Presence Of Ruthenium Catalyst Research Articles

Visible-Light-Promoted Click [3+2] Cycloaddition of Aziridine with Alkyne: An Efficient Synthesis of Dihydropyrrolidine

AbstractA photocatalytic [3+2] cycloaddition of aziridines with activated alkynes is reported under visible-light irradiation in the presence of ruthenium catalyst. This chemical transformation provides polysubstituted pyrrolidines in good yields based on the click chemistry philosophy. The reaction successfully represents a primary trial of cyclocarboamination through photocascade catalysis combining energy transfer and redox neutral reactions.

Comparative analysis of renewable diesel and biodiesel produced from Jatropha oil

AbstractThe quest of moving from conventional diesel fuels to alternate fuels is never‐ending. Renewable diesel stands out as it has a similar molecular structure to that of diesel. Renewable diesel from hydroprocessing of Jatropha oil in presence of ruthenium catalyst is not much researched and the same has been worked upon in this paper. The objective of this paper is to analyze physiochemical properties of renewable diesel (R100), biodiesel (B100), and blends of diesel (D100) and renewable diesel and to check the operational feasibility. Renewable diesel was mixed in 10%, 20%, 30%, 40%, and 50%, by volume in diesel. It was observed that renewable diesel had better cold flow properties than diesel. Calorific value (CV) of renewable diesel and biodiesel was 1.84% and 3.92% less than diesel respectively. Present study shows up to 30% renewable diesel in diesel is a substitute fuel, as their viscosities (2.55, 2.60, 2.64cSt), densities (834.4 kg/m3, 831.87 kg/m3, 830.6 kg/m3) and CVs (42.42 MJ/kg, 42.30 MJ/kg, 42.09 MJ/kg) are close to diesel (2.42cSt, 837 kg/m3 and 42.57 MJ/kg). This is also confirmed by a storage stability test conducted for 24 weeks. Cetane number of blends of R100 greater than 30% are found to be high; this can interfere with engine power output hence requiring amendments in current engines, which is not possible, therefore it is feasible to use blends only up to 30% of R100. GC–MS and Fourier transform infrared radiation showed a higher number of hydrocarbon atoms with diminutive oxygen percentage in R100, vis‐a‐vis, higher levels of unsaturation with more oxygen in B100.

Solid Foam Ru/C Catalysts for Sugar Hydrogenation to Sugar Alcohols─Preparation, Characterization, Activity, and Selectivity

Sugar alcohols are obtained by hydrogenation of sugars in the presence of ruthenium catalysts. The research effort was focused on the development of solid foam catalysts based on ruthenium nanoparticles supported on active carbon. This catalyst was used in kinetic experiments on the hydrogenation of l-arabinose and d-galactose at three temperatures (90, 100, and 120 °C) and two hydrogen pressures (20 and 40 bar). Kinetic experiments were carried out with binary sugar mixtures at different d-galactose-to-l-arabinose molar ratios to study the interactions of these sugars in the presence of the prepared solid foam catalyst. The solid foam catalyst preparation comprised the following steps: cutting of the open-cell foam aluminum pieces, anodic oxidation pretreatment, carbon coating, acid pretreatment, ruthenium incorporation, and ex situ reduction. The carbon coating method comprised the polymerization of furfuryl alcohol, followed by a pyrolysis process and activation with oxygen. Incorporation of ruthenium on the carbon-coated foam was done by incipient wetness impregnation (IWI), using ruthenium(III) nitrosyl nitrate as the precursor. By applying IWI, it was possible to prepare an active catalyst with a ruthenium load of 1.12 wt %, which gave a high conversion of the sugars to the corresponding sugar alcohols. The catalysts were characterized by SEM, HR-TEM, TPR, and ICP-OES to interpret the catalyst behavior in terms of activity, durability, and critical parameters for the catalyst preparation. Extensive kinetic experiments were carried out in an isothermal laboratory-scale semibatch reactor to which gaseous hydrogen was constantly added. High selectivities toward the sugar alcohols, arabitol and galactitol, exceeding 98% were obtained for both sugars, and the sugar conversions were within the range of 53–97%, depending on temperature. The temperature effect on the reaction rate was very strong, while the effect of hydrogen pressure was minor. Regarding the sugar mixtures, in general, l-arabinose presented a higher reaction rate, and an acceleration of the hydrogenation process was observed for both sugars as the ratio of d-galactose to l-arabinose increased, evidently because of competitive interactions on the catalyst surface.

