Effect Of Pyridine Research Articles

Effect of reactive oxygen species (ROS) produced by pyridine and quinoline on NH4+-N removal under phenol stress: The shift of nitrification pathway and its potential mechanisms

Pyridine and quinoline are typical nitrogenous heterocyclic compounds with different structures that are found in coking wastewater. However, neither the corresponding mechanism nor its effect on the degradation of NH4+-N under phenol stress is known. In this study, the effects of pyridine and quinoline degradation on NH4+-N removal under phenol stress were evaluated using three lab-scale sequencing batch reactors. The average NH4+-N removal efficiencies of the reactors were 99.46 %, 88.86 %, and 98.64 %. With the increased concentration of pyridine and quinoline, NH4+-N and NO3--N accumulated to 58.37 mg/L and 141.37 mg/L, respectively, due to the lack of an electron donor and anaerobic environment. The addition of pyridine and quinoline significantly improved antioxidant response and altered the nitrification pathway. The nitrification process shifted from the mediation of amo and hao to the mediation of Ncd2 due to oxidative stress induced by pyridine and quinoline. Furthermore, oxidative stress interferes with the metabolism of carbon sources, resulting in decreased biomass. These results provide a new perspective for coking wastewater treatment processes.

Effect of pyridine as advanced polymeric inhibitor for pure copper: adsorption and corrosion mechanisms

The effect of pyridine (Pyr) on the corrosion of copper in 3 wt% NaCl was investigated using potentiodynamical anodic polarization, weight loss and morphological analysis. The Doehlert design simulation shows that Cpyr and immersion time are the significant factors. In addition, electrochemical measurements revealed that Pyr acts as a mixed-type inhibitor with more pronounced effect on anodic domain and the inhibition efficiency increases with increasing of inhibitor content. The adsorption of Pyr was found to obey the free polymerization during adsorption onto substrate surface. Surface characterization was performed using a scanning electron microscope and a Fourier transform infrared spectrometer, and Pyr has large negative charge in nitrogen and oxygen atoms, which results in a chemisorption of Pyr onto the copper surface and records around 97% of inhibition efficiency.

Effect of Pyridine on Zinc Electrolysis Parameters at Different Current Densities

The effect of pyridine on the parameters of electrolysis in acidic and neutral solutions of zinc sulfate was studied in a wide range of potentials and current densities. The effect of pyridine additives on the parameters of cationic discharge from the zinc sulfate electrolytes, including sulfuric acid, was analyzed. The zinc-to-sulfuric acid mass ratio in one of the three electrolytes corresponded to the composition of the commercial solutions utilized for zinc electrolysis. It was shown that an increase in the electrolyte acid content and cathode potential results in higher cation discharge rate, while an addition of pyridine causes it to decrease. The obtained experimental data evidence the preferential effect of pyridine on hydrogen cation discharge in zinc-containing electrolyte solution. It was noted that an increase in overvoltage accelerates quicker in the solution containing pyridine additives at a current density (j) in excess of 300 A/m2 , while without such additives it actually slows down. This is associated with the ability of pyridine additive to protonate and absorb a significant amount of hydrogen causing a stronger inhibition of hydrogen discharge compared to zinc in the areas with high current density. It was shown that within certain regions of the voltammetric curves with the current density exceeding 300 A/m2 , the exchange current (iex ) increases by about nine times at elevated cathode potentials and increased pyridine concentrations to 0.3 mg/liter. However, when the pyridine concentration increases to 0.6 mg/liter, the exchange current, same as the rate of ionic discharge, decreases, which is consistent with the Butler-Volmer equation for a cathodic process at high overvoltage values associated with increased current densities. The calculations of the transfer coefficients made it possible to conclude that at current densities of 600 A/m2 and higher, the transfer coefficient approaches zero, and the process of cationic discharge from acidic electrolytes with the addition of pyridine proceeds in an activationless mode. The results of the conducted study have led to the following important conclusion in terms of practical use of zinc electrolysis: in order to exclude the negative effect of pyridine, the process should be conducted below the current densities of 300–350 A/m2.

