergistic effect in the double-ligand system was detected which needs a further investigation.

Process optimization study on the carbonylation of methyl acetate

Acetic anhydride is the important organic chemical raw material, and is used widely in chemical industry,pharmaceutical industry, dyes, spices and other fields. In this paper, the process of carbonylation of methyl acetate in rhodium iodine catalyst system was studied, and the suitable reaction conditions were determined.At the same time, the kinetic model was established. The optimum reaction conditions were as follows： the reaction pressure was 5 MPa, the hydrogen content was 8%, the amount of iodomethane was 15%, the amount of lithium iodide was 3%, the reaction temperature was 150 ℃ and the reaction time is 3 h. Under the above reaction conditions, the selectivity of the reaction is close to 100% and the conversion is as high as 92%. The macroscopic kinetic model of the reaction was established in the temperature range of 120 ℃–150 ℃. The reaction is an irreversible reaction without the formation of by-products and the dynamic equation is also given in the Conclusions section.

Synthesis of spiropyrrolidine oxindoles through Rh(Ⅱ)-catalyzed olefination/cyclization of diazooxindoles and vinyl azides

A simple and efficient process involving the Rh(II)-catalyzed[1+1+3]annulation of diazooxindoles and vinyl azides has been developed for the synthesis of spiropyrrolidine oxindoles with potential biological activity and significant synthetic applications.This process involves a novel rhodium-catalyzed olefination of diazo compounds,followed by annulation with vinyl azides.This method is compatible with a broad range of substrates and affords moderate to good yields under mild reaction conditions.

羰基合成醋酐的动力学研究与工艺过程模拟

以Li I为促进剂的铑-碘液相催化剂体系作催化剂,在150—190℃的温度范围和5 MPa压力的实验条件下,对醋酸甲酯羰基合成醋酐的反应动力学进行了研究,建立了一级不可逆反应动力学模型,其反应活化能为5.582×104J/mol、指前因子为1.371×10~4min^(-1)。同时,基于该反应动力学方程,完成了16万t/a醋酐生产的工艺过程模拟计算。在处理量相同的情况下,文中催化剂体系下的醋酸甲酯转化率、醋酐收率都提高了10%左右,生产能力也提高了27.4%,而能耗则降低了4.4%。因此,文中催化剂体系在催化性能上体现了优越性,具有一定的优势,可以提高反应的转化率和生产能力,降低反应过程中的能耗,提高生产效率。

Rhodium-catalyzed aerobic N-alkylation of sulfonamides with alcohols

By using the famous Wilkinson＇s catalyst, N-alkylation of sulfonamides can be easily realized under mild aerobic conditions by using alcohols as the alkylating reagent, giving monoalkylated sulfonamides in high yields and selectivities with water produced as the only byproduct. This advantageous aerobic method is potentially general in substrate scope that it can also be applied to other amides, amines and alcohols.

Mechanism and reactivity of rhodium-catalyzed intermolecular [5+1] cycloaddition of 3-acyloxy-1,4-enyne(ACE) and CO:A computational study

The first theoretical study on the mechanism of [RhCl（CO）2]2-catalyzed [5 ＋ 1] cycloadditions of 3- acyloxy-1,4-enyne （ACE） and CO has been performed using density functional theory （DFT） calculations. The effect of ester on reactivity of this reaction has been investigated. The computational results have revealed that the preferred catalytic cycle involves the sequential steps of 1,2-acyloxy migration, CO insertion, reductive elimination to form ketene intermediate, 6π-electroncyclization, and aromatization to afford the resorcinol product. The 1,2-acyloxy migration is found to be the rate-determining step of the catalytic cycle. The electron-rich p-dimethylaminobenzoate substrate promotes 1,2-acyloxy migration and significantly increases the reactivity by stabilizing the positive charge building up in the oxocyclic transition state.