Hydrogenation of conjugated fatty acids with hydrazine

The reduction of α- and β-eleostearic acids with hydrazine has been studied. GLC analysis of the products coupled with oxidative degradation using permanganate-periodate reagent showed an initial attack mainly at the 9,10 and 13,14 bonds in the triene without change in configuration. The method should be useful in structural studies on conjugated fatty acids. Issued as NRC No. 7987.     

Hydrogenation of cyclopropenoid fatty acids occurring in cottonseed oil

The hydrogenation of cyclopropenoid acids and their relative reactivities during hydrogenation as compared to linoleic and oleic acids were examined. Pure methyl sterculate and purifiedSterculia foetida oil and its methyl esters, which have a cyclopropene content more than 60 times that of cottonseed oil, were used for the hydrogenation experiments. Nickel, palladium and platinum catalysts were used. The effect of temperature and type of catalyst were demonstrated in a series of hydrogenation experiments of safflower andS. foetida oil mixtures, and methyl oleate and methyl dihydrosterculate mixtures. Partial hydrogenation of methyl sterculate formed as many as twenty compounds in addition to the cyclopropenoid derivatives. Most of these compounds were monounsaturated. The cyclopropene group hydrogenated very readily compared to the 9,12-diene system in linoleate. The cyclopropane group obtained by hydrogenating the cyclopropenoid acids group was quite resistant to further attack by hydrogen and nickel catalyst had little effect. With palladium catalyst, a temperature of 180 C was necessary for the reaction to go to completion. Platinum in acetic acid was a good system for hydrogenolysis of the cyclopropane group at 80 C. Retired.     

Hydrogenation of unsaturated fatty acids to unsaturated fatty alcohols: III. Comparison of different soap catalyst systems

Copper oleate and cadmium oleate catalysts have been replaced by other metal compounds. Silver was the only metal which could be substituted for copper in the ratio range studied. Using nickel oleate, the degree of saturation of the double bond decreased with increasing cadmium oleate concentration. No comparable substitute was found for Cd. The composition of the final components is influenced by the use of a paraffinic solvent, which also has an effect on the saturation of the double bond. An explanation is given for the behavior of the catalyst when the reaction is not selective and is carried out in a paraffinic solvent. The catalytic system Ag/Cd soaps was also studied kinetically and analytically. The results show that the mechanism of the reaction using silver soap is identical with the one using copper soap.     

Hydrogenation of unsaturated fatty acids to unsaturated fatty alcohols: I. Study of Cu and Cd oleates as catalysts

The catalyst system containing copper and cadmium oleates as used in selective hydrogenations was analyzed. The reddish brown reaction mixture as such and after precipitation by alcohol was subjected to polarographic, spectroscopic, x-ray and electron-microscopic analysis. The conclusion drawn was that the mixture is a heterogeneous system. From an electron micrograph it was observed that the average particle size is 48 Å. It was also possible to determine the mean degree of oxidation of copper in the precipitate, the results indicating that the copper is in its metallic state. Cadmium is present as cadmiumoleate, which stabilizes the copper colloid during the reaction.     

Hydrogenation of a fatty acids is not influenced by the position it occupies on a triglyceride molecule

Randomly rearranged soybean oil (Iodine Value 128) was hydrogenated with samples being taken at decrements of 10 I.V. units. The composition of the fatty acids occupying the various positions of the triglyceride molecules of these fats was determined. The results demonstrate that the position an unsaturated fatty acid occupies on a triglyceride molecule does not influence its rate of hydrogenation.     

Metabolism of odd-numbered fatty acids and even-numbered fatty acids in mouse

Fatty acids are converted into energy via beta-oxidation. Although almost all natural occurring fatty acids are even-numbered, there are some odd-numbered fatty acids too. The details of the metabolism rate of odd-numbered fatty acids, however, are not clear. In the present study, we simultaneously administered a triacylglycerol containing four types of labeled even-numbered (palmitic acid and stearic acid) and odd-numbered (pentadecanoic acid and heptadecanoic acid) fatty acids to mice to compare the rates of their metabolism. The rates of metabolism were evaluated based on the accumulation of the labeled fatty acids in the small intestine epithelium, liver, and epididymal fat. Odd-numbered fatty acids accumulated mainly in the epididymal fat. In contrast, there was no accumulation of even-numbered fatty acids observed in the small intestine epithelium, liver, or epididymal fat. These results suggest that odd-numbered fatty acids might not be favorable substrates for beta-oxidation-related enzymes.     

