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.     

Über die Reduktion ungesättigter Fettsäuren und deren Ester zu ungesättigten Fettalkoholen durch selektive katalytische Hochdruckhydrierung V: Die katalytische Wirkung von Mischoxiden und reinen Oxiden

Reduction of Unsaturated Fatty Acids and Their Esters to Fatty Alcohols by Selective High-Pressure Catalytic Hydrogenation V: Catalytic Action of Mixed and Pure Oxides The catalytic action of mixed oxides and pure metal oxides such as zinc-chromium oxide, zinc-iron oxide, magnesium-iron oxide and zinc oxide, chromium oxide, titanium dioxide and zirconium dioxide in the high-pressure hydrogenation is described. Substances taken for testing were methyl oleate, butyl oleate, oleic acid, methyl undecenoate and methyl linolate. Optimum combinations of catalysts and the corresponding reaction conditions are reported for oxidic catalysts. The previously postulated hypothesis on the catalytic action in the selective hydrogenation is supported by considering the semiconductor properties of the metallic oxides.     

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.     

Untersuchungen über die Entstehung von Kohlenwasserstoffen in erhitzten gesättigten Fettsäuren und Fettsäureestern

Studies on the Formation of Hydrocarbons in Fatty Acids and Fatty Acid Esters on Heating The investigations on the volatile compounds of the unsaponifiable matter and the steam distillate of heated saturated fatty acids have shown that on heating in the presence of air, along with other substances, hydrocarbons having a chain length 1 to 2 C atoms shorter than the corresponding fatty acids are formed. The splitting proceeds so slowly in the case of esters that even after 4 hrs of heating at 160°C no reaction products could be detected. By heating palmitic acid under the same conditions, except that vacuum was employed, no perceptible quantities of hydrocarbons were found.     

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.     

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.     

Zur Autoxydation ungesättigter Fettsäure-Ester in Gegenwart von Methanol und Protonen I: Die Autoxydation einfach ungesättigter Fettsäure-methylester

Autoxidation of Unsaturated Fatty Acid Esters in the Presence of Methyl Alcohol and Protons I. The Autoxidation of Monounsaturated Fatty Acid Methyl Esters The methyl esters of oleic, elaidic, 2-octadecenoic and 3-nonenoic acids were autoxidised in presence of methyl alcohol and protons. The amount of the primarily formed isomeric hydroperoxides could be estimated by the quantitative determination of the aldehydic degradation products. The acidic and the Fe⁺⁺ induced degradation of oleic acid methyl ester hydroperoxide mixture was employed for the same purpose. The α-methylene mechanism is also applicable under the conditions under which preferentially the oxygen initiated autoxidation takes place.     

Über die Reduktion ungesättigter Fettsäuren und deren Ester zu ungesättigten Fettalkoholen durch selektive katalytische Hochdruckhydrierung IV: Oxidische kupfer- und cadmiumhaltige Kontakte

Reduction of Unsaturated Fatty Acids and Their Esters to Unsaturated Fatty Alcohols by Selective High-Pressure Catalytic Hydrogenation IV: Oxidic Copper- and Cadmium-Containing Catalysts The preparation of carbonate-containing oxidic copper-cadmium catalysts for the practical high-pressure selective reduction is reported in the present communication. Many variations of the catalyst have deciding effect on its action. Copper-cadmium-chromium oxides were also studied, whereby the binary mixtures of oxides of the 1st and 2nd side group with chromic oxide were considered as well. Oleic acid, methyl oleate, linoleic acid, α- and β-elaeostearic acid and undecenoic acid were tested. The mode of action of the catalysts can be explained by the observations made on pure metals and by the hypothesis of acceptor reaction in the catalytic reduction of carboxyl groups.     

Oxidatives Verfahren zur Herstellung kurzkettiger Carbonsäuren aus ungesättigten Fettsäuren

Oxidative Procedure for Production of Short-Chain Carbon Acids from Unsaturated Fatty Acids For decades, the oxidation of oleic acid to acelaic and pelargonic acid has been carried out in industrial scale by ozone. The high costs of ozone production are a problematical point in this procedure. Thanks to the high selectivity the procedure is today still economic. Efforts to replace the ozone oxidation by an oxygen one haven't yet led to a procedure which can be applied in industry. In this work the oxygen oxidation of oleic acid with aldehyds as intermediary carrier of oxygen is reported.     

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.     

Metathese ungesättigter Fettsäureester – ein einfacher Zugang zu langkettigen Dicarbonsäuren

Metathesis of Unsaturated Fatty Acid Esters – a Simple Approach to Long-Chained Dicarboxylic Acids Long-chained, symmetric unsaturated C₁₈-, C₂₀- und C₂₆-dicarboxylic acid esters are easily accessible from natural fatty acid esters by metathesis in a two-step procedure. In the first step unsaturated fatty acid esters are cleaved by metathesis with ethylene. Pure oleic acid ester or fatty acid methylesters, produced from high-oleic sunflower oil or from rapeseed oil by transesterification with methanol, are converted to 1-decene and 9-decenoic acid methylester. From erucic acid methylester 1-decene and 13-tetradecenoic acid methylester are achieved. Using our newly developed high efficient catalytic system B₂O₃-Re₂O₇/Al₂O₃-SiO₂ + SnBu₄ conversion rates of 86 – 96% are obtained and the terminally unsaturated fatty acid esters are isolated in yields of 61 – 83%. In the second step 9-decenoic and 13-tetradecenoic acid methylester as well as 10-undecenoic methylester, which is commercially obtained by pyrolysis of ricinoleic acid ester, are converted to 9-octadecenedioic-, 13-hexacosenedioic- and 10-eicosenedioic acid dimethylester, by which process ethylene is eliminated. The conversion rates are 89 – 99% and the dicarboxylic acid dimethylesters are isolated in yields of 77 – 84%.     

