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).     

Produkte der Dimerisierung ungesättigter Fettsäuren II: Die Monomerfraktion der Dimerisierung reiner Linolsäure 1. Aromatenfraktion

Products of Dimerisation of Unsaturated Fatty Acids II: The Fraction of Monomeres Obtained by Dimerisation of Pure Linoleic Acid, 1st Fraction of Aromatics The monomeric fraction obtained by dimerisation of pure linoleic acid shows after methylation a much more complex gas chromatogram as the same fraction obtained by dimerisation of oleic acid. Main compounds are p-and m-disubstituted benzene derivatives carrying one alkyl- and one alkylcarboxylic group. Besides stearic acid and stearolactone the same monomethyl branched isostearic acids are produced as observed by dimerisation of oleic acid. In contrast to the latter reaction also isomers of oleic acid could be detected in considerable amounts.     

Produkte der Dimerisierung ungesättigter Fettsäuren X: Identifizierung von Estoliden in der Anfangsphase der Dimerisierung

Products of the Dimerisation of Unsaturated Fatty Acids X: Identification of Estolides in Early Phase of the Dimerisation Dimeric fatty acids, obtained by dimerisation of the conjugated fatty acid (mixture of 9,11-Octadecadienoic acid and 10,12-Octadecadienoic acid) in presence of the catalyst molybdenum pentachloride and tin dichloride, could be separated after methylation with diazomethane. The isolated fraction of methyl-9-octadecanoyloxy-octadecanoat resp. methyl-10-octadecanoyloxy-octadecanoat and methyl-9-octadec-9-enoyloxy-octadecanoat resp. methyl-10-octadec-9-enoyloxy-octadecanoat was characterized. It could be shown that these estolides can be saponified to stearic acid, oleic acid and 9- resp. 10-hydroxyoctadecanoic acid. Thus saponification can serve as an unambiguous proof of estolide components. Analogous estolides could be identified in the early phase of the clay-catalyzed dimerisation of oleic and linoleic acid. The detection of estolides shows that at low dimerisation temperature at first hydroxy fatty acids are formed which are subsequently esterified with unsaturated fatty acids. In the final products of the dimerisation estolides are absent, because their formation is suppressed by higher temperatures.     

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.     

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.     

Produkte der Dimerisierung ungesättigter Fettsäuren I: Die Monomerfraktion der Dimerisierung reiner Ölsäure

Products of the Dimerisation of Unsaturated Fatty Acids I: The Fraction of Monomeres Obtained by Dimerisation of Pure Oleic Acid The position of methyl branches in ?isomeric stearic acids”? obtained from the monomeric fraction of the dimerisation of pure oleic acid was determined by their transformation into saturated alcanes. These compounds show mass spectra which allow a clear localisation of the position of the methyl branch. Isomeric stearic acids with a methyl branch between carbon 2 and 5 are missing. Methylheptadecanes with a branch in position 2 to 7 could be separated by GC, while the isomers with a methyl branch in position 8 and 9 turned out to be not separable. The recorded mass spectra proved that heptadecanoic acids with a branch in position 8 to 16 were present in about the same amount, while the isomeres with a branch in position 6 and 7 were produced in the course of the dimerisation only in minute amounts. Fatty acids with two methyl branches could not be detected. The fraction of the monomeres contains traces of dialkyl-substituted cyclohexenones, too. The structures of these compounds were determined by microchemical transformation of the ketones followed by analysis of the reaction mixture by GC/MS.     

