Fatty acids trimers

The clay-cataly2ed iatermolecular condensation of oleic and/or linoleic acid mixtures on a commercial scale produces approximately a 60 40 mixture of dimer acids and higher polycarboxyUc acids) and monomer acids (C g isomerized fatty acids). The polycarboxyUc acid and monomer fractions are usually separated by wiped-film evaporation. The monomer fraction, after hydrogenation, can be fed to a solvent separative process that produces commercial isostearic acid, a complex mixture of saturated fatty acids that is Hquid at 10°C. Dimer acids can be further separated, also by wiped-film evaporation, iato distilled dimer acids and trimer acids. A review of dimerization gives a comprehensive discussion of the subject (10). 

Cowan Teeter (1944) reported a new class of resinous substances based on the zinc salts of dimerized unsaturated fatty acids such as linoleic and oleic acid. The latter is referred to as dimer acid. Later, Pellico (1974) described a dental composition based on the reaction between zinc oxide and either dimer or trimer acid. In an attempt to formulate calcium hydroxide cements which would be hydrolytically stable, Wilson et al. (1981) examined cement formation between calciimi hydroxide and dimer acid. They found it necessary to incorporate an accelerator, alimiiniiun acetate hydrate, Al2(OH)2(CHgCOO)4.3H2O, into the cement powder. 

Dimerization of unsaturated fatty acids, to. so-called dimer acids, is widely practised in industry, where acid-treated clays are invariably used as a catalyst. In the case of oleic acid the major products are dimers, trimers, and isosteric acid. Koster et al. (1998) have investigated the relative importance of the various acid sites as well as structural and textural parameters of montmorrilonite. The interlamellar space dominates the oleic acid dimerization and the active site is the tetrahedrol substitution site. 

The carryover of caustic into a finished fuel blend usually has minimal effect alone on the corrosion of ferrous metals. However, in fuel systems containing a conventional tall oil dimer-trimer fatty acid or partially esterifled corrosion inhibitor, caustic can react with and negate the effect of the corrosion inhibitor. As a calcium or sodium salt, these inhibitors will no longer function effectively as an oil-soluble, fuel corrosion inhibitor. 

Failure of sensitive filtration tests such as ASTM D-2276, Particulate Contamination in Aviation Fuel by Line Sampling, can be due to caustic neutralized corrosion inhibitor salts. Sodium or calcium salts of dimer-trimer fatty acid corrosion inhibitors are gel-like in character. Filtration of jet fuel containing gelled corrosion inhibitor will be impeded due to plugging of fuel filter media by the inhibitor gel. This slowdown of filtration can result in failure of jet fuel to pass this critical performance test. 

The fatty acid chains are evidently embedded in the outer membrane as an anchor. About one-third of the lipoprotein molecules are attached covalently to the peptidoglycan through an amide linkage between the side chain amino group of the C-terminal lysine of the protein and a diaminopimelic acid residue of the peptidoglycan (Fig. 8-29). Thus, the protein replaces one of the terminal D-alanine residues of about one in ten of the murein peptides. There are 2.5 x 105 molecules of the bound form of the lipoprotein per cell spread over a surface area of peptidoglycan of 3 pm2. They appear to be associated as trimers located primarily in the periplasmic space.589... 

The acetal ester does not trimerize and can be stored for years before hydrolysis and use34. The deuterium-labelled fats have been needed in multigram quantities for studies of the metabolism of configurational and positional fatty acid isomers in humans. 

Heterotrimeric G-proteins are guanine nucleotide-binding membrane-associated proteins that directly intermediate between the G-protein-coupled (heptahelical) receptor and the target effector protein. They are composed of a, P and y subunits. The trimer is anchored in the membrane via palmitoyl or myristoyl fatty acids at the N-terminus of the a subunit and a prenyl moiety at the C-terminus of the y-subunit (see Gilman 1987 Oldham and Hamm 2006 for details). 

Fatty acid dimers, (II), trimers, and tetramers effective as PLA2 inhibitors having antioxidant and anti-inflammatory properties were prepared by Franson (2) and used in treating nerve and tissue damage in central and peripheral neurological inflammatory conditions. 

The nonidealities of equilibrium mixtures result from various combinations of molecular interactions one such interaction that has been recently studied is molecular association. Molecules of fatty acids such as acetic acid typically form dimers and, to a lesser extent, trimers by hydrogen bonding in the vapor and liquid states. Failure of the equilibrium data of binary systems containing acetic acid to meet established criteria of consistency based upon the Gibbs-Duhem relation has been observed by Rius et al. (I), Campbell et al. (2), Herington (3), and... 

