Über die Autoxydation von Linolsäuremethylester in Wasser V: Isolierung und Identifizierung einiger Carbonsäuren mittlerer Kettenlänge

Autoxidation of Methyl Linoleate in Water V: Isolation and Identification of Some Medium Chain Carboxylic Acids From the product of autoxidation of methyl linoleate the following carboxylic acids were isolated and identified as their N,N-dimethyl-p-aminobenzolazophenacyl esters: monomethyl suberate, α-hydroxy oenanthic acid, 4-hydroxy-2-transnonenoic acid, 4-hydroxy-12-carbmethoxy-2-trans-dodecenoic acid, and an ω-carbmethoxy carboxylic acid of unknown chain length.     

Der Einfluß stereoisomerer und konjugierter Fettsäuren,insbesondere dehydratisierter Rizinusöl-Fettsäuren,auf die Eigenschaften von Alkydharzen

The Influence of the Stereoisomeric and Conjugated Fatty Acids, Especially Dehydrated Castor Oil Fatty Acids, on the Properties of Alkyd Resins Alkyds with 60% oil content were prepared from the drying oils with different contents of conjugated and stereoisomeric fatty acids, specially dehydrated castor oil, and the autoxidation and film forming properties of these were investigated. Trans-trans-dienoic fatty acids oxidised fastest but hindered the through-drying. Throughdrying is dependent on this hinderence and the total content of conjugated dienoic fatty acids. The hardness of the film, measured after 7 days by Sward-Rocker method, is a function of the total amount of conjugated and nonconjugated polyunsaturated fatty acids.     

Zum Einfluß von Antioxidantien natürlichen Ursprungs auf die Stabilität von Linolsäuremethylester in Modellsystemen

The Effect of Natural Antioxidants on the Stability of Methyl Linoleate in Model Systems This paper presents a model system based on linoleic acid methylester on potato starch which allows to estimate the antioxidative effects of certain additives in oxygen-sensitive foods of low lipid content. It is shown that a tocopherol mixture from natural sources (Covi-Ox T70) and an extract from rosemary (RM) were much more effective than the conventional ascorbyl palmitate (AP). So concentrations of 2 ppm Covi-Ox T70 or 20 ppm RM, respectively, were more effective than 200 ppm AP. Reducing intermediates of the Maillard reaction (Amadori compounds) do not show antioxidative effects in all cases; in our investigations only fructose-γ-aminobutyric acid and fructosearginine were able to retard linoleic acid oxidation to some extent; however, in the latter case, the free amino acid showed a similar effect. The antioxidative effect of the different additives tested is due to their radical scavenging character; only AP was able to reduce the hydroperoxides arising from autoxidation processes to the corresponding hydroxy compounds which cannot be decomposed to rancid products anymore.     

Ascorbic acid and ascorbyl palmitate have only minor effect on the formation and decomposition of methyl linoleate hydroperoxides

Effects of ascorbic acid (AA) and ascorbyl palmitate (AP) on lipid hydroperoxides were evaluated during the formation and decomposition of methyl linoleate hydroperoxides (ML‐OOH). AA and AP at 1 and 10 mM levels had no effect on the formation of ML‐OOH during the autoxidation of methyl linoleate at 40 °C. However, depending on the reaction medium, AA and AP at 0.2 and 2 mM either slightly inhibited or accelerated the decomposition of 40 mM cis, trans ML‐OOH in hexadecane or in hexadecane‐inwater emulsion. The increased decomposition rate of ML‐OOH, when compared to a control sample, was apparently due to the reductive activity of AA and AP on metal ions present in the system, as the addition of EDTA improved the stability of ML‐OOH. The more detailed analysis of the decomposition reactions of ML‐OOH suggests that under favorable reaction conditions AA and AP were, to some extent, capable of acting as hydrogen atom donors to peroxyl radicals and reducers of hydroperoxides to more stable hydroxy compounds. However, since all these effects of AA and AP on lipid hydroperoxides were relatively small, it is assumed that the antioxidative activity of AA and AP as well as their effect on the stability and reactions of lipid hydroperoxides in biological systems and in foods is mainly related to their synergistic interactions with other antioxidative compounds such as tocopherols.     

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.     

