Photoabbau von PVC-Folien. III. Einfluß von Wärmestabilisatoren

PVC-films containing variable concentrations of thermal stabilizer (dioctyltin bis-(iso-octylthioglycolate)) have been irradiated by a high-pressure mercury lamp under air and nitrogen. The dehydrochlorination and discoloration have been recorded. The main function of the stabilizer is the suppression of absorptions in the visible region. There are indications of a participation of the stabilizer in the photoreaction.     

Photoabbau von PVC-folien. I. Einfluß von bestrahlungsstärke und temperature

Films from mass-PVC have been irradiated by a high pressure mercury lamp under nitrogen. The influence of variable light intensity and temperature of the sample on the dehydrochlorination reaction and changes in the absorption spectrum of the polymer were investigated.     

Photochemische Primärprozesse von Xanthenfarbstoffen. III. Blitzlichtspektroskopische Untersuchungen zum Einfluß von kationischen Mizellen auf die Photoredoxprozesse von Selenopyronin

Photochemical Primary Processes of Xanthene Dyes. III. Investigations of the Influence of Cationic Micelles on the Photoredox Processes of Selenopyronine by Flash Excitation Cationic micelles have no influence on the decay of the triplet state of selenopyronine (³F⁺). The products of photoredox reactions ³F⁺ + ³F⁺ (F⁺) → F^· + F and ³F⁺ + DABCO → F^· + DABCO live longer in the presence of the cationic micelles. The reason for the change of the lifetime is a separation of the photoredox products by micelles. F^. is stored in the interior of the micelles. The positively charged F and DABCO are repelled from the micelles and the electron back transfer is hindered.     

Photochemische Primärprozesse von Xanthenfarbstoffen. II. Blitzlichtspektroskopische Untersuchungen zum Einfluß von anionischen Mizellen auf die photochemischen Primärprozesse von Selenopyronin

Photochemical Primary Processes of Xanthene Dyes. II. Investigations of the Influence of Anionic Micelles on the Primary Processes of Selenopyronine by Flash Excitation In aqueous solutions containing anionic micelles, the dye cations of selenopyronine are present at the micellar surface. If the concentration of the dye ions is much lower than the concentration of micelles, only monomolecular triplet decay (k₁^aM = 2 · 10⁻³s⁻¹) is observed. Under these conditions, the half-oxidized and half-reduced form of selenopyronin is not formed. If the concentration of the dye ions is much higher than the concentration of micelles, two or more dye ions are present at every micelle, and a fast bimolecular decay of the triplet state during the flash is observed. The quenching of the triplet state with p-benzoquinone (k₇^aM = 1,9 · 10⁹ l/mol s), DABCO (k₁₀^aM = 1,6 · 10⁷ l/mol s) and EDTA (k₁₁^aM = 1,3 · 10⁵ l/mol s) and the decay processes of the half-reduced and half-oxidized form in the micellar solution are investigated.     

Synthese von Heterocyclen durch C-C-Knüpfung. II. Katalytische Cyclisierung von N-Alkyl-N-allyl-acrylamiden und N.N-Diallyl-carbonsäureamiden

Synthesis of Heterocycles by C C-Bond Formation. II. Catalytic Cyclization of N-Alkyl-N-allyl-acrylamides and N,N-Diallyl Carbonic Acid Amides N-Alkyl-N-allyl-acrylamides 2 cyclize in the presence of PdCl₂ to 1-alkyl-3,4-dimethyl-3-pyrrolin-2-ones 4 and 1-alkyl-4-methyl-3-methylene-pyrrolidin-2-ones 5 . Compounds 4 predominate in the mixture. With RhCl₃, ring closure gives comparable amounts of lactams 4 and 7 (1-alkyl-3,4-dimethyl-3-pyrrolin-2-ones) besides some product of allyl elimination. N. N-Diallyl carboxylic amides 3 form cyclic enamides (1-acyl-3,4-dimethyl-2-pyrrolines, 9 ) on the action of PdCl₂ besides the products 10 of allyl elimination. RhCl₃ effects cyclization of 3 to form 1-acyl-3-methyl-4-methylene-pyrrolidines 11 besides some 9 . The acid amide groups of compounds 9 and 11 are shown by n.m.r. spectroscopy to exist as rotamers.     

