Photochemie substituierter Cycloheptatriene. XV. Zur Charakterisierung der Elektronischen Übergänge in 1-Aryl-4-(p-dimethylaminophenyl)-cycloheptatrienen

Photochemistry of Substituted Cycloheptatrienes. XV. About the Characterization of the Electronic Transitions in 1-Aryl-4-(p-dimethylaminophenyl)-cycloheptatrienes The absorption spectra of the title compounds are discussed in dependence on polarity of the solvent and its ability to form hydrogen bonds. The results suggest a hybridization of the N-atom of the dimethylamino group between sp³ and sp² in the ground state. Contrary to this, the nitrogen has sp²-hybridization in the short wavelength (SE) fluorescing state. In a second fluorescence state the geometry of the seven-membered ring should change. Therefore the viscosity of the solvents influences both the position and the quantum yield of this long wavelength emission (LE). The influence of polarity and viscosity of the solvents is described by multiple regression. The temperature dependence of fluorescence quantum yields is discussed, as well.     

Derivate des Phosphorsäure-o-phenylenesters. XV [1]. Synthese von Tris-(o-phenylendioxy)-phosphorat(V)

Derivatives of o-Phenylenephosphate. XV. Synthesis of Tris-(o-phenylenedioxy)-phosphorate(V) The structure of an orthophosphate which had been supposed earlier to represent type 1 , has been proven to be a compound having only one P-nucleus in the molecule, with a penta( 4 ) resp. hexacoordinated ( 5 ) structure depending on the solvent. The triethyl-ammonium salt 8 of this first example of a hexacoordinated phosphoric acid with 6 P O-bonds ( 5 ) is formed simply from tri- als well as from tetra- and pentacoordinated derivatives of phosphorous resp. phosphoric or thiophosphoric acid.     

Komplexkatalyse. XV. Kationische η3-Allyl-bis(triorganylphosphit)nickel(II)-Komplexe als Katalysatoren für die stereoreguläre Butadienpolymerisation

Complex Catalysis. XV. Cationic η³-Allyl-bis(triorganylphosphite)nickel(II) Complexes as Catalysts for the Stereoregular Butadiene Polymerisation Synthesis and catalytic properties of [C₃H₅NiL₂]PF₆ complexes 1a –f with L = tri-ethyl-, -isopropyl-, -phenyl-, -o-tolyl-, -thymyl- and o-biphenylylphosphite are described. It is shown how electronic and steric effects of the phosphite ligands in these complexes control their catalytic activity and selectivity in 1,4-polymerization of butadiene.     

Der „Nornialisierungsfaktor”︁ für die Toinatenmutante chloronerva. XV. Peptidanaloga des Phytosiderophors Nicotianamin

The “Normalizing Factor” for the Tomato Mutant chloronerva. XV. Peptide Analogues of the Phytosiderophore Nicotianamine Some peptide analogues of the phytosiderophore nicotianamine, (2 S , 3′ S , 3″ S )- N -[3-(3-amino-3-carboxypropylamino)-3-carboxypropyl]-azetidine-2-carboxylic acid, have been synthesized from protected amino acids by the EEDQ or the DCC method. They exhibited no biological effect with regard to the phenotypical normalization of the tomato mutant chloronerva.     

Massenspectroskopie von Naturstoffen. XV. Vergleichende Kationen-Anionen-Massenspektroskopie von Azidogibberellinen

Mass Spectrometry of Natural Products. XV. Comparative Positive-Negative Ion Mass Spectrometry of Azidogibberellins The fragmentation behaviour of 1-azido-3-hydroxy-gibberellin derivatives has been studied by means of positive and negative ion mass spectrometry, high resolution and metastable transitions. The results obtained allow a mass spectrometric distinction to be made between epimers with different stereochemistry of the ring A substituents.     

