Die katalytische Wirkung von Kupfer auf die Reduktion von Eisen(III) durch Thiosulfat

Ohne Zusammenfassung     

Die Wirkung der Aggregation (Mizellbildung) auf die Höhe der Viskosität

Zusammenfassung Auf Grund angeführter Beispiele wird gezeigt, daß die Aggregation zu konzentrationsunabhängigen Aggregaten infolge Änderung des Formfaktors eine maximale Änderung von [] von etwa 1 zu 2,5 bedingt, was in der Größenordnung der früher festgelegten Lösungsmittelabhängigkeit von [] infolge Änderung der Solvatation liegt. Die Aggregation kann auch zu einer Herabsetzung von [] führen.Herrn Prof. Dr. K. Heß danke ich für das dieser Arbeit entgegengebrachte fördernde Interesse, Herrn Dr. H. Kießig für die freundliche Hilfe bei der Abfassung der Arbeit. Ferner spreche ich der Süddeutschen Zellwolle AG. in Kehlheim/Donau und im besonderen Herrn Direktor K. Borst für die Förderung der Arbeit meinen ergebenen Dank aus und der Firma Böhme Fettchemie G. m. b. H., Chem. Laboratorium, für die liebenswürdige Überlassung einiger Paraffinderivate.     

Darstellung der supraleitenden ternären Phase PbMo6S8 durch chemischen Transport

Preparation of the Superconducting Ternary Phase PbMo₆S₈ by Chemical Transport Reactions The only ternary phase existing in the system Pb? Mo? S is the superconducting compound Pb_xMo₆S_y (PMS). It can be transported by CTR using PbBr₂ if an equilibrium mixture of PMS and Mo is present at the starting side, or if there is the pure PMS phase not exceeding a critical sulphur content. The transport conditions were deduced from a thermodynamical analysis of the system Pb? Mo? S? Br. Now it can be stated that all condensed phases occuring in the Pb? Mo? S system can be deposited from vapour phase by CTR or by sublimation: Pb, Mo, S, PbS, Mo₂S₃, MoS₂, PMS.     

Über die Ringspannung in pentacyclischen Azofarbstoff-Chrom(III)-Komplexen

In pentacyclic chromium-azo dyestuff complexes in which two azo dyestuffs in a vertical position to each other are so linked that a metal-containing hetero ring is formed, the number of members of this hetero ring was systematically increased. The alterations occurring in the electron spectra express the change in the position of the two azo dyestuff residues or the change in tension occurring in the hetero ring. When the number of ring atoms is sufficiently large, which in this series of compounds was 15 (n = 10), the electron spectrum is identical with that of the «open» form, i.e. with that of the corresponding 1:2 complex devoid of this particular ring. The position of the two azo dyestuff residues, therefore, must be identical in both complexes, and this is only possible when the adjoining ring is completely free from tension. The phenomenon of ring tension can, therefore, be visibly followed in these examples.     

Über die Hydrolyse von Eisen(III)Salzlösungen. I. Die Hydrolyse der Lösungen von Eisen(III)chlorid

When a very diluted iron(III)chloride solution is slowly alkalified by a weak base, the deprotonation of [Fe(H₂O)₆]³⁺ proceeds in a first stage to form mono- and dinuclear hydroxoaquo-complexes. In a second stage 4 dimers condense around a chloride ion to form an eight membered ring, an embryon, which grows fast to very small crystals of the composition Fe₄O₃(OH)₅Cl and the structure of the β-FeOOH. These crystalline micells remain colloidally dissolved. If the pH is raised above approximately 3.4 the Cl^?- are exchanged against OH^?-ions and flocculation occurs. This shows that Pauli, assuming the micells of such sols to be polynuclear complex ions, is basically correct, and it follows that micells can also be micro-crystals. When an iron(III)chloride solution is neutralized fast with a strong base, an ‘amorphous’ precipitation is obtained which gives with MoK_α-X-rays only two broad reflections, showing that the iron oxide hydroxide octahedra are condensed in a highly disordered way. The coherently scattering areas of this precipitate are probably tetramers. Small amounts of primarily formed amorphous iron(III)hydroxide are transformed into β-FeOOH.     

Photochemische Eigenschaften der Systeme von Chloroeisen(III)-Komplexen in einigen nicht-wäßrigen Lösungsmitteln

Photochemical properties of Fe^III Chloro Complex Systems in Some Non-aqueous Solvents The results on the relationship between the composition of Fe^III chloro complexes in acetone, methanol, their mixtures resp., and their photochemical properties are presented. It has been found that the presence of Fe^II ions in irradiated systems is observed till a certain time. This time as well as the values of Phi; Fe^II depend on the ratio of [Fe^III]:[Cl^?] and the composition of the solvent mixture. Photochemical properties of some Fe^III chloro complexes are discussed.     

