Dicarboxylic fatty acids

After LLE of phenols and carboxylic acids in water, on-line methylation with 51 was applied together with large volume injection (100 xL). The solvent was removed before the analytes were transferred into the GC column with MS detection in full scan mode. Volatile fatty acids, dicarboxylic acids, benzoic acids and phenols in water, at concentrations of 0.4 to 0.1 p.M, could be determined in 5 mL samples. Lactic, pyruvic and malonic acids required higher concentrations due to their higher water solubility and lower methylation rates" . Samples of particulate matter were subjected to LLE with THE, and hydrolysis/methylation of the extract with tetramethylammonium hydroxide. 

The second limitation of Py-GC-MS is that the complex pyrolysate was not just pyrolysis products it consisted of evaporation and combustion products of HS. ° It was reported that free compounds, e.g., alkanes, and fatty acids in HS macromolecules evaporated quickly under pyrolysis, and stmctural units split off through burning in the presence of oxygen and can be further incorporated into HS. For example, lipids, e.g., alkanes, fatty acids, dicarboxylic acids, and ketones were often found as free or solvent-extractable compounds in soils and soil HS. These compounds can be synthesized by microorganisms and plants, and can occur upon combustion of fossil fuels and biomasses. Alkylfurans and methoxylated phenols were considered pyrolysis products of... 

N-Chloromethylphthalimide (ClMPI), N-chloromethyl-4-nitrophthalimide (ClMNPl) and N-chloromethylisatin (ClMIS) react quantitatively with fatty acids, dicarboxylic acids and barbiturates (Figure 11) [105]. The reactivity of these labels is due to the high mobility of the chlorine atom. This reaction is similar to those with phenacyl bromide. For a complete reaction it is necessary to convert the acids to alkali metal or ammonium salts. Triethylamine or a crown ether is used as catalyst. Aprotic solvents such as acetonitrile, methanol and diethyl ether are suitable reaction media. The reaction is complete within 30—40 min at 60 °C. The disadvantage of these labels is reactivity to alcohols and primary and secondary amines, and as a result the selectivity is limited. HPLC separation of phthalimidomethyl esters was performed on a reversed phase column (Cg) with acetonitrile/water in various proportions as the mobile phase. Detection was at 254 nm. 

Very-long-chain fatty acids as erucic acid (A -docosenoic acid, C22 l), polyunsaturated fatty acids, methyl-branched fatty acids, dicarboxylic fatty acids, prostaglandins, and the cholesterol side chain in bile acid synthesis are preferentially or exclusively oxidised in peroxisomes. Peroxisomal P-oxidation starts with introduction of a A2,3-double bond catalysed by acyl-CoA oxidase, which consumes O2 and produces H2O2 (Foerster et al. 1981). 

Oilseed Seeds of sunflowei rapeseed and soybean Sunflower oil, rapeseed oil and soy bean oil Glycerine, long chain fatty acids Fatty alcohols, fatty acids, dicarboxylic acids, 1,3-propanediol and 3HP... 

New sorbitol ester quaternary compounds are prepared by treating trialkanolamines with a mixture of fatty acids, dicarboxylic acids, and sorbitol. Optionally the mixture is alkoxylated and finally quaternized. The resulting cationic surfactants are useful in shampoos and other cosmetic applications [164]. 

The formation of acyl-CoAs is catalysed by several acyl-CoA synthetases. The overlapping of their chain length specificities and their tissue distribution are such that any saturated or unsaturated fatty acid in the range 2-22C or more can be activated in animal tissues, though at different rates. These enzymes can also activate branch chain fatty acids, dicarboxylic acids and carboxylic acids with unusual groups. Bile acids require separate, specific enzymes, however. 

The dimer acids [61788-89-4] 9- and 10-carboxystearic acids, and C-21 dicarboxylic acids are products resulting from three different reactions of C-18 unsaturated fatty acids. These reactions are, respectively, self-condensation, reaction with carbon monoxide followed by oxidation of the resulting 9- or 10-formylstearic acid (or, alternatively, by hydrocarboxylation of the unsaturated fatty acid), and Diels-Alder reaction with acryUc acid. The starting materials for these reactions have been almost exclusively tall oil fatty acids or, to a lesser degree, oleic acid, although other unsaturated fatty acid feedstocks can be used (see Carboxylic acids. Fatty acids from tall oil Tall oil). 

Dicarboxylic acids react more sensitively than do monocarboxylic acids. Fatty acids and amino acids cannot be detected. 

In the endoplasmic reticulum of eukaryotic cells, the oxidation of the terminal carbon of a normal fatty acid—a process termed ch-oxidation—can lead to the synthesis of small amounts of dicarboxylic acids (Figure 24.27). Cytochrome P-450, a monooxygenase enzyme that requires NADPH as a coenzyme and uses O, as a substrate, places a hydroxyl group at the terminal carbon. Subsequent oxidation to a carboxyl group produces a dicarboxylic acid. Either end can form an ester linkage to CoA and be subjected to /3-oxidation, producing a... 

FIGURE 24.27 Dicarboxylic acids can be formed by oxidation of the methyl group of fatty acids in a cytochrome P-450-dependent reaction. 

GC separation of derivatized carboxylic acids, 46-52 bacterial fatty acids, 51-52 bile acids, 50-51 C6-C24 monocarboxylic acids and dicarboxylic acids, 51 cyano acids, 52 higher-boiling acids, 49 itaconic acid, citraconic acid, and mesaconic acid, 49... 

