Determination of boron in copper and copper-, nickel- and cobalt-base alloys

Summary A pyrohydrolytic method for the extraction of boron from coppper and copper-, nickel- and cobalt-base alloys has been developed. For concentrations higher than 0.1 %, boron is determined by an alkalimetric method in the presence of mannitol and phenolphthalein or by a potentiometric method. For samples containing less than 0.1% of boron, it is determined by spectrophotometry with azomethine H. Standard deviations are in the range of 0.008 to 0.15% B.

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Bestimmung von Bor in Kupfer sowie Legierungen auf Kupfer-, Nickel- und Kobaltbasis

Zusammenfassung Zur Extraktion von Bor aus diesen Proben wurde ein pyrohydrolytisches Verfahren ausgearbeitet. Die Borbestimmung erfolgt bei Gehalten >0,1% B alkalimetrisch in Gegenwart von Mannit und Phenolphthalein oder potentiometrisch, bei Gehalten <0,1% B durch Spektralphotometrie mit Azomethin H. Die Standardabweichungen liegen im Bereich von 0,008–0,15% B.

     

Microdetermination of the amine oxide group in organic compounds by reduction with titanium(III)

A rapid and selective method for the determination of water-soluble boron in complex fertilizers is described. Boron is separated from the sample solution, which should be approximately 0.1 N in hydrochloric acid, by shaking twice with 20% solution of 2-ethyl-1,3-hexanediol in hexone. Following this extraction boron is back-extracted into the aqueous phase with 0.5 N sodium hydroxide. It is finally determined spectrophotometrically at 415 nm using azomethine H as reagent.     

Electrochemical Determination of Boron in Natural Waters

Abstract

A sensitive voltammetric method for the determination of trace boron, based on the formation of the complex of boric acid with 4‐hydroxy‐5‐[salicylideneamino]‐2‐7‐naphthalenedisulfonic acid (azomethine H) is described. The reduction of the boric acid‐azomethine H complex at a hanging mercury drop electrode was exploited by square wave voltammetry (SWV) and cyclic voltammetry to determine boron in natural water samples, which were collected in the regions surrounding the boron mines of Central Anatolia. A reduction peak that belongs to the boric acid‐azomethine H complex at this electrode was observed at ?1.05 V vs. Ag/AgCl/KCl_(sat.). The effects of various parameters, such as ligand concentration, boric acid concentration, and formation time of the boric acid‐azomethine H complex, were investigated. Electrochemical experiments were conducted in 1.0 M HOAc/0.5 M NH₄OAc buffer at pH of 4.4±0.2. Linear working range was established by regression analysis between 5.0×10^?8 M and 1.0×10^?4 M. The probable metal cation interferences in water samples were eliminated by adding EDTA (ethylenediaminetetraacetic acid) to the samples. Data obtained using the square wave voltammetric (SWV) technique was compared statistically with inductively coupled plasma mass spectroscopy (ICP‐MS) data. Evaluation of the method based on statistical data was performed and the values of the limit of detection (LOD) and limit of quantitation (LOQ) were found to be 4.17×10^?6 M and 1.39×10^?5 M, respectively.     

Remarques sur le microdosage du bore et du germanium dans les composes organiques et mineraux

A wet destruction in a Kjeldahl flask followed by spectrophotometric measurement with azomethine H as reagent, combustion in oxygen in a Parr bomb, and destruction by heating with sodium peroxide followed by acidimetric titration of the mannitol—boric acid complex have been tested for the microdetermination of boron in organic and inorganic compounds and compared with the Schöniger-flask method, which fails to give good results in the case of inorganic compounds; the wet-combustion method is the most useful. Similar techniques, combined with the acidimetric titration of the mannitol—germanic acid complex, or spectrophotometric measurement using phenylfluorone as a complexing reagent, or gravimetric determination as GeO₂, have been tested for the microdetermination of germanium, but none of them is entirely satisfactory, for reasons of lack of either universality or precision.     

Spectrophotometric determination of boron in siliceous materials with azomethine h

A rapid and simple colorimetric method is described for the determination of minor levels of boron in siliceous materials with azomethine H. The reaction is carried out in aqueous medium. Samples are decomposed by alkaline fusion and taken up in dilute acid, and interferences are masked with an EDTA–NTA solution. After pH adjustment, the boron is reacted with azomethine H and the absorbance of the colored product is measured at 415 nm. The precision and accuracy are about ±3% relative as indicated by analysis of National Bureau of Standards No. 92 low-boron glass. The procedure has been applied to a wide variety of glasses and glass-ceramics and compared with other accepted methods.     

