Kontinuierliches Verfahren zur Anreicherung von mehrfach ungesättigten Fettsäuren

Continuous Process for the Concentration of Polyunsaturated Fatty Acids Polyunsaturated fatty acids of the n-6 and n-3 series are of great nutritional interest. For special studies and applications, these acids ae required in high concentrations. Several acids of these series are, however, only available in concentrations of up to 25% in vegetable or animal oils. In an evaluation of different fractionation techniques with blackcurrant seed oil as example, reasonable results were obtained with urea fractionation in methanol. Applying this method, a specific separation of α- and γ-linolenic acid could be achieved, whereas stearidonic acid (C18 :4,n-3) had to separated from γ-linolenic acid (c18 :3,n-6) by subsequent preparative HPLC. During scaling up of this batch process to the ton scale, difficulties became apparent, requiring an increased number of fractionation steps, probably deu to insufficient heat exchange and to incomplete formation of occlusion crystals. These inconveniences were eliminated by developing a continuous process using heat exchangers with a scraped surface as reactors for urea occlusion formation. This continuous technique was also applied to other oils, as e. g. fish oil, borage oil and evening primrose oil.     

Zur Hydrocarboxymethylierung von ungesättigten Fettsäureestern

On the Hydrocarboxymethylation of Unsaturated Fatty Acid Esters The hydrocarboxymethylation of technical oleic acid and eruca acid methyl ester was tested in the presence of the catalyst system cobalt/4-picoline. It was known for non terminal olefins that the formation of unbranched carboxylic acid derivatives is facilitated with the cobalt/picoline system. So up to 75% of the unbranched product is obtained during the hydrocarboxymethylation of μ-olefins. It was shown in the case of the unsaturated fatty acid methyl esters that here, too, by precise control of the reaction temperature, promoter/catalyst ratio and CO pressure the hydrocarboxymethylation can be carried out in such a way that up to 60% of the α, ω-dicarboxylic acid dimethyl esters are obtained.     

Fraktionierung mehrfach ungesättigter Fettsäuren aus verschiedenen natürlichen Rohstoffen

Fractionation of Polyunsaturated Fatty Acids from Various Natural Oil Sources Blackcurrant seed oil, borage oil and evening primrose oil are known to be sources of γ-linolenic acid (GLA) with values of up to 25% for borage oil. These GLA concentrations are sufficient for most of the applications of these oils as such but some particular utilisations require higher concentrations of up to 70% γ-linolenic acid or more. Different fractionation techniques have been evaluated. Distillation as well as fractionated crystallization at various temperatures did not give any reasonable results. Preparative high performance liquid chromatography gives only separations on reversed phase columns of the RP 18 type. However, specific enrichment in γ-linolenic acid is obtained by urea fractionation in methanol, also with blackcurrant seed oil which contains up to 14% α-linolenic acid. On a large scale basis of around ton scale it was possible to enrich blackcurrant seed oil fatty acids to 70-80% γ-linolenic acid in a preferably 2-stage fractionation process.     

Produkte der Dimerisierung ungesättigter Fettsäuren VI: Untersuchungen zur Kinetik der Bildung dimerer Fettsäuren

Products of Dimerisation of Unsaturated Fatty Acids VI: Kinetic Studies about the Formation of Dimeric Fatty Acids During the dimerisation reaction of a mixture of 60% oleic acid and 40% linoleic acid samples were collected in time intervals. The samples were converted into their dimethylates by diazomethane and separated by thin layer chromatography in one fraction of monomers and one of dimers. The monomeric fractions were further separated by GC, the dimeric fractions by HPLC. First linoleic acid reacts, either by cyclisation or by attacking another molecule of linoleic acid. Thus linoleic acid has already disappeared nearly completely at the end of the heating up period (after 60 min). The less linoleic acid is present, the more molecules of linoleic acid react with oleic acid molecules. The primary cyclic dimerisation products are slowly converted to aromatic compounds as well as cyclohexane derivatives. The oleic acid is transformed already in the heating up period into its isomer, elaidic acid and isomers thereof with double bonds in other positions of the chain. These products are converted slowly partly to stearic acid, partly to isostearic acids. Dimeric compounds of MW 592 (methylates) are produced as well by reaction of 2 molecules of oleic acid. They are slowly converted to open chain dimeric acids of MW 594 (methylates).     