Produkte der Dimerisierung ungesättigter Fettsäuren III: Trennung dimerer Fettsäuren mittels GC und HPLC — Nachweis aliphatischer und verzweigter Dicarbonsäuren

Products of the Dimerisation of Unsaturated Fatty Acids III: Separation of Dimeric Fatty Acids with the Aid of GC and HPLC — Identification of Branched Aliphatic Dicarboxylic Acids From dimers produced by dimerisation of pure oleic acid we obtain by freezing small amounts of compounds, which can be separated further by GC. The separated compounds are isomers with a molecular weight of 594. They are saturated branched aliphatic dicarboxylic acid esters. They are obviously produced by en-reaction followed by hydrogenation. A much more effective separation than by GC is possible by HPLC, using a detector based on light scattering. Thus the dimeric fatty esters can be separated into four fractions: the first fraction consists of aromatics, the second obviously of alicyclic and unsaturated dicarboxylic acids, the third and fourth consist of aliphatic dicarboxylic acid esters of MW 594. Fatty acids obtained by dimerisation of a starting material rich in linoleic acid contain large amounts of aromatic compounds, those which are obtained by dimerisation of starting material rich in oleic acid contain rather high amounts of aliphatic dicarboxylic acids and practically no aromatic compounds.     

Produkte der Dimerisierung ungesättigter Fettsäuren XI: Die Fraktion der alicyclischen Dimerfettsäuren

Products of Dimerisation of Unsaturated Fatty Acids XI: The Fraction of Alicyclic Dimeric Acids Dimeric fatty acids can be separated as their dimethylates by HPLC-chromatography [W. Link, G. Spiteller, Fat Sci. Technol. 92 , 135 (1990)]. The main fraction of dimeric fatty acids obtained by the dimerisation of linoleic acid consists of alicyclic unsaturated dimeric fatty acids with the molecular weights 588 and 590. The structures of these compounds remained unknown until now. This fraction was subjected to hydrogenation, epoxidation and dehydrogenation with SeO₂ and Pd/C. The investigation of the reaction products provided evidence that these dimeric acids are a mixture of the following compounds: Dimeric acids with a 6-ring and one double bond and dimeric acids with two 6-rings and a double bond could be identified. In both types of compounds the double bond can be either situated in the ring as well as outside the ring. In dimeric acids containing two rings this ring system can be condensed or separated by a C-chain. Besides dimeric acids with two 6-rings dimeric acids with one 6-ring and one 5-ring were found. Essential contributions to these deductions were obtained by an investigation of model compounds and model fractions.     

Produkte der Dimerisierung ungesättigter Fettsäuren VIII: Über die Zusammensetzung der Fraktion der “Intermediates” bei der Fettsäuredimerisierung

Products of Dimerisation Unsaturated Fatty Acids VIII: The Fraction of “Intermediates” Obtained by Dimerisation of Unsaturated Fatty Acids The fraction of “intermediates” which is obtained by dimerisation of unsaturated fatty acid contains straight chain saturated fatty acids with 20-24 carbon atoms as well as methyl branched isomers thereof. The production of these compounds is probably caused by the presence of small amounts of monounsaturated fatty acids with 20-24 carbon atoms in the starting material. The fraction of “intermediates” contains in addition monocarboxylic acids with 36 carbon atoms. These are probably formed after dimerisation by an intramolecular cyclisation reaction under participation of one carboxylic group, followed by hydrogenation of the produced carbonyl group. Finally the formed alcoholic group is eliminated as a water molecule, and the produced double bond is hydrogenated.     

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.     

Anlagerung von unterjodiger Säure an ungesättigte Fettsäuren bei den Bedingungen des Schnellverfahrens von Margosches zur Bestimmung der Jodzahl von Fetten I: Öl- und Elaidinsäure

Addition of Hypoiodous Acid to Unsaturated Fatty Acids under Conditions Employed in the Rapid Method for the Determination of Iodine Value of Fats According to Margosches I: Oleic and Elaidic Acids Investigations showed that the addition of hypoiodous acid to oleic and elaidic acids does not proceed stereospecifically; instead, a mixture of both the diastereomeric iodo-hydroxystearic acids are obtained. The configuration of the diastereomeric DL-9(10)-iodo-10(9)-hydroxy acids was determined by stereospecific conversions to products of known configuration. In the conversion of the diastereomeric iodo-hydroxystearic acids to hydroxyacetoxystearic acids with the help of silver acetate or sodium acetate in acetic acid, ca. 25% of 9(10)-ketostearic acid were also formed.     

