Methyl esters of unsaturated fatty

In addition, polymeric phosphine-Pd(II) complexes are shown to be useful in the hydrogenation, hydrosilylation and hydroformylation of methyl ester of unsaturated fatty acid (118). 

Figure 7. Methyl esters of unsaturated fatty acids as resolved on the 25%-cyanopropyl-25%-phenyl methyl siloxane DB-225. Split Injection to a 30m x 0.25mm column coated with a 0.25 m bonded film, hydrogen carrier at 46cm/sec, isothermal at 200 °C. Components 1, 14 1 methyl myristoleate 2, 16 1 trans methyl palmite-laidate 3, 16 1 cis methyl palmitoleate 4, 18 1 trans methyl elaidate 5, 18 1 cis methyl oleate 6, 18 2 trans methyl linolea-laidate 7, 18 2 cis methyl linoleate 8, 18 3 methyl linoleate ...

The hydration method first proposed for analysing hydrocarbons [229] and methyl esters of unsaturated fatty acids [230] was then applied to studies of compounds of various classes such as alcohols, amines, amides, ketones, esters and nitriles [227]. It was shown [227] that at 140-250° C partial hydrogenolysis of halogenides, aldehydes and mercaptans takes place, which makes possible their determination without hindering structural studies. 

It has been possible to show with the help of adsorption TLC, that isomers are formed when the methyl esters of unsaturated fatty acids are ozonised each of the isomers from methyl oleate has been isolated in a pure state [175]. Compounds which are not easily fractionated by argentation TLC, like as-methyl octadecenoate (methyl oleate) and mw5- mw5-methyl octadecadienoate (trans-trans methyl hnoleate ) or the corresponding triglycerides, have been separated as their ozonides [170]. This method is suitable, however, only for lipids with up to four double bonds. Ozone reacts with more highly unsaturated compounds to form short chain ozonides and undelfined side products [170]. 

Small amounts of unsaturated lipids can be isolated using argentation TLC and the structure of these compounds then determined through analysis of their ozonolysis products. This method has been worked out above all for analysing mixtures of the methyl esters of unsaturated fatty acids [169]. 

Nishida, T.H., Tsuchiyama, H., Inoue, M. and Kummerow, F.A. (1960) Effect of intravenous injection of oxidized methyl esters of unsaturated fatty acids on chick encepha-lomalacia. Proc. Soc. Exp. Biol. Med. 105, 308-312. 

A total of 21 compounds present in the surface and cephalic extracts of the queen bumblebee, Bomhus terrestris, evoked responses in male antennae. These included saturated and unsaturated fatty acids, ethyl and methyl esters of the fatty acids, heptacosene, 2-nonanone, and geranyl geraniol. A blend of synthetic versions of these compounds elicited typical male mating behavior. 

Deman and Deman (1983) have investigated the determination of trans unsaturation in milk fat by infrared analysis and found values of 7.4% (winter) to 9.9%(summer) when the TGs were analyzed. These are higher than the quantities found by infrared analysis of methyl esters of the fatty acids. These quantities are isolated total trans bonds and do not give an estimate of the positional and polyunsaturated isomers which are present. The trans contents obtained by Deman and Deman are higher than the 4% found by Smith et al. (1978). 

Solvents. Table 71 contains solvent mixtures suitable for fractionating the most important lipid classes. Besides these solvents, the following have also been often used the methyl esters of unsaturated, positionally isomeric fatty acids have been separated from one another by triple development at —15° C using toluene [142] triglycerides have been fractionated with chloroform-carbon tetrachloride-methanol-acetic acid (50 -I- 50 + 1.5 -1- 0.5) [6, 7]. The separation of lecithins on silica gel H, impregnated with silver nitrate [5], is very satisfactory using chloroform-methanol-water (65 -1- 25 + 4) [5] (see also [57, 88]). 

The separation of the methyl esters of the fatty acids of pig testis lipids on the Carbowax 20M column is illustrated in Figure 5.8. Each of the main chain-length groups is reasonably well resolved. For example, three 16 1 isomers are seen and they are distinct from the C y fatty acids. Similarly the important C g components are clearly separated from a minor 19 1 fatty acid, and this is in a different region from each of the C20 unsaturated constituents. With the last, the only serious overlap problem is with 20 3(n-3), which co-chromatographs with 20 4(n-6) these are, however, just separable on a slightly more polar Silar 5CP column. Finally, all the biologically important C22 fatty acids are cleanly resolved. 