Verfahren und Anlagen zur Fraktionierung von synthetischen Fettsäuren

Processes and Plants for the Fractionation of Synthetic Fatty Acids Synthetic fatty acids, prepared by oxidation of paraffins, can be used to save valuable edible fats. Fractional distillation of these fatty acids enable their manifold application. For this, the paraffins have to fulfil certain criteria of quality. In a multiple stage vacuum fractionation process provided with material balance regulator, high boiling complex mixtures can be processed to distillates of high purity. Such a multi-column plant is equipped with stills, fractional columns and rectifying columns, and the plant is controlled by feeding machines. Many years of experience and production data have shown that synthetic fatty acid distillates can be produced economically and these products meet the technical requirements of soap and detergent industry.     

Die katalytische Metathese von ungesättigten Fettsäureestern

Catalytic Metathesis of Esters of Unsaturated Fatty Acids Several active and selective catalysts have been developed for the metathesis of unsaturated hydrocarbons in homogeneous medium. These are based on WCl₆ and MoCl₅ with Sn(CH₃)₄, Sn(C₆H₅)₄ and Pb(C₆H₆)₄ as the most important co-catalysts. These catalyst systems also permit the metathesis of compounds having functional groups, such as esters of fatty acids and halogenated hydrocarbons. The metathesis of esters of fatty acids enables the synthesis of numerous compounds, which so far were either unknown or difficult to synthesize. Such compounds are, for instance, certain long chain unsaturated dicarboxylic acids which are derived from monoenoic fatty acids, such as oleic acid and erucic acid. From technological viewpoint the unsaturated dicarboxylic acids might be significant as raw material for the preparation of unsaturated polyesters and polyamides, as well as for the synthesis of certain flavoring agents. The metathesis of fatty oils (glycerides) leads to the formation of high molecular weight compounds. The metathesis of semi-drying and drying oils offers the possibility to prepare stand oils having good drying properties.     

Der Einfluß der Chloroplasten auf die Bildung von ungesättigten Fettsäuren in reifenden Rapssamen

Influence of Chloroplasts on the Formation of Unsaturated Fatty Acids in Maturing Rapeseeds In general, seeds that store fats, contain only C₁₈-fatty acids which are desaturated upto linoleic step. Exceptions to this general pattern are the seeds of cruciferae, legumenae and linaceae. Embryos of these seeds develop, especially during the initial stages of maturation, photosynthetically active chloroplasts with a high content of linolenic acid. Therefore, for the breeding of rapeseed plants (cruciferae) having low linolenic acid content in the seed oil, one has to select either such seeds in which very little chloroplasts are formed during maturation, or seeds in which chloroplasts are reduced at an early stage.     

Produkte der Dimerisierung ungesättigter Fettsäuren V: Die Aromatenfraktion dimerer Fettsäuren

Products of Dimerisation of Unsaturated Fatty Acids V: The Aromatic Fraction of Dimeric Acids The aromatic fraction of dimeric fatty acid esters can be separated according to a decreasing grade of unsaturation by HPLC using an UV-recorder. Hydrogenation experiments of the collected fractions allowed the determination of the number of rings. If the aromatic fraction are oxidized with KMnO₄ using a phase-transfer catalyst benzene 1,2,4- and 1,3,5-tri-, 1,2,4,5-and 1,2,3,5-tetra- and the pentacarboxylic acid were obtained as main products. Consequently we have to conclude that the catalyst causes intramolecular extensive migration of alkyl chains. Finally 2,3-dihydrobenzofurantetracarboxylic acids with different position of the carboxylic groups were detected in the mixture of oxidation products.     

