Saturated fatty acids, esters

The intermediate m hydrogenation formed by reaction of the unsaturated ester with the hydrogenated surface of the metal catalyst not only can proceed to the saturated fatty acid ester but also can dissociate to the original ester having a cis double bond or to its trans stereoisomer Unlike polyunsaturated vegetable oils which tend to reduce serum cholesterol levels the trans fats produced by partial hydrogenation have cholesterol raising effects similar to those of saturated fats... 

Most of the technically produced a-sulfo fatty esters are prepared from unbranched saturated fatty acid esters that are derived from 8 22 carboxylic acids and Cj-C3 alcohols. In particular the C12 (lauric), C14 (myristic), C16 (palmitic), and C18 (stearic) acids are interesting because the ester sulfonates... 

Some metalworking formulators have noted fallout problems with methyl lardate and methyl tallowate if their products are stored in drums or tanks without agitation, especially in cooler weather. Over time, the saturated fatty acid esters tend to crystallize and settle, leaving a cloudy or opaque substance in the bottom of the storage container. In sample bottles, this settled opaque material can appear to be as much as 50% of the volume of the total sample. 

Carotenoid esters have been reported from a few plant sources (Hitchcock and Nichols, 1971). Flower pigments, for example, are known to contain saturated fatty acid esters of carotenoid alcohols. These compounds are also found in green algae. Where dihydroxy alcohols are involved then both substituents are usually esterified, for example ... 

Deuterium labelling has been extremely useful in MS studies. For instance, the unexpected formation of the (M—43) ion in the mass spectra of saturated fatty acid esters, resulting from the intrachain expulsion of C-2, C-3 and C-4 was demonstrated using deuterium labelling (Ryhage and Stenhagen, 1959, 1960). Deuterium has also been used to elucidate the mechanisms by which water is lost under electron impact conditions from glycerides (Morrison et al., 1970 Aasen etaL, 1970 Klein and Kemp, 1977). 

In this experiment, you will convert the liquid methyl oleate, an "unsaturated" fatty acid ester, to solid methyl stearate, a "saturated" fatty acid ester, by catalytic hydrogenation. 

Most of the technically produced a-sulfo fatty esters are prepared from unbranched saturated fatty acid esters that are derived from C8-C22 carboxylic acids and Ci C3 alcohols. In particular, the C12 (lauric), C14 (myristic), C16 (palmitic), and Cig (stearic) acids are interesting because the ester sulfonates with these carbon chains have the best properties for surfactant applications. Triglycerides with the needed number of carbons are available in coconut oil (—48% C12, 17% C14), palm kernel oil (-50% C12, 17% C14), palm oil (—46% Cie), and tallow (—26% Cie, 23% Cig) [3,8]. Unsaturated esters normally contained in natural oils and tallow (e.g., tallow contains about 43% of oleic oil) cause an undesirable color of the ester sulfonates. Therefore, the esters must be distilled or hydrogenated before sulfonation so that their iodine number is less than 0.5 [38]. 

Natural fats are glycerol esters of fatty acids known as triglycerides. Unsaturated fats are generally liquids (oils) at room temperature, while triglycerides rich in saturated fatty acids are generally solids. View tristearin and triolein. Which one of these is saturated and which is unsaturated Are die double bonds in the unsaturated fat cis or transl... 

SFC has played an important role in the extraction and isolation of fatty acids [355,356]. Underivatised fatty acids and methyl esters of fatty acids are surprisingly easy to elute using a bonded phase or a silica based packed column and pure C02, probably due to the long hydrocarbon tails on the molecules [357]. On the other hand, most aromatic and polysubstituted acids will not elute. Triglycerides with saturated fatty acids can be analysed faster with pSCF-ELSD than with GC-FID and do not require sample preparation [358]. Using... 

Fig.i General biosynthetic pathways for the production of alcohol, aldehyde, and acetate ester pheromone components in female moths. Top production of saturated fatty acids. Middle production of monounsaturated fatty acids and limited chain shortening produces intermediate compounds that can be reduced to an alcohol. Aldehyde and acetate ester pheromones are produced by an oxidase and acetyl-transferase, respectively. Bottom biosynthetic pathway for the production of the acetate ester pheromone components in the cabbage looper moth, Trichoplusia ni. The CoA derivatives are reduced and acetylated to form the acetate esters. Additional pheromone components include 12 OAc and ll-12 OAc... 

PGF2a-1,15-lactone-11-acetate (140) and PGF3ct-l,15-lactone-11-acetate (141) [174-176]. Further, T. fimbria reproductive tissues and egg masses contained a relatively high concentration of saturated and unsaturated long-chain fatty acid esters of PGF2 and PGF3(r (142, 143) [177, 178]. 

The physical and chemical properties of individual oils and fats are determined by the nature and proportions of fatty acids that enter into the triglycerides composition. Animal and dairy fat like plant oils are dominated by triacylglycerols, with steroids present as minor components, cholesterol and its esters being the most significant. The triacylglycerols of animal fats differ from plant oils since they contain more of the saturated fatty acids and consequently are solid at room temperature. 

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. 

Fatty acid esters also play a role in the communication system of the hide beetle, Dermestes maculatus. In a sex specific gland, situated at the ventral side of the fourth sternite, males produce a bouquet of isopropyl esters of fatty acids showing 12,14,16,and 18carbon atoms [211]. Apart from the esters ofthefour saturated acids and isopropyl (Z)-hexadec-9-enoate as well as isopropyl oleate,... 

Nizigiyimana, L. Rajan, P.K. Haemers, A. Claeys, M. Derrick, P.J. Mechanistic Aspects of High-Energy Collision-Induced Dissociation Proximate to the Charge in Saturated Fatty Acid n-Butyl Esters Ca-tionized With Lithium. Evidence for Hydrogen Radical Removal. Rapid Commun. Mass Spectrom. 1997, 11, 1808-1812. 

Methyl linoleate, methyl oleate from methyl linoleate, methyl oleate, methyl esters of saturated fatty acids KY Toluene [184]... 

Fats and oils are esters of the trihydric alcohol glycerol with long-chain fatty acids. The descriptor fat or oil is applied according to whether the material is a solid or liquid at room temperature it has no chemical meaning. All three fatty acids in the ester may be the same, or they may be different. Common saturated fatty acids... 

Ester synthesis of cholesterol linoleate. Cholesterol fatty acid ester is an important cell membrane lipids and has many applications in cosmetics, pharmaceutical and other industries. Akehoshi et aL(7) reported the ester synthesis of the cholesterol fatty acid ester with native lipase. Synthesis of the cholesterol fatty acid ester was also carried out in water-saturated n-hexane by palmitic acid-modified lipase. As shown in Table III, this system made it possible for the synthesis of the cholesterol fatty acid ester in organic solvents using the modified lipase. 

Lecithins and related phospholipids usually contain a saturated fatty acid in the C-l position but an unsaturated acid, which may contain from one to four double bonds, at C-2. Arachidonic acid is often present here. Hydrolysis of the ester linkage at C-2 yields a l-acyl-3-phosphoglycerol, better known as a Iysophosphatidylcholine. The name comes from the powerful detergent action of these substances which leads to lysis of cells. Some snake venoms contain phospholipases that form Iysophosphatidylcholine. Lysophosphatidic acid (l-acyl-glycerol-3-phosphate) is both an intermediate in phospholipid biosynthesis (Chapter 21) and also a signaling molecule released into the bloodstream by activated platelets.15... 

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