Kupferkomplexe von Bisamiden: Struktur und Stabilität I

Complex formation between Cu²⁺ and several ligands, each containing two amino and two amide groups, has been studied potentiometrically and spectrophotometrically. A digital computer was used to determine the composition of the complex species formed and to calculate their stability constants. N,N′-diglycyl-1, 2-diaminoethane and its homologues form 5-, 6-, 7-, 8- and 9-membered rings between the two amide groups, respectively. No tendency towards formation of binuclear species has been observed.     

Bestimmung der Stabilitätskonstanten gemischter Hexahalogenokomplexe von Osmium(IV)

Determination of the Stability Constants of Mixed Hexahalogeno Complexes of Osmium(IV) The individual and total stability constants of the complex series [OsX_xY_6?x]^2?; X ≠ Y = Cl, Br, I; x = 0–6 are determined by radiometric measurements of the equilibrium concentrations of all compounds. The thermodynamical stability increases from the hexabromo- over the hexachloro- to the hexaiodo-complex. The total stability constants are in ratio of 1:5,2:1225. With the individual constants the equilibrium diagrams are calculated. The photometric determination of the cis/trans ratio in complexes with x = 2, 3, 4 gives the statistical distribution of the ligands in the octahedrons. The relationship between thermodynamical and kinetical data is discussed.     

Komplexbildung von Ionophoren vom Typ der Dioxakorksäurediamide mit Alkali- und Erdalkaliionen. Stabilitätskonstanten in Äthanol

Complex Formation of Ionophores of the Dioxaoctane Dicarboxylic Acid Diamide Type with Alkali and Alkaline Earth Cations. Stability Constants in Ethanol. Stability constants are reported for two noncyclic, neutral ionophores in interaction with alkali and alkaline earth metal cations in ethanol. The ligands studied give high selectivity of alkaline earth in respect to alkali metal cations when used in liquid membrane electrodes.     

Chelate von β-Dicarbonylverbindungen und ihren Derivaten. XXIV. Stabilitätskonstanten von Metallchelaten unterschiedlich substituierter Pivaloylacylmethane

Chelates of β-dicarbonyl compounds and their derivatives. XXIV. Stability constants of metal chelates with differently substituted acylpivaloylmethanes Stoichiometric stability constants of copper(II), beryllium(II), nickel(II), cobalt(II) and zinc(II) chelates of 25 differently substituted acylpivaloylmethanes are determined in dioxane-water mixture and relations for calculating thermodynamic constants are given. The influence of aromatic and aliphatic substituents of the β-diketones on complex stability is discussed.     

Stabilitätsuntersuchungen an Kupferkomplexen substituierter Acetessigsäure-2-amidopyridine und -pyrimidine II

The stability constants of the copper complexes of acetoacet-2-amidopyridine and-2-amidopyrimidine have been determined by potentiometric pH-measurements. The variation of stability constants with pyridyl and pyrimidyl substituents is interpreted.     

Bestimmung von Stabilitätskonstanten in Ethanol für Li+-selektive Ionophore mittels differentieller Dampfdruckosmometrie

Determination of Stability Constants in Ethanol for Li⁺-selective Ionophores by Differential Vapour Pressure Osmometry Stability constants of some neutral carriers and their bridged isologues in interaction with Li⁺ and Na⁺ are determined by a differential vapour pressure osmometry method in ethanol utilizing Bjerrum formation curves. All ionophores studied induce high Li⁺ selectivity in solvent polymeric membranes.     

Die Hydrolyse von Phospholinsäureamiden

Hydrolysis of Amides of Phospholinic Acid The acid catalysed hydrolysis of (= OAP, R = organic substituent) has been investigated kinetically. Provided the pH remains constant, the hydrolysis is a first order reaction. From the temperature dependance of the rate constant the activation energy E_a as well as the thermodynamic data ΔH* and ΔS* have been calculated. In comparison to the compound with R = H aromatic substituents and additional the t-butyl group enhance E_a whilst aliphatic substituents included the benzyl group diminish E_a. The first step of the reaction is a protonation at the oxygen or nitrogen resulting in the formation of an equilibrium. After the determination of the basicity constant K_A of some OAPs it was possible to calculate the respective rate constants of the rate determining step of the reactions and the corresponding thermodynamic data E_F, ΔH and ΔS. It is assumed that the mechanism of the hydrolysis takes place according to the same scheme which has been assumed for the hydrolysis of cyclic esters of the phosphinic acid by Ugi [1] and colaborators.     

Molekulargewichtsbestimmung durch Gelchromatographie von Oligoimidophosphorsäureamiden

Determination of Molecular Weights by Gel Chromatography of Oligoimidoamides of Phosphoric Acid. Oligoimidoamides of phosphoric acid were eluted with nonionic water on a Sephadex LH-20 column. The measured distribution coefficient of the oligoimidoamides of phosphoric acid was independent of sample concentration and pH of the eluent. Andrews equation was obeyed: a linear relation exist between elution volume and logarithm of molecular weight both cyclic and acyclic oligoimidoamides of phosphoric acid.     