Synthetic fatty acids

Manufacture of fatty acids from petroleum and natural gas is a large industry worldwide and has important implications in the U.S. Eastern Europe produces an estimated 1.2 billion pounds by air oxidation of hydrocarbons compared to an estimated 956 million pounds of natural fatty acids from the U.S., in 1978 (exclusive of tall oil fatty acids). The enormous production of SFA’s in Eastern European countries and in Russia is done by continuous air oxidation of fresh and recycled mixed aliphatic hydrocarbons. Since the products contain proportions of odd-numbered straight chain acids, they have not been used edibly, but have been applied to the manufacture of industrial products such as soap, lubricants, plasticizers and the like. Another European approach (Liquichimica, Italy) for SFA is the caustic fusion (and oxidation) of branched chain alcohols produced by carbonylation and reduction of olefins. American potential technology is diversified but has not yet been translated to production scale, presumably because of the plentiful supply of natural fats and oils that is available.     

Production of fatty alcohols from fatty acids

Detergent-range alcohols from natural feedstock can be produced by high pressure hydrogenation of either methyl esters or fatty acids. The increasing quantities of fats and oils on the world market secure a reliable and economically priced material. Although fatty acid is an abundant worldwide commodity, most alcohol producers hydrogenate methyl esters, because direct hydrogenation of fatty acids is difficult as the catalyst is sensitive to acid attack. The process described here makes it possible to hydrogenate fatty acids directly to alcohols of high quality without prior esterification. The reaction takes place in the liquid phase over a fine-grained copper chromite slurry in a single reactor vessel. A special reactor design with an optimum arragement of the feeding nozzles causing an appropriate circulation of the reacting components inside the reactor facilitates the rapid “in situ” esterification reaction. This minimizes the free fatty acid concentration in the reactor to nearly zero. This results in a low consumption of catalyst. The most important advantages of the process are: direct feed of fatty acids of various origins, use of reasonably priced raw materials such as soapstock fatty acids and lower grade tallow acids, no process steps with methanol, and excellent economics. The process is industrially proven.     

Separation of fatty acids

Fatty acid separations which do not involve fractional distillation are discussed. Various methods of separating fatty acids from a practical point of view and the most salient facts of each process are described.     

Essentiality of fatty acids

All fatty acids have important functions, but the term “essential” is applied only to those polyunsaturated fatty acids (PUFA) that are necessary for good health and cannot be completely synthesized in the body. The need for arachidonic acid, which is utilized for eicosanoid synthesis and is a constituent of membrane phospholipids involved in signal transduction, is the main reason why the n-6 class of PUFA are essential. Physiological data indicate that n-3 PUFA also are essential. Although eicosapentaenoic acid also is a substrate for eicosanoid synthesis, docosahexaenoic acid (DHA) is more likely to be the essential n-3 constituent because it is necessary for optimal visual acuity and neural development. DHA is present in large amounts in the ethanolamine and serine phospholipids, suggesting that its function involves membrane structure. Because the metabolism of n-6 PUFA is geared primarily to produce arachidonic acid, only small amounts of 22-carbon n-6 PUFA are ordinarily formed. Thus, the essentiality of n-3 PUFA may be due to their ability to supply enough 22-carbon PUFA for optimal membrane function rather than to a unique biochemical property of DHA.     

Hydrogenation of fatty acid methyl esters to fatty alcohols at supercritical conditions

Extremely rapid hydrogenation of fatty acid methyl esters (FAME) to fatty alcohols (FOH) occurs when the reaction is conducted in a substantially homogeneous supercritical phase, using propane as a solvent, over a solid catalyst. At these conditions, the limitations of hydrogen transport are eliminated. At temperatures above 240°C, complete conversion of the starting material was reached at residence times of 2 to 3 s, which is several orders of magnitude shorter than reported in the literature. Furthermore, formation of by-products, i.e., hydrocarbons, could be prevented by choosing the right process settings. Hydrogen concentration turned out to be the key parameter for achieving the above two goals. As a result of the supercritical conditions, we could control the hydrogen concentration at the catalyst surface independently of the other process parameters. When methylated rapeseed oil was used as a substrate, the hydrogenation catalyst was deactivated rapidly. However, by using methylated sunflower oil, a catalyst life similar to that obtained in industrial processes was achieved. Our results showed that the hydrogenation of FAME to FOH at supercritical conditions is a much more efficient method than any other published process.     

Estolides from meadowfoam oil fatty acids and other monounsaturated fatty acids

The formation of estolides was detected during the studies on dimerization of meadowfoam oil fatty acids. By adjusting the reaction conditions, it was possible to produce monoestolides with little dimer or trimer formations. Estolides have potential use in lubricant, cosmetic and ink formulations and in plasticizers. This paper reports the conditions for production of estolides from mixed meadow-foam fatty acids, commercial oleic acid, high-oleic sun-flower oil fatty acids,cis-5,cis-13-docosadienoic acid, petroselinic acid and linoleic acid.     

