Search

The Ru atomic catalyst-doped GaN (Ru-GaN) model was established by density functional theory (DFT), and the adsorption models of transformer oil dissolved gas (CO, H2, CH4, C2H2, C2H4 and C2H6) by a Ru-GaN monolayer were optimised. From the adsorption energy, differential charge density, electron state density, molecular orbital and desorption properties, the modification mechanism of Ru-GaN and the gas-sensitive response mechanism of Ru-GaN to CO, H2, CH4, C2H2, C2H4 and C2H6 were systematically studied. The introduction of metal Ru increases the defect state of GaN to provide the active site for the adsorption of gas molecules and reduces the adsorption barrier of GaN to gas molecules. The results show that Ru metal-doped GaN can adsorb CO, C2H2 and C2H4 by chemisorption, with Eads of −2.068 eV, −2.422 eV and −1.877 eV and Qt of −0.1696 e, −0.0671 e, −0.1222 e. In addition, charge redistribution leads to changes in the density of states, molecular orbitals and the conductivity of CO, C2H2 and C2H4 adsorption systems, indicating excellent gas sensitivity to the three gases. The desorption time further verified that Ru-GaN is an ideal CO and C2H2 gas scavenger and a recyclable material for C2H4 gas sensors. [ABSTRACT FROM AUTHOR]

Oxidation of Natural Products Hypervalent iodine reagent mediated oxidation of Juncuenin B gave stereoisomeric quinone products with methoxy and ethoxy substituents based on the solvent used (Scheme 259). Due to steric reasons in the case of Au metal catalyst, the C SB 4 sb alkynylated product is formed; whereas, in the case of Rh catalyst, TIPS-EBX acts as Bronsted base and gives the C SB 8 sb alkynylated product (Scheme 276).[82] Conclusion This review discusses the preparation of new hypervalent iodine(III) reagents, having cyclic, bicyclic, pseudocyclic and spirocyclic structures, as well as hypervalent Iodine(V) reagents. Oxidation Reactions Anodic oxidation generated hypervalent iodine reagent, in combination with ruthenium catalyst, mediates C-H oxygenation of aromatic amides and ketones (Scheme 245). 1,3-Iodoamination of 2-methyl indoles using hypervalent iodine reagent as oxidant, bis(sulfonyl)imides as amine and PIDA as iodine source to afford 2-aminomethyl-3-iodoindole was reported (Scheme 221). [Extracted from the article]

With respect to the CM protocol between cholesterol allyl ether and glucose allyl amide, the results are listed in Table 1. In conclusion, the use of the robust Hoveyda-Grubbs second generation catalyst and the two readily accessible terminal olefins demonstrated the applicability of cross-metathesis for the preparation of glycosteroids under mild conditions. Cross-metathesis between allyl ether of cholesterol ( B 2 b ) and allyl amide of glucose ( B 3 b ). [Extracted from the article]

Chemical utilization of CO2 is one of the fundamental strategies to synthesize value-added chemicals and reduce the CO2 emission. N-formyl-1,2,3,4-tetrahydroisoquinoline derivatives (FTHIQs) are important chemicals for the synthesis of medical intermediates and alkaloids. N-formylation of isoquinoline derivatives (IQs) with CO2 is an ideal protocol to synthesize the FTHIQs and utilize the CO2 source. In the present work, we prepared a heterogeneous Ru/ZIF-8 catalyst with a Ru loading of 2 wt% by a simple impregnation method and assessed its performances in the N-formylation of IQs and CO2 with H2. The Ru/ZIF-8 catalyst offered high IQ conversion of 98% and FTHIQ selectivity of 93% in the reaction under relatively mild conditions (150 °C, 2 MPa CO2, and 6 MPa H2). The catalyst possessed good universality and reusability, showing a potential in wide application of N-formylation of highly unsaturated nitrogen-containing isoquinolines. [ABSTRACT FROM AUTHOR]

Following nanoarchitectural approach, mesoporous halloysite nanotubes with internal surface composed of alumina were loaded with 5-6 nm RuCo nanoparticles by sequential loading/ reduction procedure. Ruthenium nanoclusters were loaded inside clay tube by microwaveassisted method followed by cobalt ions electrostatic attraction to ruthenium during wetness impregnation step. Developed nanoreactors with bimetallic RuCo nanoparticles were investigated as catalysts for the Fischer-Tropsch process. The catalyst with 14.3 wt.% of Co and 0.15 wt.% of Ru showed high activity (CO conversion reached 24.6%), low selectivity to methane (11.9%), CO2 (0.3%), selectivity to C5+ hydrocarbons of 79.1% and chain growth index (α) = 0.853. Proposed nanoreactors showed better selectivity to target products combined with high activity in comparison to the similar bimetallic systems supported on synthetic porous materials. It was shown that reducing agent (NaBH4 or H2) used to obtain Ru nanoclusters at first synthesis step played a very important role in the reducibility and selectivity of resulting RuCo catalysts. [ABSTRACT FROM AUTHOR]

With respect to the azide component, the reaction proceeded with average to good yields with benzyl azide and other substituted aliphatic azides while aromatic azides such as azidobenzene B 37(e) b failed to give the desired triazole derivatives. Emerging Approaches for Synthesis of 1,2,3-Triazole Derivatives. Microwave assisted synthesis Acridone-containing triazole derivatives were obtained by both conventional and microwave methods (Scheme 31).[48] The dipolar cycloaddition of an alkyne-containing acridone ( B 142 b ) and an acyl azide ( B 143 b ) in the presence of copper sulphate and sodium ascorbate furnished triazole derivatives ( B 144 b ). The corresponding click reaction using Ru metal as a catalyst produced 1,5-disubstituted triazole derivatives; however, the heterogeneous Ru catalyst gave 1,4-disubstituted triazole derivatives in average to excellent chemical yield. [Extracted from the article]

