Electrochemical reduction of some compounds of two-coordinate phosphorus and arsenic in an aprotic medium

The electrochemical reduction of a series of compounds of two-coordinate phosphorus and arsenic with linear structure was investigated for the first time. The main polarographic characteristics indicate irreversibility of the electrode process and its complication by kinetic limitations. The products of controlled-potential electrolysis were analyzed, and schemes are presented for the electrochemical reduction, which consists in hydrogenation with cleavage of the P=E bond of most of the studied compounds (1,2, and4) and in cleavage of the C_Ar-P bond in sterically hindered compound3. The electrolysis products underwent further transformation in the presence of oxygen and moisture of air.DeceasedA. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific Center, Russian Academy of Sciences, 420083 Kazan'. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1754–1760, August, 1992.     

Spectrophotometric determination of phosphorus and arsenic in pharmaceutical organic compounds

Summary A simple and accurate method is described for the microdeter-mination of phosphorus and arsenic in some pharmaceutical organic compounds. It is based on the conversion of phosphorus and arsenic into phosphate and arsenate ions respectively, followed by precipitation with quinoline and sodium molybdate reagents. The excess quinoline in the supernatant is spectrophotometrically measured at 312.5 nm in an ammonium acetate background of pH 5.5. The results obtained with 24 structurally different phosphorus and arsenic compounds show an average recovery of 99% and a mean standard deviation of ±1%. Excipients and diluents normally used in drug formulations do not interfere.

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Spektrophotometrische Bestimmung von Phosphor und Arsen in organischen Arzneimitteln

Zusammenfassung Eine einfache und genaue Methode zur Mikrobestimmung von Phosphor und Arsen in einigen organischen Arzneimitteln wurde angegeben. Sie beruht auf der Umsetzung des Phosphors zu Phosphat und des Arsens zu Arsenat sowie deren Fällung mit Chinolin und Natriummolybdat. Der Chinolinüberschuß wird spektrophotometrisch bei 312,5 nm in Ammonium-acetat bei pH 5,5 gemessen. Die mit 24 strukturell verschiedenen Phosphorbzw. Arsenverbindungen erhaltenen Resultate ergaben eine durchschnittliche Wiederfindungsrate von 99% und eine rel. Standardabweichung von ±1%. Arzneimittelträger und Verdünnungsmittel stören nicht.

     

Configurational stability in some 3-coordinate phosphorus compounds

PMR spectra of a variety of 4,4,5,5-tetramethyl-1,3,2-dioxaphospholanes, bearing different substituents at phosphorus, have been determined at different temperatures. There is no inversion at phosphorus detectable. The P-chloro compound undergoes a chemical exchange process the rate of which is concentration dependent.     

Structure of some organic compounds containing tin and phosphorus

Summary On the basis of Malatesta's results and of our confirmatory experiments, it must be considered that the organic compounds of tine and phosphorus under consideration are esters of phosphorus acids in which tine is linked to phosphorus through oxygen.     

Preparation and properties of some transition metal phosphorus trisulfide compounds

Transition metal phosphorus trisulfide compounds with the general formula MPS₃, with M = Mn, Fe, Ni, have been prepared by chemical vapor transport, vapor sublimation, and direct combination of the elements. Chemical transport is accomplished by using 75 Torr of chlorine gas as a transport agent and a temperature gradient of 750° → 690°C or 700° → 640°C. The structure of these three compounds, which belongs to the monoclinic space group $\text{C2}\text{m}$, is related to that of CdCl₂ with a distorted cubic close-packing of the sulfur atoms. Metal atoms and phosphorus-phosphorus pairs occupy the trigonally distorted octahedral holes in a ratio of 2:1 and are ordered throughout the structure. Magnetic susceptibility measurements indicate that all three compounds are antiferromagnetic. The paramagnetic moments indicate that the metal ions in each case exist in the divalent high-spin state.     

