Conversion Of Pyridine Research Articles

Conversion of Pyridine to Imidazo[1,2-a]pyridines by Copper-Catalyzed Aerobic Dehydrogenative Cyclization with Oxime Esters

A rapid and environmentally friendly conversion of pyridine to imidazo[1,2-a]pyridines has been developed via copper-catalyzed aerobic dehydrogenative cyclization with ketone oxime esters.

Formation and catalytic activity of novel water soluble di[ethylenediaminetetraacetato bis(N-oxido)] lanthanides

Reaction of hydrogen peroxide with ethylenediaminetetraacetato lanthanides results in the formation of water-soluble isomorphous N-oxido ethylenediaminetetraacetato lanthanides K 5 [Ln(edtaO 2 ) 2 ] · 12H 2 O [Ln = La ( 1 ), Ce ( 2 ), Nd ( 3 ), H 4 edta = ethylenediaminetetraacetic acid C 10 H 16 O 8 N 2 ] in weak basic solution, where lanthanide ions are octa-coordinated by two quardentate N-oxido edta ligands, resulting in a distorted anti-tetragonal prism. Based on the comparisons of solid and solution 13 C NMR spectra, these compounds are fully dissociated in solution. Catalytic reaction of K 5 [La(edtaO 2 ) 2 ]·12H 2 O shows 96% conversion for the reaction of pyridine to pyridine N-oxide at 70 °C. Lanthanum N-oxido ethylenediaminetetraacetate catalyzes the oxidation of pyridine with hydrogen peroxide with a yield of 96%. Peroxo groups are trapped by ethylenediaminetetraacetate. • Reaction of hydrogen peroxide and edta lanthanide forms N-oxido edta lanthanide. • Water-soluble N-oxido edta lanthanide fully dissociates in solution. • N-oxido edta lanthanide catalyzes the conversion of pyridine to pyridine N-oxide in 96% yield.

Ni Promotion of WP/SiO2 Catalysts for Pyridine Hydrodenitrogenation

WP/SiO2 catalysts promoted with Ni were prepared by wet impregnation with various molar ratios of Ni to W and then evaluated in the reaction of pyridine hydrodenitrogenation for pyridine conversion and product selectivity. The addition of Ni to the WP/SiO2 catalysts resulted in increased pyridine conversion and selectivity to pentane. The molar ratios of Ni:W:P are important, because nickel and tungsten compete for phosphorous and form WP, W3O, Ni2P and/or W crystals.

A kinetic study of NO formation during oxy-fuel combustion of pyridine

In this work, pyridine-N was converted into NO and N 2 by using a flow reactor and the dominant NO evolution pathways were identified by means of a kinetic modeling under O 2/CO 2 atmosphere in temperature range of 1073–1473 K for different stoichiometries. The experimental results indicated higher temperatures promoted the formation of NO, with conversions varied from 1.26–18.64% to 3.85–43% for fuel-rich and fuel-lean conditions respectively. As for N 2 formation, conversion of pyridine to N 2 had a slight increase from 1073 to 1173 K then declined rapidly in oxidizing atmosphere, whereas this conversion stabilized at about 36% before decreasing to 29% above 1173 K in the presence of insufficient O 2. Increasing the equivalence ratio led to a monotonic increase of NO in both O 2/Ar and O 2/CO 2 atmospheres, and the gap between these atmospheres developed with α. The simulation results showed that the high CO 2 concentration reduced the availability of oxygen thus altered the evolution of NO through promoting reaction HNO + M ↔ H + NO + M and limiting reaction HNO + O 2 ↔ HO 2 + NO. This was even more important at higher temperatures. Besides, the major pathways for NO consumption were taken through reaction with NCO and NH as intermediates. In general, the model of Terasa09 described the experimental trends well, and this combustion kinetic was applicable to oxy-fuel conditions.