Complexation, extraction and determination of the H(3)CHg(+) ion with cadion [1-(p-nitrophenyl)-3-(p'-azobenzene)-triazene

The partition constants of Cadion, i.e., 1-(p-nitro-phenyl)-3-(p'-azobenzene)-triazene, of its complex with the methylmercuric ion, and of methylmercury chloride were determined in the system toluene/aqueous phase containing 40 vol.% methyl alcohol; they have the values of 4.3 x 10(3), 3.0 x 10(3), and 2.6 respectively. The reagent has an absorption maximum at 406 nm, whereas the methylmercury complex at 460 nm. The K(HR) value corresponding to the H(+) + R(-) right harpoon over left harpoon HR equilibrium is 10(10.85), HR being the reagent molecule and H belongs to the NH of the triazenic group (NNNH). The K(ext) value corresponding to the equilibrium H(3)CHg(+) + (HR)(o) right harpoon over left harpoon (H(3)CHgR)(o) + H(+) is 1.0, where the "o" indicates the species present in the organic phase. The reagent/H(3)CHg(+) combination ratio is 1/1. The formation constant of the methylmercury complex, K(H(3)CHgR), which corresponds to the equilibrium H(3)CHg(+) + R(-) right harpoon over left harpoon H(3)CHgR, has a value of 10(10.8) as estimated by means of two different methods. The IR spectra allowed some conclusions to be drawn concerning the formation of the complex. The complex is stable up to 180 degrees , and the reagent up to 140 degrees . The molar absorptivity is of 3.46 x 10(4) 1.mole(-1).cm(-1) and the H(3)CHg(+) can be determined in the range 0.025-4 ppm. The determination is highly selective.     

Synthese und polarographisches Verhalten von 2H-Isoindol-4,7-dionen

Summary 2-Phenylthio-1,4-benzoquinone (1 a) reacts with azomethine ylide AY-A to give 2-methyl-5-phenylthio-2H-isoindole-4,7-dione (4 f). With 2-(N-methylanilino)-5-methyl-1,4-benzoquinone (1 b), the azomethine ylide AY-B undergoes cycloaddition to yield an inseparable mixture of 5a-methyl-8-(N-methylanilino)-2,3,5,5a,9a,9b-hexahydro-pyrrolo[2,1-a]1H-isoindole-6,9-dione (5 bI) and 9a-methyl-7-(N-methylanilino)-2,3,5,5a,9a,9b-hexahydropyrrolo[2,1-a]1H-isoindole-6,9-dione (5 bII). The structures of5 bI and5 bII were established on basis of two-dimensional-NMR-techniques. The mechanism of the cycloaddition of azomethine ylides to 1,4-quinones was studied on basis of cyclovoltammetric investigations. To determine the electron affinity of the isoindoledione derivatives4 a–f and5 a–b the peak potentials were measured by differential pulse polarography (DPP).

     

5-Methyl-2-[3-(4-phenylthiazol-2-yl)triazenyl]benzenesulfonic acid as a chromogenic reagent of N-cetylpyridinium chloride Synthesis, mechanism and analytical application

Despite that triazene reagents have been widely used for spectrophotometric determinations of cationic surfactants, the mechanism underlying such applications has yet to be studied. We report the synthesis of a new triazene reagent 5-methyl-2-[3-(4-phenylthiazol-2-yl)triazenyl]benzenesulfonic acid (MPTTBSA) and its interaction with N-cetylpyridinium chloride (CPC). The reagent was synthesized by coupling 4-methyl-2-sulfobenzenediazonium salt with 2-amino-4-phenylthiazole. Spectral evidence suggests that the neutral reagent (H(2)R) exists in a triazenium sulfonate zwitterion form. Two ionizations were detected at weak acidic (H(2)R/HR(-), pK(a1) 2.71+/-0.20) and alkaline pH (HR(-)/R(2-), pK(a2) ca. 13.5), respectively. In the presence of 3.5 equivalents of CPC, a 2.71 unit decrease in pK(a1) and a 3.0 unit decrease in pK(a2) were observed. While the optical properties of H(2)R are essentially unaffected, CPC causes a 53nm red shift and a 31nm red shift in maximum absorption wavelengths (lambda(max)), and a 24% increase and a 29% increase in extinction coefficients (epsilon) of HR(-) and R(2-), respectively. These data suggest that CPC forms ion associates with HR(-) and R(2-), but its interaction with H(2)R is weak. Associations of CPC with HR(-) and R(2-) both follow a 3:1 stoichiometry, and the apparent stability constants of the two associates were estimated as 6.02x10(18) and 2.42x10(22)M(-3), respectively. Consistent with their high stability constants, the two ion associates did not show any changes in optical properties under submicellar and micellar conditions. The strict 3:1 association stoichiometry was interpreted in terms of electrostatic-induced, topology-defined pi-stacking and hydrophobic interactions, which not only change the optical properties of the reagent anions, but also provide the driving force to shift the two ionization equilibria to the right and cause the decreases in pK(a). Compared to the first ionization, perturbation of the second ionization by CPC provides a color reaction that is more sensitive and has a better color contrast, which was used to develop a new protocol for spectrophotometric determination of CPC. This is the first mechanistic study on the interaction between a triazene reagent and a cationic surfactant.     

