Gas-chromatographische Zinnbestimmung in Zircaloy

Zusammenfassung Die quantitative gas-chromatographische Bestimmung des Zinngehaltes von Zirkonium-Zinnlegierungen (Zircaloy) wird beschrieben. Die Metallprobe wird mit gasförmigem Chlor umgesetzt. Nach Abtrennung des Zirkoniumtetrachlorids und des Chlorüberschusses erfolgt die Bestimmung von Zinnchlorid auf gas-chromatographischem Wege. Die Genauigkeit des Verfahrens ist derjenigen der herkömmlichen Verfahren vergleichbar. Der Zeitaufwand einer Bestimmung beträgt 30 min.

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Determination of tin in zircaloy by gas chromatography

The quantitative determination of tin in zirconiumtin alloys (Zircaloy) is described. The metallic sample is submitted to a reaction with gaseous chlorine. After removing the zirconium tetrachloride and an excess of chlorine, the tin tetrachloride is determined by gas chromatography. The accuracy of the method is comparable to that of the usual procedures. 30 min are required for one determination.

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Die vorliegende Arbeit ist Teil der Diplomarbeit von H. J. Becker. Sie wurde unter Anleitung der Herren Professoren Dr. J. Besson, Directeur de l'Ecole Nationale Supérieure d'Electrochimie et d'Eleotrométallurgie de Grenoble, und Dr. N. G. Schmahl, Direktor des Instituts für Physikalische Chemie der Universität des Saarlandes, im Centre d'Études Nucléaires de Grenoble durchgeführt. Die Verfasser danken an dieser Stelle Herrn Prof. Dr. J. Besson und Herrn Prof. Dr. N. G. Schmahl für ihr freundliches Interesse und ihre wohlwollende Unterstützung.     

The Mechanism of the Polymerization of Styrene by Perchloric Acid

Abstract

The kinetics of the polymerization of styrene, initiated by anhydrous perchloric acid in carbon tetrachloride solution and in mixtures of methylene chloride and carbon tetrachloride, have been studied by NMR and GLC methods. In carbon tetrachloride the reaction is zeroth order. The kinetics, together with the known effects of dielectric constant and pressure on the reaction rate, suggest that the rate-determining step may be the formation of a carbonium perchlorate ion-pair, associated with neutral molecules of styrene.     

Vinyl Polymerization by Metal Complexes. XXIII. UV and Kinetic Studies on the Photopolymerization with Iron(III)-Amine-Carbon Tetrachloride Systems

Abstract

In order to elucidate the initiation reaction of the photopolymerization with iron(III)-amine-carbon tetrachloride systems, the photochemical reaction process among iron(III), amine, and carbon tetrachloride in methanol solution was followed at 0°C by UV spectroscopy as for iron(III) ion. The rate constants of both the reduction of iron (III) under irradiation with light and the oxidation of iron(II) in the dark were measured, and were related to the rates of photopolymerization of methyl methacrylate. Kinetic study on the photopolymerization of methyl methacrylate with iron(III)-triethylenetetramine-carbon tetrachloride system was made in parallel in methanol solution at 0°C. The initiation mechanism of the photopolymerization was postulated.     

Polymer Networks for Solid Phase Extraction

Abstract

Macronet polystyrene (PS) and styrene-ethylene/butylene-styrene triblock copolymer (SEBS) were tested in respect to the sorption of traces of toluene, carbon tetrachloride and 1,2 dichloroethane in water. The studied networks were prepared by a previously developed post-polymerization crosslinking method. The uptake experiments showed a significant sorption efficiency for macronet SEBS especially in the case of carbon tetrachloride. Macronet PS exhibited only a low ability in the sorption of toluene.     

GLC determination of silicon in alloys after chlorination with carbon tetrachloride

Summary By using carbon tetrachloride as chlorinating agent, the silicon contained in alloys can be quantitatively converted to silicon tetrachloride under certain conditions in a sealed glass tube (microreactor). This microreactor is then crushed by a special device which at the same time serves as an injection port to a gas chromatograph where the volatile products are separated and quantitatively determined. This method has been applied to a number of silicon alloys and is not time-consuming or costly, as many samples can be analysed in an hour with the use of common gas chromatographic systems. It is sensitive and selective, and it gives very accurate and precise (relative standard deviation <±0.5) results over a very wide range of silicon composition (1–99%).     

