Polarographic study of complexes of metal ions and dibasic acids-II Complexes of lead with malonic, succinic, glutaric and adipic acids

The malonate, succinate, glutarate and adipate complexes of lead have been examined polarographically and the overall stability constants evaluated. The values found are log beta(1) = 2.60, 2.40, 2.48, 2.38; log beta(2) = 3.62, 3.73, 3.45, 3.20; log beta(3) = 4.32, 4.11, 3.90, 3.69, for the malonate, succinate, glutarate and adipate complexes respectively.     

Chromatographic study of anionic complexes

Summary In this paper we have reported our results on the attempted separation of copper(II), nickel(II), cobalt(II) and iron(III) in mixtures by filter paper strip chromatography, using aqueous ethanol as solvent. The effect of the presence of varying concentrations of citrate ion as a complexing agent in the mixtures has been studied. The complexing agent has been added in the metal solution, and not in the solvent as usually done by previous workers.     

Effect of bromination on the thermal properties of poly(2,6-dimethyl-1,4-phenylene oxide)

The thermal behavior of poly(2,6-dimethyl-1,4-phenyiene oxide) (PPO R resin), poly(3-bromo-2,6-dimethyl-1,4-phenylene oxide), and a series of their statistical copolymers with identical average molecular lengths has been characterized by thermogravimetry and computer-interfaced differential scanning calorimetry. The heat capacities are found to be additive with respect to the concentrations of the two components. The change in heat capacity at the glass transition ( C _p) is independent of composition for bromination of up to 75% of the repeat units. At higher bromine levels C _p decreases abruptly. This behavior is attributed to the temperature dependence of C _p for the two components. The glass transition temperature (T _g) of the copolymers varies nearly linearly with composition. A comparison of the experimental values ofT _g is made with various equations derived for statistical copolymers and homogeneous polymer blends. A modification of the Couchman equation is presented taking into account the temperature dependence ofC _p.

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Zusammenfassung Das thermische Verhalten von Poly(2.6-dimethyl-1.4-phenylenoxyd) (PPO R-Harz), Poly(3-brom-2.6-dimethyl-1.4-phenylenoxyd) und einer Reihe von statistischen Copolymeren dieser Verbindungen mit gleicher durchschnittlicher Moleküllänge wurde durch Thermogravimetrie und Differential-Scanning-Kalorimetrie mit Computerinterface charakterisiert. Die Wärmekapazitäten sind hinsichtlich der Konzentrationen der beiden Komponenten additiv. Die Veränderung in der Wärmekapazität beim Übergang zum Glas (C_p) ist unabhängig von der Zusammensetzung bei Bromierung bis zu 75% der wiederho-lungseinheiten. Bei höheren Bromierungsgraden nimmtC _p abrupt ab. Dieses Verhalten wird der Temperaturabhängigkeit vonC _p der beiden Komponenten zugeschrieben. Die Glasübergangstemperatur (T_g) der Copolymeren verändert sich nahezu linear mit der Zusammensetzung. Ein Vergleich der experimentellen Werte von T_g wird mit verschiedenen für statistische Copolymere und Mischungen homogener Polymere abgeleiteten Gleichungen ausgeführt. Eine die Temperaturabhängigkeit vonC _p berücksichtigende Modifikation der Gleichung von Couchman wird angegeben.

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, , (2,6- -1,4), (3--2,6--1,4- ) . , ë . ë (C ) 75%. C . C . T . . T . , . , C .

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This work was supported by the National Science Foundation, Polymers Program (DMR 78-15279) and the General Electric Corporate Research and Development Center. The authors are indebted to the following individuals at General Electric CRD for their experimental assistance: S. R. Weissman and P. E. Gundlach (molecular weight characterizations); D. W. Marsh (X-ray analysis); V. H. Watkins and E. L. Hall (electron microscopy); and N. A. Marotta (thermogravimetry). P. E. Donahue and E. A. Williams are gratefully acknowledged for carrying out and interpreting the NMR experiments.