Silver-ion chromatography (Ag LC) has been successfully used for the separation of all lipid classes for instance, it is widely employed for the separation of triacylglycerols. Here, the elution order is related to the increasing degree of unsaturation and the configuration of the double bonds within each fatty acid, for the separation of positional isomers. In addition, SEC with two columns in series has been used, for instance, to separate oxidized triacylglycerols or to quantify products of oxidation in methyl ester of several fatty acids. Since every unsaturated lipid can undergo oxidation preparative LC is useful for the isolation of oxidation products for subsequent identification. 

Anyway, it is well known that micellar effects are common in hydroformylation conducted in all varieties of aqueous systems. The addition of surfactants often helps the reactions in biphasic media, possibly due to solubilization of hydrophobic reagents in micelles, which thus function like cooperative phase-transfer agents. For example, the hydroformylation of unsaturated fats or methyl esters of unsaturated long-chain natural fatty acids (oleic, linolenic acids) can be successfully done using biphasic tech-... 

Polymers Catalytic reactions involving C=C bonds are widely used for the conversion of unsaturated fatty compounds to prepare useful monomers for polymer synthesis. Catalytic C-C coupling reactions of unsaturated fatty compounds have been reviewed by Biermann and Metzger [51]. Metathesis reactions involving unsaturated fatty compounds to prepare co-unsaturated fatty acid esters have been applied by Warwel et al. [52], Ethenolysis of methyl oleate catalyzed by ruthenium carbenes developed by Grubb yields 1-decene and methyl 9-decenoate (Scheme 3.6), which can be very useful to prepare monomers for polyolefins, polyesters, polyethers and polyamide such as Nylon 11. 

Argentation thin-layer chromatography is an extemely useful procedure for the separation of methyl esters of fatty acids. Saturated fatty acids have the highest Rf values, which decrease with the increasing degree of unsaturation, and for a particular acid, the trans isomer usually travels ahead of its corresponding cis isomer. The solvents most commonly used contain hexane and diethyl ether (9 1) although a mixture of 4 6 is used to separate compounds with more than two double bonds. In order to separate positional isomers of the same acid, conditions must be carefully controlled and multiple development in toluene at low temperatures is often necessary. 

The solubility of C60 and C70 in a series of vegetable oils, namely olive, sunflower, peanut, soybean, linseed and castor oil, has been determined quantitatively spectrophotometrically. Additionally, the solubility of C60 and C70 has been determined quantitatively in the methyl esters of brassica oilseed and only qualitatively in molten cow butter, molten stearic acid and molten behenamide. The experimental results show that the solubility of fullerenes appears to be dependent on the unsaturation level of the fatty acids composing the vegetable oils being lower in oils with higher unsaturation level. The solubility has been found dependent also on the polarizability parameter of the vegetable oils. 

In an effort to improve separation efficiency, a novel configuration was reported by Albert and coworkers [107] describing a splitless capillary setup capable of separating components of a mixture of unsaturated fatty acid methyl esters. The chromatographic setup consisted of a versatile splitless connection enabling easy exchange between... 

Naturally occurring fatty alcohols used in the fragrance industry are produced principally by reduction of the methyl esters of the corresponding carboxylic acids, which are obtained by transesterification of natural fats and oils with methanol. Industrial reduction processes include catalytic hydrogenation in the presence of copper-chromium oxide catalysts (Adkins catalysts) and reduction with sodium (Bouveault—Blanc reduction). Unsaturated alcohols can also be prepared by the latter method. Numerous alcohols used in flavor compositions are, meantime, produced by biotechnological processes [11]. Alcohols are starting materials for aldehydes and esters. 

The flavour of distillates from apple and pear is characterised by typical aroma compounds from these fruits formed by enzymatic degradation of fatty acids to C6-fragments like hexanol, trans-2-hexenol, as well as ethyl esters and acetates of hexanoic acid. In distillates of pears, especially of the variety Bartlett pear, the characteristic pear flavour is mainly dominated by the ethyl and methyl esters of frans-2-czs-4-decadienoic acid and trans-2-trans-A-decadienoic acid [27-29], The biogenesis of these monounsaturated, diunsaturated, and triunsaturated esters may be explained by -oxidation of unsaturated linoleic and linolenic acid in the fruits. The sesquiterpene compound a-farnesene, which is formed during postharvest ripening and storage of Bartlett pears [28], shows that quality and intensity of distilled pear spirits is mainly influenced by the quality and degree of ripeness of the fruits. 

Smith et al. (1978) have described a procedure for the GLC determination of cis and trans isomers of unsaturated fatty acids in butter after fractionation of the saturated, monoenoic, dienoic, and polyenoic fatty acid methyl esters by argentation TLC. Total trans acids were much higher, as measured by infrared spectrophotometry than by GLC, probably because some of the acids could have two or more of the trans bonds designated as isolated by infrared spectrophotometry. Enzymatic evaluation of methylene-interrupted cis, cis double bonds by lipoxidase resulted in lower values than those obtained by GLC. The authors mention that the lipoxidase method is difficult, requiring considerable skill, and suggest that their method is suitable for the determination of the principal fatty acids in complex food lipids such as bovine milk fat. 

