Pyridine In Aqueous Solution Research Articles

Kinetic Studies of the Electron Transfer Reaction in Iron(II) and Iron(III) Systems. X. The Electron Transfer Reaction between Iron(II) and Iron(III) in the Presence of Pyridine in Aqueous Solution

Abstract When pyridine is added to the reaction system of the electron transfer between Fe(II) and Fe(III) in aqueous solution at constant [HClO4]o, the apparent rate constant k grows rapidly with [Py]o at [Py]o<C[HClO4]o, while k suddenly diminishes to a small and constant value at [Py]o>[HClO4]o. The predominant paths of the reaction will be discussed.

Temperature Dependence of Structural Propensity of 1-Butanol in Water

Abstract The temperature dependence of structural propensity of 1-butanol has been studied by investigating its effect on the temperature of sound velocity maximum (TVM) in aqueous mixtures of glycerol and pyridine. The structural contribution to the shift in TVM of binary solution, [ΔTstr]exp was found to be positive at low concentrations of 1-butanol for aqueous pyridine solutions whose TVM are 37.6 °C and 23.7 °C. For aqueous glycerol solutions whose TVM is 43.3 °C, [ΔTstr]exp values, in the entire concentration range of 1-butanol studied, are found to be negative. The results indicate that below 40 °C 1-butanol behaves as a structure promoter while above 40 °C it behaves as a structure breaker.

Studies of the reorientational relaxation of pyridine in water by depolarized Rayleigh light scattering

The depolarized Rayleigh spectra of aqueous solutions of pyridine have been studied using a high-finesse Fabry–Perot interferometer as a function of temperature and concentration. The Rayleigh relaxation times are found to have a complex concentration and viscosity dependence. The classical Stokes–Einstein–Debye equation for molecular reorientation breaks down in this system. The Rayleigh relaxation time of pyridine molecules is not determined by the macroscopic shear viscosity of the solution. The specific interaction due to the formation of hydrogen bonds between pyridine and water molecules plays a very important role in affecting the relaxation time. At a fixed temperature the plot of πray/η versus pyridine concentration shows two maxima at low and high pyridine concentrations. The low concentration maximum is due to the incorporation of pyridine molecules in the water network structure and the high concentration maximum is associated with the formation of individual pyridine–water complexes. The activation energy for the reorientation of pyridine molecules depends on the pyridine concentration. At low pyridine concentration the activation energy corresponds well to the N⋅⋅⋅H–O hydrogen bonding energy. Above 70% volume the activation energy decreases with increasing pyridine concentration, and above this concentration range the reorientational relaxation time becomes less structure controlled.

Catalytic oxidation of ascorbic acid by molecular oxygen in aqueous pyridine in the presence of Co2+, Ni2+, Mn2+ and Zn2+ ions

In aqueous pyridine solutions, Co2+, Ni2+, Mn2+ and Zn2+ effectively catalyze the oxidation of ascorbic acid by molecular oxygen. A kinetic expression consistent with the experimental data is given and a possible mechanism proposed.

Some properties of vicinal diol-epoxides derived from benz(a)anthracene and benzo(a)pyrene

The alkylating properties of pairs of syn- and anti-isomers of 2 diolepoxides derived from benzo(a)pyrene (BP) and of 1 derived from benz(a)anthracene (BA) have been investigated. Of the anti-diol-epoxides, anti-BP 7,8-diol-9,10-oxide was the most reactive compound towards DNA, towards sodium p-nitrothiophenolate in a non-aqueous solvent system, and towards 4-( p-nitrobenzyl)pyridine in aqueous solution; anti-BP 9,10-diol-7,8-oxide was of intermediate reactivity and anti-BA 8,9-diol-10,11-oxide was least reactive. The syn-diol-epoxides gave unsatisfactory results with DNA and 4-( p-nitrobenzyl)pyridine because of their rapid solvolysis in aqueous solution, but with sodium p-nitrothiophenolate showed the order of reactivity syn-BP 7,8-diol-9,10-oxide > syn-BA 8,9-diol-10,11-oxide > syn-BP 9,10-diol-7,8-oxide. The products of the reaction between diol-epoxides and nucleic acids were examined by Sephadex LH-20 chromatography followed by high-pressure liquid chromatography (HPLC) and the diol-epoxides were shown to react principally with the guanosine and adenosine moieties of RNA.