Chlorination of secondary phosphine chalcogenides with carbon tetrachloride in the absence of bases

The interaction of bis(2-phenylethyl)phosphine sulfide, bis(2-phenylethyl)phosphine selenide and bis[2-(2-phenyl)propyl]phosphine selenide with carbon tetrachloride under heating (80°C, 8–20 h) leads to the formation of the corresponding chlorophosphine chalcogenides with the yield of 80–90%.

     

A Novel Synthesis of Isothiocyanates from Amines Using Triphenylphosphine/Carbon Tetrachloride

Abstract

Triethylammonium dithiocarbamates (RNHC (S) S.HNEt₃), prepared from aliphatic and/or aromatic amines, carbon disulfide and triethylamine, were treated with triphenylphosphine/carbon tetrachloride to give the corresponding isothiocyanates in good yields.     

On the Reaction of Phosphorous Acid Esters with Nucleophiles in the Presence of Carbon Tetrachloride

Abstract

Esters of N-Phosphoryl phosphazenes are prepared by a modified Atherton-Todd reaction from di- and triesters of phosphorous acid, sodium azide, and carbon tetrachloride in high yields. The utilization of the two-component system trialkyl phosphite/ carbon tetrachloride for preparing phosphazenes, (RO)₃P[dbnd]NY (Y: PO(OR)₂, SO₂R, COR, CN), and dialkoxyphosphoryl compounds, (RO)₂P(O)X (X: NHR, NR₂, OPh, CN, F, NCO), is presented.     

Polymerization of Methyl Methacrylate by the System Ribonucleic Acid–Water in the Presence of Carbon Tetrachloride and Copper(11) Ion

Polymerization of methyl methacrylate (MMA) was carried out in the presence of ribonucleic acid (RNA), water, carbon tetrachloride, and copper(II) ion. The overall activation energy for the polymerization is proportional to the square root of the amount of RNA. The rate increased at first with the amount of MMA, but then became independent of the amount of MMA.

Polymerization was inhibited by the presence of air. Carbon tetrachloride and copper(II) ion are able to give RNA the ability to initiate polymerization. Conversion of MMA is accelerated by the addition of tertiary amine derivatives instead of carbon tetrachloride.     

Sequential Thin-Layer Chromatography of 2,4-D and Related Compounds

Abstract

Separations and identification of carboxylic herbicidal substances such as 2,4-dichlorophenoxyacetic acid, trichloroacetic acid, 2,4,5-trichlorophenoxyacetic acid and plant growth regulators such as benzoic acid, cinnamic acid, indole-3-acetic acid, β-naphthaleneacetic acid, β-naphthoxyacetic acid, phenoxyacetic acid have been made by sequential thin-layer chromatography on calcium sulphate layer with acetone, benzene, carbon tetrachloride, chloroform, ethyl acetate, dioxan, propanol as solvents and bromophenol blue as detector.     

Einflüsse der Lösungsmittel auf das ESR-Spektrum von Kupfer-acetylacetonat

Effect of 11 inert solvents (carbon tetrachloride, nitrobenzene, acetonitrile, sulpholane, propylene carbonate, acetone, ethyl acetate, tetrahydrofuran, dimethylformamide, dimethylsulfoxide and hexamethylphosphoramide) on the ESR spectrum of copper acetylacetonate have been studied at the temperature about 298 K. There was stated that hyperfine splitting linearly decreases with the increasing ofGutmann's donor number of solvent. This phenomenon was discussed in terms of solvent—solute interaction.

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Mit 2 Abbildungen     

Imino Diels–Alder Reactions: Efficient Synthesis of Pyrano and Furoquinolines Catalyzed by ZrCl4

Abstract

Anhydrous zirconium tetrachloride is found to be an efficient catalyst for the Imino Diels–Alder reactions of N‐benzylideneanilines with 3,4‐dihydro‐2H‐pyran and 2,3‐dihydrofuran to afford pyrano and furo [3,2‐c] quinolines in good yields.     

Selective Determination of Organic and Inorganic Thiocyanates in Aqueous Solution by IR Spectrophotometry

Abstract

A new spectrophotometric method for the determination in aqueous solution of both organic and inorganic thiocyanates is described. Organic thiocyanates are determined by measuring at wavenumber of 2150 cm^?1 the absorption of solutions directly extracted with carbon tetrachloride. Inorganic thiocyanates require a previous derivatization reaction with dimethylsulfate, and are determined as methylthiocyanates. The method is quick, accurate and selective. The results obtained suggest its utilization in analysis of aqueous samples.     