Selective Synthesis of Secondary and Tertiary Amines by Reductive N‐Alkylation of Nitriles and N‐Alkylation of Amines and Ammonium Formate Catalyzed by Ruthenium Complex

AbstractA new ruthenium catalytic system for the syntheses of secondary and tertiary amines via reductive N‐alkylation of nitriles and N‐alkylation of primary amines is proposed. Isomeric complexes 8 catalyze transfer hydrogenation and N‐alkylation of nitriles in ethanol to give secondary amines. Unsymmetrical secondary amines can be produced by N‐alkylation of primary amines with alcohols via the borrowing hydrogen methodology. Aliphatic amines were obtained with excellent yields, while only moderate conversions were observed for anilines. Based on kinetic and mechanistic studies, it is suggested that the rate determining step is the hydrogenation of intermediate imine to amine. Finally, ammonium formate was applied as the amination reagent for alcohols in the presence of ruthenium catalyst 8. Secondary amines were obtained from primary alcohols within 24 hours at 100 °C, and tertiary amines can be produced after prolonged heating. Secondary alcohols can only be converted to secondary amines with moderate yield. Based on mechanistic studies, the process is suggested to proceed through an ammonium alkoxy carbonate intermediate, where carbonate acts as an efficient leaving group.

Synthesis of Six-Membered N-Heterocycles Using Ruthenium Catalysts

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 worked with high activity in organic reactions. 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. This article mainly focused on the synthesis of six-membered N-heterocylces in the presence of ruthenium catalyst.

H/D Exchange Using Hot Heavy Water.

Metal-catalyzed H/D exchange in hydrothermal deuterium oxide, performed in an autoclave using external heating or in a sealed glass tube under microwave irradiation, was shown to be an efficient method for preparing various deuterium-labeled compounds. Phosphonium salts for the Wittig reaction were deuterated at the α-position in the presence of MS 4A under microwave irradiation; primary alcohols and primary/secondary amines were deuterated at the α-position in the presence of ruthenium catalyst under microwave irradiation; metal-catalyzed direct C-H functionalizations on sp³ and sp² carbon gave the corresponding fully deuterated products under hydrothermal conditions. These methods gave various deuterium-labelled compounds efficiently using D₂O as a D-atom source.

Ruthenium‐Catalyzed Site‐selective Enone Carbonyl Directed ortho‐C−H Activation of Aromatics and Heteroaromatics with Alkenes

AbstractAn efficient and versatile protocol for enone carbonyl directed ortho C−H activation of aromatics and heteroaromatics with alkenes for the construction of functionalized ortho‐olefinated chalcone derivatives in excellent yields in a regio‐ and stereoselective fashion has been developed for the first time. This general protocol involves chelation assisted oxidative coupling in the presence of ruthenium catalyst through C−H bond activation. This protocol has been further emphasized by the exhibition of functional group tolerance.magnified image

Ru-catalyzed direct amidation of carboxylic acids with N-substituted formamides

The direct amidation of carboxylic acids with N-substituted formamides has been accomplished via ruthenium catalysis. In the presence of ruthenium catalyst, a versatile range of carboxylic acids and N-substituted formamides undergoes amidation reaction to produce synthetically useful amides in good yields. CO in amide product came from benzoic acid but not N-substituted formamides, and which was confirmed by Isotope experiment.

Catalytic One-Pot Synthesis of End-Functionalized Poly(9,9′-di-n-octylfluorenevinylene)s by Acyclic Diene Metathesis (ADMET) Polymerization Using Ruthenium–Carbene Catalysts

Synthesis of end-functionalized poly(9,9′-di-n-octylfluorenevinylene)s (EF-PFVs) has been achieved by (i) catalytic olefin metathesis of vinyl groups (chain ends) in once prepared PFVs by acyclic diene metathesis (ADMET) polymerization with 1,2-disubstituted (bifunctional) olefins (DOs) or (ii) one-pot synthesis by combined ADMET polymerization (of 2,7-divinyl-9,9-di-n-octhylfluorene, DVF) with end-functionalization/chain transfer using DOs in the presence of ruthenium catalyst, RuCl2(PCy3)(IMesH2)(CHPh) [Ru(1), Cy = cyclohexyl, IMesH2 = 1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene]. Efficient one-pot synthesis of a series of high molecular weight EF-PFVs has been achieved when DOs were added after a certain period of the ADMET polymerization.