Apparent molal heat capacities and volumes of pyridine and methyl-substituted pyridines in aqueous solution at 25�C

We have made calorimetric measurements leading to apparent molal heat capacities of pyridine and four methyl-substituted pyridines in aqueous solution at 25.0°C. Measurements of densities of the same solutions have led to apparent molal volumes. The results are as follows: pyridine, φC° = 305.7 J−°K−1-mole−1 and φV° = 77.5 cm3-mole−1; 2-methylpyridine, φC° = 370.0 J−°K−1-mole−1 and φV° = 94.3 cm3-mole−1; 3-methylpyridine, φC° = 380.2 J−°K−1-mole−1 and φV° = 93.7 cm3-mole−1; 4-methylpyridine, φC° = 378.9 J−°K−1-mole−1 and φV° = 94.3 cm3-mole−1; 2,6-dimethylpyridine, φC° = 441.8 J−°K−1-mole−1 and φV° = 109.9 cm3-mole−1. These φC° and φV° values are discussed in terms of effects of substitution of CH3-for H− in the various solute molecules.

Photohydration of pyridine in aqueous solution. An undergraduate experiment in photochemical kinetics

Photohydration of pyridine in aqueous solution. An undergraduate experiment in photochemical kinetics

Vapor-liquid equilibria of some pollutants in aqueous and saline solutions Part I: experimental results

Vapor-liquid equilibria were measured for dilute aqueous solutions of formic acid, acetic acid, pyridine, aniline, isobutyl alcohol, isoamyl alcohol, n-butyl acetate, dimethyl phthalate, diethyl phthalate and dioxane, respectively, at various pH, temperatures and concentrations of sodium chloride. The substances chosen are very important raw materials or intermediates in chemical industry and are widely used. Phthalates are used as plasticizers and leach, in small amounts, into water from plastics. Recently in Japan, we are recognizing phthalates as a new polluting material in sea water and river water. The vapor-liquid equilibria were severely affected by the pH of the solution, not only for the electrolytes (such as formic acid and pyridine), but also for esters. This is probably due to the effect of pH on the degree of the dissociation of electrolytes and on the hydrolysis of esters. The phase equilibria of some organic materials which are less soluble in water (such as phthalates and higher alcohols) were greatly affected by the salting-out effect of salinity. If the feed sea water to distillation plants is contaminated by volatile organic materials, some of them concentrate in the distilled water. Therefore, attention must be given to the properties of volatile, polluting materials in sea water when the product water from desalination processes is for human consumption.

Structural and kinetic matrix effects in polymerization of 4-vinyl pyridine in aqueous solutions of sodium polystyrene-sulphonate and sodium dodecylsulphate

A comparative study of polymerization of 4-vinyl pyridine (4-VP) in aqueous solutions of sodium polystyrene-sulphonate (PSS) and sodium dodecylsulphate (DDS) shows that in both systems a similar kinetic matrix effect is observed, which is due to the same cause — similar interaction of PSS macromolecules and DDS micelles with protonized and unprotonized forms of 4-VP. Structural matrix effect was only observed in PSS solutions which proves that it is due to the presence in the polymerization system of a macromolecular matrix of chain structure, capable of forming with the ionene to be synthesized a salt poly-complex of given structure, preventing the association of ionene chains.