A small loading of highly dispersed Ru on Ni/MgAl2O4 catalyst was investigated in the dry reforming of methane (DRM) process. The catalysts were synthesized by impregnation and deposition-precipitation methods; the DRM reaction was performed at CH4/CO2/N2 = 1/1/1 and 600‒750°C. The bimetallic Ni‒Ru catalysts exhibited improved reducibility and metal dispersion compared with that of the Ni catalyst. Among the synthesized catalysts, the Ru(D)/Ni(I)/MgAl2O4 catalyst had the highest metal dispersion (7.23%) and largest amount of CO2 desorption (135 μmol/g). Thus, this catalyst exhibited the highest CH4 conversion (85.6%) at 750°C. Additionally, coke deposition of only 2.69% occurred during the stability test. [ABSTRACT FROM AUTHOR]

The decarboxylation of 9-cis-octadecenoic (oleic) acid to aromatic and aliphatic hydrocarbons suitable as blend components for aviation fuel applications utilising ruthenium dodecacarbonyl [Ru3(CO)12] with a variety of other catalysts is presented. Due to the different relative rates of decarboxylation and hydrogenation/dehydrogenation, different product distributions are possible when the catalyst is varied. Chloro-1,5-cyclooctadiene iridium (I) dimer [(C8H12IrCl)2] gave a similar conversion to the ruthenium system but provided an altered product distribution. Aromatic contents of up to 35% were achieved in the iridium system, thereby providing a wider range of blending options for fuel producers. Additionally, both catalytic systems were found to decarboxylate high-oleic soybean oil fatty acids, giving a product of similar energy content to that obtained using high grade oleic acid. [ABSTRACT FROM AUTHOR]

Conversion of levulinic acid (LA) to γ-valerolactone (GVL) via catalytic transfer hydrogenation (CTH) using conventional heating (CH) involves long reaction times, and low yields. Microwave (MW) heating seems a solution to address these issues as MW accelerates reactions and enhances yields. In this study, three typical catalysts, Ru/C, Pt/C and Pd/C, are compared for LA conversion using MW heating. In comparison to CH processes, MW-assisted processes significantly enhance LA conversion to GVL with higher yields by Ru/C and Pt/C. While elevated temperatures and secondary alcohols are favorable for LA conversion by these catalysts, Ru/C appears as the most effective catalyst as it can reach LA conversion as 100%, selectivity of GVL as 99% and yield of GVL as 99% at 160 °C. The results of this study confirm that MW was a promising process for enhancing LA conversion and Ru/C shows the highest catalytic activity, followed by Pt/C and Pd/C. [ABSTRACT FROM AUTHOR]

Reactions of C10H7-1-N(PPh2)2 (1) and C10H7-1-N(P(Se)Ph2)2 (2) ligands with mercury(II)iodide in equimolar ratio gave cis-[HgI2{1-κ2P,P}] (3) and cis-[HgI2{2-κ2Se,Se}] (4). Also, refluxing of monooxidized thioyl and selenoyl bis(phosphino)amine ligands C10H7-1-N(P(E)Ph2)(PPh2) (E = S (5), Se (6)) with [Ru(CO)3Cl2]2 dimer afforded cis-[Ru(CO)2Cl2{5-κ2P,S}] (7) and cis-[Ru(CO)2Cl2{6-κ2P,Se}] (8). Complexes 3, 4, 7 and 8 were identified and characterized by multinuclear NMR (1H, 13C, 31P and 77Se NMR) and IR spectroscopy. The molecular structure of 5 was determined by single X-ray crystallography. 5 is the first structurally characterized example of this kind of κ2P,S -bidentate ligand. The novel ruthenium(II) complexes 7 and 8 show high catalytic activity in the transfer hydrogenation of acetophenone derivatives to 1-phenylethanol derivatives in the presence of 2-propanol as the hydrogen source. [ABSTRACT FROM AUTHOR]

The study of oxidation kinetics of drug molecules is of much noteworthy in order to understand their mechanistic chemistry in redox systems. Taurine, being a potent drug molecule, has a wide range of activities in biological system. Therefore, the kinetics of oxidation of taurine (TAU) by bromamine-T (BAT) in HCl medium, catalyzed by Ru(III) and in NaOH medium, catalyzed by Os(VIII) has been investigated at 313 K. The rate law in acidic medium is: rate = k[BAT]t[TAU]0[Ru(III)]0.95[H+]−0.67. But, it takes the form, rate = k[BAT]t[TAU]0.46[Os(VIII)]0.89[OH−]−0.53 in basic medium. Addition of halide ions and p-toluenesulfonamide had no significant effect on the rate in both the cases. Decrease in dielectric constant of medium decreases the reaction rate in both the media. The conjugate acid, CH3C6H4SO2NHBr (TsNHBr), is assumed to be the oxidizing species in both the media. Equilibrium and decomposition constants have been evaluated in each case. [ABSTRACT FROM AUTHOR]

Ruthenium catalyzed oxidative dearomatization-alkoxylation of N-Boc indoles for the synthesis of 2-alkoxyindolin-3-ones was described. The N-Boc indoles can be transformed into 2-alkoxyindolin-3-ones with RuCl3·3H2O as catalyst and tert-butyl hydroperoxide (TBHP, 3.0 equiv) as oxidant in dichloromethane/alcohol. Furtherly, the mechanism had been proposed on the basis of control experiments and isolation of intermediates. [ABSTRACT FROM AUTHOR]