Catalytic hydrothermal hydrodenitrogenation of pyridine

We herein report on the hydrothermal catalytic conversion of pyridine to hydrocarbons. The catalytic activity of several supported noble metal (5wt%) catalysts (Pt/C, Pd/C, Ru/C and Rh/C, sulfided Pt/C, and Pt/γ-Al2O3), a traditional hydrodenitrogenation (HDN) catalyst (sulfided CoMo/γ-Al2O3), a transition metal carbide (Mo2C) and sulfide (MoS2), and a noble metal oxide (PtO2) toward the HDN of pyridine in a hydrothermal reaction medium between 250 and 400°C was determined. The Pt/γ-Al2O3 catalyst proved to be the most active for hydrothermal HDN of pyridine, and we report the effects of batch holding time, reaction temperature, catalyst loading, initial hydrogen pressure, and water density on the Pt/γ-Al2O3-catalyzed HDN of pyridine in supercritical water. The latter two process variables had the greatest influence on the product yields and distribution. Conditions were identified that lead to essentially 100% conversion of pyridine to N-free hydrocarbons. The catalyst shows some modest loss in activity upon being reused. An HDN reaction network for pyridine under hydrothermal conditions was proposed. The main HDN products are n-butane and n-pentane. Nitrogen was removed as ammonia.

Assisted electrochemical conversion of nitrogen heterocompounds using active hydrogen passing through a Pd membrane. A non conventional diesel and VGO hydrotreating option

The conversion of pyridine (PY), quinoline (QUI) and meso-tetraphenylporphyrin (TPP) using active hydrogen passing through a Pd membrane under mild conditions (25 °C and ambient pressure) by applying −1.92 mA cm −2 is reported. Moreover, some results regarding VGO and diesel hydrotreating, under similar conditions, are shown. Relative kinetic conversion constants ( k′), calculated for each tested molecules, support the following reactivity order: PY ( k′ = 87 × 10 −4 min −1) > QUI ( k′ = 5 × 10 −4 min −1) > TPP ( k′ = 1 × 10 −4 min −1). Based on the reduction and increasing factors found for aromatic and saturated fractions respectively, it can be established that diesel is easier to transform than VGO. Nevertheless, hydrodenitrogenation seems to be more notable for VGO than for diesel.

ChemInform Abstract: An Easy Direct Conversion of Pyridine- and Pyrimidine-thiones into Multi-Fused Heterocyclic Compounds.

The reaction of azine-thiones with ethyl chlorofluoroacetate afforded 2-fluorothienoazines. The latter underwent self-condensation and gave multi-fused heterocyclic compounds. A wide range of unique heterocycles could be obtained on treatment of 2-fluorothienoazines with nitrogen nucleophilic reagents. The reactivity of the pyrimidine-thiones towards a variety of electrophilic reagents was studied. Chemical and spectroscopic evidence of the newly synthesized compounds are described.

Selective oxidation of pyridine to pyridine- N-oxide with hydrogen peroxide over Ti-MWW catalyst

The oxidation of pyridine to pyridine- N-oxide (PNO) with hydrogen peroxide has been investigated on various titanosilicate catalysts. Superior to other titanosilicates like TS-1, Ti-Beta and Ti-MOR, Ti-MWW showed a higher catalytic activity and product selectivity. The reaction parameters such as solvent, temperature, hydrogen peroxide/substrate ratio, the amount of catalyst and Ti content were optimized to maximize the PNO yield. Ti-MWW was capable of giving pyridine conversion and PNO selectivity both over 99% under optimum reaction conditions. Ti-MWW was a highly active, selective, and reusable catalyst for the synthesis of PNO. The mechanism for the oxidation of pyridine over titanosilicates has also been considered. Ti-MWW was further structurally modified to posses open reaction spaces by interlayer expansion, which reduced the diffusion limitations in the oxidation of pyridine derivatives with bulkier molecular dimensions.

Effect of citric acid on the synthesis of tungsten phosphide hydrotreating catalysts

The effect of using citric acid in the synthesis of unsupported tungsten phosphide (WP) hydrotreating catalyst was investigated by synthesizing WP using varying amounts of citric acid. Catalyst characterization was done using nitrogen physisorption, CO chemisorption, X-ray diffraction (XRD), temperature-programmed reduction (TPR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The activities of the catalysts were tested on a high pressure kinetics rig using the hydrodenitrogenation of pyridine as a test reaction. The use of citric acid in the preparation resulted in smaller WP particles—1–10 μm versus >100 μm when no citric acid was used. The characterization results suggest that the citric acid formed complexes with the W ions and limited the agglomeration of these ions during calcination. The smaller WP particles were more active catalysts for pyridine conversion on both per volume and per site basis.