Figure 2 A selection of nonribosomal peptides. Chemical and structural features that contribute to the vast diversity of this class of metabolites are highlighted Heterocycle (bacitracin), lactone (surfactin, daptomycin), ornithine and lactam (Tyrocidine), sugar, chlorinated aromats, C-C crosslink (Vancomycin), N-formyl groups (Coelichelin and linear gramicidin), fatty acid (daptomycin), dihydroxybenzoate and trimeric organization (bacillibactin), dimeric organization (gramicidin S), and ethanolamine (linear gramicidin).

Dimer acids. Dimer acids are produced by heating monoene or diene fatty acids (e.g., tall oil acids, a byproduct of wood pulping) with a cationic clay catalyst (92). Typical conditions are 4% montmoriUonite at 230°C for 4—8 hours. After distillation, the product is a complex mixture of acyclic, cyclic, and bicyclic dimers along with some trimer. Dimer acids are dibasic and react with diamines and tria-mines to give polyamides. Imidazole derivatives are used as corrosion inhibitors and esters as lubricants. 

The synthesis of dimeric fatty acids is based on the reaction between a fatty acid with one double bond (oleic acid) and a fatty acid with two double bonds (linoleic acid) or three double bonds (linolenic acid), at higher temperatures in the presence of solid acidic catalysts (for example montmorillonite acidic treated clays). Dimerised fatty acids (C36) and trimerised fatty acids (C54) are formed. The dimer acid is separated from the trimeric acid by high vacuum distillation. By using fatty dimeric acids and dimeric alcohols in the synthesis of polyesters and of polyester polyurethanes, products are obtained with an exceptional resistance to hydrolysis, noncrystalline polymers with a very flexible structure and an excellent resistance to heat and oxygen (Chapter 12.5). Utilisation of hydrophobic dicarboxylic acids, such as sebacic acid and azelaic acid in polyesterification reactions leads to hydrolysis resistant polyurethanes. 

Dimer acid, trimer acid, and small amounts of higher polymers are formed when tall oil fatty acid is treated with an active clay (37). In the same process, part of the fatty acid is isomerized to methyl-branched acids. These can be hydrogenated to produce a mixture of isostearic and stearic acids, which can be separated by a solvent crystallization process. Dimer acids are separated from trimers by thin-film or molecular distillation. 

Polyanhydrides were synthesized from dimer and trimer of unsaturated fatty acids. The dimers of oleic acid and erucic acid, prepared by radical coupling via... 

Soybean oil may be hydrolyzed into glycerol and fatty acids, or soybean oil soap-stocks (foots) may be acidified to produce fatty acids. Crude soybean fatty acids are used to make adhesive tape, shaving compounds, textile water repellents, carbon paper, and typewriter ribbons. Consumption of fatty acids in the United States, Western Europe, and Japan was 2.3 MMT (2.5 million t) in 2001. These soybean fatty acids can be separated into various fractions by distillation, and are used in candles, crayons, cosmetics, polishes, buffing compounds, and mold lubricants. These fatty acids can be converted to FAME by esterification, alkyl epoxy esters by epoxidation, fatty alcohols by hydrogenation (Kreutzer, 1983 Voeste Buchold, 1983), and dimer and trimer acids by conjugation or amines and amides as shown in Fig. 17.7 (Maag, 1983). 

Clay-catalysed oligomerisation of unsaturated acids from oil crops leads to Cse-dimer, C54-trimer and Cig-monomers. The monomeric fatty acid fraction is subjected to distillation, hydrogenation tmd following separation into solid stearine and liquid isostearic acids widely used as semifinished items in surfactants and emollients [88]. 

In Chapter 3 the adsorption isotherms where discussed for some surfactant systems showing the formation of small aggregates (dimers or trimers) within the adsorption layer. There are quite a number of surfactants, which can be described by this model perfectly, for example the homologous series of fatty acids or alcohols or the alkyl sulphates [81],... 

ArIhrobaciKns. Glycolipid antibiotic complex formed by an Arthrobacter sp. No. 2967 and stored in the cells. A. represent cyclic trimeric esters of long-chain 3-()S-D-galactopyranosyloxy)-fatty acids which. 

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