Produkte der Dimerisierung ungesättigter Fettsäuren XII: Die Dimerisierung von Konjuensäure

Products of Dimerisation of Unsaturated Fatty Acids XII: The Dimerisation of Conjugated Fatty Acids Dimeric fatty acids obtained by the clay-catalyzed dimerisation of the conjugated fatty acid (mixture of 9,11-octadecadienoic acid and 10,12-octadecadienoic acid) can be separated via HPLC in form of their dimethylates in three fractions in accordance with results obtained by separation of dimeric fatty acids of linoleic acid. The first fraction of aromatic dimeric fatty acids with the molecular weight 586 mainly contains compounds with a tetrasubstituted ring system. The second fraction, consisting of alicyclic unsaturated dimeric fatty acids, is characterized by the molecular weight 590 and a cyclohexene ring system. The third fraction corresponds to alicyclic saturated dimeric fatty acids. Dimeric fatty acids resulting of a Diels-Alder-reaction were detected neither in the end products nor as products in the early phase of the dimerisation. The results obtained by the investigation of the dimerisation of conjugated fatty acids are similar to those of the dimerisation of linoleic acid. Consequently a Diels-Alder-reaction is not involved in the formation of dimeric fatty acids. Although conjugated fatty acids are predominated to undergo a Diels-Alder-reaction no such products could be detected. This result strengthens the thesis that the dimerisation of unsaturated fatty acids is initiated by a cationic mechanism. The composition of the dimeric fatty acid using conjugated fatty acids is more uniform than that of usual mixtures of linoleic and linolenic acid. This provides evidence that a modification of the educt fatty acids can yield new structures of the dimerisation products.     

Selektivhydrierung von Fettstoffen mit metallorganischen Mischkatalysatoren nach Ziegler-Sloan-Lapporte III: Selektivhydrierung von gesättigten und ungesättigten Fettnitrilen zu gesättigten und ungesättigten,primären und sekundären Fettaminen

Selective Hydrogenation of Fats and Derivates Using Ziegler-Type Organometallic Catalysts III: Selective Hydrogenation of Saturated and Unsaturated Fatty Acid Nitriles to Saturated and Unsaturated Primary and Secundary Amines A tallow oil nitrile fraction with 66% oleonitrile and 27% stearonitrile was hydrogenated under use of homogeneous nickel- or cobalt-metallorganic catalysts from Ziegler-type with high selectivity to the corresponding saturated primary and secondary amines or under conservation of the double bond in the oleonitrile to unsaturated primary or secondary fatty amines. The realized selectivities were: 97% for stearylamine, 100% for oleylamine, 97% for distearylamine and 76% for dioleylamine.     

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.     

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 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.     

Neue ergebnisse bei der stabilisierung von ungesättigten polyesterharzen

The shelf-life at 50°C of unsaturated polyester resins which contain phenolic stabilizers can be increased by a factor of about three by addition of 0.1% hexamethylphosphoric triamide (HMPT) as costabilizer. The activity of the costabilizer is explained by an increase of the acidity (indicated by NMR-spectroscopy) of the phenolic protones of the inhibitor which accelerates the rate of inhibition. Suitable stabilizers are hydroquinone, toluhydroquinone, tert.-butylhydroquinone, p-tert.-butyl-o-dihydroxybenzene, 3.5-di-tert.-butyl-o-dihydroxybenzene or p-benzoquinone. Non suitable stabilizers for interaction with HMPT are 2.5-di-tert.-butyl-hydroquinone, 2.5-di-tert.-butyl-p-benzoquinone, tetrachloro-p-benzoquinone and p-hydroxymethoxybenzene. Their failure is assumed to be caused by steric effects or by their inability to regenerate hydroquinones by disproportionation during the inhibition reaction.     

Zur Autoxydation ungesättigter Fettsäure-Ester in Gegenwart von Methanol und Protonen II: Die Autoxydation von Linolsäure-methylester

Autoxidation of Unsaturated Fatty Acid Esters in Presence of Methanol and Protons II: The Autoxydation of Methyl Linoleate The amounts of the 7 possible isomeric hydroperoxides formed by the autoxidation of methyl linoleate in presence of methanol and protons are determined by quantitative estimation of the 2,4-dinitrophenylhydrazones of the saturated and unsaturated aldehydes and aldehyde esters contained in the cleavage products. The quantitative separation of the 2,4-dinitrophenylhydrazones from the osazones was accomplished by paper, partition and thin-layer chromatography. 70% of the hydroperoxides formed were derived from the conjugated fatty acids. The C–H-bonds of the 8th C-atom are less reactive towards oxygen than those of the 14th C-atom. The α-methylene group of the shorter alkyl rest is preferentially autoxidised.     

Produkte der thermischen En-Reaktion von ungesättigten Fettstoffen und Maleinsäureanhydrid

Products of the Thermal Ene-Reaction of Unsaturated Fatty Compounds and Maleic Anhydride The thermal ene reaction of the methylates of unsaturated fatty acids 10-undecenoic acid, oleic acid and (E)-10-eicosendioic acid with maleic anhydride was carried out at 190°C. The mono addition products were isolated and their stereochemistry was deduced from ¹HNMR- and ¹³C-NMR-spectroscopy.