Kinetic Modeling of Hydrodenitrogenation of Pyridine

This study is aimed at developing a kinetic model for the hydrodenitrogenation (HDN) of pyridine. The developed model deals with the selectivity of piperidine, one of the products obtained from the HDN of pyridine and with the conversion of pyridine to piperidine. Kinetic parameters were estimated from the results of the experimental data obtained from literature sources where the reactions were carried out in a trickle-bed reactor in the liquid phase over Mo2C, NbMo2C, and MoS2/SiO2 catalysts at temperatures of 480 to 590 K. POLYMATH 5.0 software was used to solve the proposed first-order model. It was shown that during the course of the HDN reaction of pyridine the conversion increases exponentially with temperature while selectivity of piperidine with respect to pyridine decreases with temperature. The changes in activation energies evaluated for the catalysts were 80.30 kJ/mol, 55.10 kJ/mol, and 40.85 kJ/mol for Mo2C, NbMo2C, and MoS2/SiO2, respectively.

Hydrogenation of Pyridine and Its Derivates Catalyzed by Poly(ethylene glycol)-Stabilized Amorphous RuB Nanoparticles

Poly(ethylene glycol)(PEG)-stabilized amorphous RuB nanoparticles were prepared and characterized by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS) and transmission electron microscopy(TEM).Results showed that Ru was reduced to zero valence and the average particle diameter of the RuB crystallites was about 2.4 nm.This catalytic system shows excellent activity and selectivity for the hydrogenation of pyridine and its derivates.At a reaction temperature of 100 ℃,a hydrogen pressure of 3.0 MPa,a reaction time of 60 min and using a molar ratio of 1/670 Ru to pyridine,the conversion of pyridine was found to be 99.0% and the selectivity for piperidine was 100%.The activity of the catalyst for substrates with different substituents was as follows:2-methylpyridine2,6-dimethylpyridinepyridine.

Activation of Pyridinium Salts for Electrophilic Acylation: A Method for Conversion of Pyridines into 3‐Acylpyridines.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Comparison of bulk CoMo bimetallic carbide, oxide, nitride and sulfide catalysts for pyridine hydrodenitrogenation

Abstract Bimetallic cobalt–molybdenum oxide (CoMoO x ) has been prepared and converted into CoMoN x , CoMoC x and CoMoS x materials by temperature-programmed reactions with ammonia, ethane or hydrogen sulfide, respectively. These new bimetallic materials have been characterised using X-ray diffraction (XRD) and solid state NMR and tested for pyridine hydrodenitrogenation (HDN) at various temperatures. The initial HDN activity of the catalysts decreases in order CoMoC x ∼ CoMoN x ∼ CoMoO x > CoMoS x . The stability order of the first three of catalysts is CoMoC x > CoMoN x > CoMoO x , and their activities decrease with the time on stream. In contrast the pyridine conversion over CoMoS x is more stable and activity increases with the time on stream, from 30 to over 50%, this is accompanied by the formation of CoMoSC x material. The high catalytic activity of the CoMoC x catalyst may reflect the ability to hydrocrack pyridine to yield methane. The CoMoS x catalyst system has the highest selectivity to the products cyclopentane (35%) and pentane (27%).

Activation of Pyridinium Salts for Electrophilic Acylation: a Method for Conversion of Pyridines into 3-Acylpyridines

Cyanide adducts of N-MOM pyridinium salts react with strong acylating reagents to provide 3-acyl-4-cyano-1,4-dihydropyridines that can be aromatized to 3-acylpyridines using ZnCl2 in refluxing ethanol.