Zur Reaktionsweise von Diphenylcyclopropenon mit β-Carbonyl-enolaten. I. Einsatz von Acetylaceton,Acetessigsäure-methylester, 2-Äthoxycarbonyl-cyclododecanon und Malonsäure-dimethylester

Reaction of Diphenylcyclopropenone with β-Carbonyl-enolates. I. Use of Acetylacetone, Methyl Acetoacetate, 2-Ethoxycarbonyl-cyclododecanone and Dimethyl Malonate The reaction of the sodium salts of acetylacetone ( 6 ), methyl acetoacetate (7) , 2-ethoxycarbonyl-cyclododecanone (8) , dimethyl malonate (19) and its methyl derivative 20 with diphenylcyclopropenone ( 5 ) in dimethylformamide at room temperature led to the unsaturated γ-lactones 14, 15, 17, 22 and 36 . In the case of dimethyl malonate ( 19 ), the halfester 21 , the acyl-malonic ester 24 and the indenone-malonic ester 23 were also isolated. Several intermediates and the final products were characterised by reactions and spectroscopically. A general mechanism is discussed for the addition of cyclo-propenones ( 1 ) to the enolate salts of β-dicarbonyl compounds 4 involving the bicyclic lactone-enolates 18 and 32 as intermediates. The products formed via 18 and 32 are considered to be the result of an attack of one of the oxygen atoms of the β-carbonyl-enolate anion ( 4 ), the product 24 , on the other hand, of the attack of the α-carbon atom of 4 ; in both cases the attack is on the carbonyl C-atom of 5 .     

Darstellung und Stabilität von Aroxy-fluor-silanen

Preparation and Stability of Aroxy-fluoro-silanes. Different possibilities for preparation of aroxy-fluoro-silanes (esp. substituted phenoxy-fluoro-silanes) are investigated. The reaction was proved as the best method of preparation. The aroxy-fluoro-silanes are disposed to dismutation reactions.     

Ionophore für Li+: Membranselektivität,Darstellung und Stabilitätskonstanten in Äthanol

Membrane Selectivity and Syntheses of Ionophores for Li⁺. Stability Constants in Ethanol Electrically neutral, lipophilic complexing agents were prepared which induce Li⁺ selectivity in solvent polymeric membranes. Stability constants for group IA and IIA cations of one such ligand in ethanol have been determined. The selectivity behaviour of this ligand in membranes as well as in extraction systems is studied and discussed in terms of model considerations.     

NMR-spektroskopische Untersuchung der Keto-Enol-Tautomerie von Acetessigs?ureamiden

Zusammenfassung Aufgrund der unterschiedlichen chemischen Verschiebungen von Protonen der mittelständigen CH- und CH₂-Gruppe einerseits sowie der CH₃-Gruppe in der Keto- und der Enolform von Acetessigsäureamiden lassen sich durch NMR-spektroskopische Untersuchungen Enolgehalte sowie die Lage des Keto-Enol-Gleichgewichts feststellen. Wie wir fanden, hängt das Keto-Enol-Gleichgewicht von der Art der Snbstituenten an der Amidgruppe, von der Polarität des Lösungsmittels sowie von der Temperatur ab. Werte für die Gibbssche Freie Energie, für die Enthalpie sowie die Entropie des Gleichgewichtes wurden errechnet.

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NMR-spectroscopic investigation of the keto-enol tautomerism of acetoacetamides

Based on the differing chemical shifts of the CH- versus the CH₂-groups, and the methyl groups of the keto versus the methyl groups of the enol form of the acetoacetamides, it is possible to study the keto-enol equilibrium. It was found, that this equilibrium depends on the kind of substituent at the amido group, the polarity of the solvent and the temperature. Values for the Gibbs's free energy, the enthalpy and the entropy of the equilibrium are given.

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Herrn Prof. Dr. H. Specker zum 60. Geburtstag gewidmet.     

Zur Stabilität der Metallkomplexe von Methantriessigsäure und cis,cis-1,3,5-Cyclohexantricarbonsäure

The stabilities of the Mn²⁺-, Co²⁺-, Ni²⁺-, Cu²⁺- and Zn²⁺-complexes with 2-(carboxymethyl)glutaric acid ( 2 ) and cis,cis-1,3,5-cyclohexanetricarboxylic acid ( 3 ) were measured potentiometrically at 25° and I = 0.5 (KNO₃). Beside the complexes ML^? protonated species MLH and MLH are also formed. Their stability constants are given in Table 1. A comparison between the stabilities of 2 or 3 and those of acetate, as a model for a monocarboxylate, or succinate and glutarate, as examples for dicarboxylates, indicates that in all species only one carboxylate is strongly bound whereas the second and third ones are probably not. The observation that Δlog K₁ = log K ? log K as well as Δlog K₂ = log K ? log K are practically constants with values of 0.34 ± 0.05 and 0.49 ± 0.07, respectively, for both ligands and the five metal ions studied is also in line with the proposed monodentate structures of the complexes ML^?, MLH and MLH.