Extraction—spectrophotometric determination of boric acid with 1,8-dihydroxynaphthalene-4-sulfonic acid and zephiramine

l,8-Dihydroxynaphthalene-4-sulfonic acid (DHNS) is described as a new reagent for the extraction—spectrophotometric determination of boric acid. The reagent and its boron complex are extracted into 1,2-dichloroethane as ion-associates with tetradecyldimethyl-benzylammonium chloride (zephiramine). The extracted complex of boron—DHNS—zephiramine has the composition 1:2:3 and is stable to back-washing with 1 M sodium chloride solution (pH 9.2), whereas the excess of reagent co-extracted is removed to the aqueous phase. The apparent molar absorptivity of the complex in the organic phase is 2.45 × 10⁴ l mol^-1 cm^-1 at 341 nm, which is 1.7 times larger than that with chromotropic acid. Addition of EDTA prevents most interferences. The improved method with DHNS is successfully applied to the determination of boron as boric acid in waters. The exchange equilibrium constants,

, for the reagent and complex were also determined for four monovalent anions (X^- = Cl^-, Br^-, NO₃^-and I^-). Some of these constants are compared with those pertaining to chromotropic acid and 1,8-dihydroxynaphthalene.     

Spectrophotometry Determination Of Boron With 4-(P-Sulfophenylazo)-1, 8-Dihydroxynaphthalene

Abstract

4-(p-Sulfophenylazo)-l, 8-dihydroxynaphthalene (SPADN) was synthesized to study as a new reagent for the spectro-photometric determination of boron, measuring its absorbance on addition of boron present as boric acid at pH 8.6. The procedure involved mixing aliquots of the sample, ammonium buffer, EDTA and SPADN solutions. Various exchange equilibrium constants in the ion-association extraction systems of SPADN with zephiramine were also determined.     

Die Beeinflussung des optischen Drehverm?gens der D-Weins?ure durch optisch inaktive Zus?tze und deren analytische Verwertung

Zusammenfassung Neue polarimetrische Bestimmungsmethoden für Wolfram und Bor werden beschrieben. Als Reagens dient in beiden Fällen D-Weinsäure, deren optische Drehung durch ansteigende Wolframkonzentrationen einerseits, andererseits durch ansteigende Borkonzentrationen linear zunimmt. Bei der Wolframbestimmung wurde der Einfluß verschiedener Anionen festgestellt. Untersucht wurden ein Ferrowolfram auf Wolfram und ein Borglas auf Bor, wobei in beiden Fällen die Brauchbarkeit der beschriebenen Methoden bestätigt wurde.

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Summary New methods for the polarimetric determination of tungsten and boron are described, employing D-tartaric acid as reagent. An increasing concentration of tungsten or boron results in a linear increase of the optical rotation of D-tartaric acid. The influence exerted by different anions has been investigated in the case of tungsten. The practical use of the described methods has been demonstrated by their application to the determination of tungsten in ferrotungsten and of boron in glass.

     

Ferrocenyl-substituted Schiff base complexes of boron: synthesis, structural, physico-chemical and biochemical aspects

Biological important complexes of boron(III) derived from 1-acetylferrocenehydrazinecarboxamide (L1H), 1-acetylferrocenehydrazinecarbothioamide (L2H) and 1-acetylferrocene carbodithioic acid (L3H) have been prepared and investigated using a combination of microanalytical analysis, melting point, electronic, IR, 1H NMR and 13C NMR spectral studies, cyclic voltammetry and X-ray powder diffraction studies. Boron isopropoxide interacts with the ligands in 1:1, 1:2 and 1:3 molar ratios (boron:ligand) resulting in the formation of coloured products. On the basis of conductance and spectral evidences, tetrahedral structures for boron(III) complexes have been assigned. The ligands are coordinated to the boron(III) via the azomethine nitrogen atom and the thiolic sulfur atom/enolic oxygen atom. On the basis of X-ray powder diffraction study one of the representative boron complex was found to have orthorhombic lattice, having lattice parameters: a=9.9700, b=15.0000 and c=7.0000. Both the ligands and their complexes have been screened for their biological activity on several pathogenic fungi and bacteria and were found to possess appreciable fungicidal and bactericidal properties. Plant growth regulating activity of one of the ligand and its complexes has also been recorded on gram plant, and results have been discussed.     