橡胶百科（十五）

概要叙述了天然橡胶和合成橡胶的发展历程，分别从橡胶化学和橡胶物理的角度介绍了橡胶的基本性质。     

Polymer swelling. XV. Swelling and deswelling studies of polystyrene–liquid systems in binary solutions

The specific sorption capacities of poly(styrene-co-divinylbenzene) [i.e., (Sty)_1?x (DVB)_x samples for binary solutions of toluene (α = 1.98)] and a second solvent [i.e., heptane (α = <0.01), methanol (α = <0.06), acetone (α = 0.92) or chloroform (α = 3.00)] were correlated with the corresponding DVB mole fraction (x) in the sorbent polymer samples (0.01 < x < 0.11), with the volume fraction (z) of toluene in the sorbed binary liquid (which was cycled at least twice from z = 0 to z = 1 and back to z = 0 in increments of 0.1) and with the adsorption parameter (α) of the sorbed liquid. These correlations demonstrated that the sorption capacity during the initial transit from z = 0 to 1 reflects the molecular architecture in the original dry state. Once the samples have been swelled to saturation in toluene (z = 1), however, the “memory” of the former dry state is erased; thereafter the sorption capacity reflects only the architecture established in the fully swollen state, and the composition of the sorbed solution. The molecular nature of the solvent exchange processes is discussed in the text. © 1994 John Wiley & Sons, Inc.     

Search for new seed oils. XV. Oils of boraginaceae

In a search for a preferred source of γ-linolenic (all-cis-6,9,12-octadecatrienoic) acid, seed oils of 33 species of Boraginaceae were examined. The desired triene was found primarily in the subfamily Boraginoideae in amounts ranging from 0.2 to 18%. Oils of this subfamily also contain 0.2 to 15% of the tetraene, all-cis-6,9,12,15-octadecatetraenoic acid. Total unsaturation and the relative proportions of the common acids varied widely in oils of the family. Monoene predominated in the subfamily Cordioideae, diene in Heliotropioideae, and a diverse composition among the Boraginoideae; seven had iodine values of 200 or above.Cordia verbenacea seed oil was unique among those examined in having 43% of C₂₀ acids and 23% of components more volatile in gas chromatography than the usual triglycerides. Presented at AOCS meeting, New Orleans, May 1967. Earlier papers of this series carried the running title “Search for New Industrial Oils.” The revised title is more appropriate for the basic chemical compositional data reported, that can be useful in a broader context than originally implied. No. Utiliz. Res. Dev. Div., ARS, USDA. ARS, USDA.     

Oberflächenstrukturierung polymerer Fasern durch UV-Laserbestrahlung. 4. Der Einfluß äußerer Spannungsfelder

This paper reports the results of UV-laser-irradiations of elastomer fibres under application of varying external tensions on the fibres and under varying laser conditions. It is known that tension as well as temperature fields can lead to these synergetic effects that are supposed to cause the surface structuring by UV-laser-irradiation. Therefore the purpose of the reported experiments was to evaluate whether tension or temperature as the source of the system instabilities eventually lead to surface structuring.     

Über heteroorganische Verbindungen. IL. Zur Umsetzung von N-Morpholinoschwefelchlorid mit O-Alkyl-äthanthiophosphoniger Säure und O-Äthyl-äthan-dithiophosphonsäure

Heteroorganic Substances. IL. Reactions between N-morpholinosulfenylchloride and Ethane-alcoxy-thiophosphonous Acids and Ethane-ethyl-dithiophosphonic Acid The syntheses of bis-(ethane-alkoxy-thiophosphonyl)-monosulfides 3a – c and bis-ethane-ethoxy-thiophosphonyl)-trisulfide 5 are described. It is established, that the reaction path depends on the acidity of the starting compounds. In the first case (pK ∼ 7 the reactions between ethane-alkoxy-thiophosphonous acids and morpholinosulfenylchloride are three-step reactions, the intermediates being the unknown S-morpholino-ethane-alkoxy-dithiophosphonates 1a – c as well as the sulfenylchlorides of ethane-alkoxy-thiophosphonic acid 2a – c . In the second case (pK ∼ 3) a fourth reaction has to been taken into account. The intermediate sulfenamide derivatives are isolated and characterised. The sulfenylchlorides derivatives could not been isolated; their presence was indirectly demonstrated by chemical reactions.