Investigation of the electrokinetic properties of paraffin suspension. 2. In cationic and anionic surfactant solutions

Electrical phenomena at nonionogenic hydrophobic surfaces (solid or liquid) in water, electrolyte, and/or surfactant solutions still attract research. In part 1 of this paper we described the electrokinetic behavior of paraffin wax suspension in water and electrolyte solutions (NaCl or LaCl3). On the basis of the latest data of water structure near hydrophobic surfaces it was concluded that immobilized water dipoles at the interface can play an essential role in the zeta potential formation. In this paper were investigated the zeta potentials of paraffin wax in cationic surfactants cetyltrimethylammonium bromide, C16H33(CH3)3NBr, and octadecyltrimethylammonium chloride, C18H37(CH3)3NCl, and anionic surfactant sodium dodecyl sulfate, C12H25SO4Na. Also changes in wettability of the paraffin surface due to the surfactant's adsorption were studied via wetting contact angle measurements and calculation of the surface free energy. It was concluded that at a low surfactant concentration (10(-6) M) the water dipole structure still contributes to the zeta potential, but at a higher one the zeta potential is determined by the surfactant molecules' adsorption. A special role of OH- ions is also clearly seen. Moreover, a functional relationship was found between the surface free energy of the surfactant-covered paraffin surface and the zeta potential.     

Zur Verbrennung fluor-, phosphor- und metallhaltiger Verbindungen mit einem CHN-Automaten

Zusammenfassung Durch Hinzunahme von Magnesiumoxid zur Verbrennungsrohrfüllung wird der Anwendungsbereich des CHN-Automaten auf fluor- und phosphorhaltige Proben erweitert. Diese beiden Elemente werden im wesentlichen in der Magnesiumoxidzone der Füllung gebunden. Bei manchen phosphorhaltigen Verbindungen macht die geringe Pyrolysegeschwindigkeit einen längeren Analysezyklus notwendig. Die längere Verbrennungszeit wird durch eine Reduzierung des Gasstromes ermöglicht. Bei metallhaltigen Proben geben alle Verbindungen, deren Metalle unter den herrschenden Bedingungen definierte Rückstände bilden, ohne besondere Maßnahmen gute Werte. Die Bildung carbonathaltiger Rückstände bei Alkali und Erdalkali wird meistens von der Apparatur als solche registriert.

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Summary The field of application of the CHN-automatic combustion devices is extended to samples containing fluorine and phosphorus by including magnesium oxide in the filling of the combustion tube. These two elements are essentially bound in the magnesium oxide zone. Many compounds containing phosphorus make it necessary to reduce the speed of the gas stream because of the low pyrolysis velocity. When samples containing metals are being analyzed, excellent results are obtained with all compounds whose metals yield definite residues under the prevailing conditions. The formation of residues containing carbonate in the case of alkali and alkaline earths is usually registered as such by the apparatus.

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Die Firma Technicon hat uns für diese Untersuchungen dankenswerterweise einen CHN-Analyzer zur Verfügung gestellt.     

Zum Mechanismus der Thermischen Dehydratisierung von Natriumdihydrogenphosphat

Mechanism of Thermal Dehydration of Sodium Dihydrogenphosphate The thermal dehydration of sodium dihydrogenphosphate (P₁) to sodium cyclotriphosphate (CP₃) and sodium polyphosphate, the so-called Maddrell's salt (MS), is controlled by nucleation and crystallization of CP₃ and MS, respectively. The wellknown influence of various formation conditions on the CP₃:MS product ratio is caused by amorphous and crystalline intermediate phases and their ability to form CP₃ or MS nuclei. On seeding P₁ with CP₃ or MS the dehydration proceeds structure-controlled via dihydrogendiphosphate to pure CP₃ or pure MS. The particularities of thermal dehydration of crystalline sodium dihydrogendiphosphate, and also the dehydration and reorganization of sodium phosphate glasses (Na:P = 1:1) with different mean chain lengths, under formation of CP₃ or MS are described.     

The role of the π-bonding network for trigonal level splittings of tris-bidentate Cr(acac)3 and Cr(ox) 3 3−

The varying -bonding contributions in the title compounds caused by the different electronic and molecular structure of the chelate rings are used for explaining the large band splittings in the absorption spectra by trigonal symmetry. It is shown that usual ligand field theory and the angular overlap model are not able to account for the trigonal level splitting of Cr(acac)₃ for which the coordination sphere of oxygen atoms is nearly octahedrally arranged. The experimental finding can, however, be rationalized by an extended angular overlap model which considers the phase coupling of -orbitals in the ligands leading to non-additive contributions to the metal-ligand bond energy.On leave of absence from the Bulgarian Academy of Sciences, Sofia, Bulgaria     

Splitless injection of up to hundreds of microliters of liquid samples in capillary GC: Part II,experimental results

Sample evaporation in splitless injection of large volumes is rapid: depending on the experiment, results indicate that 200 μl of hexane, for instance, evaporates in 2–10 s, producing vapor at a rate of many hundreds of milliliters per minute. A 60 × 4 mm packed bed of 20–35 mesh Tenax TA enabled injection of 200 μl volumes of all solvents tested, and even 1 ml injections were possible provided they were performed over a period of 30 s. Retention of volatile sample components depends on the sample solvent, the injection volume, and the injection speed, but only little on the injector temperature. Losses of n-tridecane varied from hardly 15 % (when dissolved in pentane) to ca 60 % (ethyl acetate); losses of n-heptadecane were usually below 20 %. The column temperature during injection should be at least ca 20–30°C above the standard solvent boiling point.     