Industries using arsenic and arsenic compounds

This paper reviews industries using arsenic and arsenic compounds such as wood preservatives and agricultural chemicals, the use of arsenic trioxide in glass manufacture, and the applications of metallic arsenic in non-ferrous alloys and of high-purity arsenic in the electronics industry.     

An indirect sequential determination of phosphorus and arsenic in high-purity tungsten and its compounds by atomic-absorption spectrophotometry

Summary An indirect atomic-absorption spectrophotometric method based on selective extraction of heteropolymolybdic acids has been developed for determination of small quantities of P and As in highpurity tungsten metal and tungsten compounds. The method is suitable for determination of 5–100 ppm of phosphorus and arsenic. The relative standard deviation is 38–5% for P and 31–3% for As, depending on the concentrations.

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Indirekte Bestimmung von Phosphor und Arsen in hochreinem Wolfram und dessen Verbindungen durch AAS

Zusammenfassung Eine indirekte, auf selektiver Extraktion der Heteropolymolybdänsäuren beruhende AAS-Methode zur Bestimmung kleiner Mengen Phosphor und Arsen in hochreinem Wolfram und seinen Verbindungen wurde ausgearbeitet. Das Verfahren eignet sich für 5–100 ppm Phosphor und Arsen. Die rel. Standardabweichung beträgt 38–5% für P und 31–3% für Arsen, je nach deren Konzentration.

     

Simultaneous determination of arsenic and phosphorus

Summary A simple, rapid, accurate and reliable method for the simultaneous determination of arsenic and phosphorus in the presence of each other is reported. The method involves the selective solvent extraction of phosphomolybdic acid by isobutyl acetate, the direct reduction of the phosphomolybdic acid in the solvent phase by 1-amino-2-naphthol-4-sulphonic acid in the presence of perchloric acid, and the reduction of the arsenomolybdic acid in the aqueous phase with hydrazine sulphate.

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Zusammenfassung Ein einfaches, rasches und genaues Verfahren zur gleichzeitigen Bestimmung von Arsen und Phosphor nebeneinander wurde beschrieben. Es beruht auf der selektiven Extraktion der Phosphormolybdänsäure mit Isobutylacetat, deren unmittelbare Reduktion in der Lösungsmittelphase durch 1-Amino-2-naphthol-4-sulfonsäure in Gegenwart von Perchlorsäure und der Reduktion der Arsenmolybdänsäure in wäßriger Phase mit Hydrazinsulfat.

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Résumé On communique une méthode simple, rapide, précise et sûre pour le dosage simultané de l'arsenic et du phosphore en présence les uns des autres. La méthode met en jeu l'extraction sélective par solvant de l'acide phospho-molybdique en phase solvant par l'acide sulfonique-4 amino-1- naphtol en présence d'acide perchlorique et la réduction de l'acide arsénomolybdique en phase aqueuse par le sulfate d'hydrazinium.

     

Determination of arsenic and arsenic compounds in natural gas samples

Organic arsenic compounds (trialkylarsines) present in natural gas were extracted by 10 cm³ of concentrated nitric acid from 1 dm³ of gas kept at ambient pressure and temperature. The flask containing the gas and the acid was shaken for 1 h on a platform shaker set at the highest speed. The resulting solution was mixed with concentrated sulfuric acid and heated to convert all arsenic compounds to arsenate. Total arsenic was determined in the mineralized solutions by hydride generation. The arsenic concentrations in natural gas samples from a number of wells in several gas fields were in the range 0.01–63 μ As dm^?3. Replicate determinations of arsenic in a gas sample with an arsenic concentration of 5.9 μ dm^?3 had a relative standard deviation of 1.7%. Because of the high blank values, the lowest arsenic concentration that could be reliably determined was 5 ng As dm^?3 gas. Analysis of nonmineralized extracts by hydride generation identified trimethylarsine as the major arsenic compound in natural gas. Low-temperature gas chromatography-mass spectrometry showed more directly than the hydride generation technique, that trimethylarsine accounts for 55–80% of the total arsenic in several gas samples. Dimethylethylarsine, methyldiethylarsine, and triethylarsine were also identified, in concentrations decreasing with increasing molecular mass of the arsines.     