Faraday, in 1834, was the first to encounter Kolbe-electrolysis, when he studied the electrolysis of an aqueous acetate solution [1], However, it was Kolbe, in 1849, who recognized the reaction and applied it to the synthesis of a number of hydrocarbons [2]. Thereby the name of the reaction originated. Later on Wurtz demonstrated that unsymmetrical coupling products could be prepared by coelectrolysis of two different alkanoates [3]. Difficulties in the coupling of dicarboxylic acids were overcome by Crum-Brown and Walker, when they electrolysed the half esters of the diacids instead [4]. This way a simple route to useful long chain l,n-dicarboxylic acids was developed. In some cases the Kolbe dimerization failed and alkenes, alcohols or esters became the main products. The formation of alcohols by anodic oxidation of carboxylates in water was called the Hofer-Moest reaction [5]. Further applications and limitations were afterwards foimd by Fichter [6]. Weedon extensively applied the Kolbe reaction to the synthesis of rare fatty acids and similar natural products [7]. Later on key features of the mechanism were worked out by Eberson [8] and Utley [9] from the point of view of organic chemists and by Conway [10] from the point of view of a physical chemist. In Germany [11], Russia [12], and Japan [13] Kolbe electrolysis of adipic halfesters has been scaled up to a technical process. 

Stephanou EG (1992) a,cd-dicarboxylic acid salts and a,co-dicarboxylic acids. Photooxidation products of unsaturated fatty acids, present in marine aerosols and marine sediments. Naturwiss 79 28-131. 

Stephanou EG, N Stratigakis (1993) Oxocarboxylic and a,co-dicarboxylic acids photooxidation products of biogenic unsaturated fatty acids present in urban aerosols. Environ Sci Technol 27 1403-1407. 

Craft DL, KM Madduri, M Eshoo, CR Wilson (2003) Identification and characterization of the CYP52 family of Candida tropicalis ATCC 20336, important for the conversion of fatty acids and alkanes to a,(o-dicarboxylic acids. Appl Environ Microbiol 69 5983-5991. 

Self-associative lateral interactions can only occur with the AB-type analytes, chromatographed in sufficiently mild chromatographic conditions. In planar chromatography, this type of lateral interaction was first demonstrated on monocarboxylic fatty acids and a,co-dicarboxylic acids, chromatographed on microcrystalhne cellulose with aid of decalin and 1,4-dioxane as monocomponent eluents, respectively [8,20,23]. 

Dibasic salts of dicyclopentadiene dicarboxylic acid are claimed to be active as corrosion inhibitors [444], Certain salts of fatty acids (metal soaps), together with benzotriazole, are claimed to give synergistic effects for corrosion in antifreeze-agent formulations [446]. 

Ordinary dicarboxylic acids or dimeric fatty acids are condensed with fatty amines to give emulsion breakers [822,823,1029,1030]. Oxalkylated fatty amines and fatty amine derivatives have properties other than emulsion braking in particular, they can act as corrosion inhibitors and pour-point depressants. 

Warwel, S., Sojka, M., and Rusch, M. Synthesis of Dicarboxylic Acids by Transition-Metal Catalyzed Oxidative Cleavage of Terminal-Unsaturated Fatty Acids. 164, 79-98 (1993). Wexle.r, D., Zink, J. I., and Reber, C. Spectroscopic Manifestations of Potential Surface Coupling Along Normal Coordinates in Transition Metal Complexes. 171,173-204 (1994). Willett, P., see Artymiuk, P. J. 174, 73-104 (1995). 

How the aliphatic monomers are incorporated into the suberin polymer is not known. Presumably, activated co-hydroxy acids and dicarboxylic acids are ester-ified to the hydroxyl groups as found in cutin biosynthesis. The long chain fatty alcohols might be incorporated into suberin via esterification with phenylpro-panoic acids such as ferulic acid, followed by peroxidase-catalyzed polymerization of the phenolic derivative. This suggestion is based on the finding that ferulic acid esters of very long chain fatty alcohols are frequently found in sub-erin-associated waxes. The recently cloned hydroxycinnamoyl-CoA tyramine N-(hydroxycinnamoyl) transferase [77] may produce a tyramide derivative of the phenolic compound that may then be incorporated into the polymer by a peroxidase. The glycerol triester composed of a fatty acid, caffeic acid and a>-hydroxy acid found in the suberin associated wax [40] may also be incorporated into the polymer by a peroxidase. 

Warwel, S., Sojka, M., and Rusch, M. Synthesis of Dicarboxylic Acids by Transition-Metal Catalyzed Oxidative Cleavage of Terminal-Unsaturated Fatty Acids. 164, 79-98 (1993). 

Figure 8.9 Total ion current chromatograms of (a) acidic and (b) neutral fractions of the sample collected from the Palaeolithic flint flake, taOHCx y are hydroxy fatty acids of chain length x with the hydroxy group at position cu and with y double bonds a,uidiCx y are a, uj dicarboxylic fatty acids of chain length x and with y double bonds...

The pyrolysis of glycerolipid materials requires the use of a suitable derivatising agent, in order to increase the detectability of fatty acids and dicarboxylic acids, which may be present in a mature paint film as free acids, metal soaps, as well as esterified with glycerol. The oils and fats commonly used in samples from works of art have been analysed by means of pyrolysis using TMAH [12,23,25,26,32 38], and HMDS [37,39]. 

The conquest of the land by plants necessitated the development of a coating, the cuticle, that would reduce water loss. Suberin and cutin vary in their proportion of fatty acids, fatty alcohols, hydroxyfatty acids, and dicarboxylic acids. The cuticle is synthesized and excreted by the epidermis of aerial portions of the plant, such as the primary stems, leaves, flower organs, and fruits. The two major hydrophobic layers that contribute to the cuticle are composed of phenolic molecules combined with lipid polymers. Cutin is a polymer found in the outer cell wall of the epidermis, which is... 

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