Fatty acid halogen addition

Bromination of fatty acids in the a-position can be effected quite readily in the presence of phosphorus trichloride, red phosphorus or pyridine as catalysts or halogen carriers with acetic acid, the addition of acetic anhydride (to ensure the absence of water) improves the yield and facilitates the bromination. Examples are —... 

Other Reactions of Phospholipids. The unsaturated fatty acid groups in soybean lecithin can be halogenated. Acetic anhydride combined with the amino group of phosphatidylethanolamine forms acetylated compounds. PhosphoHpids form addition compounds with salts of heavy metals. Phosphatidylethanolamine and phosphatidjhnositol have affinities for calcium and magnesium ions that are related to interaction with their polar groups. 

In this work, halogens were added across the double bonds of unsaturated fatty acids (commercial available sunflower oil) to form addition compounds and the degree of uptake was measured. A measured excess of iodine monobrontide (IBr) was allowed to react with the oil in the dark. At the end of a timed period, an excess of K1 was added to convert the remaining IBr to The 1 formed was then titrated with standard thiosulfate. This was a back-titration method. A back-titration blank was also required, where the sample was omitted. The uptake of iodine was calculated... 

The pharmacokinetics of PFOS and PFOA have been investigated in animal studies [22-24]. Results indicate that both PFCs are well absorbed following oral exposure, and poorly eliminated. In addition, PFOS and PFOA are very persistent as they are not metabolized and undergo extensive enterohepatic circulation [25,26]. PFSAs and PFCAs are unique among other persistent halogenated organic contaminants as they do not preferentially accumulate in fatty tissues, but instead are predominately distributed in the liver, serum and kidney [22-24]. This may be explained by the fact that PFOS and PFOA bind to proteins, specifically )8-lipoproteins, albumin and liver fatty acid-binding proteins [27, 28]. 

The Codex Alimentarius standard includes limits for acidity, volatile matter, insoluble impurities, peroxide value, colour, odour, taste, iron, copper, K27o, AK, permitted additives, contaminants (lead, arsenic, halogenated solvents), refractive index, saponification value, iodine value and unsaponifiable matter. Physical and chemical constants, such as iodine value and saponification value, are not found in the EU regulation. This is explained by the fact that more definite information is obtained by determining fatty acid composition, sterol and wax composition, trans fatty acid content, stigmastadiene, and so on. 

The rate of addition of halogen to unsaturated fatty acids decreases in the order Cl2 > Br2 > I2. Unsaturated acids and their esters and amides usually give good yields of bromine adducts at temperatures as low as —5 to —25° in the usual solvents — esters also without solvents — irradiation having considerable accelerating effect. 

Terpene esters can be made by the direct addition of fatty acids and halogenated and thiocyanated fatty acids to terpene hydrocarbons, ethers, and esters. Since the bicyclic terpimes (camphene, a-rpinene, and /3-pinene) are more reactive than the monocyclic, they are the preferable starting materials. 

Beres et al. (1957) have described the preparation of I -triolein as follows I -monochloride has been added to one of the double bonds in the fatty acid part of glyceryl trioleate. This material is a clear, colorless oil liquid at room temperatiure. Repeated assays have shown that 98 to 100% of the P is bound to the neutral fat. However, thin-layer chromatography has revealed that P and P can react to a greater extent widi minor lipid contaminants than with the triolein itself (Tuna et al., 1963 Snyder and Kimble, 1965). Presumably, the iodine and chlorine atoms of ICl add randomly at tihe double bond of oleic acid. The addition of Cl across the double bond of monoolein was recently described by Sink et ail. (1965). The reader is further referred to a detailed review by Sonntag (1961) for a discussion of reaction mechanisms involved in the halogenation of unsaturated lipids. 

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