Electronic and spatial structure of five-membered oxygen-or sulfur-containing cyclic phosphorus and arsenic compounds based on quantum-chemical calculations

We have carried out nonempirical quantum-chemical calculations for five-membered heterocyclic molecules containing O or S atoms and also P or As atoms in the ring, using RHF/6-31G(d) and MP2/6-31G(d) methods with full optimization of their geometry. We have studied their electronic and spatial structure and the characteristics of the interaction between atoms in the molecules. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 629–634 April, 2006.     

Chemistry of arsenic,antimony and bismuth compounds derived from xanthate,dithiocarbamate and phosphorus based ligands

The chemistry of both tri- and penta-valent compounds of arsenic, antimony and bismuth derived from xanthate, dithiocarbamate and phosphorus based ligands have been reviewed. Synthesis, properties, structural aspects and applications of their compounds have been described.     

Fluorine absorption spectra and some fluorides in condensed state

The absorption spectra of liquid F₂, NF₃, N₂F₄, CF₄, BF₃, NF₃, SF₆ have been obtained at diminished temperatures in the near ultra-violet region of the spectrum. It is shown that the absorption spectrum does not differ from the spectra in the gaseous phase, therefore the elementary absorption act is characterized by the cross section of photon absorption by an individual molecule. The absorption cross sections of the above mentioned molecules are represented in the liquid phase, which do not differ strongly from absorption cross sections of these molecules in the gaseous phase. The dependence of the absorption cross sections of liquid fluorine on its concentrations in solutions with N₂, Ar, NF₃, O₂ at - 196°C has been studied. The cross sections of photon absorption by the fluoride molecule in different liquid media with small fluorine concentrations have been obtained.     

Voltammetric determination of some organic compounds of arsenic reduced at the mercury electrode

Cyclic voltammetric scans for methylarsonic acid, dimethylarsinic acid and 3-acetamido-4-hydroxyphenylarsonic acid at a mercury electrode in an acidic medium show anodic adsorption waves when the starting potential is sufficiently negative; the related arsines are formed on the electrode. Detection limits are at the micromolar level for the absorption peak found at about ?0.1 V vs. SCE for all three compounds. Interferences are discussed.     

Reactions of xenon difluoride. Part 6. Some reactions of phosphorus,arsenic and iodine compounds

The reaction of XeF₂ with some organo-phosphorus, -arsenic and-iodine compounds is described. The products were identified by fluorine nmr spectroscopy and the conditions under which fluorine exchange occurs were briefly investigated. Organoiodine (III) difluorides are suitable for the conversion of Ph₂Te to Ph₂TeF₂; the decomposition of RIF₂liberates IF and fluoroalkane.     

The reaction of esters of thioacids of tervalent arsenic with halides and some halogen-containing compounds

Conclusions The reaction of esters of thioaeids of tervalent arsenic with chlorine, bromine, iodine chloride, sulfuryl chloride, thionyl chloride, HCl, PCl₅, dichloro(phenyl)phosphine, and chloro(ethyl)phenylphosphine leads to the complete cleavage of the As-S bonds with the formation of corresponding halogenoarsines and sulfur-containing compounds.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1612–1616, July, 1972.     

The NMR spectra of some 3-coordinate phosphorus compounds containing chloromethyl and isopropyl groups

Analysis of the proton NMR spectra of Pr¹PCINMe₂ indicates magnetic non-equivalence of the methyl groups due to the adjacent asymmetric phosphorus atom. High temperatures, or the addition of chloride ion, induce an exchange reaction with inversion of configuration at phosphorus. The corresponding fluoride is configurationally stable at high temperatures. The compounds CICH₂PXNR₂ (X = Cl, F; R = Me, Et) have non-equivalent protons in the chloromethyl group. The two HCP coupling constants in the chlorides of this series are of opposite sign, whereas in the fluorides they are of the same sign.