Ruthenium catalyzed oxidative dearomatization-hydroxylation of N-Boc indoles for the synthesis of 2-hydroxyindolin-3-ones was described. The N-Boc indoles can be transformed into 2-hydroxyindolin-3-ones with RuCl3·3H2O as catalyst, p-toluenesulfonic acid (TsOH·H2O) as promoter and tert-butyl peroxide (TBHP, 3.0 equiv) as oxidant in acetonitrile. The mechanism had been proposed on the basis of control experiments and isolation of intermediate. [ABSTRACT FROM AUTHOR]

Due to their unique physical and chemical features, dendronized polymers (DPs) have received increasing attention in various fields such as hierarchically structured materials, stimuli-responsive materials, catalysis, biosciences, optoelectronic devices, and so on. A large number of synthetic strategies also have been reported to prepare various functionalized DPs. Among these strategies, ring-opening metathesis polymerization (ROMP) and metathesis cyclopolymerization (MCP) using highly active and group-tolerant Ru-based catalysts as initiators were used as living and controlled techniques to fabricate well-defined DPs. The two efficient techniques present a promising prospect in the design and preparation of functional DPs. In this review, we focus on the synthesis of various classes of DPs by ROMP and MCP of dendritic macromonomers, and describe their characteristic structures and properties, as well as various functional applications. [ABSTRACT FROM AUTHOR]

In this work, ruthenium catalysts were obtained by alloying-dealloying approach and used in the dehydrogenation reaction of ammonia borane. Ruthenium and aluminum were sputtered simultaneously and aluminum was etched from the alloy by dealloying with sodium hydroxide. The resulting catalysts were analyzed with TEM, SEM, and Zeta-Sizer. Aluminum sputtering power was found to be effective on the catalytic activity of the catalysts. Moreover, the highest turnover frequency was calculated as 290.9 min−1. Also, the activation energy of the dehydrogenation reaction of ammonia borane with Ru particles was found to be 18.43 kJ mol−1. Furthermore, the catalysts could conserve their performance upto 10 consecutive runs. [ABSTRACT FROM AUTHOR]

Existing energy resources are not sufficient to meet the energy needs of the increasing world population so the need for clean and renewable energy systems is increasing day after day. Hydrogen is a good alternative energy source because of its clean by-products and high energy capacity. Studies on hydrogen storage systems that provide instant hydrogen production in the literature are of great interest. In this study, poly-2-vinylpyridine (p(2-VP)) polymer was prepared by photopolymerization method and reacted with 2,6-bis(2-benzimidazolyl)pyridine ligand containing Ru(II) complex to give p(2-VP) supported Ru(II) material. The synthesized Ru(II) complex was characterized by FT-IR, UV-Vis and 1H-NMR spectroscopic techniques. Also the p(2-VP) polymer was characterized by FT-IR spectroscopy. The obtained p(2-VP) supported Ru(II) material was used as catalyst in hydrogen generation from NaBH4 metanolysis reaction and the reaction kinetic was investigated. [ABSTRACT FROM AUTHOR]

Existing energy resources are not sufficient to meet the energy needs of the increasing world population so the need for clean and renewable energy systems is increasing day after day. Hydrogen is a good alternative energy source because of its clean by-products and high energy capacity. Studies on hydrogen storage systems that provide instant hydrogen production in the literature are of great interest. In this study, poly-2-vinylpyridine (p(2-VP)) polymer was prepared by photopolymerization method and reacted with 2,6-bis(2-benzimidazolyl)pyridine ligand containing Ru(II) complex to give p(2-VP) supported Ru(II) material. The synthesized Ru(II) complex was characterized by FT-IR, UV-Vis and 1H-NMR spectroscopic techniques. Also the p(2-VP) polymer was characterized by FT-IR spectroscopy. The obtained p(2-VP) supported Ru(II) material was used as catalyst in hydrogen generation from NaBH4 metanolysis reaction and the reaction kinetic was investigated. [ABSTRACT FROM AUTHOR]

The oxidation of alkanes is important in the chemical industry. However, green chemical processes in the oxidation reaction of alkanes have developed slowly. Most oxidation reactions of alkanes still rely on sacrificial oxidants, solvents and additives, as well as high temperature and pressure. Hence, the key to make alkane oxidation occur under the mild condition is to find a catalyst with high activity. Here, we prepared a new heterogeneous catalyst used for n-tetradecane oxidation by loading tetraruthenium (IV)-substituted tungstogermanate polyanion [{Ru4O4(OH)2(H2O)4} (γ-GeW10O36)2]10- (GeW10Ru2) on 3-aminopropyltriethoxysilane (Apts)-modified SBA-15. The characterization of this heterogeneous catalyst consists of XRD, N2-adsorption measurements, Raman and FT-IR spectroscopy. In the process of catalytic oxidation of n-tetradecane, air was used as the oxidant to replace sacrificial oxidant without adding any solvents and additives under normal atmospheric pressure and low temperature. As a green catalyst, this heterogeneous catalyst has high-efficiency, good-stability and re-usability. Ultimately, this system proved to be an efficient and green catalytic process through a series of experiments. The turnover frequency (TOF) for n-tetradecane is over 29,000 h−1 under the optimum experimental conditions. [ABSTRACT FROM AUTHOR]

