Oleic acid esterified

Unlike many fats and oils, the cocoa butter used to make chocolate is remarkably uniform in composition. All triacylglycerols contain oleic acid esterified to the 2° OH group of glycerol, and either palmitic acid or stearic acid esterified to the 1 ° OH groups. Draw the structures of two possible triacylglycerols that compose cocoa butter. 

Carbonylation, or the Koch reaction, can be represented by the same equation as for hydrocarboxylation. The catalyst is H2SO4. A mixture of C-19 dicarboxyhc acids results due to extensive isomerization of the double bond. Methyl-branched isomers are formed by rearrangement of the intermediate carbonium ions. Reaction of oleic acid with carbon monoxide at 4.6 MPa (45 atm) using 97% sulfuric acid gives an 83% yield of the C-19 dicarboxyhc acid (82). Further optimization of the reaction has been reported along with physical data of the various C-19 dibasic acids produced. The mixture of C-19 acids was found to contain approximately 25% secondary carboxyl and 75% tertiary carboxyl groups. As expected, the tertiary carboxyl was found to be very difficult to esterify (80,83). 

There has been only one major use for ozone today in the field of chemical synthesis the ozonation of oleic acid to produce azelaic acid. Oleic acid is obtained from either tallow, a by-product of meat-packing plants, or from tall oil, a byproduct of making paper from wood. Oleic acid is dissolved in about half its weight of pelargonic acid and is ozonized continuously in a reactor with approximately 2 percent ozone in oxygen it is oxidized for several hours. The pelargonic and azelaic acids are recovered by vacuum distillation. The acids are then esterified to yield a plasticizer for vinyl compounds or for the production of lubricants. Azelaic acid is also a starting material in the production of a nylon type of polymer. 

Another type of sulphated product, an ester sulphate, can be prepared by esterifying a fatty acid such as ricinoleic or oleic acid with a short-chain (C3-C5) alcohol and then sulphating. Such products are particularly useful foaming, wetting and emulsifying agents an example is sulphated butyl ricinoleate (9.11). 

This structure shows a triglyceride with three identical saturated fatty acids. Tripalmitin, in which all fatty acids are palmitic acid (n = 14), provides one example of a fat. Triolein is an oil containing only oleic acid moieties esterified to glycerol. In contrast to these two examples, it is by no means necessary that the three fatty acid groups be derived from only one fatty acid. For example, we might have a triglyceride that contains one saturated fatty acid, say palmitic acid, one monounsaturated fatty acid, say oleic acid, and one polyunsaturated fatty acid, perhaps arachidonic acid. 

Figure 11.15 The reaction catalysed by lecithin cholesterol acyltransferase (LCAT). LinoLeate is transferred from a phospholipid in the blood to cholesterol to form cholesteryl linoleate, catalysed by LCAT. The cholesterol ester forms the core of HDL, which transfers cholesterol to the liver. Discoidal HDL (i.e. HDL3) is secreted by the liver and collects cholesterol from the peripheral tissues, especially endothellial cells (see Figure 22.10). Cholesterol is then esterified with lin-oleic acid and HDL changes its structure (HDL2) to a more stable form as shown in the lower part of the figure. R is linoleate.

Seed oil triglycerides consist of three fatty acids esterified to glycerin. Although most plants produce at least some Cie fatty acids, the majority of the triglycerides are comprised of Cig fatty acids. The balance of the fatty acids is quite specific to the plant from which the oil is derived, but the most prominent fatty acids among all plant species consist of a series of 18-carbon fatty acids containing zero, one, two, or three sites of unsaturation. These fatty acids are stearic, oleic, linoleic, and linolenic acids, respectively. These are the main fatty acids found in most seed oils and are illustrated in Fig. 5. 

The structures of common lipids, (a) The structures of saturated and unsaturated fatty acids, represented here by stearic acid and oleic acid, (b) Three fatty acids covalently linked to glycerol by ester bonds form a triacylglycerol. (c) The general structure for a phospholipid consists of two fatty acids esterified to glycerol, which is linked through phosphate to a polar head group. The polar head group may be any one of several different compounds—for example, choline, serine, or ethanolamine. 