Catalytic conversion of bio-oil in supercritical water: Influence of RuO2/γ-Al2O3 catalysts on gasification efficiencies and bio-methane production

Catalytic supercritical water gasification of heavy (dewatered) bio-oil has been investigated in a batch reactor in the presence of ruthenium catalysts in the form of RuO2 on γ-Al2O3 support. The reactions were carried out at temperatures of 400°C, 450°C and 500°C and reaction times of up to 60min using 15wt% of bio-oil feed. Increased ruthenium oxide loading led to increased carbon gasification efficiencies (CGE) and bio-methane production. Hence, using the 20wt% RuO2/γ-Al2O3 catalyst, CGE was 97.4wt% at 500°C and methane yield reached nearly 30wt% of the bio-oil feed, which gave a CH4/CO2 molar ratio of 1.28. There was evidence that the RuO2 was involved in the initial conversion of the bio-oil to carbon oxides and hydrogen as well as the reduction of the CO2 to methane via CO methanation. However, competition for CO consumption via the water-gas shift reaction was also possible due to the large presence of water as the reaction medium. This work therefore demonstrates that high concentrations of heavy fraction of bio-oil can be catalytically converted to a methane-rich gas product under hydrothermal conditions at moderate temperatures. The calorific values of the gas product reached up to 54MJkg−1, which is nearly 3 times the HHV of the bio-oil feed.

N-Alkylation and N,C-Dialkylation of Amines with Alcohols in the Presence of Ruthenium Catalysts with Chelating N-Heterocyclic Carbene Ligands

A series of new benzimidazolium salts and ruthenium(II) complexes containing chelating N-heterocyclic carbenes (NHCs) functionalized with a benzylic group and an acetal group were prepared. All of the synthesized compounds were characterized by elemental analysis and NMR spectroscopy, and the molecular structures of 2c and 2d were determined by X-ray crystallography. All of the complexes were tested in the alkylation of cyclic amine derivatives with alcohols and showed excellent activity in this reaction. Cyclic amines were alkylated with primary and heteroaromatic alcohols. The Ru–NHC complexes also catalyzed N,C3-dialkylation of cyclic amines.

Catalytic reduction of Np(V) with hydrazine in nitric acid solutions in the presence of ruthenium catalysts

The reduction of Np(V) with hydrazine in HNO3 solution in the presence of Ru/SiO2 catalysts was studied by spectrophotometry. The back oxidation of Np(IV) with nitric acid, also catalyzed by ruthenium, occurs concurrently with the Np(V) reduction with hydrazine. The contribution of each process is determined by the HNO3 concentration. The mechanism of the ruthenium-catalyzed reduction of Np(V) with hydrazine was suggested on the basis of the kinetic data. The effect of the size of Ru nanoparticles on the activation energy of the catalytic reduction of Np(V), characterizing the structural sensitivity of the heterogeneous-catalytic reaction (positive size effect), was revealed.

α‐Amino‐Oximes Based on Optically Pure Limonene: A New Ligands Family for Ruthenium‐Catalyzed Asymmetric Transfer Hydrogenation

A new family of bifunctional, optically pure α-amino-oxime ligands based on (R)-limonene has been synthesized and used as chiral inducers for enantioselective hydrogen transfer reactions on various ketones in the presence of ruthenium catalysts. The X-ray structures of Ru-amino-oxime complexes are also described.

Eugenol as a renewable feedstock for the production of polyfunctional alkenes via olefin cross-metathesis

The ruthenium-catalyzed cross-metathesis of eugenol derivatives with electron deficient olefins is reported. It is shown that in the presence of ruthenium catalysts, eugenol and its O-protected derivatives have a high tendency to undergo carbon–carbon double bond migration before and after metathesis leading to the formation of conjugated styrene derivatives. The addition of 1,4-benzoquinone suppresses these isomerization reactions and provides an efficient access to new polyfunctional phenol derivatives upon cross-metathesis of the biosourced eugenol with acrylates, acrylonitrile and acrylamides.

Synthesis of alkylbenzine on ruthenium catalyst

The synthesis of alkylbenzine on the basis of butan-butene fraction in the presence of ruthenium catalyst was studied.