Coenzyme B12 model studies. Equilibria and kinetics of axial ligation of substituted alkylcobaloximes by pyridine in aqueous solution.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCoenzyme B12 model studies. Equilibriums and kinetics of axial ligation of substituted alkylcobaloximes by pyridine in aqueous solutionKenneth L. Brown, Douglas Lyles, Michael Pencovici, and Roland G. KallenCite this: J. Am. Chem. Soc. 1975, 97, 25, 7338–7346Publication Date (Print):December 1, 1975Publication History Published online1 May 2002Published inissue 1 December 1975https://doi.org/10.1021/ja00858a022RIGHTS & PERMISSIONSArticle Views146Altmetric-Citations60LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Colorimetric Determination of Formaldehyde via Free Radical Formation

Aliphatic aldehydes react with 2,3‐dimethyl‐2,3‐bis‐(hydroxylamino)butane and sodium periodate to form colored free radicals. These radicals were stabilized with pyridine in aqueous solution. Low levels of formaldehyde in aqueous solutions were determined utilizing this reaction.

Electrode reactions of nickel(II) at mercury electrodes in aqueous solutions of pyridine at high ionic strengths

At high ionic strength the ion pair (NiPy 2+ 4, nX −) or complex (NiPy 4X 2), n = 0, 1, 2; X − = Cl −, Br −, SCN −, N − 3, F −, NO − 3, ClO − 4; is adsorbed at the surface of mercury electrode. Under specified conditions in chloride, bromide, and thiocyanates solutions the electroreduction is preceded by a crystallization of a complex on the electrode surface. The inductive role of specifically coadsorbed Cl − ions is discussed.

Spectrophotometric Assay of Karathane Technical and Karathane Formulations

Abstract A spectrophotometry procedure for the determination of total dinitrooctylphenols and dinitrooctylphenyl crotonates in Karathane Technical (dinocap) and Karathane formulations has been collaboratively studied. The sample is dissolved in petroleum ether; the total mono- and dinitrooctylphenols are then selectively extracted with aqueous sodium hydroxide solution and examined photometrically at 410 nm. The dinitrooctylphenyl crotonates are hydrolyzed in aqueous pyridine solution and measured photometrically at 442 nm. Five collaborators analyzed Karathane Technical, Karathane LC, and Karathane WD in duplicate on each of 2 days. Statistical analysis indicates that between- laboratory precision, s, of the dinitrooctylphenyl crotonate determination, excluding outliers, was 2.05, 0.71, and 0.79% absolute at the 76, 38, and 18% assay levels, respectively. The precision of the dinitrooctylphenol determination on the same sample series was s = 0.071% at the 2.3% concentration level, 0.18% at the 1.88% level, and 0.457% at the 2.20% level, respectively. It is recommended that another collaborative study be conducted with an increased number of collaborators, incorporating changes in the procedure suggested by the collaborators.

Odor effects of pyridine-montmorillonite in aqueous solution

The threshold odor response of individuals to aqueous solutions of pyridine with and without the presence of sodium montmorillonite was determined at 24 and 40°C. At 24°C there was a significant olfactory effect at pyridine-clay concentrations that produced no effect at 40°C. The olfactory effect depended on the relative sensitivity of the panelists.

Synthesis of 4-thiouridine derivatives

The thionation of a protected uridine with the aid of P2S5 has given the corresponding 4-thiouridine derivatives, which have been phosphorylated at the 5′ or the 2′(3′)hydroxyl. On being heated in aqueous pyridine solution with liquid hydrogen sulfide, cytidine phosphates also form 4-thiouridine phosphates. 4-Thiouridine 2′,3′-cyclophosphate has been obtained.

Hydrolysis of linear polyurethanes and model monocarbamates

AbstractAlkaline hydrolysis of model carbamates, polyurethanes, and poly(urethane‐ureas) has been investigated. The model carbamates were based upon phenyl, benzyl, and cyclohexyl isocyanates. The polyurethanes and poly(urethane‐ureas) were prepared from tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), and 4,4′‐dicyclohexylmethane diisocyanate (H12MDI) and a poly(oxyethylene)glycol of 6000 molecular weight. Pseudo‐first‐order rate constants of hydrolysis were obtained in aqueous pyridine solution at 110°C, and second‐order rate constants were obtained in aqueous KOH solution for the model biscarbamates. Pseudo‐first‐order rate constants of hydrolysis were obtained in alcoholic KOH solution for the polyurethanes and poly(urethane‐ureas). The hydrolysis of the model carbamates showed that the stability increased in the following manner: phenyl < benzyl < cyclohexyl. The pseudo‐first‐order rate constants were dependent upon the pKb of the corresponding amines. The hydrolysis of the polyurethanes and poly(urethane‐ureas) showed that the stability increased in the following manner: aromatic < aralkyl < cycloaliphatic. It was shown that polyurethanes are more susceptible to alkaline hydrolysis than to acidic hydrolysis.