Effect of Pyridine on the Structure and Vibrations of Cobalt Phthalocyanine

Abstract Effect of pyridine on cobalt phthalocyanine (CoPc) has been studied by the density functional theory and Raman spectroscopy. Thermal evaporation method has been used for the preparation of a thin film of CoPc and then Raman spectra of CoPc film have been recorded with and without exposure of pyridine. The molecular structure of CoPc and its coordinated complexes with pyridine have been computed using B3LYP/6-31(d,p) level of density functional theory calculations by employing Gaussian program package. Calculations show some in-plane and out-of-plane distortions in the structure of CoPc. Some noticeable changes have been observed in the Raman spectrum of CoPc thin film after its exposure with pyridine. Changes in wavenumbers and relative intensities of some of the bands have been observed. Most of the observed bands show downward shifts in the wavenumbers. These changes, are attributed to the weakening of some bonds and change of symmetry of CoPc, and confirm the coordination of pyridine molecule(s) with CoPc molecule

Donor Strengths Determination of Pnictogen and Chalcogen Ligands by the Huynh Electronic Parameter and Its Correlation to Sigma Hammett Constants.

The suitability and accuracy of the Huynh electronic parameter (HEP) was further tested to reveal remote substituent effects in pyridines, which are located five or six bonds away from the reporter probe. These values show an excellent correlation to Hammett σ‐constants of the respective substituents with coefficients of R 2=0.9856 (σ m) and R 2=0.9857 (σ p). Based on this observation, a methodology for the re‐evaluation of certain Hammett constants with larger uncertainties has been proposed and demonstrated. Moreover, the scope of HEP was extended to various neutral pnictogen and chalcogen donors during which “transphobia effects” were revealed for mixed NHC complexes containing phosphites, arsine and stibine for the first time.

Effects of pyridine and pyrrole moieties on supercapacitive properties of imine-rich nitrogen-doped graphene

In this study, a series of imine-rich nitrogen-doped graphenes (IR-NGs), where pyridine and pyrrole functionalities were selectively incorporated in the near vicinity of imine groups, were synthesized, and used as electrode materials for supercapacitors. The facile acid-catalyzed dehydration reactions of graphene oxide (GO) with 6-aminoquinoline and 5-aminoindole could produce specific pyridine- and pyrrole-modified IR-NGs, respectively, denoted as PD-NG and PR-NG, respectively. In addition, aniline was reacted with GO to obtain the reference AN-NG, which only contains imine groups. The compositional and structural features of these three IR-NG compounds were confirmed using various spectroscopic and microscopic measurements. The specific capacitances of these IR-NGs in 6 M aqueous KOH solution as an electrolyte gradually increased as follows: PD-NG < AN-NG < PR-NG. The highest capacitance of 174 F g−1 was obtained from PR-NG at the current density of 1.0 A g−1, whereas the capacitances of PD-NG and AN-NG were limited to 125 and 138 F g−1, respectively, under the same conditions. These results indicated that the contributions of the pyridine and pyrrole moieties on the supercapacitive properties of IR-NGs were significant.

Influence of pyridine treatment on the optical properties of organic-inorganic perovskite films

Исследованы обработанные парами пиридина пленки органо-неорганических перовскитов составов CH3NH3PbI3 и CH3NH3Pb(I0,57Cl0,43)3. Анализ измеренных спектров пропускания, фотолюминесценции, а также кинетик интенсивности и центра масс полосы фотолюминесценции в процессе непрерывного освещения показал, что влияние пиридина на органо-неорганические перовскиты неоднозначно: наряду с фотостабилизацией (уменьшением скорости изменения параметров полосы фотолюминесценции при освещении) возникает нежелательный эффект, проявляющийся в резком снижении темновой стабильности (изменении фазового состава в процессе хранения).