Über die Hydrolyse von Eisen(III)-Salz-Lösungen. II Die Alterung der Hydrolyseprodukte

On the Hydrolysis of Iron (III) Salt Solutions. II. Ageing of Hydrolysis Products The long time ageing up to 15 years of the products obtained by alkalifying iron(III) chloride solutions to different neutralisation degrees has been studied. The concentration of the Fe³⁺ and the Cl- ions, the strength of the alkali, and the rate of its addition influence the results. Slow alkalifying produced up to 90% neutralisation β-FeOOH. The transformation of the amorphous iron(III) oxidehydroxide to β-FeOOH was promoted by a high concentration of the Cl- ions. When a large amount of amorphous iron(III) oxidehydroxide was formed, intimately intergrown crystals of α- and β-FeOOH resulted. On further ageing β-FeOOH transformed into α-FeOOH. At a degree of neutralisation of 95 and 100% transformation of the amorphous iron(III) oxidehydroxide into α-Fe₂O₃ occurred. The 100% neutralized precipitate, however, remained partly amorphous. Authors discuss the factors that determine very slow reactions leading to these results.     

C-Glykoside der N-Acetylneuraminsäure. Synthese und Untersuchung ihrer Wirkung auf die Vibrio cholerae Sialidase

C-Glycosides of N-Acetylneuraminic Acid The synthesis of the C-glycosides 8 , 15 , and 9 of N-acetylneuraminic acid is described. Hydroxymethylation of the Li-ester enolate, derived from 5 , yielded the protected C-glycosides 7 and 10 (46%; 3:1), which were deprotected to yield 8 (54%) and 15 (51%; Scheme 2). The mesylate 16 was obtained from 7 (73%) and transformed via the azide 17 (75%) into the acid 18 (66%) and the amino acid 9 (Scheme 3). The configuration at C(2) of 17 was proved by transforming 17 into the bicyclic lactam 19 . Both 8 and 15 are very weak inhibitors of Vibrio cholerae sialidase; 9 appears to stimulate this enzyme.     

Zum Einfluß der Zusammensetzung gemischter Lösungsmittel auf die Stabilitäts- und Bildungskonstanten von Kupfer(II)- und Nickel(II)-Komplexen substituierter 1,2-Dioxime

Influence of the Composition of Mixed Solvents on the Stability and Formation Constants of Copper (II) and Nickel(II) Complexes of Substituted 1,2-Dioximes The stability constants ^cK₁, ^cK₂, and _cβ₂ of the complexes which are formed in the systems M²⁺/DH₂, M²⁺/Ac? DH₂, and M²⁺/Et, Me\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm N}\limits^ \oplus $\end{document}? DH₂ (M²⁺ ? Cu²⁺, Ni²⁺; DH₂, Ac? DH₂, Et₂Me\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm N}\limits^ \oplus $\end{document}? DH₂ = 1,2-dioximes) are determined in water and in water-dioxane mixtures (25, 50 and 75 per cent). Because of the stabilisation of the l,2-complexes by intramolecular hydrogen bonds ^cK₂, is always higher than ^cK₁. On account of the decrease of the dielectricity constant the constants ^cK₁, ^cK₂, and ^cβ₂, rise with increasing contents of dioxane in the mixtures. The influence of the dielectricity constant may be eliminated by considering the formation constants ^cK_1(B), ^cK_2(B), and ^cβ_2(B). The individual formation constants ^cK_1(B) of the 1,l-complexes investigated are independent of the composition of the solvent, but among the overall formation constants ^cβ_2(B) this comes true only for the complexes Ni(Ac? DH)₂, Ni(Et₂Me\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm N}\limits^ \oplus $\end{document}? DH)₂, and Cu(Et₂Me\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm N}\limits^ \oplus $\end{document}? DH)₂. With Cu(DH₂) and Cu(Ac? DH)₂ a linear relation between log ^cβ_2(B) and the molar fraction of water is stated. This effect is attributed to a specific solvatation of the chelates Cu(DH)₂ and Cu(Ac? DH)₂ by water.     

Die Komplexbildung der neutralen Amidgruppe mit Cu2+ in wässeriger Lösung

The interaction between Cu²⁺ and the terdentate ligands N-picolinoyl-ethylenediamine, glycine-2-pyridylmethylamide, N^α-(2-pyridylmethyl)-glycinamide and N^α-(2-pyridylmethyl)-glycine-ethylamide, respectively, has been studied by spectrophotometry and potentiometry. At high pH values the ionised amide group undergoes complex formation and the resulting chelates have similar structures and stabilities. In slightly acidic solution however, each ligand gives rise to a different species. These facts are explained by assuming that the neutral amide group coordinates through its carbonyl oxygen atom. The stability constant and the absorption spectrum of each complex have been calculated by computer programmes.     