ChemInform Abstract: Hydrogenation of β‐N‐Substituted Enaminoesters in the Presence of Ruthenium Catalysts.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Hydrogenation of β- N-substituted enaminoesters in the presence of ruthenium catalysts

β-Aminoesters were prepared in two simple steps from β-ketoesters derivatives and primary amines under mild conditions. Their hydrogenation was performed at 50 °C in the presence of several organometallic catalysts under acidic conditions. The new β- N-substituted aminoesters were isolated in moderate to good yields.

Novel [Ruthenium(substituted‐tetramethylcyclopentadiene) (2‐quinolinecarboxylato)(allyl)] Hexafluorophosphate Complexes as Efficient Catalysts for Highly Regioselective Nucleophilic Substitution of Aliphatic Allylic Substrates

AbstractStable [ruthenium(R‐substituted‐tetramethylcyclopentadiene)(2‐quinolinecarboxylato)(1‐R′‐substituted‐allyl) hexafluorophosphate (R=Me, R′=H, Me, n‐Pr, Ph; R=t‐Bu, R′=Me) and [ruthenium(pentamethylcyclopentadiene)(2‐quinolinecarboxylato)(1‐n‐propylallyl)] tetrafluoroborate (4′a), as allylruthenium(IV) complexes, have been synthesized in one step, starting from [ruthenium(R‐substituted‐tetramethylcyclopentadiene)tris(acetonitrile) hexafluorophosphate or tetrafluoroborate complexes, quinaldic acid, and allylic alcohols. Single stereoisomers are obtained and the X‐ray single crystal structure determinations of 3b (R=t‐Bu, R′=Me) and 4′a allow one to specify the preferred arrangement. Complexes 3a (R=R′=Me) and 3b are involved as precatalysts favoring the formation of branched products in regioselective nucleophilic allylic substitution reactions, starting from ethyl 2‐(E)‐hexen‐1‐yl carbonate and chlorohexene as unsymmetrical aliphatic allylic substrates. Phenols, dimethyl malonate, and primary (aniline) and secondary (pyrrolidine, piperidine) amines have been used as nucleophiles under mild basic conditions. For the first time, the regioselectivity in favor of the branched product obtained from purely aliphatic allylic substrates is close to the high regioselectivity previously reached starting from cinnamyl‐type substrates in the presence of ruthenium catalysts.

Preparation of Cyclohexene-d10 by H/D-Exchange Reaction

Abstract Preparation of fully deuterium-labeled cyclohexene by H/D-exchange reaction was performed efficiently in the presence of ruthenium catalyst under irradiation of microwaves. The reaction proceeds via a repetition of hydroruthenation and β-elimination.

Synthesis and Ring‐Opening Metathesis Polymerization (ROMP) Reactivity of endo‐and exo‐Norbornenylazlactone Using Ruthenium Catalysts

AbstractSummary: Norbornenylazlactone (NBAz) was prepared by a Diels‐Alder cycloaddition between cyclopentadiene and 2‐vinyl‐4,4‐dimethyl‐5‐oxazolone. The stereoselectivity of this pericyclic reaction was in favour of endo isomers. The ring‐opening metathesis polymerization (ROMP) of NBAz was carried out in presence of ruthenium catalysts [(PCy3)2(Cl)2RuCHPh 1; (SIMes)(PCy3)(Cl)2RuCHPh 2 (SIMes: 1,3‐dimesityl‐4,5‐dihydroimidazol‐2‐ylidene); (PiPr3)2(Cl)2RuCHSPh 3; (PiPr3)(Cl)2RuCH(CH2)2C, N‐2‐C5H4N 4]. It was found that the exo isomer is much more reactive than the corresponding endo isomer. Some hypotheses of mechanism are suggested to justify the low polymerization rate of endo isomer using the results of NBAz derivatives as the hydrolyzed NBAz, 5, and the coupling product between NBAz and glycine methyl ester hydrochloride, 6. For exo‐NBAz, the propagating rate constant, kp, was determined with the four Ru‐initiators and their activity decreases in the order 2 > 1 > 3 > 4. Complementary kinetic measurements with 1 and 2 were given as kp/ki ratio. The ROMP of exo isomer was faster with 2 than 1 in spite of a worse control of the chains size. The azlactone ring survived intact during the polymerization and may be used for further reactions with nucleophiles.ROMP of NBAz by ruthenium initiators.magnified imageROMP of NBAz by ruthenium initiators.