Herstellung modifizierter Carbonsäuren aus α-Olefinen durch Hydroxycarbonylierung

Preparation of Modified Carboxylic Acids from α-Olefins by Hydroxycarbonylation The hydroxycarbonylation of α-olefins to carboxylic acids was investigated. Yields around 95% were achieved using NiJ₂ as catalyst at temperatures of ca. 200°C and carbon monoxide pressure of 30 atm. and higher for 3–7 hrs. The acids are composed mainly of isomers having 2-methyl branching as well as the normal ones and the 2-ethyl acids. Ca. 95% of the NiJ₂ is recovered from the reaction product by washing with water.     

Wiederveresterung von Konzentraten mehrfach ungesättigter Fettsäuren

Reesterification of Polyunsaturated Fatty Acid Concentrates Fatty acids of the n-6 series such as γ-linolenic acid (C18:3) and of the n-3 series such as α-linolenic (C18:3), stearidonic (C18:4), eicosapentaenoic (C20:5) and docosahexaenoic acid (C22:6) are of great nutritional interest. These acids can be obtained by urea fractionation in concentrated form from natural sources like blackcurrant seed oil, borage oil, evening primrose oil, linseed oil and fish oil, respectively. Certain dietary applications require a reesterification of these fatty acid concentrates with glycerol to triglycerides. Industrial scale methods of reesterification could not be applied as such for the present polyunsaturated fatty acid systems. Therefore reaction conditions had to be adapted to these highly sensitive substances. A one step reesterification method, using ZnCl₂ as catalyst, was optimized for three different fatty acid concentrates composed of the above mentioned acids. Under the given reaction conditions, it could be observed that α-linolenic acid is much more sensitive to polymerization than γ-linolenic acid. Different purification methods of the crude triglycerides have been evaluated, obtaining best results by liquid chromatography methods, in particular with respect to decoloration of the final products.     

Herstellung von Alkylenglykomonoestern durch Alkoxylierung von Carbonsäuren

Preparation of Alkyleneglycol Monoesters by Alkoxylation of Carboxylic Acids A new process of alkoxylation using amines as catalysts is reported for the preparation of alkyleneglycol monoesters of aliphatic carboxylic acids. Prim., sec. and tert. amines act as highly selective catalysts at about 80°C. The monoester contents amount to 85–100%. The formation of diester and polyglycol is almost completely suppressed.     

Cis-trans-Isomerisierung ungesättigter Fettsäuren im Laufe der Alkydharz-Herstellung

Cis-trans Isomerisation of Unsaturated Fatty Acids during the Preparation of Alkyds We studied the influence of the preparation conditions of alkyd resins with the help of infrared spectroscopy of soya and linseed oil on the cis-trans-isomerisation of the unsaturated fatty acids present. The most important of all conditions was the temperature. The higher content of trans-isomers can be seen in the properties of alkyd resins.     

Mischpolymer-Latices aus Vinylacetat-Vinylestern von aus Tetrapropylen Hergestellten Carbonsäuren

Copolymer Latices Based on Vinyl Acetate and Vinyl Esters of Carboxylic Acids Derived from Propylene Tetramer Vinyl esters of carboxylic acids prepared from propylene tetramer were obtained by interesterification with vinyl acetate and the parameters for the copolymerization with vinyl acetate were determined. The properties of latices and coating films were evaluated with reference to the composition of the copolymer. Compared to other types of latices, coating films based on the above copolymers exhibit good properties. Especially, the resistance towards diluted alkali is excellent.     

Gaschromatographische und dünnschichtchromatographische Untersuchung von Fettsäuren: Die Anwendung von gepackten Glaskapillarsäulen zur Trennung von cis- und trans-ungesättigten Fettsäuren

Gas Chromatographic and Thin-Layer Chromatographic Studies on Fatty Acids: The Application of Packed Glass Capillary Columns for Separation of cis- and trans-Unsaturated Fatty Acids from Saturated Fatty Acids Packed glass capillary columns were used for the quantitative determination of trans- and cis-unsaturated fatty acids in the presence of saturated fatty acids by gas chromatography. The fatty acids were analyzed as methyl esters after interesterification of the triglyceride samples. The conversion of glyceryl esters of fatty acids into methyl esters could be followed using short GC columns and by thin-layer chromatography.     