Die Anwendung der Potentiometrie bei konstantem Strom auf die Titration von Kobalt mit Kaliumhexacyanoferrat (III)

Ohne Zusammenfassung     

Über die Chemie der Oberfläche des Titandioxids. III. Reaktionen der basischen Hydroxylgruppen auf der Oberfläche

Adsorption of various acids on anatase of high surface area was studied. Phosphoric, arsenic, sulphuric and acetic acid are specifically adsorbed; hydrochloric and perchloric acid are not adsorbed. Phosphate ions are bound on the TiO₂ surface also from NaH₂PO₄ and Na₂HPO₄ solutions; sodium ions are adsorbed at the same time. OH^? ions on the surface are replaced by anions such as H₂PO in these reactions. The bonding of adsorbed phosphate ions is not purely ionic. Infrared spectra show that adsorbed acetic acid is bound as acetate. NO₂ reacts with the basic OH^? ions undergoing disproportionation; OH^? ions are replaced by NO ions. Phophoric acid adsorption corresponded always to half the total OH population on five different TiO₂ samples. The TiO₂ surface is not completely covered by OH groups. The maximum coverage is ca. 7.5 μMol OH/m².     

Nachweis und Bestimmung von Jodspuren auf Grund ihrer katalytischen Wirkung auf die Ce(IV)-Sb(III)-Reaktion mit Hilfe der Simultankomparationsmethode

Zusammenfassung Die Ce(IV)-Sb(III)-Reaktion wird durch Jodid katalysiert. Diese katalytische Wirkung eignet sich zum Nachweis und zur Bestimmung von Jodspuren. Die Reaktion wird in schwefelsaurem Medium durchgeführt; um Sb(III) in Lösung zu halten, wird Weinsäure zugesetzt. Zur Indizierung des Endpunktes wurde Ferroin angewendet. Die Empfindlichkeit des Nachweises beträgt 5 · 10^–3 g Jodid/5 ml. Zur Bestimmung von Jod in Ultramikromengen wurde die SimultankomparationsmethodeBognárs, benützt. Die damit erreichbare Genauigkeit der Jodbestimmung beträgt ±1,7%. Der von fremden Ionen ausgeübte Einfluß wurde quantitativ untersucht.

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Summary The Ce(IV)-Sb(III) reaction is catalyzed by iodine. This catalytic effect lends itself to the detection and determination of traces of iodine. The reaction is conducted in sulfuric acid medium; tartaric acid is added to keep antimony(III) in solution. Ferroin is employed to indicate the endpoint. The sensitivity of the test is 5 · 10^–3,g iodide/5 ml. The simultaneous comparison method ofBognár is employed for determining iodine in ultramicro amounts. The precision of the iodine determination attained in this way is ±1.7%. A quantitative study was made of the influence exerted by foreign ions.

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Résumé L'iode catalyse la réaction Ce-IV-Sb-III. Cette action catalytique permet la recherche et le dosage de traces d'iode. La réaction s'effectue en milieu acide sulfurique; pour obtenir Sb-III en solution, on ajoute de l'acide tartrique. On utilise la Ferroine comme indicateur du point équivalent. La sensibilité de la recherche s'élève à 5 · 10^–3 g d'iodure/5 ml. Pour le dosage de l'iode en quantités ultramicro on utilise la méthode de comparaison simultanée deBognár. L'exactitude que l'on obtient ainsi pour le dosage de l'iode s'élève à ±1,7%. On a fait l'étude quantitative de l'influence exercée par les ions étrangers.

     

Zur Kenntnis von Dinitrito-kobalt(III)-Komplexen. I Darstellung und Absorptions-Spektren der Dinitrito-di(äthylendiamin)-kobalt(III)-perchlorate

On Dinitrito Cobalt(III) Complexes. I. Preparation and Absorption Spectra of Di(ethylenediamine) Cobalt(III) Perchlorates Cis and trans dinitrito diethylenediamine cobalt perchlorates could be prepared starting with carbonato and trans dichloro ethylenediamine cobalt perchlorate. Spectroscopic data are reported and compared with those of the corresponding dinitro complexes.     

Spektrophotometrische Untersuchung der Komplexbildung von Eisen(III) mit Ethylendiamintetraessigsäure und einigen Thioliganden

Spectrophotometric Investigation of the Complexation of Iron(III)with Ethylene Diamine Tetraacetic Acid and Some Thioligands . In the system Fe^III/EDTE/R? SH (Thiophenol, Toluen-3,4-dithiol, Thioethanol bzw. Thioglycollic acid) ternary complexes could be detected in solution. By means of spectrophotometric measurements the ratio of components in the species Fe:L:L′=1:1:1 was determined. The optical properties of the complexes are discussed.