Zur Bildung von Ölsäureepoxid bei der Lagerung technischer Ölsäure

Formation of Oleic Acid Epoxide at the Storage of Oleic Acid of Technical Quality Oleic acid epoxid 1 is produced by reaction with 9S-hydroperoxy-10-cis-12-trans-otadecadienoic acid 2 (9S-linoleic acid hydroperoxid, 9S-LOOH) slowly at room temperature. 9S-LOOH is obtained in a slow reaction, if linoleic acid is kept at room temperature in the air. Thus oleic acid of technical quality which contains always 10–30% of linoleic acid is transformed slowly even at room temperature (via oxidation of linoleic acid to its hydroperoxide) into oleic acid epoxide.     

Cis-trans isomerization of oleic,linoleic and linolenic acids

The equilibrium composition ofcis andtrans isomers obtained by isomerizing oleic, linoleic, and linolenic acids with selenium or nitrous acid has been studied using gas chromatography and infrared spectroscopy. The oleic/elaidic equilibrium mixture was found to contain 75–80% elaidic acid instead of the generally accepted 66% value. It is felt that the greater accuracy of gas chromatography and infrared analyses over older methods allows this equilibrium to be defined with greater precision. Similar studies on thecis-trans isomerization of linoleic and linolenic acids indicated that their equilibrium mixtures also contained 75–80%trans double bonds. With linoleic acid, thesetrans bonds were shown to be randomly distributed among the double bonds present. Cis-trans isomerization of linoleic or linolenic acids with selenium produced by-products having elution times equivalent to 18∶2, 18∶1, and 18∶0 on a gas chromatograph. No such by-products were observed when oleic acid was isomerized. Apparently some type of hydrogen-transfer reaction accompanies thecis-trans isomerization of polyunsaturated acids with selenium. Presented at the AOCS meeting in Toronto, Canada, 1962.     

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.     

The hydrolysis of fatty acid chlorides

Summary Fatty acid chlorides of octanoic, decanoic, lauric, myristic, palmitic, stearic, oleic, elaidic, and linoleic acids were hydrolyzed at 25° C, in water and the amounts of unchanged acid chlorides determined after different periods of reaction. Contrary to expectations, the chlorides of the longer chain fatty acids, palmitic and stearic, reacted at a more rapid rate than the chlorides of the shorter chain fatty acids. Lauryl chloride appears to be more resist-ant to hydrolysis than either the chlorides of the lower molecular weight octanoic and decanoic acids or the chlorides of the higher molecular weight myristic to stearic acids. The chlorides of the unsaturated acids, oleic, elaidic, and linoleic, are hydrolyzed less rapidly than stearyl chloride. However, elaidyl and myristyl chlorides exhibit the same relative rates of hydrolysis during the first two hours of reaction. Myristyl chloride hydrolyzes more rapidly than elaidyl chloride after the first two hours. The addition of either hydrochloric acid or free fatty acids to the reaction mixture was found to have no pronounced effect on the hydrolysis of the acid chlorides. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Versuche zur Herstellung linolsäurearmen Ölsäureesters über eine Hydrierung mit Palladium

The Preparation of Oleic Ester with Reduced Linoleic Acid Content by Hydrogenation with Palladium By hydrogenation with palladium on charcoal low contents of linoleic acid can be reduced quite selectively in the presence of an excess of oleic acid ester. In a mixture of fatty acid methylesters the content of linoleic acid was reduced from 10% to 2% with the formation of 3% cis-, 4% transmonoenes and 1% saturated acid.     