Natürliche Antioxidantien III Zur Kinetik der antioxidativen Wirkung von α-Tocotrienol

Natural Antioxidants III: Kinetics of Antioxidative Action of α-Tocopherols Kinetics of antioxidative action of α-tocotrienol was compared to that of other tocopherols. Specially purified methyl esters of total fatty acids of sunflower oil served as substrates, whose first ?stable”? autoxidation product is linoleic acid hydroperoxide. In all reactions studied, α-tocotrienol was somewhat more effective than α-tocopherol. The maximum inhibition was reached at a concentration of 0.02%. With increasing concentration, the well known phenomenon of reversion occurs with α-tocotrienol to a greater degree than with α-tocopherol. α-Tocotrienol, added in an amount of 0.12%, causes a more rapid decomposition of peroxides than α-tocopherol.     

Bestimmung aromatischer Fettsäuren in hydrierten cyclischen Fettsäuren

Determination of Aromatic Fatty Acids in Hydrogenated Cyclic Fatty Acids Small amounts of aromatic fatty acids, besides hydrogenated cyclic fatty acids, in an urea non-adduct from hydrogenated fatty acids can not be determined by gas chromatography. A direct determination by UV-spectroscopy is also inaccurate, since the strong end absorption of the carbonyl group makes an evaluation of the aromatic band in the range of 260 to 275 nm difficult. After reducing the acids or esters with lithium aluminium hydride to the corresponding alcohols, a proper quantitative determination of aromatic fatty acids can be carried out even at low concentrations of the latter.     

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.     

Über die Darstellung isomerenfreier verzweigter Carbonsäuren

Preparation of Branched Carboxylic Acids Free from Isomers A method for the preparation of branched saturated and unsaturated carboxylic acids, free from isomers, from tertiary γ-lactones by means of alkyl aluminium chlorides is reported. Saturated branched carboxylic acids were obtained in high yields by the reaction with ethyl aluminium chloride, whereas the reaction with diethyl aluminium chloride yielded the unsaturated acids. Splitting of lactones with mixtures of both the ethyl aluminium chlorides gave mixtures of saturated and unsaturated acids. The structure of the unsaturated carboxylic acid was determined by hydrogenation, ozonolysis, iodine value and gas chromatography.     

γ‐ and δ‐tocopherols are more effective than α‐tocopherol on the autoxidation of a 10% rapeseed oil triacylglycerol‐in‐water emulsion with and without a radical initiator

The antioxidative effects of γ‐ and mainly δ‐tocopherol in a multiphase system were hardly considered up to now. The aim of this study was i) to assess the effects and ii) to follow the degradation of α‐, γ‐ and δ‐tocopherol in concentrations of 0.01%, 0.05%, 0.1% and 0.25% during the oxidation of a 10% purified rapeseed oil triacylglycerol‐in‐water emulsion at 40 °C in the dark for 15 wk in a system containing a low oxygen concentration. Oxidation experiments were performed weekly by assessing the formation of hydroperoxides and hexanal, and the stability of the tocopherols was determined using high‐performance liquid chromatography. Storage tests were conducted with and without the addition of 0.01% α, α′‐azoisobutyronitrile (AIBN), which is a known radical initiator. α‐Tocopherol increased the formation of hydroperoxides in both tests as well as the generation of hexanal when the radical initiator was added; furthermore it was the least stable. γ‐Tocopherol delayed the formation of hexanal and prolonged the stability of the emulsion in a dose‐dependant manner. δ‐Tocopherol was the most stable and also the most effective in delaying lipid oxidation in the emulsions. Each concentration that was tested reduced the rate of hydroperoxide and especially hexanal formation. Hexanal was only formed to a slight extent after 15 wk of oxidation in the test with AIBN and the lowest dose of 0.01% δ‐tocopherol. For all tocopherols, strong correlations were found between tocopherol stability and the extent of oxidation. Results suggest that i) mainly δ‐tocopherol, but also γ‐tocopherol even less pronounced, are very good antioxidants in order to stabilize and prolong the shelf life of oil‐in‐water emulsions, ii) the antioxidative effects were intensified with increasing amounts.     

