Neue Derivate der 2-Acylamino-thiophen-(und-benzo[b]thiophen-)-3-carbonsäure sowie des ([1]Benzo-)Thieno[2,3-d]-pyrimidin-4(3H)-ons

The title substances1 and2 were prepared by acylation of the corresponding ethyl 2-amino-thiophene- (or:-4,5,6,7-tetrahydro-benzo[b]thiophene)-3-carboxylates, in some cases followed by reactions introducing a basic substituent.Additionally a group of 2-aroylamino-thiophene-(or:-4,5,6,7-tetrahydro-benzo[b]thiophene)-3-carboxamides was subjected to ring closure reactions, yielding the corresponding 2-aryl-thieno[2,3-d]pyrimidin-4(3H)-ones and 2-aryl-[1]benzothieno[2,3-d]pyrimidin-4(3H)-ones (both:3).

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Zum Teil unter Mitarbeit vonFerdinand Fuhrmann     

Absorption properties of commercial lead chromates

For the cyanide determination in waste waters containing more than 2.5×10^?6 Mol of CN^?/l a conductometric method has been proposed. The sulphuric acid containing samples were distilled and the obtained HCN was passed into a 5×10^?4 Mol/l AgNO₃ solution, of which the conductivity was measured. The method offers the possibility of a precise observation of the completion of the HCN distillation and also the direct measurement of the cyanide concentration by the change of conductivity. The analysis time is about 40 min.     

Die Stabilität der Kobalt(II)- und Kupfer(II)-Komplexe mit α-, β- und γ-Aminobutyrat

Stability constants of cobalt(II) and copper(II) complexes with α-, β-, and γ-aminobutyrate as well as the protonation constants of these ligands have been determined by potentiometric titration. ΔG ^? values, computed from the stability constants, increase in the orderAABA. The increase in ΔG ^? AABA→BABA amounts approx. 15 per cent. The same difference was observed for α- and β-alaninato complexes with various transition metal ions.     

Electrocatalysis by foreign metal monolayers: Oxidation of formic acid on platinum

It was demonstrated that some foreign metal monolayers formed by underpotential deposition have pronounced catalytic effects on the oxidation of formic acid on platinum. The explanation of these effects was sought within the framewor of existing data on the formic acid oxidation and the underpotential deposition. It was found that the catalytic effect of foreign metal monolayers originates in the decrease of hydrogen adsorption thus preventing the formation of the main poisoning species COH. At the same time these experiments confirm the previously postulated mechanism of formation of the poisoning species involving adsorbed hydrogen.     

Volumetric determination of Pt(IV) in the presence of Ir,Pd, and Rh with ferrous ammonium sulfate in alkaline mannitol medium

A potentiometric reductimetric method for the determination of platinum (Pt(IV)Pt(II)) with a standard Fe(II) solution in an alkaline medium of mannitol is described. The method, the error of which does not exceed 2%, can be used in the presence of palladium, iridium, and rhodium.     

Heterogeneous reactions of solid nickel(II) complexes

The influence of different modes of preparation on the stoichiometry of thermal decomposition of isothiocyanatonickel(II) complexes with ammonia was studied. It was found that the complex Ni(NCS)₂(NH₃)₄ (I) prepared by heterogeneous reaction undergoes decomposition in two steps (–2 NH₃, –2 NH₃), while for complex II, of the same composition but prepared by homogeneous reaction from solution, the decomposition proceeds in three steps (–1 NH₃, –1 NH₃, –2NH₃). Electronic and infrared absorption spectra were used for the study of the spectral properties of the starting complex. It was found that the different stoichiometries of thermal decompositions of complexes I and II do not cause differences in the bonding strength of the ammonia molecules (chemical factor); this effect is rather brought about by physical factors such as different imperfections of the crystal lattice.

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Zusammenfassung Der Einfluß der Herstellung auf die Stöchiometrie der thermischen Zersetzung von Amin-Komplexen des Isothiocyanatonickels wurde studiert. Der Zerfall des Komplexes Ni(NCS)₂(NH₃)₄ (I), hergestellt durch heterogene Reaktion, verlief in zwei Etappen (–2 NH₃, –2 NH₃). Beim selben Komplex (II), hergestellt durch homogene Reaktion in Lösung, wurden jedoch drei Etappen beobachtet (–1 NH₃, –1 NH₃, –2 NH₃). Die Eigenschaften des Ausgangsproduktes wurden durch Elektronen- und IR-Spektroskopie untersucht. Das unterschiedliche thermische Verhalten ist nicht auf eine verschiedene Bindungsstärke der NH₃ Moleküle, sondern auf physikalische Ursachen, wie z. B. Unregelmässigkeiten im Kristallgitter zurückzuführen.