In this paper, RuIII(edta) was used as a highly efficient absorbent for the removal of NO due to its desirable properties of high NO affinity and oxygen insensitivity. The effects of the RuIII(edta) concentration, reaction temperature, initial solution pH, oxygen concentration, inlet NO concentration, and liquid-to-gas ratio on denitration performance were examined. The results indicated that RuIII(edta) showed excellent denitration performance at low concentrations and that an increase in the concentration of RuIII(edta) resulted in an increase in NO removal efficiency. In addition, NO removal efficiency increased to its optimum value at first and then declined as both the reaction temperature and initial solution pH rose. The optimal reaction temperature and ideal initial solution pH were determined to be 45°C and 5.0 respectively. The suitable liquid-to-gas ratio was found to be 51.5 L/m3. NO removal efficiency was less affected by the oxygen concentration in the range of 0–12% due to a superior anti-oxidation performance at pH = 5.0. Furthermore, the NO removal efficiency decreased significantly as the inlet NO concentration increased. The addition of 5 wt% urea to an aqueous solution of RuIII(edta) enhanced denitration performance, and an RuIII(edta) and urea mixed solution were able to exceed 65.07% NO removal efficiency within 30 min under optimal experimental conditions. This work proposed an alternative absorbent for NO removal and provided fundamental data for industrial denitration with RuIII(edta) absorbents. [ABSTRACT FROM AUTHOR]

In this study, tridentate 2,6-bis(5,6-dimethyl-1H-benzimidazol-2-yl)pyridine ligand (L1) and eight derivatives (L2–9) were prepared by substitution with alkyl chains and Ru(II) complexes of these ligands (C1–9) were synthesized. The synthesized ligands and their Ru(II) complexes were characterized by FTIR, UV–vis, 1H-NMR, and ESI/MS spectroscopic methods. The absorption and the emission spectra of the complexes were examined, HOMO–LUMO energy levels of the complexes were determined by cyclic voltammetry and their use as photosensitizer in dye-sensitized solar cells (DSSCs) was investigated. The effects of alkyl chain substitution on absorption in the visible region and on the current–potential characteristics of the complexes are discussed. The effects of this modification on the important parameters for DSSCs such as absorption, current density were examined and power conversion efficiency values of the Ru(II) complexes are reported. [ABSTRACT FROM AUTHOR]

The interaction of [Ru(η6-arene)(μ-Cl)Cl]2 and Ir(η5-C5Me5)(μ-Cl)Cl]2 with a new Ionic Liquid-based phosphinite ligand, [(Ph2PO)-C6H9N2Ph]Cl, (2) gave [Ru((Ph2PO)-C6H9N2Ph)(η6-p-cymene)Cl2]Cl (3), [Ru((Ph2PO)-C6H9N2Ph)(benzene)Cl2]Cl (4) and [Ir((Ph2PO)-C6H9N2Ph)(C5Me5)Cl2]Cl (5), complexes. All the compounds were characterized by a combination of multinuclear NMR and IR spectroscopy as well as elemental analysis. Furthermore, the Ru(II) and Ir(III) catalysts were applied to asymmetric transfer hydrogenation of acetophenone derivatives using 2-propanol as a hydrogen source. The results showed that the corresponding alcohols could be obtained with good activity (up to 55% ee and 99% conversion) under mild conditions. Notably, [Ir((Ph2PO)-C6H9N2Ph)(C5Me5)Cl2]Cl (5) is more active than the other analogous complexes in the transfer hydrogenation (up to 81% ee). [ABSTRACT FROM AUTHOR]

Three new ruthenium(II) carbonyl complexes that bear phenoxy-imine chelate ligands, [RN = CH(C6H4O)]2Ru(CO)2 (1: R = 2,6-Me2C6H3; 2: R = 4-OMeC6H4; 3: R = 4-ClC6H4) have been synthesized. These mononuclear ruthenium(II) complexes were fully characterized by elemental analysis, FT‒IR, and 1H and 13C NMR. Furthermore, the molecular structures of 1-3 were determined by X-ray crystal diffraction analysis. In the presence of NaHCO3 as the base, the Ru carbonyl complexes showed moderate to good catalytic activities for the conversion of aldehydes to nitriles via the dehydration of aldoximes. [ABSTRACT FROM AUTHOR]

An easy and convenient synthesis of a new series of octahedral ruthenium(III) complexes bearing Schiff base ligands of general formula [RuCl2(EPh3)2(L)] (where E = P, As and L = O,N-donor Schiff bases) has been reported. The composition of all complexes has been unequivocally characterized by spectral (IR, UV-vis, EPR) and ESI-MS techniques. The substituted Schiff base ligands behave as bidentate O,N-donors and coordinate to ruthenium via the phenolic oxygen, the azomethine nitrogen. Complexes 1–6 have been proven to catalyze the transfer hydrogenation of linear, cyclic and aromatic ketones to their corresponding secondary alcohols in the presence of i-PrOH/KOH at 80 °C with conversion up to 99%. The effect of other variables on the transfer hydrogenation reaction such as solvent, base, and catalyst loading is also reported. [ABSTRACT FROM AUTHOR]

The chiral homoallylamines with orthogonal bifunctional handle, an amine, and a pendant allyl unit are available to be easily converted into N-heterocycles. The N-allylation and Ru-catalyzed ring-closing metathesis delivered the bioactive 2-arylpiperidines, Nicotiana tabacum alkaloids (R)-anatabine and (R)-anabasine in three steps. A formal synthesis of (R)-N-methylanatabine and (R)-N-methylanabasine is also completed. [ABSTRACT FROM AUTHOR]