Spectrophotometric determination of molybdenum(V) with oxine in aqueous pyridine solution

Molybdenum(V) and oxine formed a yellowish red colored complex having 1 : 1 molar ratio soluble 40 vol% pyridine solution. At its maximum absorption, 405 nm, the molar absorptivity was 4.4 × 103. The recommended procedure was as follows.Take the sample solution containing 0.020.6 mg of molybdenum and neutralize with 6 N sulfuric acid. Add 1 ml of 6 N sulfuric acid and 4 ml of 3% hydrazinesulfate solution, and heat the solution to ca. 1 ml. The reduction of molybdenum(VI) to molybdenum(V) occurred at this stage. Cool the solution, add 2 ml of 0.6% oxine solution and 10 ml of pyridine, and dilute to 25 ml with water. Measure the absorbance at 405nm against the reagent blank. Beer's law held for 0.824 ppm of molybdenum. Interference from tungsten was removed by measuring the absorbance at 405 nmand 450 nm. Since iron and copper etc. interfered with the determination of an extent of 0.7% molybdenum ion ores, molybdenum(V) was subjected to the spectrophotometric procedure by treatment with oxine and pyridine after the separation of precipitate as α-benzoinoximate from iron and copper etc. in sulfuric acidic solution.

Thermodynamics of proton dissociation in dilute aqueous solution: xvii. p K, Δ H°, and Δ S° values for proton ionization from several monosubstituted pyridines at 10, 25, and 40°C

A calorimetric study has been made of proton ionization from several monosubstituted protonated pyridines in aqueous solution at 10, 25, and 40°. Values of Δ C° p were calculated from the variation of the Δ H° values with temperature. A linear relationship was found between p K and Δ H° with the exception of the ortho-halogen substituted protonated pyridines. A discussion of the resulting thermodynamic quantities is given.

A reaction of glucose with peptides.

Valylhistidine (Val-His) reacts with glucose (Glc) in a mixture of pyridine and acetic acid to form glucosylvalylhistidine (Glc-Val-His). The pK of the alpha-amino group is thereby lowered to about 5.6 as judged by electrophoretic mobility. The reaction: [Formula: see text] also occurs in an aqueous solution of pyridine and acetic acid of pH6.2 at 50 degrees C, in which it exhibits a half-time of about 30h and a dissociation constant of about 0.3m. Isoleucyltyrosine and glucose react similarly in aqueous solution. The Glc-Val-His has the chromatographic, electrophoretic and chemical properties reported by Holmquist & Schroeder (1966a) for the substance released by proteolysis from the N-terminus of the beta-chains of haemoglobin A(Ic); the value of the dissociation constant means that the concentration of haemoglobin A(Ic) found naturally could be explained by reaction of haemoglobin A with the blood glucose.

Nuclear magnetic resonance studies of quadrupolar and dipolar relaxation effects. Complexes of lithium halides with pyridine in aqueous solution

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNuclear magnetic resonance studies of quadrupolar and dipolar relaxation effects. Complexes of lithium halides with pyridine in aqueous solutionDavid W. LarsenCite this: J. Phys. Chem. 1972, 76, 1, 53–59Publication Date (Print):January 1, 1972Publication History Published online1 May 2002Published inissue 1 January 1972https://doi.org/10.1021/j100645a010RIGHTS & PERMISSIONSArticle Views35Altmetric-Citations2LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (743 KB) Get e-Alerts