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.     

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%.     

Cyclohexadien-C18-Fettsäuren aus mit KOH in Äthylenglykol isomerisiertem Leinöl

Cyclohexadienoic C₁₈-Fatty Acids from Linseed Oil Isomerized with KOH in Ethylene Glycol Cyclic C₁₈-fatty acids are obtained in 10% yield by the isomerization of linseed oil for 25 min. with a 6.5% solution of KOH in ethylene glycol at 180° C. The cyclic acids consist of cyclohexadienoic isomers having the structures IV, V and VI. Only traces of cyclohexadienoic isomers of the structures VII, VIII and IX are present. The position of conjugated double bonds was determined by reacting with dimethyl esters of acetylenic dicarboxylic acids according to Alder-Rickert. The assumption that the substance IV is formed at first by the cyclization of a linear conjugated trienoic C₁₈-fatty acid is supported by the fact that the presence of this compound could be detected.     

Übergangsmetallkatalysierte Oxidationen ungesättigter Fettsäuren — Synthesen von Keto- und Dicarbonsäuren

Transition-metal Catalyzed Oxidation of Unsaturated Fatty Acids — Synthesis of Ketocarboxylic Acids and Dicarboxylic Acids Terminal unsaturated C₁₀–C₁₄-fatty acid methylesters (9-decenoic-, 10-un-decenoic-, 13-tetradecenoic methylesters) were converted to methylketocarboxylic methylesters (yields: 60–75%, isolated) by oxidation with O₂/H₂O at roomtemperature under catalysis of PdCl₂/CuCl₂. Using RhCl₃/FeCl₃ at 80°C yields of 40–60% were obtained. For the first time methyl oleate was converted directly to a mixture of 9-oxo- and 10-oxo-stearic acid methylester by palladium catalyzed oxidation. In DMF/H₂O the selectivity to these two ketoesters was 85% (15% isomers), in dioxane/H₂O the selectivity droped to 55% while the yield of the oxostearic acid esters climbed to 70%. The Mn-catalyzed oxidative cleavage of methylketocarboxylic acid esters with O₂ at 115°C led in each case to a mixture of two dicarboxylic acid esters in a molar ratio of 2 : 1. Starting with 9-oxodecanoic acid azelaic and suberic acid were obtained at a conversion rate of 90%. Analogous 10-oxoundecanoic acid led to C₁₀/C₉- and 13-oxotetradecanoic acid led to C₁₃/C₁₂-dicarboxylic acids. The oxidative cleavage of 9-/10-oxostearic acid methylester yielded mixtures of C₈–C₁₀-monocarboxylic acids and methylesters of C₈–C₁₀-dicarboxylic acids.     

Über die Säuren HOOCCH(SX)CH(SX)COOH (X  CH2COOH,C6H5) und ihre Methylester

The Acids HOOCCH(SX)CH(SX)COOH (X  CH₂COOH, C₆H₅) and their Methyl Esters The acids HOOCCH(SX)CH(SX)COOH with X  CH₂COOH and C₆H₅ and their methyl esters have been prepared by addition of thiols to acetylene dicarboxylic acid as salt and methyl ester. The structures and configurations have been discussed.     

Beiträge zur Analytik von Estersulfonaten

Contributions to the Analysis of Sulfonated Esters Several methods for the characterization and determination of α-Sulfo fatty acid methyl esters are described. The sulfonated ester is detected by thin layer chromatography on silica gel plates with tetrahydrofuran + acetone (1+9 v/v) as solvent and with pinacryptol yellow/UV-light for the visualization. Pyrolysis-gas liquid chromatogrphy with heating a sample/P₂O₅-mixture at 400°C yields the chain length distribution of the fatty acids initially used. The amount of an α-sulfo fatty acid ester is determined by extraction with i-propanol and by two-phase titration (Epton). the saponification product of the sulfonated ester is in the i-propanol insoluble part. For a quantitative determination of the α-sulfo fatty acid methyl ester by thin layer chromatography the sample solution is directly applied to the thin layer plate. A range of defined volumes, with increasing amounts of the sample are applied to the plate by means of an applicator. The chromatograms are visually compared. Ion chromatogrphy with the mobile phase, NH₃/Acetonitrile separates the α-sulfo fatty acid esters by chain-length. Determination is achieved by standards with defined chain-length.     