Effect of pyridine and pyridine with substituent on photoluminescence of nanoparticles CdS prepared by liquid –liquid interface reaction

Liquid – liquid interface reaction is the method forpreparation nanoparticles (NP'S) which depend on the supersaturation of ions that provide by using the system that consist fromtoluene and water, the first one is above the second to obtainnanoparticles (NP's) CdS at the interface separated between thesetwo immiscible liquid. The structure properties were characterized byXRD-diffraction and transmission electron microscopy.The crystalline size estimate from X-ray diffraction patternusing Scherer equation to be about 7nm,and by TEM analysis give usthat ananosize is about 5 nm which give a strong comparable withBohr radius. Photoluminescence analysis give two emission peak,the first one around the 380 nm and the second around the 760nmwhich indicate to the band edge and surface defect emissionrespectively and the intensity of these emission change with thechange of the pyridine substituent.

Effects of Pyridine and Furan Pretreatment on the Corrosion Resistance of Rust Coating on Mild Steel

Effects of Pyridine and Furan Pretreatment on the Corrosion Resistance of Rust Coating on Mild Steel

Effect of Pyridine and Tribenzylamine on the Hydrolysis Kinetics of Benzoyl Chloride in Water-Dioxane System

Effect of Pyridine and Tribenzylamine on the Hydrolysis Kinetics of Benzoyl Chloride in Water-Dioxane System

Synthesis and characterization of novel polyimides derived from 4,4’-bis(5-amino-2-pyridinoxy)benzophenone: effect of pyridine and ketone units in the main

A diamine monomer, 4,4’-bis(5-amino-2-pyridinoxy)benzophenone, was designed and synthesized, and used to react with commercially different kinds of aromatic dianhydrides to prepare a series of polyimides containing pyridine and ketone units via the classical two-step procedure. Glass transition temperatures (Tg) of the resultant polyimides PI-(1–5) derived from 4,4’-bis(5-amino-2-pyridinoxy) benzophenone with various dianhydrides ranged from 201 to 310 °C measured by differential scanning calorimetry. The temperatures for 5%wt loss of the resultant polyimides in nitrogen atmosphere obtained from the thermogravimetric analysis curves fell in the range of 472–501 °C. The temperatures for 10%wt loss of the resultant polyimides in nitrogen atmosphere fell in the range of 491–537 °C. Meanwhile, the char yields at 800 °C were in the range of 55.3–60.8%. Moreover, the moisture absorption of polyimide films was measured in the range of 0.37–2.09%. The thin films showed outstanding mechanical properties with tensile strengths of 103–145 MPa, an elongation at break of 12.9–15.2%, and a tensile modulus of 1.20–1.88 Gpa, respectively. The coefficients of thermal expansion of the resultant polyimides were obtained among 26–62 ppm °C−1. To sum up, this series of polyimides had a good combination of properties applied for high-performance materials and showed promising potential applications in the fields of optoelectronic devices.

Resistencia a la pudrición y estabilidad dimensional de la madera acetilada con y sin catalizador

El propósito del presente trabajo fue evaluar la resistencia a la pudrición blanca (Coriolus versicolor) y café (Coniophora puteana) en madera acetilada de pino escocés (Pinus sylvestris) y el efecto de la piridina como catalizador. Las pruebas de biodegradación se realizaron sobre cultivos puros en malta agar al 4% por 12 semanas, conforme a lo establecido en la norma europea EN1 13. Adicionalmente, se comparó la estabilidad dimensional de la madera impartida por la acetilización, en sistemas de modificación química catalizada y sin catalizar. La modificación química proporcionó resistencia a la biodegradación de la madera contra hongos de la pudrición café y blanca. Se requirió de un nivel de acetilización mayor para inhibir la pudrición café, en comparación con el requerido para impedir la pudrición blanca. Los patrones de pudrición y las pérdidas de peso registradas indicaron que la piridina como catalizador no influyó en la resistencia a la pudrición de la madera acetilada, cuando los resultados fueron comparados dentro de la misma especie de hongo. La estabilidad dimensional impartida por la acetilización, medida por la eficiencia de antiexpansión (ASE), resultó satisfactoria en ambos sistemas de reacción, aunque el sistema no catalizado fue significativamente más eficiente. Seconcluyó que la ganancia porcentual en peso, debida a la modificación química, es un buen indicador del grado de expansión parcial permanente de los bloques de madera, así como de la estabilidad dimensional y la resistencia a la pudrición de la madera acetilada.