Metal‐Xenon Complexes

Long after the first isolation of a xenon compound in 1962 the first compounds with metal‐xenon bonds are prepared. The metal atoms are so far Au and Hg. The most stable metal xenon compounds decompose under loss of xenon slightly above room temperature. They can only exist if solvents and counter ions are weaker bases than atomic xenon. Solvents and counter ions used so far are HF, (SbF₆)^—, and (Sb₂F₁₁)^—.     

Theory of chirality functions,generalized for molecules with chiral ligands

The theory of chirality functions described in a previous publication is generalized to allow for chiral ligands. In the earlier theory, all symmetry operations of the molecular frame could be thought of as permutations of the ligands among the sites; in the present work, improper rotations not only permute the ligands, but convert them into mirror images. The group that generates all isomers from a given ordered molecule belonging to a frame with n sites is now the hyperoctahedral group of order 2ⁿ n! consisting of all possible combinations of permutations and site reflections. The representation theory of these groups is described, and applied to the problem of constructing qualitatively complete chirality functions, and of deciding which ligand partitions, and which isomer mixtures, are chiral. It is found useful to classify chiral representations of the covering group as ligand specific and class specific. The ligand specific representations describe chiral properties which are common to all frames and arise purely from the chirality of the ligands, while the class specific representations describe the chiral properties of the frame. A number of examples are explicitly worked out.     

Zur Darstellung von Imidazolidin-thionen-(4) und Imidazolin-(3)-thionen-(5)

Zusammenfassung 2,2,5-Trisubstituierte Imidazolidin-thione-(4) lassen sich mittels Schwefels mit guten Ausbeuten zu Imidazolin-(3)-thionen-(5) dehydrieren. Hierüber sowie über einige Verbesserungen der bisher bekannten Synthesen für insbesondere 2,2,5-trisubstituierte Imidazolidin-thione-(4) wird berichtet.

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Dehydration of 2.2.5-trisubstituted imidazolidine-(4)-thiones with elementary sulfur gives in good yields 3-imidazoline-(5)-thiones. This reaction and improved methods of the well known syntheses of especially 2.2.5-trisubstituted imidazolidine-(4)-thiones are described.

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Mitt.:F. Asinger, W. Schäfer undH. Triem, Mh. Chem.97, 1510 (1966).

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Teil der Dissertation vonH. Meisel, Techn. Hochschule Aachen, 1963.

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Teil der Dipl.-Arbeit vonHilde Kersten, Techn. Hochschule Aachen, 1963, und Teil der Dissertation vonHilde Kersten, Techn. Hochschule Aachen, 1965.     

The platinum catalyst [bpyrPtCl2] in superacidic solution

The methane oxidation catalyst [bpyrPtCl(2)] (bpyr = bis-pyrimidine) dissolves in superacidic HF/SbF(5) solution under formation of a dinuclear cation [H(2)bpyrPt(mu-Cl)(2)PtbpyrH(2)](6+). Two crystal forms are isolated, [Pt(2)Cl(2)bpyr(2)H(4)](6+)(SbF(6)(-))(4)(Sb(2)F(11)(-))(2).2HF (I) (triclinic, Ponemacr;, a = 814.8(2) pm, b = 1444.8(3) pm, c = 2300.5(5) pm, alpha = 89.627(4) degrees, beta = 84.285(4) degrees, gamma = 84.665(4) degrees, Z = 2) and [Pt(2)Cl(2)bpyrH(4)](6+)(Sb(2)F(11)(-))(6).4HF (II) (triclinic, Ponemacr;, a = 879.4(2) pm, b = 1170.4(3) pm, c = 1789.9(5) pm, alpha = 95.37(2) degrees, beta = 99.97(2) degrees, gamma = 100.41(2) degrees, Z = 1). The cation in I has an angle of 148.4(1) degrees between the two square plane platinum environments, while the cation in II is fully planar. The non-platinum-bound nitrogen atoms are all protonated in the superacidic medium.     

Mass spectrometric analysis of androstan-17β-ol-3-one and androstadiene-17β-ol-3-one isomers

Mass spectrometric identification and characterization of steroids using electrospray ionization and tandem mass spectrometry has advantages in drug testing and doping control analysis attributable to limitations of gas chromatography followed by electron ionization mass spectrometry. Steroids with an androstadiene-17beta-ol-3-one nucleus and double bonds located either at C-1 and C-4, C-4 and C-9, or C-4 and C-6 were used to determine characteristic fragmentation pathways. Diagnostic dissociation routes are proposed using deuterium labeling, MS3 experiments, and analyses of structurally closely related compounds. Steroids such as boldenone (androst-1,4-diene-17beta-ol-3-one) produced characteristic product ions at m/z 121, 135, and 147. Compounds with double bonds at C-4 and C-9 generated abundant product ions at m/z 145 and 147. Conjugated double bonds at C-4 and C-6 gave rise to an intense and characteristic signal at m/z 133. Stereochemical differentiation between 5alpha- and 5beta-isomers of androstan-17beta-ol-3-ones was possible because of significant differences in relative abundance of product ions generated by elimination of acetone from alpha,beta-saturated 3-keto steroids.