The vegetable oil used was rapeseed oil (Nacalai Tesque Kyoto, Japan) without further treatment. The fatty acid content of the rapeseed oil mainly consisted of unsaturated fatty acids (93 wt%), with the saturated fatty acids of palmitic and stearic acids accounting for only a small amount (7 wt%). Various fatty acids of oleic (C181), linoleic (C18 2), linolenic (C18 3), and palmitic (C16 0) acids as well as their methyl esters were purchased from Nacalai Tesque. Anhydrous methanol and distilled water were also supplied by the same company. 

Cold properties of biodiesel are highly correlated to the fatty acid composition. Biodiesel with a high content of saturated fatty acids, such as that from palm oil and coconut oil, possesses poor cold flow properties. On the other hand, biodiesel with a high content of unsaturated fatty acids possesses better flow properties at lower temperatures. However, biodiesel from highly unsaturated fatty acids with more than two double bonds has combustion problems. Therefore, in some countries, the content of highly unsaturated fatty acid methyl esters in biodiesel is kept low (5). 

Figure 4.2 GC/MS analysis of methyl esters prepared from a whole cell lipid extract of the YEpOLEX-HzPGDsI-transformed ole1 strain of S. cerevisiae total ion spectrum of fatty acid methyl esters resolved by capillary GLC. The culture was grown in liquid complete medium (YPD) at 30°C to a density of 2 x 107 cells/ml prior to extraction and methylation. The external mass standard nonadecanoic acid methyl ester (19 Me) was added to the cell pellet prior to extraction. Peaks corresponding to Z9-16 Me and Z9-18 Me reflect trace amounts of unsaturated fatty acids in the growth medium. (Reproduced with permission from Rosenfield et at, 2001. 2001 by Insect Biochemistry and Molecular Biology.)...

Also, bulky phosphite-modified rhodium catalysts are highly reactive for the hydroformylation of unsaturated fatty acid esters [23]. The catalyst was able to yield turnover numbers (TON) of 400-500 when moderate conditions with 20 bar synthesis gas pressure and 100°C were applied. These phosphites, like tris (2-ferf-butyl-methyl) phosphite, have higher activity than phosphines like triphenylphosphine. 

For the study of the physical and chemical properties of triply unsaturated fatty acids and for the comparison with y-linolenoic acid [6Z,9Z.12Z)-6,9,l2-octadeca-trienoic acid] coworkers of the Unilever Research Centre in Vlaardingen (Netherlands) synthesized some methyl esters of ( ,Z,Z)-trisunsaturated fatty acids 73). For the preparation of the esters of (2E,9Z, 12Z)-2,9,12-octadecatrienoic acid and of (2 ,11Z,14Z)-2,11,14-eicosatrienoic acid (68 a and b) they used the Wittig reaction to introduce the ( )-2-double bond into the starting diunsaturated aldehyde. Reduction of the acid chlorides of (7Z,10Z)-7,10-hexadecadienoie acid and of linolenoic acid (65a and b) with lithium tri-tert-butoxyaluminium hydride affords the corresponding aldehydes 66 a and b which can be olefinated with the stable ylide 67 to methyl ( ,Z,Z)-alkatrienoates 68a, b with a (Z)-2-isomer content of 4.6%73) (Scheme 13). 

To further the identification of the minor fatty acids in evening primrose oil, methyl esters of fatty acids were separated by column chromatography on a silver nitrate-silicic acid absorbent according to their degree of unsaturation (De Vries, 1963). The data obtained are summarized in Table 4.4 based on identification by gas chromatography-mass spectrometry. Of the saturated fatty acids, C13 0, C19 0, C21 0 and C23 0 had not been reported previously. A number of monounsaturated fatty acids have been reported previously in EPO... 

The methyl esters of the long-chain fatty acids can be subjected to exactly the same examination as outlined earlier in this chapter. In the usual case, these fatty acid esters will be composed largely of unsaturated (olefinic) linkages with little or no saturated components. This follows the pattern noted before for the substituents located at the C-2 position in other phosphoglycerides. A quantitative analysis of these fatty acids will show that there is 1 mol per mol of lipid phosphorus. The lysoalkenyletherphosphatidylcholine can then be studied further. 

Splitting, or the hydrolysis of triglycerides is usually performed with high-pressure steam, resulting in the formation of split crude fatty acids and glycerin. The production of fatty acids by more sophisticated splitting processes, such as hydrolysis of fatty methyl esters, ozono lysis of unsaturated fatty acids, and chemical oxidation is practiced in special situations. 

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