Über die katalysierte Flüssigphasenoxidation von cis- und trans-Oct-4-en

The Catalyzed Liquid-Phase Oxidation of cis- and trans-Oct-4-ene The influences of MoO₂(acac)₂

1 acac-Acetylacetonat.

, MoO ₃ and Co(acac) ₃ on the liquid-phase oxidation of cis- and trans-oct-4-ene at 110°C were studied. In the presence of molybdenum catalysts the yield of epoxides and the stereoselectivity of epoxide formation are increased. The results are in good agreement with the hypothesis that molybdenum compounds effect only the stereospecific reaction of the hydroperoxides formed with the starting olefin yielding the corresponding epoxide. The cobaltic complex increases the rate of autoxidation, but has no remarkable influence on the yield of epoxides. In the presence of Co(acac)₃ more trans-epoxide is formed from cis-oct-4-ene than in the uncatalyzed reaction. This can be explained by an increase of the lifetime of the intermediate peroxyalkyl radical, effected by complex formation of the radical with a cobalt species.     

Über den Druckeinfluß auf die Katalysierte Flüssigphasenoxidation von cis- und trans-Oct-4-en

About the Influence of Pressure on the Catalyzed Liquid-Phase Oxidation of cis- and trans-Oct-4-ene The investigation of the influence of pressure on the liquid-phase oxidation of cis- and trans-oct-4-ene shows that the reaction rate increases up to 491 kPa in the non-catalyzed oxidation reaction, but up to 981 kPa in the MoO₂(acac)₂-catalyzed reaction n-oct-1-ene reacts more slowly than cis- and trans-oct-4-ene as well in the pressure-less reaction as in the oxidation under pressure. In the non-catalyzed oxidation reaction the cis/trans- ratios don't depend on the pressure, but in the MoO₂(acac)₂-catalyzed oxidation reaction the cis/trans-epoxide ratios increase with increasing pressure. The optimum of the reaction temperature lies between 110 and 130°C.     

Über die bevorzugte Bildung von trans-Epoxiden bei der Technetiumkatalysierten Flüssigphasenoxidation von cis/trans-n-Alkenen

About the Formation of trans-Epoxides in the Liquid Phase Oxidation of cis/trans-n-Alkenes Catalyzed by Technetium The liquid-phase oxidation of n-oct-1-ene, cis-oct-4-ene and cis/trans mixtures of oct-4-ene with molecular oxygen in the presence of the technetium complexes 1 to 10 was studied. Low epoxide yields (≦10%) are characteristic features of the reactions. Pure cis-oct-4-ene and mixtures of cis/trans-oct-4-ene yields in cis/trans-epoxide ratios lower than 0.05. Isomerization reactions and nucleophilic epoxide ring opening reactions are not responsible for the low epoxide yield and the favoured formation of trans-epoxide. Epoxide decomposition by a Tc-catalyzed radical reaction which prefers the cis-epoxide is discussed.     

Flüssigphasenoxidation von 1,3-Dioxolanen

Liquid Phase Oxidation of 1,3-Dioxolanes The oxidation rate and the kind of oxidation products in the oxidation reactions of the 1,3-dioxolanes ( 1a to 1f ) with molecular oxygen in liquid phase were investigated. The 2-methyl-substituted 1,3-dioxolane ( 1b ) has a lower, the 4-methyl-substituted 1,3-dioxolane ( 1d ) has a higher oxidation rate than the non-substituted 1,3-dioxolane ( 1a ). The 2,2-disubstituted 1,3-dioxolanes show no oxidation but a hydrolytic reaction. The main-products of the liquid-phase oxidation of the 1,3-dioxolanes 1a , 1b , 1d and 1e are the glycol-carbonic acid-monoesters 8 and the 2-oxo-1,3-dioxolanes 6 . Their formation is proved by gaschromatography, GC/MS-coupling, DC and ¹³C-n.m.r.-spectroscopy.     

Flüssigphasenoxidation von Ethan-1,2-diol

Liquid-phase Oxidation of 1,2-Ethane Diol The oxidation rate and the kind of oxidation products in the reaction of 1,2-ethane diol ( 1 ) with molecular oxygen in liquid phase at 150°C were investigated. 1 has a very low oxidation rate. Cu-, Zn-, Fe-, Co- and Al-acetylacetonates as catalysts increase the reaction rate. The main-products of the investigated reaction are the 1,3-dioxolan ( 2 ), the 2-methyl-1,3-dioxolan ( 3 ) and the 2-methylol-1,3-dioxolan ( 4 ). The formation of formic and acetic acids and of the 1,3-dioxolanes is proved by GC, DC and HPLC.     