Selectivity Control in the Catalytic Dehydration of Methyl Lactate: The Effect of Pyridine

Catalytic dehydration of biomass-derived methyl lactate to produce acrylic acid and its esters promises a renewable route to produce a major commodity chemical. Alkali metal cation exchanged zeolites are capable of catalyzing this reaction; however, selectivity control toward the dehydration pathway remains a challenge. Through combined kinetic and transmission spectroscopic investigations, we demonstrate that introducing pyridine, a base, to the reaction feed increases selectivity to acrylates while inhibiting the formation of side products (i.e., acetaldehyde and coking). The ratio of the turnover frequencies for the desired dehydration and undesired decarbonylation pathways (TOFDH/TOFAD) increases by a factor of ∼20 when pyridine is included in the feed (pyridine/methyl lactate 1/10), in comparison to the case where pyridine is absent. Transmission FTIR investigations show that the reduced decarbonylation activity can be directly related to pyridine quenching Bronsted acid sites generated during the re...

Effect of Pyridine on the Mesophase of Teraryl Liquid Crystals: A New Series of Nematic Liquid Crystals Named 2-(4-Alkoxybiphen-4'-yl)-5-methylpyridines.

A new series of teraryl 2-(4-alkoxybiphen-4′-yl)-5-methylpyridines (nO-PPPyMe, n = 3–8) nematic liquid crystal compounds, bearing a biphenylene core and a picoline terminus, were synthesized using a short two-step reaction, and overall yields between 34% and 38% were obtained. Spectral analysis results were in accordance with the expected structures. The thermotropic behavior of the teraryl liquid crystal compounds was investigated through polarized optical microscopy and differential scanning calorimetry. All compounds exhibited a solely enantiotropic nematic phase at the medium–high temperature range of 162.4–234.2 °C. Furthermore, the results for the nO-PPPyMe series were analyzed relative to three other compound series, mO-PPPyCN (m = 2–8), iO-PPQMe (i = 3–8) and xO-PPyPMe (x = 1–10). Consequently, the effect of pyridine on the mesophase of teraryl liquid crystals was demonstrated.

Konig 반응을 이용한 CK 작용제 탐지젤 개발에 관한 연구

A simple and sensitive hydrogel-based detecting gel has been presented for the qualitative determination of cyanogen chloride(CK) using Konig reaction. To optimize Konig reaction conditions, the effects of pyridine and barbituric acid concentration were investigated. Under the optimized conditions, CK gas concentration was directly related with absorbance change at 567 nm. Based on aqueous solution test results, we finally prepared CK detecting hydrogel by absorbing pyridine and barbituric acid solution. Color change of the prepared CK detecting hydrogel was clearly observed when the detecting gel was exposed to 10 ppm CK gas.

Co(salen) catalysed oxidation of synthetic lignin-like polymer: Pyridine effects

Co(salen) [salen = N, N'-bis(salicylidene)ethylenediamine] complexes can perform catalytic oxidations, but their corresponding reaction pathways are still not fully understood. In this study, the Co(salen)catalyzed oxidization of synthetic lignin-like polymer (S- and G-type lignin model polymer) by H2O2 in alkaline aqueous solution in the presence of pyridine was elucidated with FTIR, 13C NMR and gas chromatography–mass spectrometry. Co(salen) was active catalyst, increasing the oxidation rate of the S- and G-type lignin model polymer. The oxidation of lignin model polymer, irrespective of the S- and G-type, occurs selectively at benzylic position as in all experiments as benzaldehyde was the main observed product. The effect of pyridine was noted to be critical and the reactivity of the catalyst increased with addition of pyridine.