Pyridine conversion in a flow reactor and its interaction with nitric oxide

An experimental study of the oxidation of pyridine both in the absence and in the presence of NO has been performed. The experiments were conducted in an isothermal quartz flow reactor at atmospheric pressure in the temperature range 700-1500 K. The influence of temperature, air excess ratio (corresponding to fuel-rich, stoichiometric, and lean conditions), and NO on the concentrations of CO, CO 2 , HCN, and NO has been analyzed. The current work contributes to a series of works on the conversion of volatile nitrogen compounds with experimental results related to pyridine. Also, a reaction mechanism based on various literature mechanisms has been used for simulating the experimental results.

ChemInform Abstract: Efficient Catalytic Conversion of Pyridine N‐Oxides to Pyridine with an Oxorhenium(V) Catalyst.

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.

Vapor-phase methylation of pyridine with methanol to 3-picoline over Zn 1− xCo xFe 2O 4 ( x=0, 0.2, 0.5, 0.8 and 1.0)-type ternary spinels prepared via a low temperature method

The reaction of pyridine with methanol was carried out over Zn 1− x Co x Fe 2O 4 ( x=0, 0.2, 0.5, 0.8 and 1.0)-type systems in a fixed-bed down-flow reactor. The influences of surface acidity, cation distribution in the spinel lattice and various reaction parameters are discussed. The activity and selectivity were shown to be strongly dependent on the surface acidity of the systems. Over all compositions of the systems, 3-picoline was formed as the major product, even though the activity and selectivity show a strong dependence on composition and reaction conditions. Generally, the systems possessing more acidic sites ( x≥0.5) favor the production of 3-picolines and 3,5-lutidine. Pyridine conversion increased with the progressive substitution of Zn 2+ ions by Co 2+ ions. Cation distribution in the spinel lattice influences their acidic properties. These factors have been adequately considered as helpful to evaluate the activity of the systems.

Efficient catalytic conversion of pyridine N-oxides to pyridine with an Oxorhenium(V) catalyst

The compound CH(3)Re(O)(SR)(2)PPh(3), where (SR)(2) represents the dianion of 2-(mercaptomethyl)thiophenol, catalyzes the rapid and efficient transfer of an oxygen atom from a wide range of ring-substituted pyridine N-oxides to triphenylphosphine, yielding the pyridines in high yield.

Selective synthesis of 3-picoline via the vapor-phase methylation of pyridine with methanol over Ni1-xCoxFe2O4 (x = 0, 0.2, 0.5, 0.8 and 1.0) type ferrites

A series of Ni–Co ferrites with the general formula Ni1-x Co x Fe2O4 (x = 0, 0.2, 0.5, 0.8 and 1.0) was prepared by a low-temperature hydroxide coprecipitation route. The catalyst systems were characterized by adopting various physico-chemical techniques. Alkylation of pyridine with methanol was carried out in a down-flow vapor-phase reactor. The influence of surface acid–base properties, cation distribution in the spinel lattice and various reaction parameters are discussed. It was observed that the systems possessing x values ≥0.5 are selective for 3-picoline formation, whereas the ones with x values 0 and 0.2 give a mixture of 2- and 3-picolines. Pyridine conversion increased with the progressive substitution of Ni2+ ions by Co2+ ions. Cation distribution in the spinel lattice influences their acidic and basic properties, and these factors have been adequately considered as helpful to evaluate the activity of the systems.

Catalytic supercritical water oxidation of pyridine: kinetics and mass transfer

Catalytic supercritical water oxidation (CSCWO) is a technology that has been developed to treat aqueous waste streams. The addition of Pt/γ–Al 2O 3 catalyst increased the reaction rates and complete conversion of pyridine was obtained at temperatures as low as 370°C. The main products from this reaction were carbon dioxide, nitrous oxide, and nitrate ion. The presence of mass transfer limitations was investigated. Experimental results indicate the absence of external mass transfer limitations, whereas the reaction was limited by the diffusion of the reactants in the pores of the catalyst. The intrinsic rate of reaction, assuming power-law kinetics, was obtained. The diffusion coefficient of pyridine in a mixture of supercritical water and air was estimated, to allow the estimation of effectiveness factor and the Thiele modulus. The effectiveness factor decreased from 0.96 to 0.2 as the particle size was increased from 0.09 to 0.7 mm.