A wide variety of biological activities are possessed by nitrogen, oxygen, and sulfur containing heterocycles and many methods are explored for the preparation of these heterocyclic compounds. Metal catalysts are used in organic reactions with high activity. The synthesis of heterocycles with the help of metal catalysts became very important in organic synthesis. New protocols have been investigated for the synthesis of heterocycles in the last decades. In present review article I have concentrated on the synthesis of seven and higher-membered heterocylces in the presence of ruthenium catalyst. [ABSTRACT FROM AUTHOR]

Due to significant biological activity associated with N-, O-, and S-heterocycles, several reports for their synthesis have appeared in recent decades. Traditional approaches require expensive or highly specialized equipment or would be of limited use to the synthetic organic chemist due to their highly inconvenient approaches. This review summarizes the applications of ruthenium metal with emphasis of their synthetic applications for oxygen-containing six-membered heterocylces. In summary, this review article describes the synthesis of heterocyclic rings containing different heteroatoms. [ABSTRACT FROM AUTHOR]

Latent metathesis catalysts equipped with boronate esters of diols as exchangeable end-groups on their NHC ligands and an S-chelated ruthenium-benzylidene core were synthesized. The stable S-chelated ruthenium complexes underwent hydrolysis under mild acidic conditions, allowing easy exchange of terminal units by several 1,2- and 1,3-diols, without degrading the central ruthenium benzylidene. Using this strategy, we also prepared metathesis catalysts equipped with diallyl substrates at the termini that showed concentration dependency on RCM reactions. Notably, the larger dendritic catalysts were more efficient at the more dilute condition. [ABSTRACT FROM AUTHOR]

Effluents from the pharmaceutical and dye industries contain chlorinated organic pollutants. The effective treatment of such effluents constitutes a challenging task. In this work, 4-chlororesorcinol (PCRE) and 4-chloro-2-aminophenol (PCAP) were selected as model chloro-organic compounds. Catalytic hydrodechlorination (HDC) of PCRE and PCAP in the aqueous phase was investigated in a slurry reactor using commercial carbon supported ruthenium catalyst. HDC reactions of PCRE and PCAP were studied over the ranges in temperature, 313-353 K, H2 partial pressure, 0.69-2.76 MPa, and catalyst loading, 0.2-1.2 kg/m3. The performance of Ru/C catalyst for hydrodechlorination and ring saturation was promising. The kinetic data were modeled using Langmuir-Hinshelwood-Hougen-Watson kinetics. The HDC reaction of PCRE and PCAP using Ru/C catalyst proceeds via a dual-site mechanism, wherein atomic H2 reacts with the adsorbed organic substrate. The activation energy for the hydrodechlorination reactions of PCRE and PCAP was 41.6 and 49.4 kJ/mol, respectively. [ABSTRACT FROM AUTHOR]

Gas phase conversion of acetylene to benzene, assisted by a single metal cation such as Fe(+), Ru(+) and Rh(+), offers an attractive prospect for application of computational modelling techniques to catalytic processes. Gas phase processes are not complicated by environmental effects and the participation of a single metal atom is a significant simplification. Still the process is complex, owing to the possibility of several low-energy spin states and the abundance of alternative structures. By density functional theory modelling using recently developed models with range and dispersion corrections, we locate and characterise a number of extreme points on the FeC6H6(+) surface, some of which have not been described previously. These include eta-1, eta-2 and eta-3 complexes of Fe(+) with the C4H4ring. We identify new FeC6H6(+) structures as well, which may be landmarks for the Fe(+)-catalysed production of benzene from acetylene. The Fe(+) benzene complex is the most stable species on the FeC6H6cation surface. With the abundant energy of complexation available in the isolated gas phase species, detachment of the Fe(+) and production of benzene can be efficient. We address the issue raised by other investigators whether multi-configurational self-consistent field methods are essential to the proper description of these systems. We find that the relative energy of intrinsically multi-determinant doublets is strongly affected, but judge that the density functional theory (DFT) description provides more accurate estimates of energetics and a more plausible reaction path. [ABSTRACT FROM AUTHOR]

The novel multi-walled carbon nanotube (MWCNT) supportedbis(diphenylphosphinomethyl)amine [MWCNT@CHO-NHArN(CH2PPh2)2type] ligands and their Ru(II) complexes have been synthesized and characterized with Fourier Transform Infrared Spectrometry (FT-IR), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray (EDX), Transmission Electron Microscopy (TEM), Ultraviolet-Visible Spectrometry, X-Ray Diffraction Spectrometry (XRD), and Thermal analysis (TG/DTA) techniques. In addition, MWCNT@CHO-NHArN(CH2PPh2)2Ru(p-cymene)Cl2type complexes were tried as catalysts in the catalytic transfer hydrogenation reactions of acetophenone derivatives. The crystallite size and lattice strain of the MWCNT-based compounds were calculated by the Scherrer's equation. The optical parameters of the MWCNT-based structures were analyzed and the band gap enhanced from 4.42 eV to 4.98 eV. It was confirmed that the reduction of bromo and chloro acetophenone derivatives using all the catalysts, the conversions were high. The results showed that MWCNT-supported Ru(II) complexes were efficient catalysts in the reduction of bromo and chloro acetophenone derivatives with 99% efficiency in K2CO3media at 80°C. [ABSTRACT FROM PUBLISHER]