Ricinoleic acid (Figure 3.8) is the major fatty acid found in castor oil from seeds of the castor oil plant (Ricinus communis Euphorbiaceae), and is the 12-hydroxy derivative of oleic acid. It is formed by direct hydroxylation of oleic acid (usually esterified as part of a phospholipid) by the action of an 02- and NADPH-dependent mixed function oxidase, but this is not of the cytochrome P-450 type. Castor oil has a long history of use as a domestic purgative, but it is now mainly employed as a cream base. Undecenoic acid (A9-undecenoic acid) can be obtained from ricinoleic acid by thermal degradation, and as the zinc salt or in ester form is used in fungistatic preparations. 

Intestinal acyl-CoA cholesterol acyltransferase (ACAT-2, also present in liver), which esterifies free cholesterol with palmitic or oleic acid, is another enzyme that was identified early on as a potential target to inhibit cholesterol absorption because most cholesterol in chylomicrons is esterified before being secreted by enterocytes (6, 14). As for CEL, various inhibitors of this enzyme were also developed and tested with mixed results (10, 15-17). However, the importance of ACAT-2 was later confirmed by studies of gene-knockout mice, which exhibit markedly reduced cholesterol absorption and atherosclerosis when fed Western diet (18). Nonetheless, progress in developing effective ACAT inhibitors has been slow, in part because of concerns about the potential for deleterious systemic effects resulting from inhibition of the more widely expressed ACAT-1 (19). Despite these... 

Glyceryl Monooleate occurs as a clear liquid at room temperature. It has a mild, fatty taste. It is prepared by esterifying glycerin with food-grade oleic acid in the presence of a suitable catalyst such as aluminum oxide. It also occurs in many animal and vegetable fats such as tallow and cocoa butter. It is soluble in hot alcohol and in chloroform very slightly soluble in cold alcohol, in ether, and in petroleum ether and insoluble in water. It melts at around 15°. It may also contain tri- and diesters. 

It was shown by Balasubramanian et al. [51] that mixtures of non-esterified fatty acids, isolated from intestinal brush-order cells, were powerful inhibitors of lipid peroxidation apparently quite substantial amounts of free fatty acids are present in these cells. Subsequent work showed that the principal active constituent of this lipid mixture was oleic acid [52], and that it is highly likely that the mode of action of inhibition by the monounsaturated fatty acids of lipid peroxidation involves complexing transition metals which are therefore not available to act as catalysts in the peroxidation mechanism [53]. 

Fatty acids react with alkaline catalysts to form catalytically inactive soaps (3). The chemical reaction consumes one mole of fatty acid per mole of alkaline catalyst. Although fatty acid composition of the starting material varies, the content determined by titration reflects the amount of catalyst that would be consumed in a chemical reaction. By calculation, it may be determined that one gram of fatty acid (expressed as oleic acid) will react with about 0.2 g of anhydrous potassium hydroxide or 0.14g of anhydrous sodium hydroxide. Often, additional catalyst must be added to esterify a vegetable oil containing higher levels of fatty acids (3). Conversely, acid catalysts are not inactivated by fatty acids (3). In a unique reaction, fatty acids produced during biodiesel manufacture are actually used as a catalyst in their own esterification (see below). 

Triterpenols and sterols are present as free or esterified with fatty acids (oleic acid and linoleic acid as the most relevant). Total content of triterpens is between 100-300 mg/100 g of oil. 24-Methylen-cycloartanol and cycloartenol are dominant. Erythrodiol, uvaol and triterpenic acids (ursolic, oleanolic acids etc) have been described in the imsaponifiable fraction of olive oil. The terpenoid fraction is complex and many constituents are still imdefined. 

Thus, the oleic acid is a molecule having a significant lateral chain (Cl8) and, when esterified with glycerol, a bulky terminal ester group. Therefore, it cannot or just very slowly diffuse in the micropores of K1481 which has a crosslinking of 8 %. The reaction occurs mainly on the surface of the microspheres. On the other hand, the comparison of the activity of K1481 with that of the Amberlyst 119 resin shows that the sites located on the surface are accessible only by oleic acid since the conversion is much lower with the resin in bead form. 

In the TAG molecule, a chiral center develops when both primary hydroxy groups of the glycerol are esterified with two different FA, so that — owing to the position of the FA — a distinction can be made between sn-l, sn-2, and sn-3. The 1-position in the TAG of egg yoUc is primarily occupied by palmitic acid, the 2-position by oleic and linoleic acids, while there are oleic acid and saturated FA at the 3-position (Christie and Moore, 1970). In the PC fraction, the 2-position is occupied up to 87% by unsaturated FA (Privett et al., 1962 Gomall and Kuksis, 1971) (Table 14.6). 

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