Kurzfristige Fütterungsversuche mit Methylestern dimerer Fettsäuren

Short-Time Feeding Tests with Methyl Esters of Dimeric Fatty Acids Fatty acid methyl esters ex safflower oil were polymerised at high temperature and separated by distillation. Feeding experiments with rats at a level of up to 50 cal-% in the food showed the highest degree in growth retardation with those fractions which contained esters of dimeric fatty acids. Esters of dimeric fatty acids of well defined structure, were fed to mice per os to determine acute toxicity. With the compounds applied the toxicity was far higher than 20 ml/kg body weight. After feeding radiocarbon labelled dimeric fatty acid esters, it could be shown that a high percentage of the material fed was excreted. However, a small amount is metabolised since ¹⁴CO₂ was observed in the exhaled air, and radioactive monomeric fatty acids were found in the body fat. Finally a small amount of the labelled dimeric fatty acids fed to the rats was recovered from the body fat indicating direct incorporation.     

Displacement of the double bonds during hydrogenation of unsaturated fatty acid methyl esters

Summary The displacement of the double bond of several unsaturated fatty acid methyl esters during hydrogenation with a nickel-kieselguhr catalyst at 180°C. was investigated. The analysis of the dicarboxylic acids (obtained by oxidation of the reaction products with KMnO₄ in acetic acid solution) by means of partition chromatography enabled a reliable semiquantitative determination of the position isomers formed. During hydrogenation of methyl esters of oleic, elaidic, petroselinic, and linoleic acid formation of large amounts of position isomers was proved to occur. Migration of the double bonds in both directions took place but was in all cases strongly pronounced in a direction opposite the ester group. The place and configuration (cis or trans) of the double bonds in the starting material apparently were of little importance in this respect. It follows that hydrogenation of fatty acid esters leads to products which are far more complicated, as is generally known. This is especially of importance with respect to the application of hydrogenated fatty oils in the food industries.     

Fatty acids,fatty alcohols,wax esters,and methyl esters fromCrambe abyssinica andLunaria annua seed oils

Crambe abyssinica andLunaria annua, members of the Cruciferae family, have seed oil glycerides containing ca. 55–65% of C₂₂ and C₂₄ unsaturated fatty acids. Fatty acids were prepared by saponification; fatty alcohols, by sodium reduction of glycerides; liquid wax esters, byp-toluenesulfonic acid-catalyzed reaction of fatty acids with fatty alcohols; and methyl esters, by reaction of fatty acids with diazomethane. Solid hydrogenated glyceride oils and wax esters were compared with several commercial waxes. Chemical and physical constants were determined for the seed oils and their derivatives. Position of unsaturation in theCrambe fatty acids was determined by gas chromatographic analysis of the permanganate-periodate degradation products. The major dicarboxylic acid was brassylic (C₁₃), proving the docosenoic acid to be erucic. Presented in part at the AOCS meeting in New Orleans, La., 1962. A laboratory of the No. Utiliz. Res. & Dev. Div., ARS, U.S.D.A.     

Homogeneous catalytic metathesis of unsaturated fatty esters: New synthetic method for preparation of unsaturated mono-and dicarboxylic acids

The catalytic metathesis of unsaturated fatty esters is a new, versatile method for the synthesis of a variety of fatty derivatives and alkenes. Monounsaturated esters are converted into unsaturated dicarboxylic esters which might be important technologically for the production of new polyesters and polyamides, and for the synthesis of civetone-type perfumes. Metathesis of linoleate and linolenate leads to a variety of hydrocarbons and mono- and dicarboxylates of different unsaturation. Joint reactions of unsaturated esters and alkenes are a useful means for the synthesis of homologues of oleic acid and other fatty acids. Metathesis of unsaturated fatty oils (olive, soybean, linseed, etc.) leads to the formation of high molecular dicarboxylic acid glyceryl esters with improved drying properties.     

Hydrogenation of unsaturated fatty acid methyl esters using decalin for hydrogen transfer

A laboratory procedure was developed for hydrogenation of methyl esters of unsaturated fatty acids using decalin as a hydrogen-transfer agent and 10% Pd/C as catalyst. The esters of 10-undecenoic, oleic, elaidic, stearolic, linoleic, cycloaliphatic C₂₁ di-, C₂₂ tri- and C₃₆ dicarboxylic acids, and a mixture of hydrnocarpic, chaulmoogric and gorlic acids were hydrogenated. Chromatographic and spectral analyses showed complete saturation. This procedure is simple, requiring no external source of hydrogen.     