Application des Capteurs Automatises DTO,COT et DCO au Dosage des Hydrocarbures dans L'Eau

Abstract

Among the objectives of this study was the determination of the oxidation yields for pure hydrocarbons in water (alkanes, alkenes, aromatics), following the TOD, TOC and COD methods, and the extraction efficiency of carbon tetrachloride followed by infra-red dosage (NFT90203).

For the global oxidative pollution tests, the best oxidation yields were obtained with TOC, followed by the TOD; COD results were clearly poor. The solvent extraction procedure afforded reliable results.

Correlation studies with the methods proposed enable the grouping of hydrocarbons in two main categories, according to the oxidation criteria: aliphatics and aromatics. Generally, it can be said that the correlations found were satisfactory.     

Halocarbons in Antarctic Surface Waters

Abstract

Surface water samples taken during the 1988–89, 1989–90 and 1990–91 Italian expeditions were analyzed for the presence of carbon tetrachloride, trichloroethylene and tetrachloroethylene. The sample analysis was carried out by solvent extraction and capillary GC-ECD-MS determination. The above-mentioned halocarbons were at ng/l level in all water samples investigated.     

Photolysis of <Emphasis Type="Italic">o</Emphasis>-iodo- and <Emphasis Type="Italic">o</Emphasis>-bromophenols in aqueous solution of sodium sulfite and organic solvents

The photochemical reaction of o-iodo- and o-bromophenol in an aqueous sodium sulfite solution proceeds via both nonchain and chain mechanisms. The formation of the intermediate product, aromatic radical anion, was observed. The quantum yield of the photochemical reaction of o-iodophenol increases, when the electron donor diphenylamine is irradiated. In the photolysis of o-halophenols in organic solvents, free iodine is evolved in addition to aromatic products. The products of the photolysis of o-iodophenol in ethanol and carbon tetrachloride were identified by gas chromatography-mass spectrometry. These are phenol in the case of ethanol and a mixture of o-chlorophenol and hydroxychloro-substituted biphenyls in the case of carbon tetrachloride. The quantum yields were determined for all photochemical reactions studied.     

A Radiochemical Method for Selective Determination of Traces of Lead

Abstract

A very simple and rapid radiochemical method for the determination of 0.01–1 meg of lead has been developed. It consists of adding carrier-free ²¹²Pb to the analysed sample, followed by shaking with a standard lead diethyldithiocarbamate solution in carbon tetrachloride. The amount of non-active lead in the sample is determined from activities of the organic and aqueous phases. A 10-fold excess of bismuth and more than 50–100-fold excess of other metals extractable as diethyldithiocarbamates do not interfere in the determination.     

Correlation and prediction of solute transfer to chloroalkanes from both water and the gas phase

Data have been compiled from the published literature on the partition coefficients of solutes and vapors into chloroform, carbon tetrachloride, dichloromethane and 1-chlorobutane from both water and from the gas phase. The logarithms of the water-to-chloroalkane (log P) and gas-to-chloroalkane partition coefficients (log K) are correlated with the Abraham solvation parameter model. The derived correlations describe the observed log P and log K values within standard deviations of about 0.13–0.20 log units. For chloroform and carbon tetrachloride, the derived correlations were validated using training set and test set analyses.     

Ultra-Preconcentration and Determination of Multiple Pesticide Residues in Water Samples Using Ultrasound-Assisted Dispersive Liquid–Liquid Microextraction and GC-FID

In this study, a simple and efficient method has been developed to analyze pesticides in water samples using ultrasonic-assisted dispersive liquid–liquid microextraction (UA-DLLME) combined with gas chromatography-flame ionization detection (GC-FID). Several parameters, including type and volume of extractant and dispersant, extraction time, and amount of salt on extraction performance, were optimized in detail. A mixture of acetonitrile (1.0 mL, dispersant) and carbon tetrachloride (15 μL, extractant) was used for extraction. Under optimal conditions, enrichment factors were obtained between 315 and 1153. The linearity of the method ranged from 1 to 100 μg L⁻¹ with correlation coefficients ≥0.9990. Limits of detection (S/N = 3) ranged between 0.09 and 0.57 μg L⁻¹, depending on the compounds. Relative standard deviations were <8.0 % (n = 5) for both intra- and inter-day analyses. The proposed method was successfully applied for the preconcentration and determination of pesticides in water samples (river water, tap water, and lake water) with recoveries that varied from 90.5 to 107.7 %.