Der Reaktionsverlauf bei der Hydrierung von Triglyceriden Glykolester als Modellsubstrat

Course of Reaction During Hydrogenation of Triglycerides —Glycolates as Model Substratum A mixture of diundecenoicacidglycolate and octanoicauidundecenoicacidglycolate was hydrogenated with various catalysts and in different extent. The reaction products were analysed by gaschromatography. Basing on the results two parameters could be calculated which determine the distribution of unsaturated fatty acids over the molecules of a hydrogenated triglyceride according to an earlier laid down theory ^{1, 2}. The parameters had characteristic values for each catalyst and therefore the process seems to give valuable informations about the properties of different catalysts. Hydrogenations of undecenoicacid triglyceride could be described by parameters found on the glycolates. On the other hand hydrogenation results found earlier with linolenic acid containing triglycerides did not correspond to the calculated values.     

Aspekte bei der Hydrierung von Fetten und Fettsäuren

Aspects of Hydrogenation of Fats and Fatty Acids Hydrogenation of fat products is of great significance, both for human and animal nutrition as well as for technical purposes. In the area of nutrition, adequate food for the increasing world population is unthinkable without utilization of all fat resources, that can be made available as food fats only after catalytic hydrogenation. In the area of technical use, a similar development is observed owing to shortage of mineral oils. Thus, fatty alcohols derived from vegetable oils and waxes can already compete in price with fully synthetic fatty alcohols derived from mineral oils. In the past 70 years of hydrogenation of fats till the present time, catalysts based on nickel have been most commonly used. In addition, small proportions of catalysts based on copper and noble metals have also been used. Homogenous catalysts have been used very recently. The present communication deals primarily with the hydrogenation of neutral fats and fatty acids using nickel catalysts. The aspects of selectivity and isomerization in the partial hydrogenation of neutral fats are discussed. In the hydrogenation of fatty acids and their derivatives, emphasis is laid on other factors, such as activity, poisoning and acid resistance of the catalyst. These factors are discussed.     

Zur Gleichgewichtseinstellung bei der Glycerinolyse von Triglyceriden I

Attainment of Equilibrium in the Glycerolysis of Triglycerides The quantitative determination of the amounts of glycerine, mono-, di- and triglycerides which are formed during the glycerolysis of triglycerides was carried out with the help of column, thin-layer and gas chromatography in order to study the formation of these substances as a function of the temperature, molar composition of the starting materials - glycerine and triglycerides - as well as the chain length of the fatty acid components. Setting in of a equilibrium between 1- and 2-monoglycerides as well as between 1,2- and 1,3-diglycerides was also determined quantitatively. The authors came to the conclusion that the reactivity of the primary OH-groups between each other is not the same and the equilibrium constant K does not permit the calculation of particular equilibria like 1- and 2-monoglyceride or 1,2- and 1,3-diglyceride.     

Erfahrungen bei der Hydrierung von einigen Ölen und Fetten mit einem Kupferkatalysator

Experiences on the Hydrogenation of Fats with a Copper Catalyst Soybean oil, rapeseed oil and lard were hydrogenated using a copper catalyst. The products of hydrogenation were refined after the removal of copper following a new technique. The aforesaid oils were also hydrogenated with a nickel catalyst to the same iodine value and then refined. The products of hydrogenation using copper showed a better stability towards oxidation than those obtained with nickel.     

Untersuchungen zur kontinuierlichen Hydrierung von Ölen und Fettsäuren V: Grad der Ausnutzung der Ni-Katalysatoroberfläche bei der Hydrierung

Investigations of Continuous Hydrogenation of Oils and Fatty Acids V: Degree of Utilization of Ni-Catalyst Surface During Hydrogenation Hydrogenation of olive oil by Ni-catalyst according to the trickling process was investigated in a simplified reactor model. The tests were carried out by discontinuous proceeding on pelletted Ni-catalyst with elimination of the influences of the outer diffusion and by discontinuous proceeding with elimination of the outer and internal diffusion (powdery catalyst). The obtained values of the effective factor of the outer diffusion showed that the laminar film on the surface of the pellets causes a small resistance to mass transfer. The measurements of the effective factors of the internal diffusion showed that the degree of the exploit of the internal catalyst surface during hydrogenation of oils on pelletted Ni-catalyst is low.     

Umesterung und Hydrierung der Schlachttierfette

Interesterification and Hydrogenation of Animal Fats. Directed and indirected interesterification of fats alters the distribution of fatty acids in triglycerides and thus changes the physical properties, such as melting behaviour, crystallization and plasticity. Slight refining (hydro-refining) improves the stability of fats. Industrial processes and their possible applications, either individually or in combination, for the modification of animal fats (lard and beef tallow) are reviewed. These processes enable better utilization of animal fats.     

Vergleich der Verteilungskurven der Katalysatorkorngrößen bei der Hydrierung von Fetten

Comparison of the Distribution Curves of the Particle Sizes of Catalysts in the Hydrogenation of Fats In the present paper the particle sizes of 14 hydrogenation catalysts and 2 kinds of commercial kieselguhr were studied using a laser analyzer. Assuming a log-normal distribution the distribution curves for the particle sizes were treated by the least-squares method. From the μ and σ parameters obtained the different characteristics of the catalysts were discussed.     

Der kinetische isotopieeffekt bei der elektrochemischen oxidation von alkoholen

A comparison of the oxidation rates of alcohols and deutero-alcohols at gold electrodes in alkaline electrolytes show that the splitting of the α-carbon bonded hydrogen is the rate determining step.     

Der einfluß der luftfeuchte bei der verfärbung von PVC während der bewitterung und bei der anschließenden dunkellagerung

The influence of humidity on the light-fastness and the dark time yellowing of white PVC and special changes of the irradiated surfaces are described. The results show, that the boundary surface climate at the irradiated specimen surfaces has a decisive influence on the ageing results.     

Elementarprozesse bei der Herstellung und Stabilisierung von Emulsionen

Elementary processes in the production and stabilization of emulsions. When developing new emulsifying agents with a specially low environmental impact, when using emulsifying agents in various branches of industry, and when breaking down emulsions (a very frequent requirement), an understanding of the elementary processes which take place is of great help. The paper provides a comprehensive account of the various elementary processes involved in the production and stabilization of emulsions otherwise scattered throughout the literature. The interplay of the individual elementary processes shows how emulsifying agents and stabilizers differ in their modes of operation. In discussing the structures which occur in aqueous tenside systems, it is pointed out that the swelling of micelles is an elementary process responsible for solubilization and cream formation.     

HPLC-Trennung von Triglyceriden

HPLC Separation of Triglycerides The high performance liquid chromatography on reversed phases represents an effective method for qualitative separation of triglycerides. First the chromatographic system was optimized by investigations concerning the influence of the column material, of the eluent and the temperature on qualitative separation of complex triglyceride mixtures. Then conditions of quantitative analysis could be established. On the one hand model mixtures of known composition were used, and on the other hand triglycerides, isolated from vegetable oils by column chromatography, whose composition was calculated by analysis of fatty acids and lipase hydrolysis. The results, obtained by high performance liquid chromatography, provide more detailed knowledge about the triglyceride composition of fats and oils than gaschromatography.