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One of the authors (R. C. Bopp) would like to thank A. R. Shultz, J. T. Bendler, and D. M. White at General Electric CRD for their helpful discussions of this work and express his sincere appreciation to Professor P. R. Couchman (Rutgers University) for his illuminating discussions of the thermodynamic basis of his equation.     

A polyaniline-containing filter paper that acts as a sensor, acid, base, and endpoint indicator and also filters acids and bases

In this paper we report a new idea for synthesizing polyaniline in an ordinary filter paper. The synthesis was carried out by a process in which aqueous acidic aniline solution and the oxidizing agent H(2)O(2) was added to the paper drop by drop and in sequence. Uniform polymerization could be obtained with the addition of reagents in either sequence. The polymer formation led to a green coloration of the paper. Formation of the emeraldine salt of polyaniline was confirmed by UV-vis and FTIR spectroscopy. Scanning electron microscopic measurements were made for surface characterization of the polymer formed in the paper. The same paper was used as a sensor for ammonia in vapor and in solution, for acid and base as well as endpoint indication, and also to filter acids and bases. We found that, using the polymer-containing paper, ammonia concentrations in a solution as low as 14 ppm could be measured.     

Enantioselective total synthesis of (+)-amphidinolide t1

An enantioselective first total syntheis of amphidinolide T1 (1) is described. Amphidinolide T1 (1), a 19-membered macrolide isolated from Amphidinium sp., has shown potent antitumor properties against a variety of NCI tumor cell lines. The synthesis is convergent and involves the assembly of C1-C10 segment 2 and C11-C21 segment 3 by an oxocarbenium ion-mediated alkylation and Yamaguchi macrolactonization sequence. The synthesis of fragment 2 involves an efficient cross metathesis and hydrogenation sequence between the terminal olefins of 5 and 6 to form the C4-C5 carbon-carbon bond. Enol ether 4 is designed to be the surrogate of fragment 3 where the sensitive C16-exo-methylene and the C13-hydroxyl group were protected as the bromoether derivative during the Lewis acid-catalyzed alkylation process. Both stereocenters in fragment 5 as well as the C2 and C3 stereocenters in fragment 4 are accessed by a highly diastereoselective ester-derived titanium enolate-mediated syn-aldol reaction. The bromoether derivative 24 was unraveled at the final stage of the synthesis, providing (+)-amphidinolide T1.     

Electrode kinetics and thermodynamic study of complexes of palladium(II) at D.M.E.

Polarographic study of Pd(II) reveals that it reduces quasireversibly at d.m.e. in 0.2M-pyridine+0.1N-HCl medium. Kinetic parameters of Pd(II) in various concentrations of -resorcyclic acid were calculated usingGellings method and thus the effect of concentration of -resorcyclic acid on the kinetics of the reduction of Pd(II) has been explained.DeFord/Hume graphical extrapolation method and the mathematical method ofMihailov have been employed for the evaluation of overall formation constants of the complexes formed with -resorcyclic acid. The logarithmic values of overall formation constants ₁, ₂ and ₃ obtained by the two methods are 7.47, 8.60, 9.66 (DeFord andHume Method) and 7.44, 8.64, 9.66 (Mihailov Method) at 298 K. Thermodynamic parameters of these complexes are reported.

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Elektrodenkinetik und thermodynamische Untersuchungen an Pd(II)-Komplexen mittels polarographie

Zusammenfassung Pd(II) zeigt eine quasireversible Reduktion in 0,2M-Pyridin/0,1N-HCl. Kinetische Parameter wurden mittels der Methode vonGelling ermittelt und damit der Effekt verschiedener -Resorcylsäurekonzentrationen erklärt. Bildungskonstanten der entsperechenden Komplexe wurden nachDeFord/Hume und nachMihailov ermittelt. Die logarithmischen Werte der Gesamtbildungskonstanten ₁, ₂ und ₃ bei 298 K betragen nach derDe Ford/Hume-Methode 7,47, 8,60 und 9,66, nach derMihailov-Methode 7,44. 8,64 und 9,66. Die thermodynamischen Parameter der Komplexbildung werden angegeben.