Binäre Gleichgewichte im System Fettsäure-methylester Dimethylsulfoxyd

Binary Equilibriums in the Fatty Acid Methyl Ester-Dimethyl-sulfoxide-System The solubility of methyl esters of C₁₀ to C₁₈ fatty acids in dimethylsulfoxide is low. Mathematical relations for the calculation of solubility of the homologous methyl ester series are derived. Esters of sugar increase the solubility whereas saccharose diminishes it.     

Analytik von Phosphorsäurepartialestern

Analytic of Phosphoric Acid Partial Esters Phosphoric acid partial esters are best synthesized by reaction of fatty alcohol with P₂O₅. The chosen mol ratio of fatty alcohol and P₂O₅ determines the amounts of mono-, di- and trialkylester, of oligomeric esters, of free fatty alcohol and of phosphoric acid. Several methods are used for the characterisation and determination of the individual components, the potentiometric titration, the ³¹P-nuclear magnetic resonance, the gel permeation chromatography, the ion chromatography and the supercritical fluid chromatography. The combination of all the results of the applied methods provides the key to the composition of the phosphoric acid ester. The results of the analysis are checked by a phosphorus calculation. This analytical procedure can be applied to phosphoric acid partial esters in the acid and salt form. The analysis of alkylethoxyphosphoric esters is done with the exclusion of the chromatographic methods.     

Production of branched-chain fatty acids from sterculia oil

Methyl sterculate was rearranged by use of 0.5% of rhodium catalyst to isomeric conjugated diene fatty acid methyl esters containing both methylene-and methyl-branched isomers. The rearanged products were hydrogenated directly to saturated, methyl-substituted, branched-chain fatty acid methyl esters with the methyl substituent at one of the positions formerly occupied by the cyclopropenoid ring. The crude branched-chain fatty acids from these esters were purified by recrystallization from a mixed solvent of ethanol and water (80:20, v/v) and flash distillation; the product contained about 90% of branched-chain fatty acids (C₁₉:80%, C₁₈:10%). Esters of the branched-chain fatty acid were prepared with 2-ethylhexyl alcohol or trimethylolpropane, and the characteristic properties of these esters were investigated. The branched-chain fatty esters appear to have potential utility in lubricants; other uses may be possible. Presented at the AOCS meeting in New Orleans, May 1981.     

Preparation of malvalic and sterculic acid methyl esters from Bombax munguba and Sterculia foetida seed oils

A method has been developed for the preparation of highly pure malvalic (cis-8,9-methyleneheptadec-8-enoic) and sterculic (cis-9,10-methyleneoctadec-9-enoic) acid methyl esters starting from Bombax munguba and Sterculia foetida seed oils. The methyl esters of these oils were prepared by sodium methylate-catalyzed transmethylation followed by cooling (6°C) the hexane solution of crude methyl esters and separation of insoluble fatty acid methyl esters by centrifugation in the case of B. munguba and by column chromatography in the case of S. foetida. Subsequently, the saturated straight-chain fatty acid methyl esters were almost quantitatively removed by urea adduct formation. Finally, methyl malvalate and methyl sterculate were separated from the remaining unsaturated fatty acid methyl esters, in particular methyl oleate and methyl linoleate, by preparative high-performance liquid chromatography on C₁₈ reversed-phase using acetonitrile isocratically. Methyl malvalate and methyl sterculate were obtained with purities of 95–97 and 95–98%, respectively.     

Eiution characteristics of fatty acid methyl esters on capillary columns

The elution characteristics of fatty acid methyl esters on support-coated and open tubular capillary columns were investigated using reference standards and natural mixtures of fatty acid methyl esters. Over an extended range of fatty acid methyl esters chain lengths (C-11–C-26), the plot of the log of the adjusted retention time, t′_R, vs. number of carbon atoms in the fatty acid chain was not linear, as has been previously assumed by many investigators. With support-coated open tubular columns and with diethylene glycol succinate as the stationary phase, the relationship between the log of the retention time and carbon number was best approximated by a second-order equation: log (t′_R)_x=α+β(CN_x)+γ(CN_x)² where α, β, and γ are the virial coefficients of the equation. In addition, for the longer fatty acid methyl esters, the plots all tended to converge. Hence, for data from capillary columns, especially over a wide range of carbon numbers, all tentative indications based upon linear log plots and parallel lines for different homologous series of fatty acid isomers should be viewed with caution. A method is presented for identifying peaks from capillary columns; it uses quadratic equations and three reference fatty acid methyl ester standards for each homologous series being studied.     