Über die Reduktion ungesättigter Fettsäuren und deren Ester zu ungesättigten Fettalkoholen durch selektive katalytische Hochdruckhydrierung II: Zur Isomerisierung und Sättigung der Doppelbindungen,Teil 2, Polyensäuren und Ozonisierungsversuche

Reduction of Unsaturated Fatty Acids and their Esters to Unsaturated Fatty Alcohols by Selective Catalytic Hydrogenation under High Pressure II: The Isomerisation and the Saturation of Double Bonds: Part 2, Polyenoic Acids and Ozonization Experiments The side reactions, which take place along with the main reaction during the selective catalytic reduction with hydrogen to corresponding unsaturated fatty alcohols, are studied by investigating the behaviour of definite unsaturated fatty acids. The relationship between the structure of an unsaturated fatty acid and the selectivity of the hydrogenation process carried out in the presence of a special catalyst is studied.     

Über die Reduktion ungesättigter Fettsäuren und deren Ester zu ungesättigten Fettalkoholen durch selektive katalytische Hochdruckhydrierung II: Zur Isomerisierung und Sättigung der Doppelbindungen,Teil 1, Allgemeines und Monoensäuren

Reduction of Unsaturated Fatty Acids and Their Esters to Unsaturated Fatty Alcohols by Selective Catalytic Hydrogenation Under High Pressure II: The Isomerisation and the Saturation of Double Bonds: Part 1, General Information and Monoenoic Acids The side reactions which take place along with the main reaction during the selective catalytic reduction with hydrogen to corresponding unsaturated fatty alcohols, are studied by investigating the behaviour of definite unsaturated fatty acids. The relationship between the structure of an unsaturated fatty acid and the selectivity of the hydrogenation process carried out in the presence of a special catalyst is studied.     

Auswirkungen unterschiedlicher α-Tocopherol- und Selenzusätze in Rationen mit hohen Gehalten an Polyensäuren auf Regenbogenforellen (Salmo gairdnerii,R.)

Effects of Different α-Tocopherol and Selenium Additions in Ratios with High Contents of Polyen Acids on Rainbow Trouts (Salmo gairdnerii, R.) Polyen acids as phosphoric lipids are components of cellular membrane structures. Because of their autoxidative tendence a special protection of these fatty acids and by that of the cellular membrane is necessary. This is especially valid for trouts, because they have a great need of essential n-3 polyen acids. Selenium and tocopherols have a protective function against oxidations damages. Both active substances have been tested in two separated tests with rainbow trouts. The first test was carried out in a flow plant with selenium additions in steps from 0 to 0.6 mg. The α-tocopherol contents in the ratios of the second test, carried out in a partial circuit plant, varied from 0 to 400 mg/kg feed. After about 10 weeks the first deficiency symptoms occurred in the shape of feed refusal and by that coherent growth depressions in the deficiency groups. Afterwards a nearly complete feed refusal and increased mortality took place. The fishes had pale, swollen gills with shortened gill lids, standing off. The liver was coloured to brown-yellow and they had anaemia. The hematocrite value was significantly lowered. All the other feed groups with addition of selenium and/or higher doses of α-tocopherol-acetate showed normal increases and equivalent good feed utilization. The investigations of the livers of the deficiency groups, carried out by light microscope and electron microscope, showed pathological symptoms, which are typical for a missing antioxidative protection.     

Untersuchungen über die Struktur dimerer Fettsäuren II: Herstellung und Strukturaufklärung von Diels-Alder-Dimeren aus 9t, 11t-Octadecadiensäure-methylester

Investigations on the Structure of Dimeric Fatty Acids, Part II: Preparation and Structure Determination of Diels-Alder Dimers from Methyl-9^t,11^t-Octadecadienoate From the reaction product resulting from 6 hrs of treatment of methyl-9^t,11^t-octadecadienoate at 250°C under argon 35% by weight of dimers were obtained. The thin-layer chromatogram of the dimers showed the presence of four components, which could be isolated in preparative scale as colourless liquids. All these components exhibited a refractive index n_D²⁰ = 1.4762 ± 0.0002, iodine value 86 ± 1 and mol weight 588. The mass spectra corresponded to those of tetrasubstituted cyclohexene derivatives. Hence, the product is a mixture of various positional isomers. The complete hydrogenation of the dimers could be accomplished only after the addition of a small quantity of perchloric acid. This behaviour appears to be typical for cyclohexenoic dimers with long chain rests.     