     

Photometric determination of trivalent gallium,indium and thallium with Xylenol orange

Summary Xylenol orange reacts very sensitively with gallium(III), indium (III) and thallium(III) to form reddish violet colored chelates having _max 560 nm in case of Ga and In and _max 590 nm in case of Ti at P_H 4.0. The molar ratio for all the chelates is 1 1 (metal reagent). Optimum conditions including the range for adherence to Beer's law, effect of P_H on the color intensity, effect of excess reagent, and sensitivity are reported for the photometric determination of these metal ions using Xylenol orange.

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Zusammenfassung Xylenolorange reagiert sehr empfindlich mit Gallium(III), Indium(III) und Thallium(III) unter Bildung rötlich-violetter Chelate mit einem Absorptionsmaximum bei 560 nm im Falle von Ga und In bzw. 590 nm für Tl bei p_H 4,0. Das Molverhältnis ist in jedem Fall 11. Die besten Arbeitsbedingungen, der Gültigkeitsbereich des Beerschen Gesetzes, der Einfluß des P_H auf die Farbintensität und des Reagensüberschusses sowie die Empfindlichkeit werden für die photometrische Bestimmung der genannten Ionen angegeben.

     

Ternary complexes of copper(II), nickel(II) and zinc(II) with nitrilotriacetic acid as a primary ligand and some phenolic acids as secondary ligands

Summary The formation of ternary complexes of the MAL^3– type [where M = Cu^II, Ni^II and Zn^II ; A = nitrilotriacetic acid (NTA); L = 1-hydroxy-2-naphthoic acid (1,2 HNA) and 2-hydroxy-1-naphthoic acid (2,1 HNA)] have been studied potentiometrically in 50% v/v aqueous — ethanol (25° and µ = 0.1). Under identical conditions the binary complexes of the 1,2- and 2,1-HNA ligands have also been examined. The values of mixed ligand formation constants K_MAL have been found to be lower than K_ML (first step formation constant of binary complexes) and even less than (second step formation constant of binary complexes).     

Photometric determination of palladium with chrome azurol S

Summary Chrome Azurol S permits a simple colorimetric determination of palladium with a sensitivity of 0.4g/cm² (practical) or 0.04g/cm² (Sandell), respectively. Conditions and interferences are described in detail.

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Zusammenfassung Palladium läßt sich mit Hilfe von Chromazurol S auf einfache Weise kolorimetrisch bestimmen. Die praktische Empfindlichkeit der Methode beträgt 0,4g/cm² bzw. 0,04g/cm² nachSandell. Die Arbeitsbedingungen und die durch Fremdionen verursachten Störungen werden angegeben.

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Résumé Le chromazurol S permet un dosage colorimétrique simple du palladium, avec une sensibilité de 0,4g/cm² (en pratique) ou 0,04g/cm² (Sandell) respectivement. On décrit en détail les conditions opératoires et les interférences.

     

A novel nitrate-selective electrode based on precipitated nitron nitrate

Summary A nitrate-selective electrode based on precipitated nitron nitrate in an epoxy resin matrix has been prepared. The lower detection limit is 10^–5 M, the optimum pH range is 2.0–8.5, and the response time is 1 min. The electrode is selective in presence of CH₃COO^–, SO₄ ^2–, C₂O₄ ^2–, PO₄ ^3–, NO₂ ^–, Cl^– and Br^–, but I^– interferes. Results for nitrate in soil samples were in agreement with values obtained spectrophotometrically.

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Eine neue nitrat-spezifische Elektrode auf der Basis gefällten Nitronnitrats

Zusammenfassung Eine nitrat-spezifische Elektrode auf der Basis gefällten Nitronnitrats in einer Epoxyharz-Matrix wurde hergestellt. Die untere Nachweisgrenze ist 10^–5 M, das pH-Optimum liegt zwischen 2,0 und 8,5, die Reaktionszeit beträgt 1 Minute. Die Elektrode ist selektiv in Gegenwart von Acetat, Sulfat, Oxalat, Phosphat, Nitrit, Chlorid und Bromid; aber Jodid stört. Ergebnisse der Nitratbestimmung in Bodenproben stimmen mit spektrophotometrischen Resultaten überein.

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Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.