Hydrogenation of unsaturated fatty acids to unsaturated fatty alcohols: II. Kinetics and mechanism of the reaction using Cu and Cd oleates as catalysts

The kinetics and mechanism of the Cu and Cd-soap-catalyzed hydrogenation of oleic acid have been studied. The reaction is first order in Cd and H₂, and also first order in Cu if the double bond is completely preserved during reduction of the carboxyl group to the hydroxyl group. It will deviate from this order if the selectivity is lower owing to an increased Cu concentration. The reaction rate-determining step is independent of the Cd concentration. Its activation energy, of 13.4 kcal/mole, corresponds to that of the chemisorption of hydrogen on Cu. Unsaturated and saturated fatty acids of the same chain length have the same reaction rate. A decrease of the chain length causes a decrease in the reaction rate and in the final degree of conversion. Water and low molecular weight acids have an inhibitory effect on the reaction. A reaction mechanism is proposed which is based on the assumption that cadmium oleate plays a double role: it stabilizes the copper sol and is intermediate for the hydrogenation.     

由直链不饱和脂肪酸异构制备支链脂肪酸的研究进展

介绍了直链不饱和脂肪酸制备支链脂肪酸的研究现状,综述了脂肪酸异构机理,异构催化剂如白土催化剂、沸石催化剂,催化剂的筛选原则,着重讨论了各种常用沸石对于脂肪酸异构反应不同的影响以及现有的合成工艺。分析了脂肪酸的分离技术,包括精馏分离法、溶剂结晶法、尿素包结法、超临界流体萃取法的优缺点,指出沸石催化生产支链饱和脂肪酸的关键问题是需要解决混合脂肪酸作为原料反应的选择性问题,其相关的基础性工作,如更明确的反应机理和催化剂结构参数对反应的影响,仍是将来的研究方向。     

Hydrogenation of carboxylic acids by rhenium-osmium bimetallic catalyst

Hydrogenation of carboxylic acids to alcohols at low temperature and under low pressure was achieved by using a new catalyst system, a rhenium-osmium bimetallic catalyst. The most active catalyst was prepared by the reductionof the corresponding metal oxides with hydrogen in the presence of succinic acid. Decanoic acid was hydrogenated to decanol in high conversions at 25∼100 atm and 100∼120°C. Decane was formed as a by-product by overreduction of the alcohol. The selectivity of alcohol was improved by the addition of thiophene as a modifier of the catalyst.     

Viscosities of fatty acids and methylated fatty acids saturated with supercritical carbon dioxide

The viscosities of several types of lipids saturated with supercritical carbon dioxide (SC-CO₂) were measured with a high-pressure capillary viscometer. Oleic acid and linoleic acid were evaluated from 85 to 350 bar at 40 and 60°C. The more SC-CO₂-soluble methylated derivatives of these fatty acids were evaluated from 90 to 170 bar at 40 and 60°C. The complex mixture of anhydrous milk fat (AMF) was evaluated from 100–310 bar at 40°C. The viscosities of the methylated fatty acids saturated with SC-CO₂ decreased between 5 and 10 times when the pressure increased from 1 to 80 bar, followed by a further decrease by a factor of 2 to 3 when the pressure was increased from 80 to 180 bar. The viscosities of the fatty acids and AMF saturated with SC-CO₂ had viscosity reduction similar to the methylated fatty acids between 1 and 80 bar, but they decreased much less between 80 and 350 bar. At constant pressure, the viscosity of the fatty acids and AMF decreased with increasing temperature, whereas the viscosity of the methylated fatty acids increased with increasing temperature. The lipid/SC-CO₂ mixtures were Newtonian, and their viscosities were best interpreted by using the mass concentration of dissolved SC-CO₂ in the lipids and the pure component viscosities.     

Marine-derived fatty acids of fish oils as raw materials for fatty acids manufacture

Fish oils, often an abundant source of C₂₀ and C₂₂ fatty acids, could supplement rapessed oil in the manufacture of long chain saturated fatty acids. Herring oil, traditionally the fish oil of choice, is in very short supply due to depletion of fishery stocks. Menhaden oil, when made from fish caught in the Atlantic, could furnish a steady supply with long chain acids at about the 30% level. Oil made from other species such as anchovy or pilchard need further data on fatty acid content and variability. Manufacture of polyunsaturated fatty acids from fish oils is hampered by lack of suitable procedures. Potential markets for fish oil polyunsaturates especially in the pharmaceutical field seem promising.     

Furan fatty acids – valuable minor fatty acids in food

Furan fatty acids (F‐acids) are heterocyclic lipid components with a furan moiety in the centre of the molecule. Reports on F‐acids in the literature are rather scarce, although they are considered as particularly valuable food ingredients. F‐acids occur as minor compounds in the lipids of different food samples. Despite the low concentrations, some studies produced evidence that the F‐acids are excellent radical scavengers and thus are able to protect polyunsaturated fatty acids from lipid peroxidation. Accordingly, they may play a currently underrated and largely overlooked positive role in human nutrition. The limited data available result from difficulties in the analysis of these trace compounds. F‐acids in food can hardly be determined without selective enrichment and the use of gas chromatography with mass spectrometry for their determination. The lack of reference standards is a further drawback that hampers the exact assessment of the actual relevance of F‐acids in human nutrition.