Role of Citric Acid Modification on Hydrodesulfurization of DBT and 4,6 DMDBT in the Presence of Pyridine Over CoMo/Al2O3

In this study, the effect of pyridine as a basic nitrogen compound on HDS activity of DBT and 4,6 DMDBT in treated diesel over modified CoMo/Al2O3 by citric acid has been investigated. It has been obviously found that the modification of CoMo/Al2O3 catalyst by citric acid can inhibit the influence of pyridine on HDS activity of DBT and 4,6 DMDBT. This can be explained that when citric acid was applied in the catalyst preparation, the increasing of total amount of acid sites and the enhancement of HDN activity play an important role in the tolerance of pyridine.

Halogenated tetraphenyl porphyrin; iodosylbenzene an efficient catalytic system for olefin epoxidation

Olefin epoxidation using o-phenyl and [Formula: see text]-pyrrole substituted tetraphenyl porphyrin complexes of Fe(III) and Mn(III) as catalysts and [Formula: see text]Iodosylbenzene as oxidant was studied. Excellent yields of epoxide and secondary oxidation products were observed. Effect of pyridine, imadizole, sodium lauryl sulphate, and solvent variation was also studied. Effect of substituents on catalytic activity of the porphyrin complex is also explained. o-phenyl substituted complexes gave better yield of epoxide as compared to [Formula: see text]-pyrrole substituted complexes.

Synthesis of the 2,3,4-triacetyl-1,6-dideoxy-L-mannose and tetracetyl-3,6-dideoxy-L-mannitol and the study of the reaction mechanism by molecular modeling

The carbohydrate compounds have interesting stereochemical properties and can be used as chiral building blocks in the production of more complex derivatives. L-Rhamnose has been reported to participate in the synthesis of cytotoxic α-pyrones owing to the stereochemistry of the hydroxy groups. To study the conformational properties of acetyl derivatives of L-rhamnose, it was tosylated with the subsequent reduction and acetylation. These series of reactions produced an interesting mixture of poly-acetylated compounds. The mixture was separated by HPLC, characterized by 1D and 2D NMR techniques and compared with models obtained on DFT/B3LYP/DGDZVP theory level of calculation, taking into account the effect of pyridine as solvent in the transformation of this carbohydrate. The results show a mixture of three pyranoside products with tosyl group in positions 2, 3, and 4. These latter compounds after reduction with aluminum hydride and acetylation yielded two main products, one triacetate pyranoside and an open-chain mannositol tretraacetate.

The effects of pyridine on the structure of B-COFs and the underlying mechanism

Previous work demonstrated the ability of a trace amount of pyridine to stabilize Covalent Organic Frameworks (COF)-5 and -10 in humid air. Pyridine was found to form a mixture of Lewis and Bronsted B[4] Py–B complexes in addition to the un-complexed B[3] sites in the framework structures. Further research has shown that higher doses of pyridine convert all remaining B[3] in COF-5/-10 to Lewis B[4] and bring about the total and irreversible structural decomposition of COF-5 and COF-10. The results suggest that the accumulated strain in the five-member rings of COF-5/-10 resulting from the formation of tetrahedrally-distorted B[4] sites at high pyridine loadings, may explain the decomposition of these structures. Alternatively, COF-1 is unstable to exposure to humid air at all pyridine loadings tried, but is not unstable to high doses of pyridine. Whereas the same tetrahedrally-distorted B[4] sites are formed in COF-1, in this case the six-membered B3O3 ring can accommodate the accumulated ring strain and retain an ordered structure. A thorough solid state NMR and molecular dynamics investigation has led to a new proposed stabilization mechanism in humid air based on the formation of Bronsted B[4].