Characterization of products from clay catalyzed polymerization of tall oil fatty acids

Products obtained by acid clay catalyzed dimerization of oleic, elaidic, and tall oil fatty acids were characterized. The monomeric products (35% of total) consisted of stearic, octadecenoic (66%trans-), and mid chain monomethyl branched acids, both saturated and unsaturated. The polymeric products (65% of total) consisted of linear, alicyclic, aromatic, and polycyclic dimers. The tall oil fatty acid based dimer closely resembled oleic dimer in polycyclic character and linoleic dimer in aromatic and linear structures. Oleic dimers contained the highest linear structural content, while linoleic dimer contained the largest polycyclic content. Alicyclic structures were the principal components of all three products. The monocyclic dimer structures present consisted of six membered ring systems with linoleic and tall oil fatty acid dimers containing the highest aromatic contents. Presented at the National American Chemical Society Meeting, New York, August 1972.     

The cytotoxicity of fatty acid/α‐lactalbumin complexes depends on the amount and type of fatty acid

Complexes of the milk protein, α‐lactalbumin, and the fatty acid, oleic acid, have previously been shown to be cytotoxic. Complexes of α‐lactalbumin and five different fatty acids (vaccenic, linoleic, palmitoleic, stearic, and elaidic acid) were prepared and compared to those formed with oleic acid. All complexes were cytotoxic to human promyelocytic leukemia‐derived (HL‐60) cells but to different degrees depending on the fatty acid. The amount of fatty acid per α‐lactalbumin molecule was found to correlate with the cytotoxicity; the higher the number of fatty acids per protein, the more cytotoxic the complex. Importantly, all the tested fatty acids were also found to be cytotoxic on their own in a concentration dependent manner. The cytotoxic effect of complexes between α‐lactalbumin and linoleic acid, vaccenic acid, or oleic acid was further investigated using flow cytometry and found to induce cell death resembling apoptosis on Jurkat cells. Practical applications: Cytotoxic complexes of α‐lactalbumin and several different fatty acids could be produced. The cytotoxicity of all the variants is similar to that previously determined for α‐lactalbumin/oleic acid complexes.     

Der Einfluß der Umwelt auf Fettgehalt und Fettsäuremuster verschiedener Sonnenblumensorten

Environmental Effect on Fat Content and Fatty Acid Pattern of Different Varieties of Sunflower Crude fat content and fatty acid composition have been determined for two years on experimental crops of 8 and 15 varieties respectively of sunflower grown in two different locations in Central Europe and of one variety grown in East Africa. Crude fat content in fruits varied in the different locations (29% in Mozambique compared to 35% in Europe) and also from variety to variety (24.3% upto 45.1%). No correlation existed between the fatty acid composition and oil content. A distinct negative relationship was found between the linoleic and oleic acid content (r = –0.931). Under cold growth conditions an increase in linoleic acid content and a decrease in oleic acid was observed. Under dry and warm conditions during the short days at Mozambique, the level of linoleic acid was 46% compared to 72 in Europe. The corresponding values for oleic acid were on average 17% in Europe and 44% in Mozambique. Certain variational differences were observed, however, only to minute extent compared to locational differences.     

Thienoanellierte 6aλ4-Thia-1,6-diazapentalene durch baseninduzierte Dimerisierung von 5-Methyl-isothiazoliumsalzen

Thienoanneleted 6aλ⁴-Thia-1,6-diazapentalenes by Baseinduced Dimerisation of 5-Methyl-isothiazolium Salts Isothiazolium salts 2 and 3 are easily available by reaction of (Z/E)-β-thiocyanatovinyl aldehydes with primary aliphatic and aromatic amines in acetic acid or with aromatic amine hydrochlorides, respectively. Preparative advantages of this reaction are demonstrated and discussed. Reaction of 3 with secondary amines results in an unexpected formation of 6aλ⁴-thia-1,6-diazapentalenes 5 , a new typ of thiadiazapentalenes anellated with a heterocyclic ring system. The structure of 5 was evidenced by IR, UV, ¹H-, ¹³C-n.m.r. spectral data and supported by elemental analysis. By means of ¹⁵N- and ¹³C-n.m.r. spectroscopy the synthesized thiadiazapentalenes were found to be stable towards protonation.