[RuIII(EDTA)(H2O)]−(EDTA4− = ethylenediaminetetraacetate) catalyzes the oxidation of biological thiols, RSH (RSH = cysteine, glutathione, N-acetylcysteine, penicillamine) using H2O2as precursor oxidant. The kinetics of the oxidation process were studied spectrophotometrically as a function of [RuIII(EDTA)(H2O)]−, [H2O2], [RSH], and pH (4–8). Spectral analyses and kinetic data are suggestive of a catalytic pathway in which the RSH reacts with [RuIII(EDTA)] catalyst complex to form [RuIII((EDTA)(SR)]2−intermediate species. In the subsequent reaction step the oxidant, H2O2, reacts directly with the coordinated S of the [RuIII((EDTA)(SR)]2−intermediate leading to formation of the disulfido (RSSR) oxidation product (identified by HPLC and ESI-MS studies) of thiols (RSH). Based on the experimental results, a working mechanism involving oxo-transfer from H2O2to the coordinated thiols is proposed for the catalytic oxidation. [ABSTRACT FROM PUBLISHER]

N-acetyl L-cysteine (NAC), the substrate used presently has got diverse medicinal applications and is widely used as a mucolytic agent. The oxidation of bioactive molecules, in general, involves metal ion catalysis facilitated by the participation of metal nanoparticles. In view of this, the oxidation of NAC by a phenothiazine dye methylene blue (MB), a model electron receptor, catalyzed by Ru(III) in the absence and in the presence of Cu(II) has been investigated in acidic medium. The concentration order in MB is zero, while the order in NAC is one and two in Ru(III)-catalyzed and Ru(III)-Cu(II)- catalyzed reactions, respectively. Hydrogen ions retard the rate in Ru(III)-Cu(II)-catalyzed reaction, whereas the rate increases linearly with increasing [Ru(III)] in both the systems. The rate increases with increasing [Cu(II)] and attains a limiting value. The addition of the reaction products does not affect the rate of reaction. The reaction is characterized by a large negative entropy of activation. The kinetic deviations of the reaction, explained by presuming the participation of a reactive form of the NAC molecule or its new conformational polymorph reported recently, indicate the regulatory influence of the morphology of nanoparticles. [ABSTRACT FROM AUTHOR]

Azide alkyne cycloaddition was applied to step growth polymerization of the diazido monomer, di(3-azido-2-hydroxypropyl) ether of bisphenol-A (DAHP-BPA) with either tetraethyleneglycol dipropargyl ether (TEGDPE) or tetraethyleneglycol dipropiolate (TEGDP). Polymerizations were conducted without catalyst and in the presence of Cu(I) or Ru(II) complex. The resulting oligomers and polymers were characterized using1H- and13C-NMR spectroscopy and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), with an emphasis on the relative abundance of 1,4- vs. 1,5-disubstituted regioisomeric 1,2,3-triazoles. Uncatalyzed reaction of DAHP-BPA/TEGDPE at 70°C yielded a 55/45 mixture of 1,4/1,5-disubstituted triazoles; reaction was slow and residual alkyne end groups were observed, suggesting attritional loss of azide. Catalyzed with Cu(PPh3)3Br, the same system yielded 93/7, 1,4/1,5-disubstituted triazoles, and few residual end groups were detected, consistent with higher molecular weight and controlled 1:1 depletion of azide and alkyne. Cp*RuCl(COD) catalyst was not soluble in the bulk system, necessitating solution polymerization in THF. Ru(II) yielded 6/94, 1,4/1,5-disubstituted triazoles, and MALDI-TOF-MS showed an end group composition similar to that observed with Cu(I). Uncatalyzed reaction of the DAHP-BPA/TEGDP system, involving the more reactive propiolate, yielded a high proportion (85%) of 1,4-disubstituted triazole linkages, and MALDI-TOF-MS revealed a controlled 1:1 depletion of azide and alkyne groups. [ABSTRACT FROM PUBLISHER]

Selective hydrogenation of bicarbonate to formate catalyzed by a ruthenium(III) complex, [RuIII(edta)] (edta4− = ethylenediaminetetraacetate), at moderate H2pressure (2–8 atm) and temperature (30–40 °C) is reported. Formation of formate, the only reduction product, was identified by13C NMR analysis of the resultant reaction mixture. Based on the spectral data, a working mechanism (admittedly speculative) involving the formation of ruthenium(III)-bicarbonate complex, [RuIII(edta)(HCO3)]2−, is proposed for the catalytic reaction. [ABSTRACT FROM AUTHOR]

The ruthenium(III)-catalyzed electron-transfer reaction between hexacyanoferrate(III) and ranitidine hydrochloride is studied in alkaline medium at 25°C and at an ionic strength of 1.10 mol/dm3. The reaction stoichiometry is established and is found to be 1:4, that is, for the oxidation of one mole of ranitidine, four moles of hexacyanoferrate(III) are consumed. The reaction products were characterized by spectral studies such as IR, GC-MS,1H-NMR and13C-NMR. The reaction rate shows a less than unit order in substrate and alkali and a first-order dependence in oxidant, [Fe(CN)6]3−and the catalyst, ruthenium(III) concentrations. The active species of ruthenium(III), [Ru(H2O)5OH]2+, forms an intermediate complex with the substrate. The attack of complex by hexacyanoferrate(III) in the rate determining step produces a radical cation, which is further oxidized in the subsequent step to form the oxidation product. The effect of the reaction environment on the rate constant upon adding varying concentrations of KNO3andt-butanol was studied. The initially added products did not have any significant effect on the reaction rate. A plausible mechanism is proposed based on the experimental results. The effect of varying temperature on the reaction rate was also studied. The activation parameters for the slow step and the thermodynamic quantities for the equilibrium steps were evaluated. The mechanism of title reaction has been studied and one mole of ranitidine consumes four moles of [Fe(CN)6]3−, as shown in the following equation: [ABSTRACT FROM PUBLISHER]