Über die Reduktion ungesättigter Fettsäuren und deren Ester zu ungesättigten Fettalkoholen durch selektive katalytische Hochdruckhydrierung III: Metallische und metallisch-oxidische Kupfer-Cadmium-Kontakte

Reduction of Unsaturated Fatty Acids and Their Esters to Unsaturated Fatty Alcohols by Selective Catalytic High Pressure Hydrogenation III: Metallic and Metal Oxide Copper-Chromium Catalysts Influence of catalyst composition and reaction conditions on the high pressure reduction of unsaturated fatty acids and their esters is described for metallic and mixed metal oxide copper-chromium catalysts. From these investigations and from a comparison with the efficacy of other metals in hydrogenation a hypothesis on the mechanism of the catalytic reaction in the reduction of carboxyl group and saturation of C? C double bonds is developed. The optimum reaction data of oleic acid and methyl oleate, which were used as test substances, are given.     

Neues schonend wirkendes und energiesparendes Verfahrensprinzip zur Geradeausdestillation von überwiegend ungesättigten vegetabilischen Rohsäuren

New Mild Acting and Energy Saving Process for Straight-Run Distillation of Mainly Unsaturated Vegetable Raw Acids A remarkably gentle and newly-developed process for effective first running- and pitch separation especially suitable for the reconditioning of highly unsaturated raw acids as those derived from soybean-, cottonseed-, sunflower- and linseed oil is being discussed. The process is characterized by effective degasification at low temperatures, efficient dehydration with first running separation and high reflux ratio and extremely low evaporation temperatures for the main- and pitch stage of < 220°C or <230°C respectively by maintaining low consumption rates. The first-quality main run fatty acid yield of one flow for a splitting degree of 95 %regarding the free fatty acid content in the raw acid will amount to > 97.5%. The waste water quantity arising per hour and per to of distillate amounts to < 100 1 and only contains < 40 ppm organic substance to be decomposed.     

Produkte der Dimerisierung ungesättigter Fettsäuren IX: Kinetische Untersuchungen zur Dimerisierung von Linolsäure

Products of the Dimerisation of Unsaturated Fatty Acids IX: Kinetic Studies about the Dimerisation of Linoleic Acid To clarify the dimerisation process of linoleic acid, we investigated samples taken in different time intervals. The first reaction step is a water addition at double bonds of the starting material and not double bond isomerisation as previously assumed. The resulting unsaturated monohydroxy fatty acids can cyclize with the second double bond in an intramolecular reaction forming 2,5-disubstituted tetrahydrofuran respectively 2,6-disubstituted tetrahydropyran derivates. Linolenic acid, present nearly always in small amounts in linoleic acid, reacts to first dimerisation products with linoleic acid by formation of a C-C-bond. The aliphatic dimers cyclize in an intramolecular reaction to mono-cyclic compounds. No dimeric acids, which would result from a Diels-Alder-reaction, could be identified. Bicyclic and aromatic dimeric acids can also be found in the early phase of the dimerisation. In the further progress of the reaction isomerisations, hydrogenations and dehydrogenations of the primary reaction products occur, thus the content of aromatic substances increases steadily.     

Herstellung verzweigter Fettsäuren durch katalytische Oxidation von Alkoholen

Synthesis of Branched Fatty Acids by Catalytic Oxidation of Alcohols Transition metals fixed on solid supports are able to catalyze the oxidation of branched alcohols with air yielding branched fatty acids. As typical example 2-hexyldecanol was chosen which is well available via the guerbet reaction. Catalyst screening and reaction optimization will be described. Highest activities were obtained with palladium-, platinum- and ruthenium-catalysts. 2-hexyldecanoic acid (“isopalmitic acid”) was synthesized in yields of 65%; important by-products are wax esters and 7-pentadecanone.