Band 23, Heft 10

Ionization energies and electron affinities of organic and inorganic substances are obtainable from reversible anodic and cathodic half-wave potentials, solvation energies and the electron work function potential of the electrode metal. Solvation energies were calculated using a modified Born equation in which the molecular radius was corrected for the ionization energy. It is possible to compute the first ionization potential of organic compounds with a deviation from experimental data of less than 3 per cent. The calculated electron-affinities do not agree with values given in the literature but are equal to the difference in energy between the first excited state and ionization potential. Electron work function potential of platinum measured by an indirect method was found to be 4,43 ev.

The potential constants are obtained for the monohaloacetylenes using the general valence force field. The theory of the mean-square amplitude matrices is applied to these molecules and the parallel and perpendicular mean-square amplitudes for the interatomic distances are calculated. The perpendicular amplitudes have been used for calculating the shrinkage effect. The Coriolis coupling coefficients are also obtained for all these molecules.

Normal co-ordinate analysis has been carried out for diphosphorous tetra iodide (P 2 I 4 ) on the basis of general valence force field and the force constants have been evaluated. The values of the generalised mean square amplitudes of vibration calculated at 300 °K indicate that the vibrational amplitudes are not large even though the frequencies of vibrations are rather low. The Coriolis coupling coefficients also have been evaluated.

Der Protonenübergang vom o-Nitrophenol zu verschiedenen Aminmolekülen in benzolischen Lösungen wird bei verschiedenen Temperaturen spektrophotometrisch untersucht. Es wurde festgestellt, daß das gebildete Assoziat ein Ionenpaar der Form 1:1 darstellt, bei dem das Anion die Chinon-Anion-Form des o-Nitrophenols hat. Die Gleichgewichtskonstanten bei 15°, 20°, 25°, 30° und 35 °C werden durch Anwendung der Rose und Drago - graphischen Methode ermittelt und die thermodynamischen Daten ΔH, ΔG° 25 und ΔS° 25 berechnet.

Im System Nickel (II) acetylacetonat/Diäthylaluminiumäthoxid werden neben Äthyl-auch Äthoxidgruppen vom Aluminium an das Nickel übertragen. So bildet Tetrakis (diphenylphosphinomethyl) methan, C[CH 2 P(C 6 H 5 ) 2 ] 4 , das im allgemeinen zweimal zweizähnig und selten dreizähnig reagiert, in diesem System als lediglich zweizähniger Komplexligand bevorzugt den monocyclischen Nickeldiäthoxid-Komplex: Bei der thermischen Zersetzung zerfällt dieser u. a. in Äthanol, Acetaldehyd, Crotonaldehyd, n-Butanol, Essigsäureäthylester, Aceton, Diacetyl, Benzol, Diphenyl, Nickel und Nickelhydrid. Der Reaktionsablauf wird diskutiert.

Durch 63 Cu, 63 Cu-Breitlinien-NMR-Messungen an dem polykristallinen Thermophor β-Cu 2 [HgJ 4 ] wurde eine Quadrupolwechselwirkung II. Ordnung an den Zentrallinien m =1/2 → -1/2 gefunden. Eine gleichzeitige experimentelle Bestimmung der Quadrupol-Kopplungskonstanten | e q Q | und des Asymmetrieparameters η war möglich, da an diesem System auch die Quadrupolaufspaltung I. Ordnung gemessen werden konnte.

Der Cyclopropanring des 1.5-Cyclo-10α-androstan-2-ons (1) läßt sich säurekatalytisch öffnen. Je nach den Reaktionsbedingungen erhält man Δ 5 -10α-Androsten-2-on (2), Δ 1(10) -19-Nor-5α-methylandrosten-2-on (3), Δ 3 -5α-Androsten-2-on (4), die Spiroverbindung 11, 5α-Chlor-l0α-androstan 2-on (13) oder 5α-Hydroxy-10α-androstan-2-on (12).

The conversion of 2-thio-aryl-tryptophan and related derivatives to the corresponding 2-hydroxycompounds by acidic hydrolysis was investigated. The thioether function is introduced into the tryptophan residue by the selective reaction of sulfenyl halides with the indole nucleus. The substitution occurs under mild conditions only when the amino group of the tryptophan residue is free. The assistance of the amino group was confirmed using model compounds. Thus 2-thio-(2-nitrophenyl) -tryptamine is smoothly converted to 2-hydroxy-tryptamine whereas 2-thio- (2-nitrophenyl) -β-indolyl-propionic acid is completely stable under the same conditions. The conversion of 2-thio-aryl-tryptophan units linked in a polypeptide chain to the corresponding 2-hydroxy-tryptophan occurs only under conditions during which hydrolysis of the peptide bond occurs. It was also observed that the 2-nitro-thiophenols which are released during the hydrolysis of 2-thio- (2-nitrophenyl) -tryptophan and related compounds are converted under the conditions of the reaction to 2-aminobenzene sulfonic acids.