This work describes hydrogen (H2) production via steam reforming of ethylene glycol (EG) over a supported ruthenium catalyst. EG is chosen as a model compound for the alcohols contained in the aqueous phase of bio-oil. Using a fixed-bed reactor, experimental runs are carried out over Ru/Al2O3at various temperatures (350–500°C), ratios of the mass of the catalyst (W) to the molar flow rate (FO) of EG at the inlet (W/FO = 0.37 − 2.38 g h/mol), and feed concentrations (22.3–53.4 wt.% EG in water). The role of Ru in conversion of EG, production of H2, and product distribution of the carbonaceous species is studied. Reaction pathways previously described in the literature are used to elucidate our results. [ABSTRACT FROM PUBLISHER]

Significant progress has been made in the last few years toward synthesizing highly dispersible inorganic catalysts for application in the electrodes of direct methanol fuel cells. In addition, research toward achieving an efficient catalyst supporting matrix has also attracted much attention in recent years. Carbon black- (Vulcan XC-72) supported Platinum and Platinum-Ruthenium catalysts have for long served as the conventional choice as the cathode and the anode catalyst materials, respectively. Oxygen reduction reaction at the cathode and methanol oxidation reaction at the anode occur simultaneously during the operation of a direct methanol fuel cell. However, inefficiencies in these reactions result in a generation of mixed potential. This, in turn, gives rise to reduced cell voltage, increased oxygen stoichiometric ratio, and generation of additional water that is responsible for water flooding in the cathode chamber. In addition, the lack of long-term stability of Pt-Ru anode catalyst, coupled with the tendency of Ru to cross through the polymer electrolyte membrane and eventually get deposited on the cathode, is also a serious drawback. Another source of potential concern is the fact that the natural resource of Pt and the rare earth metal Ru is very limited, and has been predicted to become exhausted very soon. To overcome these problems, new catalyst systems with high methanol tolerance and higher catalytic activity than Pt need to be developed. In addition, the catalyst-supporting matrix is also witnessing a change from traditionally used carbon powder to transition metal carbides and other high-performance materials. This article surveys the recent literature based on the advancements made in the field of highly dispersible inorganic catalysts for application in direct methanol fuel cells, as well as the progress made in the area of catalyst-supporting matrices. [ABSTRACT FROM PUBLISHER]

Aromatic and heteroaromatic aldehydes are efficiently reduced to their corresponding alcohols in the presence of [RuCl2(p-cymene)]2and KOAc in 2-propanol under air at 80 °C. The presence of KOAc in the reaction is essential; in its absence no reduction takes place. A highly efficient, external-base-free reduction of aldehydes has also been reported with (η6-arene)ruthenium(II) complexes containing O^O chelate ligand such as [Ru(OAc)2(p-cymene)] and [RuCl(KA)(p-cymene)], obtaining alcohol in excellent yield (OAc, acetate; KA, kojic acetate). The scope of the reaction has been extended to a broad range of aromatic and heteroaromatic aldehydes. [ABSTRACT FROM AUTHOR]

Achiral monophosphine TPPTS [TPPTS: P(m-C6H4SO3Na)3]-stabilized Ru was successfully applied to catalyze the asymmetric hydrogenation of benzalacetone in ionic liquids using (S,S)-DPENDS [disodium salt of sulfonated (S,S)-1,2-diphenyl-1,2-ethylene-diamine] as chiral modifier. Under the optimized reaction conditions, the conversion of benzalacetone, chemoselectivity, and enantioselectivity of 4-phenyl-3-buten-2-ol could be reached up to 99.5%, 98.8%, and 74.6%, respectively. The TPPTS-stabilized Ru catalyst immobilized in ionic liquids could be easily separated from the resulting products by extraction withn-hexane, which could be recycled and reused five times without significant loss in activity, chemoselectivity, and enantioselectivity. [ABSTRACT FROM AUTHOR]

An operationally simple domino approach for the ruthenium-catalyzed synthesis of (E)-2,3′-bi(3H-indol)-3-oneO-alkyl oximes by the region- and stereoselective three-component, four-molecule reactions of indoles with sodium nitrite and alkyl bromides under mild reaction condition in dimethylformamide is described. Remarkably, multiple bonds including C‒C, C=N, and C‒O bonds were conveniently formed in one pot. The reaction is tolerant to air and is atom economical, in accordance with the concept of modern green chemistry. [ABSTRACT FROM AUTHOR]

Despite technological developments within the past century, ammonia synthesis from nitrogen and hydrogen is still highly energy intensive due to high-pressure operation. Even with recently introduced Ru-based catalysts with superior performance over conventional iron-based catalysts, there is still room for improvements to approach the theoretical minimum energy consumption. A novel approach is to use nanostructured components in catalyst formulation. Reducing Ru crystallite size to nanometers could greatly increase catalytic activity by increasing surface area as well as by the structure sensitivity of ammonia synthesis over Ru-based catalysts due to the increase of the density of highly active B5sites. The control of Ru particle size and shape in the nanometer range and stabilization of the particles by appropriate innovative preparation techniques are key factors for development of commercial Ru nanocatalysts. Theoretical and experimental studies on actives sites and metal-promoter and metal-support interactions by advanced computational and characterization methods are also essential. [ABSTRACT FROM AUTHOR]