Photochemische Primärprozesse von Xanthenfarbstoffen. I. Blitzlichtspektroskopische Untersuchung der Primärprozesse von Selenopyronin

Photochemical Primary Processes of Xanthene Dyes. I. Investigations of the Primary Processes of Selenopyronine by Flash Excitation The triplet-state of selenopyronine absorbs light in the whole investigated spectral range (λ_max = 400 nm, 480 nm, 690 nm). As results of the bimolecular triplet decay a half-reduced (λ_max = 430 nm) and a half-oxidized (λ_max = 475 nm) form of the dye are observed. p-Benzoquinone quenches the triplet-state (k₇ = 1,5 · 10⁹ l/mol s) and the results are the half-oxidized form and the p-benzosemiquinone ion. For these two products different decay processes exist. The reducing agents DABCO, EDTA and Hydroquinone also quench the triplet state (k₁₀ = 1,2 · 10⁶ l/mol s, k₁₁ = 1,0 · 10⁶ l/mol s, k₁₂ = 1,0 · 10⁹ l/mol s) and as result the half-reduced form is observed. Measurements with thiopyronine give analogous results, which are in good agreement with investigations published in the literature.     

Photooxidation von Leukofarbstoffen. XII. Kurzzeitspektroskopische Untersuchungen zur Photooxidation von Bis-schwefelsäuremonoestern der Leukoformen von Thioindigoverbindungen

Photooxidation of Leuco Dyes. XII. Time Resolved Investigations on the Photooxidation of Bis-sulfuric Acid Monoesters of Leucothioindigoid Compounds The photooxidation of 4, 4′-dimethyl-6, 6′-dichlorothioindigosol ( 1 ) was studied by means of laser and conventional flash photolysis. Three transients were detected and assigned to a radical R generated by homolytic splitting of one O S-bond of the parent compound and to two further radicals which are formed from R by hydrolytic cleavage of the second ester group. The latter two radicals are in a protolytic equilibrium with each other and react, depending on the nature of the solvent by H-atom abstraction, or by disproportionation forming the leuco-thioindigoid dye or both dye and leuco dye. A mechanistic scheme is proposed.     

Untersuchungen zur Sulfochlorierung von Paraffinen. IV. Über die Sulfochlorierung von Isobutan

Studies on Sulphochlorination of Paraffins. IV. On the Sulphochlorination of Isobutane In the sulphochlorination of isobutane at −20 to −10°C a mixture of 20–25% tert.-butyl and 75–80% of isobutyl sulphochlorides is formed. The mixture has been analyzed by ¹H- and by ¹³C-n.m.r.-spectroscopy. It is possible to transform the mixture of sulphochlorides into mixtures of the corresponding sulphonates, sulphonic acid methyl esters or sulphonic acid demithylamides. During the work-up of the sulphochlorination mixtures it is necessary to keep the temperature low, because tertiary butyl sulphochloride is desulphonated at a noticeable rate already at temperatures above 35°C.     

Optische Methoden zur Charakterisierung von hochpolymeren Fasern. 2. Kennzeichnung von Oberflächen durch Specklemeßmethoden.

The surface roughness of textile materials is of great influence on textile processing and practical applications. Speckle-techniques are common for integral, contactless, and non-destructive characterization of metallic surfaces. The scope of this work was to apply the analysis of the contrast of the speckle patterns and the dichromatic speckle correlation to measurements of the roughness of polymer surfaces. For this purpose it was of importance to study the influence of the optical properties of the polymer samples on the characteristics of the speckle field. Methods for measurements on filaments, yarns, and fabrics are discussed.     

Massenspektroskopie von Naturstoffen. I. Vergleichende Anionen-Kationen-Massenspektroskopie von 2,3,4,6-Tetra-O-acetyl-β-D-glucopyranosylestern

Mass Spectroscopy of Natural Compounds. I. Comparative Investigation of Anion-Cation Mass Spectra of 2,3,4,6-Tetra-O-acetyl-β-D-glucopyranosyl Esters The electron attachment mass spectra (anion mass spectra) of 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl esters with different structures of the acids are discussed and compared with the corresponding electron impact spectra. In contrast to the cation mass spectra the molecular ion peak appears in all the anion mass spectra.