Unsubstituierte Hydroxy-guanidin-O-sulfonsäure und ihre N′-Alkyl-Derivate geben in Gegenwart von Aluminiumchlorid Guanidierungen von Aromaten in hohen Ausbeuten 1 . Bei den N-Alkyl-Derivaten tritt diese Reaktion mit steigender Größe der Alkylgruppen fast ganz zurück. Als Hauptprodukte werden nun Anthracen und Diphenylmethan gefunden. Versuche mit 14 C-indizierten Verbindungen zeigen, daß nicht das C-Atom des Guanidin-Restes, sondern ausschließlich das C-1-Atom der Seitenkette eingebaut wird. Diese Fragmentierung ist von Alkylierungen der Aromaten sowie von Redoxreaktionen begleitet.

Direct potentiometric methods for the semi-micro determination of easily reducible nitro compounds with vanadium (II) sulphate have been described. It has been shown that the position and nature of the substituents in the benzene ring effect the rate of reduction.

Durch katalytische Tritiierung von Hexadecen- (10-trans) -in- (12) -ol- (1) gelang die Synthese von hoch markiertem [12.13- 3 H] -Hexadecadien- (10-trans,12-cis) -ol- (1).

Many investigations with electron spin resonance spectroscopy have shown that the spin-lattice interaction of radiation induced free radicals in organic materials is too weak to allow rapid thermal relaxation. Therefore saturation effects can be produced by a microwave power not sufficiently attenuated. The saturation effect of radiation induced free radicals in d,l-valine and d,l-leucine was studied. The linear relationship between the intensity of the spectrum and the field strength was changed by large values of the microwave power in both of the amino acids. The microwave saturation is independent of the X-ray absorbed dose in the case of d,l-leucine however not in the case of d,l-valine. After higher X-ray doses the saturation effect is obtained at larger values of the microwave field strength than after lower doses. Our results may be interpreted by the fact that at room temperature two species of free radicals occur in d,l-valine. Each of them may have a different spinlattice interaction time and the numerical proportion of the two species may be a function of the X-ray absorbed dose.

A model is given which describes the essential properties of an autoradiographic arrangement. By means of approximation methods, a contrast transfer function, a spread function, and related functions are calculated. Image functions and image contrasts for periodic and nonperiodic distributions of radioactivity can be derived from these functions.

In autoradiographic transfer two characteristic ranges can be distinguished which result from the composed kind of dose function (e −kR /R 2 ). In “photographic region” of transfer, i. e. when thickness of emulsion and object are comparable with the maximum range of beta particles, the influence of absorption or beta energy is predominant and that of geometry can be neglected. The autoradiographic transfer properties are very similiar to those of photographic transfer. In the “crossfire region” of autoradiographic transfer i. e. when the thickness of emulsion and object are very small compared with the maximum particle range, the influence of geometric parameters is predominant. High crossfire causes blurred images, typical for microautoradiography with nuclides of high energies. In addition to linear transfer of periodic and nonperiodic distributions of radioactivity, the nonlinear transfer is considered. The influence of exposure on contrast transfer and grain density is also considered. Contrast measurements, made by using 131 I- and 32 P-labelled sine wave gratings, are in agreement with the calculated contrast transfer functions.

Mit Hilfe der NMR- und IR-Spektroskopie wurde die Eigenassoziation von vier Nucleosid-Derivaten untersucht. Es zeigt sich eine gute Übereinstimmung zwischen den nach beiden Methoden erhaltenen Ergebnissen. Die thermodynamischen Daten werden diskutiert.

Die Zusammensetzung und der Stoffwechsel der Carotinoide in adulten Exemplaren von Artemia salina wurden untersucht. Unabhängig von der Fütterung mit carotinoidfreier Hefe, mit an Oxicarotinoiden reicher Nahrung oder mit Oxocarotinoid-haltigen Algen lassen sich als Hauptpigmente Canthaxanthin (4.4′-Dioxo-β-carotin) und Echinenon (4-Oxo-β-carotin) nachweisen. Daneben wurden in einer Artemia-Probe Astacin (3.4.3′.4′-Tetraoxo-β-carotin) und 3.4.4′-Trioxo-β-carotin gefunden. Außerdem konnten in geringen Konzentrationen einige der entsprechenden Oxiverbindungen (4-Oxi-, 4.4′-Dioxi-, 3.4.3′.4′-Tetraoxi-β-carotin) identifiziert werden. Diese Ergebnisse sprechen dafür, daß die Oxocarotinoide End-, nicht Zwischenprodukte im Stoffwechsel der untersuchten Krebse sind.

In the Alga Acetabularia intense light flashes produce transient depolarizing potentials which can be recorded intracellularly with 3 molar KCl glassmicroelectrodes. This rapid photoelectric effect has a latency of not more than 40 µsec. Spectral measurement showed a maximal sensitivity near 540 mµ. There is a second depolarization in the dark period after the flash. Lowering the temperature increases the amplitude of the fast depolarization and decreases the amplitude of the dark depolarization. Presumably the pigment and generator of the fast light-induced potential are associated with the cell membrane.