Fluorimetric determination of boron at microgram level

The synthesis, characterization and application of 2-(2-hydroxybenzylidenimine)benzene-arsonic acid (HBBA) as a reagent for the fluorimetric determination of boron are described. This reagent reacts with boric acid in 85% w/w sulphuric acid medium to yield a fluorescent compound. The reagent is not fluorescent in those conditions. Heating at 90 degrees for 45 min is needed for the compound to be formed. The linear calibration range is 0.1-8 microg/ml in the solution measured. The detection limit of the method is 0.01 microg/ml. The method has been applied to determine boron in vegetal material.     

Spectrophotometric determination of boron in human hair with azomethine H

Summary Investigation of methods of hair sample mineralization was made. The most profitable method of hair mineralization was by combustion in oxygen. Boron was determined spectrophotometrically with azomethine H as a spectrophotometric reagent. Boron in hair was determined in the range of 0–5 g/g.     

KF/Al2O3 mediated 1,3-dipolar cycloaddition of azomethine ylides: a novel and convenient procedure for the synthesis of highly substituted pyrrolidines

The regio- and diastereoselective synthesis of pyrrolidine derivatives through 1,3-dipolar cycloaddition of an azomethine ylide and dipolarophile mediated by KF/Al₂O₃, a versatile solid supported reagent, is reported. KF/Al₂O₃ is sufficiently basic such that it can deprotonate α-imino esters to generate azomethine ylides and it also functions as a solid supported catalyst leading to the cycloadduct rather than the Michael adduct.     

Zur Konstitution des 1,5-Diphenylcarbazonato—Diphenylbor-Chelates — ein chemischer Beweis

Further development of the reagent 1,5-diphenylcarbazone (1) with regard to higher sensitivity and better selectivity requires the knowledge of the constitution of the chelates. For this purpose 1-methyl-1,5-diphenylcarbazonato—diphenylboron was synthesized, which can only be formed from the enol-form of the so far unknown unsymmetrical 1-methyl-1,5-diphenyl-carbazone6. From the various compounds which contain the hydrazo part of 1,5-diphenylcarbazone (1). only picolinic acid phenylhydrazide14 forms a boron chelate, from which it can be concluded that the boron atom is coordinated to the N-5 of the azo group (formula5).     

Proton NMR Studies of the Electronic Effect of Substituents at the Azomethine Carbon of N,N′-Bisethylene (Salicylideniminato) Cobalt (II) Complex

The proton paramagnetic shifts of low spin N,N′-ethylenebis(salicylideniminato)cobalt(II) and its derivatives were studied to understand the effect of substituents at the azomethine carbon on the electronic structure of the Schiff-base cobalt complexes. Analysis of the ¹H paramagnetic shifts of H and CH₃ bonded to the azomethine carbon reveals that spin delocalization through a interaction is responsible for the contact contribution to the paramagnetic shift. When the phenyl group is bonded to the azomethine carbon, the plane of the phenyl group is perpendicular to the plane of the complex and the phenyl group makes a negligible contact contribution to the paramagnetic shift.     

A Comparison Study for Determining Dissolved Boron in Natural Water and Geothermal Fluid

Abstract

A comparison study was undertaken to evaluate different analytical methods for measuring boron concentrations in the geothermal fluid from the Los Alamos Hot Dry Rock Geothermal Energy Project and from natural waters collected in the vicinity of the project. Three colorimetric techniques, the carmine method and two azomethine H methods, were compared with two plasma emission spectroscopy methods and with thermal neutron capture-gamma spectroscopy. In general, the analytical results from all the methods were comparable and acceptable; however, each method had its own distinct advantages and disadvantages.     

Extraction-spectrophotometric determination of boron with 4,6-Di-tert-butyl-3-methoxycatechol and ethyl violet

4,6-Di-tert-butyl-3-methoxycatechol (DBMC) has been developed as a new reagent for boron, the complex anion formed being extracted as an ion-associate with Ethyl Violet into toluene, and the absorbance measured at 610 nm. The calibration graph is linear up to 0.43 mug of boron, the molar absorptivity is 1.02 x 10(5) 1.mole(-1).cm(-1) and the relative standard deviation 1.2%. The method has been applied to the determination of boron in sea-water and river water with satisfactory results.