Fatty acids, brominated

Hexabromide value - bro- mid val(i)yu n. Hexabromide value is a measure of the amount of acids of the linolenic types which are present in a mixture of natural fatty acids. Bromine, under suitable conditions, forms addition compounds through addition at the unsaturated linkages. The hexabromides are separated from the dibromides and tetrabromides by reason of the insolubility of the former in cold ether. The hexabromide value is the percentage of hexabromide obtainable from a given material. 

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 —... 

Purification of industrial oils, kerosene/jet fuel, lubricating oils Mono- dicumyldiphenylamine Mono- dioctyldiphenylamine Dimer fatty acids Purification of xylenes Improvement of bromine number of recycle cumene in phenol plants Improvement of bromine number of recycle ethylbenzene in styrene plants based on liquid pha.se oxidation Alkylation of xylenes with diisobutylenes to mono-/ rr-butyI derivatives Phenyl xylyl ethane... 

If the nickel is introduced into the fatty acid in the solid form it is important that it should be absolutely free from sulphur, selenium, tellurium, arsenic, chlorine, iodine, bromine. Further, it is important that the nickel should have been prepared by the reduction of the oxide at a temperature not exceeding 300° C, and should not have been long exposed to the air prior to its use. 

Brominated, or iodinated natural or synthetic esters of Cl 1 to C24 fatty acids... 

The reaction of unsaturated hydrocarbons with bromine is synthetically important. Unsaturated fatty acids have been electrobrominated in an acetic acid/acetonitrile medium and at platinum electrodes [128]. The mechanism and rate constant for the process with oleic, erucic, and linoleic acid were elucidated. The a-bromination of a,f-unsaturated ketones has been reported [129] on the basis of the electrolysis of a substrate/CF3COOH/CuBr/Et4NOTs/ MeCN reaction system. CuBr is present as a catalyst. 

Guengerich, F.P. (1994) Metabolism and genotoxicity of dihaloalkanes. Adv. Pharmacol., 27,211-236 Guha, S.N., Schoneich, C. Asmus, K.D. (1993) Free radical reductive degradation of vic-dibromoalkanes and reaction of bromine atoms with polyunsaturated fatty acids possible involvement of Br(.) in the 1,2-dibromoethane-induced lipid peroxidation. Arch. Biochem. 

Brominated fatty acids are rare in nature. They have been found in sponges and other marine animals. Recently, the presence of (5E, 7E)-18-bromo-octadeca-5,17-diene-15-ynoic acid (221) and 18-bromo-octadeca-5,7,17-triynoic acid (222) has been described in a halophilic (present in hypersaline environments) terrestrial organism, the Central Asian lichen Acorospora gobiensis [171]. 

The interaction of diaryl tellurides and the esters of halogenated fatty acids, e.g. methyl bromacetate, gives diarvl-telluretin halide alkyl esters, e.g. (C6H5)2Te(Br).CH2.COOCH3. The halogen present may be chlorine, bromine or iodine, moist silver oxide replacing the bromine by the hydroxyl group. 

The amount of oil in a sample is determined by Scott oil analysis (AOAC, 1990e). This is a bromination reaction previously used to determine the number of fatty acid double bonds. This titration method quantifies the recoverable oil in fruits and fruit products based on the release of Br2 and the formation of limonene tetrabromide (Braddock, 1999). Figure Gl.5.3 illustrates the chemical reaction for the bromination of limonene. Other monoterpenes (a-pinene and citral) also react however, the method is accurate to within 10 ppm limonene (Scott and Valdhuis, 1966). For this procedure, limonene is co-distilled with isopropanol and titrated with a potassium bromide/bromate solution. 

Fig. 3.11 Agelas sp. An example of a very common marine sponge that produces a wide variety of halogenated metabolites such as the brominated fatty acids 733 and 734 (Photo J. R. Pawlik)...

The reader is referred to the section on fatty acids (3.8), which includes brominated fatty acids containing multiple acetylene groups. 

In contrast to MPO, eosinophil peroxidase (EPO) prefers to oxidize plasma level bromide (20-100 pM) to hypobromous acid (HOBr) and several biological targets are implicated, including nucleic acids and nucleosides (1480, 1482, 2376), proteins (1812, 1813, 2377, 2378), unsaturated fatty acids (2379), and low-density lipoprotein (2380, 2381). This EPO-dependent bromination is suggested to be involved in the pathogenesis of asthma (2382). Accordingly, both 3-bromotyrosine and 3,5-dibromotyrosine (1812,1813) are produced by EPO-induced bromination of tyrosine residues in lung tissue (1813, 2382). 

Garson MJ, Zimmermann MP, Hoberg M, Larsen RM, Battershill CN, Murphy PT (1993) Isolation of Brominated Long-Chain Fatty Acids from the Phospholipids of the Tropical Marine Sponge Amphimedon terpenensis. Lipids 28 1011... 

Carballeira NM, Emiliano A (1993) Novel Brominated Phospholipid Fatty Acids in the Caribbean Sponge Agelas sp. Lipids 28 763... 

Li Y, Ishibashi M, Sasaki T, Kobayashi J (1995) New Bromine-Containing Unsaturated Fatty Acid Derivatives from the Okinawan Marine Sponge Xestospongia sp. J Chem Res (S) 126... 

Brantley SE, Molinski TF, Preston CM, DeLong EF (1995) Brominated Acetylenic Fatty Acids from Xestospongia sp., a Marine Sponge-Bacteria Association. Tetrahedron 51 7667... 

Pham NB, Butler MS, Hooper JNA, Moni RW, Quinn RJ (1992) Isolation of Xestosterol Esters of Brominated Acetylenic Fatty Acids from the Marine Sponge Xestospongia testudinaria. J Nat Prod 62 1439... 

Rezanka T, Dembitsky V (1999) Brominated Fatty Acids from Lichen Acorospora gobien-sis. Phytochemistry 50 97... 

MacMillan JB, Molinski TF (2005) Majusculoic Acid, a Brominated Cyclopropyl Fatty Acid from a Marine Cyanobacterial Mat Assemblage. J Nat Prod 68 604... 

Carr, AC, Winterboum CC, van den Berg JJM (1996) Peroxidase-Mediated Bromination of Unsaturated Fatty Acids to Form Bromohydrins. Arch Biochem Biophys 327 227... 

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