A series of alkene cross-metathesis reactions were performed using a homogeneous ruthenium-based catalyst. Using this technology, a variety of functional groups can be incorporated into the bio-based starting material, methyl oleate.Trans-stilbene, styrene, methyl cinnamate and hexen-3-ol have all been shown to give desirable products. Using this technology, aromatics, alcohols or additional esters can be incorporated into the products. For example, the cross-metathesis reaction of methyl oleate with methyl cinnamate by the second-generation Grubbs catalyst showed 70% conversion of methyl oleate into products where half of the observed products contain an aromatic group and over one-third of the products contain an α,β-unsaturated methyl ester. This promising green route is versatile, and with an appropriate selection of starting materials, it is applicable to the synthesis of polymer precursors, industrial fluids or any other application where the upgrade of natural oils is necessary. [ABSTRACT FROM PUBLISHER]

A new bridging agent, 4-amino-2-anilinopyridine (aap), was synthesized and used as an equatorial ligand in the preparation of a diruthenium complex (4,0) Ru2(aap)4Cl. Both the ligand and the diruthenium complex were characterized by thermal analysis, MALDI-TOF mass spectrometry, IR and NMR (1H and13C) spectroscopy, and X-ray crystallography. The structural analysis revealed that the complex existed as a (4,0) isomer, in which the amino group on the pyridyl moiety was not involved in chemical bonding. [ABSTRACT FROM AUTHOR]

Catalytic dimerization of methyl acrylate by homogenous ruthenium catalysts was investigated. The effect of the addition of acidic additives, supporting ligands, polymerization inhibitor, and reaction conditions on the selectivity of dimerization was studied, and possible reaction mechanism was discussed. Conversion and selectivity were significantly affected by using triphenylarsine as supporting ligand. Under mild conditions, conversion up to 98% with good selectivity to tail-to-tail product was achieved. Dimerization of methyl acrylate by ruthenium-based homogenous catalysts. The effect of the addition of supporting ligands on selectivity was studied. Conversion and selectivity were significantly affected by using triphenyl arsine. Possible reaction mechanism to achieve the tail to tail product was discussed. [ABSTRACT FROM AUTHOR]

The kinetics of oxidation of an atropine sulfate monohydrate (ASM) by hexacyanoferrate (HCF) (III) has been investigated spectrophotometrically in presence of ruthenium(III) catalyst in aqueous alkaline medium at 25°C. The stoichiometry is 1: 2. The reaction is first order in HCF(III) and has less than unit order in ASM concentrations. The effect of ionic strength and dielectric constants were studied on the rate of reaction. The active species of oxidant and catalyst are Fe(CN)63–and [Ru(H2O)5(OH)]2+, respectively. A suitable mechanism is proposed. The catalytic constant (KC) was also calculated. The activation parameters and thermodynamic quantities are also determined and discussed. [ABSTRACT FROM AUTHOR]

Hydrogenation of prochiral ketones using chiral transition-metal catalysts represents the cleanest way to access enantiomerically enriched secondary alcohols, which are important building blocks in fine chemicals synthesis. Despite excellent activity, selectivity and compatibility of metal complexes with variety of functional groups, no universal catalysts exist. In this article we summarize the advances in catalyst systems for the asymmetric homogenous and heterogenous hydrogenation of ketones that have been made in past decade. The development of catalysts is oriented in reaching as high as activity with low catalyst loadings, using “greener’’ conditions, and ensuring good recyclability of catalysts. Even though ruthenium complexes represent the largest part of the catalysts, other metals rapidly penetrate this field. [ABSTRACT FROM PUBLISHER]

An efficient and enantioselective hydrogenation ofN-acetylamino phenyl acrylic acids was successfully developed by using ruthenium catalyst. This methodology is important in the field of pharmaceuticals and provides a new process for the preparation of unnatural amino acids and tamsulosin chiral intermediate. [Supplementary materials are available for this article. Go to the publisher's online edition ofSynthetic Communications®for the following free supplemental resource: Full experimental and spectral details.] [ABSTRACT FROM PUBLISHER]

The kinetics of oxidation of D-Mannitol (D-Manni) by diperiodatoargentate(III) (DPA) both in the absence and presence of ruthenium(III) catalyst in alkaline medium at 298 K and at a constant ionic strength of 0.10 mol dm−3was studied spectrophotometrically. The reaction exhibits a 1:2 stoichiometry ([D-Manni]:[DPA]) and first order in [DPA], less than unit order in [D-mannitol] in both cases. The OH−had retarding effect and added periodate had no effect on the rate of the reaction in both cases. The order with respect to [Ru(III)] was unity. The main products were identified by spot tests, FT-IR, and LC-MS spectral studies. Based on the experimental results possible mechanisms were proposed. The reaction constants involved in the different steps of the mechanisms were evaluated. The catalytic constant (KC) was also calculated for Ru(III) catalysis at different temperatures. The values of activation parameters with respect to the catalyst have been evaluated. The activation parameters with respect to slow step of the mechanisms were computed and discussed and thermodynamic quantities were also determined. Kinetic studies suggest that the active species of DPA and ruthenium(III) were found to be [Ag(H3IO6)2]−and [Ru(H2O)5OH]2+, respectively. [ABSTRACT FROM AUTHOR]

The direct arylation of arylpyridines with aryl tosylates was carried out smoothly in the presence of 2.5 mol% RuCl3using MesCOOH as crucial promoter to generate biarylated products. The method is simple, efficient, safe, and regioselective, can be performed in the absence of expensive ligands, and does not require any precautions with regard to the exclusion of air and moisture. The biarylated products were obtained in good yields. Supplemental materials are available for this article. Go to the publisher's online edition ofSynthetic Communications® to view the free supplemental file. [ABSTRACT FROM AUTHOR]