Über die Autoxydation gesättigter Fettsäuren VI: Isolierung und Identifizierung von Oxydationsprodukten der Laurin-, Myristin-und Stearinsäure sowie ihrer Methylester

Autoxydation of Saturated Fatty Acids VI: Isolation and Identification of Cleavage Products Formed by the Oxidation of Laurie, Myristic and Stearic Acids and their Methyl Esters Besides primary reaction products, as reported earlier, also some other substances, considered to be secondary products were identified in the oxidation product of saturated fatty acids and their methyl esters. A large number of methyl ketones, aldehydes and carboxylic acids could be detected by these investigations.     

NMR- und IR-spektroskopische Bestimmung des Zahlenverhältnisses von Methyl- und Methylengruppen in Kohlenwasserstoffen,Alkoholen, Carbonsäuren und deren Estern. Besonderheiten bei verzweigten Carbonsäuren,Olefinen und cyclischen Verbindungen

NMR- and IR-Spectroscopic Determination of the Ratio Between Methyl and Methylene Groups in Hydrocarbons, Alcohols, Carboxylic Acids and Their Esters. Special Characteristics of Branched Carboxylic Acids, Olefins and Cyclic Compounds A series of typical examples of compounds from various important classes have been studied in order to compare the ratio of methyl to methylene groups (degree of branching) as determined by NMR- and IR-spectroscopy with the theoretical values. Considerable agreement was found in most of the cases, however, deviations were observed with olefins containing internal double bonds, alcohols, α-methyl branched carboxylic acids and aromatic compounds. The main reasons for such deviations were found out by comparative application of the various methods. The advantage of combined application of both the methods is demonstrated in the analysis of technical products.     

Octadecadiensäuren im Butterfett I. Mitteilung: Die Vorstufen bei der Bildung von 4-cis-Heptenal

Octadecadienoic Acids in Butter Fat I: The Precursors of 4-cis-Heptenal It was found that the creamy smell of butter is due to an aldehyde. Because of this finding, it was investigated as to which unsaturated fatty acids in butter cause the creamy smell after autoxidation. A micro-method for the determination of the position of double bonds in the substances which give rise to 4-cis-heptenal, is described.     

Vinylierung höherer Carbonsäuren an Katalysatorschmelzen

Vinylation of Higher Carboxylic Acids on Catalyst Melt After some references about the possibilities of the use of vinyl esters of higher carboxylic acids, some known methods for the synthesis of these are described in short. A new method is then reported whereby the vinylation of the α-position of branched chain higher carboxylic acids is discussed.     

Über den katalytischen Einfluß von Hämin und Hämoproteiden auf die Oxydation von Polyensäuren

Catalytic Influence of Haemin and Haemoproteids in the Oxidation of Polyenoic Acids In alkaline solution, the oxidation of linoleic acid catalysed by haemin proceeds as a first order reaction. Deviations from ideal form of equation for the reaction occur due to colloidal state of linoleic acid. Also in neutral region, the catalytic reaction proceeds as a first-order reaction with reference to surface-concentration of linoleic acid. Thereby, an inhibition is caused by the product of reaction. The catalysis is not specific for cis- or trans double bonds. On the other hand, haemin is catalytically ineffective in the oxidation of conjugated acids. Hence it is assumed that catalytic oxidation does not proceed as a chain reaction. Instead of this, by an electromeric effect absorbed haemin displaces the double bonds of linoleic acid towards conjugation and thus enables addition of oxygen.     

Über die Autoxydation gesättigter Fettsäuren V: Angriff des Sauerstoffes und Bildung von Peroxiden bei der Oxydation von Laurin- und Stearinsäure sowie ihrer Methylester

Autoxidation of Saturated Fatty Acids V: The Attack of Oxygen Consumption and the Formation of Peroxides in the Oxidation of Lauric and Stearic Acids and their Methyl Esters No unsaturated compounds were found amongst the products of oxidation. Alkan-2-ones and alkanals containing one C-atom lesser than the fatty acid chain were identified as the primary products of degradation of the acids and esters. From the composition and periodic occurrence of the products of degradation, one can conclude that preferentially a β-oxidation takes place. The formation of alkanals having chain lengths shortened by one C-atom than the starting materials indicate the occurrence of α-oxidation as well, which, however, lags far behind the β-oxidation.