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Résumé On a étudié l'influence des diverses méthodes de préparation sur la stoechiométrie de la réaction de décomposition thermique des complexes de l'isothiocyanate de nickel(II) avec l'ammoniac. On a établi que le complexe Ni(SCN)₂(NH₃)₄, (I), préparé rar réaction hétérogène, subit une décomposition en deux étapes (–2NH₃, –2NH₃), tandis que le complexe (II), de même composition, mais préparé par réaction homogène, à partir de solutions, se décompose en trois étapes (–1NH₃,–1NH₃, –2NH₃). Les propriétés spectrales du complexe initial ont été étudiées par absorption électronique et infrarouge. On a trouvé que les différences de stoechiométrie des réactions de décomposition thermique des complexes (I) et (II) n'apportaient pas de différences entre les énergies de liaison des molécules d'ammoniac (facteur chimique). C'est plutôt à des facteurs physiques, comme les différentes imperfections du réseau cristallin, que cet effet serait dû.

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(II) . , Ni(NCS)₂(NH₃)₄ (I), , (–2NH₃,–2NH₃). , II , , (–1 NH₃,–1 NH₃ –2NH₃). . , I II ( ), , .

     

Zur Kenntnis von Natrium-hexafluoromanganat(III)

Sodium hexafluoromanganate(III) has been synthesized by heating equimolecular quantities of Na₂MnF₅ and NaF in argon atmosphere. The compound is monoclinic witha=5.56 (1) Å,b=5.84 (1) Å,c=8.10 (2) Å, =90.7 (2) andZ=2. It is a high spin complex with _eff and the deformation of the octahedra is evident from its IR-spectra. Two enantiotropic transitions (at 562 and 653°C) and the melting point at 800°C have been observed.

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8. Mitt.: Mh. Chem.106, 483 (1975).     

The infrared spectra and normal coordinate analysis of syn and anti acetaldoxime

The infrared spectra of mixtures of syn and anti acetaldoxime and its deuterated analogues CH₃CHNOD, CD₃CHNOH, CD₃CDNOH and CH₃CDNOH have been recorded. The syn and anti isomers of CH₃CHNOH, CD₃CHNOH, CD₃CDNOH and CH₃CDNOH have been separated by gas chromatography [1]. The infrared spectra of separated isomers in CS₂ solution have been recorded and the assignment of ten in-plane vibrations made. From a normal coordinate analysis the Urey-Bradley force field, the potential energy distribution and additional information about assignments have been obtained.For the anti isomer the simple Urey-Bradley force field gives satisfactory agreement between the calculated and measured frequencies. For the syn isomer it is necessary to take into account the interactions between atoms separated by three bonds.     

Beitrag zur mikroskopischen Identifizierung organischer Stoffe nach L. Kofler. V

Zusammenfassung In Fortsetzung früherer Untersuchungen zum Zweck der Ergänzung und Erweiterung der Identifizierungs-Tabelle nachKofler werden für 62 Substanzen die thermomikroskopischen Konstanten mitgeteilt und die gegebenenfalls notwendigen Zusatzreaktionen beschrieben. Bei Nicotinamid, das auf Grund seiner Fähigkeit, mit vielen Stoffen wie organischen Säuren, Säureestern, Phenolen u. a. Komplexverbindungen zu bilden, häufig als Reagens in Betracht kommt, wird das polymorphe Verhalten erläutert und das Auftreten von sieben Modifikationen beschrieben.

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Contribution to the microscopic identification of organic materials after L. Kofler. V

Summary In continuation of earlier investigations for the purpose of supplementing and extending the identification tables ofKofler, the thermomicroscopic constants are given for 62 substances and when necessary the supplementary reactions are described. In the case of nicotinamide, which because of its ability to yield among other things complex compounds with organic acids, acid esters, phenols, is frequently considered as reagent, the complex behavior is illustrated and the occurrence of 7 modifications is described.

     

Ein weiterer Beitrag zum Scandiumdicarbidproblem

Zusammenfassung Die bei 1850, 2000 bzw. 2300°C durch die Reduktion von Scandiumoxid mittels Kohlenstoff in dem der Scandiumdicarbidbildung entsprechenden Molverhältnis hergestellten Produkte wurden mit Wasser zersetzt und mit Hilfe der gleichzeitigen gaschromatographischen und massenspektrometrischen Analyse untersucht. Aus den Ergebnissen geht hervor, daß bei der Scandiumdicarbidbildung gleichzeitig ein weiteres Scandiumcarbid, höchstwahrscheinlich ein Sesquicarbid, entsteht.

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Scandium(III) dicarbide problem. Further experimental results

Products obtained by the reduction of Sc₂O₃ with carbon at 1850, 2000 and 2300°C, resp., in the molar ratio corresponding to the scandium dicarbide were hydrolysed with water. Gaseous reaction products were analysed using gas chromatography combined with mass spectrometry. Results show, that during dicarbide formation another scandium carbide, probably sesquicarbide, is also formed.

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Herrn Prof. Dr.H. Nowotny gewidmet.

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7. Mitt.: Coll. Czech. Chem. Commun., im Druck.