Über die Standzeit thermoplastischer Polymerer

The effect of different machanical strains on polyethylene, polypropylene, polyvinylchloride and polyxymethylen was studied. Similar type long-time properties of thermoplastic polymers were found in a wide interval of strains. The long-time characteristic of each thermoplastic material could be given in semi-logarithmic coordinates In τ vs. σ, by a family of S-type curves, typical for a given temperature. Strain exhibits a clear maximum corresponding to the formation of a neck which is observed only in a narrow interval of stress. The mechanical and chemical degradation occuring under constant mechanical stress is considered. The effect of the chemical and light-stabilizers on the mechanical degradation was studied. It is shown that the long-time stability of the polymers could be extended considerably by applying structure modifying agents.     

Über die Kinetik der Fettkristallisation

Kinetics of Fat Crystallization The course of fat crystallization is similar to that of aggregation and flocculation of colloids. Rate formulae for aggregation and flocculation, previously derived empirically from experimental data, are applied to data on the crystallization of fats and for comparison on the separation of emulsions. The data are linearized. The rate constants are determined as functions of the solid fat index.     

Über die Zusammensetzung des Retamowachses

Composition of Retamo Wax The chief components of retamo wax like acids, alcohols and hydrocarbons are qualitatively and quantitatively compared with the corresponding amounts of known natural waxes. To this purpose several retamo wax samples were each separated into the mentioned chief components by means of ion exchange processes, selective extractions and column chromatography. The chain length distribution of the mentioned fractions were determined by gaschromatography.     

Über die morphologie von emulsions-PVC

Some aspects of the morphology of emulsion-type PVC are described, particularly: appearance, surface character and size distribution of grain of selected industrial types of PVC. The morphological investigations are related to plastisole viscosity.     

Über die Auswahl von Polymerisationsreaktoren

Choice of polymerization reactors . Industrial syntheses of polymers always yield a highly complex product whose adequate characterization often requires application-oriented tests in addition to chemical and physical parameters. In contrast to the synthesis of low-molecular mass substances subsequent corrections, e. g. by distillation or crystallization, are usually impossible. Extremely detailed reaction control is of paramount importance. Polyreactions can be classified according to kinetic aspects (monomer linkage with and without termination reaction, linkage of polymers). Apart from homogeneous bulk polymerization, there are the heterogeneous processes of precipitation-, bead-, and emulsion-polymerization. The polymerization reactors can be assigned to the known ideal types (batch reactor, continuous plug flow reactor, series of stirred tanks, and continuous stirred tank reactor). High viscosity often thwarts thorough mixing in bulk polymerization and segregation may occur. The article surveys the variants of the reactor types used for various polyreactions and polymerization processes in industry and examines the reasons for this choice. Most commonly used is the batch reactor, followed by the cascade of stirred tanks. Continuous polymer-linkage (polycondensation, polyaddition) is frequently performed in a series of several different kinds of reactors.     

Über die Lipasen und die Lipolyse der Milch

Lipases and Lipolysis of Milk After a review of the latest literature in this field, the lipase-activity of the Finnish milk is dealt with. Extensive work was carried out on the isolation of lipases from milk, whose lipase-activities were known. Preliminary results have been obtained on the concentration and identification of the lipases. With partly purified lipase fractions, hydrolysis was observed in which different proportions of short and long chain fatty acids were liberated under varying conditions. These observations are of interest from the viewpoint of a possible use of lipases in the food technology.     

Über die Auswirkungen von Tensiden auf die Mundschleimhaut

Action of Surfactants on the Mucous Membrane of the Mouth Besides suitable brush and cleaning agents, a definite time is also required for the removal of mucoproteids, that are held rather rigidly on the tooth surface, thus forming matrix for tartar and pigment deposits. Mostly, a layman does not devote this amount of time for dental care. A proper dental care is one of the most important prophylactic measures against caries and paradentopathies. Extensive cytological investigations carried out for several years have shown that certain surfactants at concentrations below 2%, preferably between 1.2 and 1.5%, facilitate the cleansing without impairing the mucous membrane of the mouth.     

Über die Kristallstruktur der Kakaobutter

Crystalline Structure of Cocoa Butter Six crystalline modifications of cocoa butter are known from the literature of which only the pre-beta and the beta forms are important for the technology of chocolate manufacture. The elucidation of the crystalline structure of these two modifications is difficult because single crystals of appreciable size can not be obtained from cocoa butter. It is shown that it is possible to analyse the structure with the help of X-ray diffraction studies of micro-crystals as well as by comparison with structures of known mono-acid triglycerides. The lattice parameters and the arrangement of molecules in pre-beta and beta forms are given.