Quantitation of fatty acids from flue-cured tobacco by combined preparative thin layer chromatography-gas chromatography

Flue-cured tobacco was subjected to alkaline hydrolysis, and, after acidification, the fatty acids and nonsaponifiables were extracted into hexane. Treatment of the hexane extract with diazomethane yielded fatty acid methyl esters. The methyl esters were separated from interfering hydrocarbons and sterols by preparative thin layer chromatography (PTLC). After addition of an internal standard, the esters were quantitated by gas chromatography on the column packing, Silar 10C. Quantitation of the C₁₄-C₃₂ fatty acid esters was possible by means of temperature programming.     

Metathesis of Unsaturated Fatty Esters

The development of a homogeneous catalyst [WCl₆/Sn(CH₃)₄) for the metathesis of unsaturated fatty esters encloses new routes in fat chemistry. By these reactions an exchange of alkylidene moities takes place, thus methyl oleate is converted into 9-octadecene and 9-octadecenedioic dimethyl ester. The metathesis of poly-unsaturated esters leads to a much larger number of products, namely polyenes, mono- and dicarboxylic esters, and cyclopolyenes. Specially the formation of 1,4-cyclohexadiene is of great interest. The metathesis of unsaturated fatty oils and the cometathesis with alkenes are also possible. Reactants of technical purity with a low acid value (<0.1) can undergo metathesis. The reaction is essentially thermoneutral; the distribution of products is statistical and no completion of the reaction occurs in one way or an other. Thus separation of reaction products and unconverted material is necessary. By the metathesis of mono-unsaturated esters this can be done by fractional crystallization. A review is given of these and other applications on account of the latest research development.     

Metathesis of Unsaturated Fatty Esters

The development of a homogeneous catalyst (WCl₆Sn(CH₃)₄) for the metathesis of unsaturated fatty esters encloses new routes in fat chemistry. By these reactions an exchange of alkylidene moities takes place, thus methyl oleate is converted into 9-octadecene and 9-octadecenedioic dimethyl ester. The metathesis of poly-unsaturated esters leads to a much larger number of products, namely polyenes, mono- and dicarboxylic esters, and cyclopolyenes. Specially the formation of 1,4-cyclohexadiene is of great interest. The metathesis of unsaturated fatty oils and the cometathesis with alkenes are also possible. Reactants of technical purity with a low acid value (< 0.1) can undergo metathesis. The reaction is essentially thermoneutral; the distribution of products is statistical and no completion of the reaction occurs in one way or an other. Thus separation of reaction products and unconverted material is necessary. By the metathesis of mono-unsaturated esters this can be done by fractional crystallization. A review is given of these and other applications on account of the latest research development.     

DSC curing study of catalytically synthesized maleic‐acid‐based unsaturated polyesters

Unsaturated polyesters were synthesized based on ethylene glycol and maleic acid as unsaturated dicarboxylic acid, using a variety of saturated acids in the initial acid mixture, without or with different catalysts. The curing of the polyesters produced with styrene was studied using differential scanning calorimetry (DSC) under dynamic‐ and isothermal‐heating conditions. The FTIR spectra of the initial polyesters and cured polyesters were also determined. Curing is not complete at the end of DSC scan and the unreacted bonds were quantitatively determined from the FTIR spectra and by estimation based on literature data. The value of the mean degree of conversion (α) of all double bonds (styrene unit and maleate unit) was approximately α = 0.40. Using an appropriate kinetic model for the curing exotherm of polyesters, the activation energy (E_a), the reaction order (x) and the frequency factor (k_o) were determined. Because the kinetic parameters (ie E_a, k, x) affect the kinetics in various different ways, the curves of degree of conversion versus time at various isothermal conditions are more useful to compare and characterize the curing of polyesters. The kinetic parameters are mainly influenced by the proportion of maleic acid in the polyesterification reaction mixture and secondarily by the residual polyesterification catalyst. The degree of conversion of already crosslinked polyesters is greatly increased by post‐curing them at elevated temperature and for a prolonged time. © 2002 Society of Chemical Industry