Alkenes fatty acids

Lipids, alkanes, alkenes, fatty acids, n-alkyl esters... 

Organic materials undergo microbial enzymatic and chemical reactions in soils to form colloidal polymers called humus (Fig. 6.1). Humus is a complex and rather microbially resistant mixture of brown to almost black, amorphous and colloidal substances modified from the original plant tissues or resynthesized by soil organisms. Humus contains approximately 10% carbohydrates, 10% nitrogen components (proteins, amino acids, and cyclical N compounds), 10% lipids (including alkanes, alkenes, fatty acids, and esters), and 70% humic substances. 

Unlike the SMB, where a 6 C fatty acid anomaly was noted, the fatty acid fraction in the Antarctic sediments exhibits a value comparable to other fractions, but lower than the bulk extracted sediment and within the range of Cje and Cjg fatty acids characteristic of marine origin (UcHiDA et al., 2001). This conclusion is also consistent with the carbon number distribution of alkanes, alkenes, fatty acids, alcohols and sterols which reflects the predominance of marine-derived carbon with little recognizable higher plant debris in the sediment. Similar molecular distribution of the lipid classes has previously been reported in sediments from the same general locations in the McMurdo Sound (Venkatesan, 1988). 

The decarbonylation-dehydration of the fatty acid 887 catalyzed by PdCl2(Ph3P)2 fO.Ol mol%) was carried out by heating its mixture with acetic-anhydride at 250 C to afford the terminal alkene 888 with high selectivity and high catalyst turnover number (12 370). The reaction may proceed by the oxidative addition of Pd to the mixed anhydride[755]. 

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. 

Scheme 6.4 Some transformations of alkene function of fatty acids...

As mentioned in the introduction, 3-hydroxy fatty acids with functional groups can also be incorporated in poly(3HAMCL). Table 2 illustrates this with many examples of alkenes, 3-hydroxyalkenoic acids, and substituted 3-hy-droxyalkanoic acids that are readily integrated in poly(3HAMCL). Long chain fatty acids have also been used successfully as substrates for poly(3HAMCL) production. De Waard et al. [44] used oleic acid and linoleic acid to produce... 

Many Pseudomonas strains accumulate MCL-PHAs from alkane, alkene, al-kanoate, alkenoate, or alkanol [5,6,14,96]. The composition of the PHAs formed by the pseudomonads of the rRNA homology group I is directly related to the structure of the carbon substrate used [6]. These results suggested that MCL-PHAs are synthesized from the intermediates of the fatty acid oxidation pathway. In almost all pseudomonads belonging to the rRNA homology group I except Pseudomonas oleovorans, MCL-PHA can also be synthesized from acetyl-CoA through de novo fatty acid synthetic pathway [97]. The -oxidation pathway and de novo fatty acid synthetic pathway function independently in PHA biosynthesis. 

Sulfated alkenes, 23 538 Sulfated carbohydrate products, 23 538 Sulfated cyclodextrin-based chiral stationary phase, 6 87 Sulfated fatty acids, 23 538 Sulfated fatty alcohol ethoxylates, 23 537 Sulfated fatty oils, 23 538 Sulfated products... 

Alcohol dehydration. Other routes to linear higher alcohols are available such as the reduction of fatty acids and an aluminium based oligomerisation of ethene followed by oxidation. The higher alcohols are used as such or they are dehydrated to make 1-alkenes. 

In addition to the unfunctionalized alkene epoxides discussed in the previous subsection, various other types of epoxides exist that are also derived from unconjugated alkenes but that share two additional features, i. e., being characterized by the presence of one or more functional group(s) and having biological significance. Thus, the present subsection examines epoxy alcohols, epoxy fatty acids, allylbenzenes 2, 3 -oxides, as well as alkene oxide metabolites of a few selected drugs. 

Unsaturated polyesters in which the alkene double bond resides in a fatty acid component such as oleic (IX) and linoleic (X) acids are referred to as alkyds or alkyd resins (Sec. 2-12a). 

Table 9.17 shows some of the organics identified in nonurban aerosols. A wide variety of organics are found, including alkanes, alkenes, aromatics, fatty acids, alcohols, and organic bases. 

In a similar manner, many additions of heteroatom radicals to unsaturated positions have been studied. In many cases, addition reactions of heteroatom radicals to alkenes are reversible and thermodynamically disfavored, but their occurrence is apparent. For example, the rapid addition and elimination of thiyl radicals to unsaturated fatty acid methyl esters results in isomerization reactions from which kinetic parameters can be obtained. Additions of group 14 (IV A) metal-centered... 

One of the primary reactions of ionizing radiation with saturated fatty acids is decarboxylation and alkane formation (2). Dimers tend to be produced by reaction of ionizing radiation with unsaturated fatty acids (2). When meats are irradiated C -C 7 n-alkanes, C2-C17 n-alkenes, and C4-Cg iso-alkanes are the predominant products from the lipid fraction (10), Irradiation of the lipoprotein fraction of meat results in the formation of the following volatile compounds Ci-C 7 n-alkanes, C2-C1J n-alkenes, dimethyl sulfide, benzene, and toluene (10). 

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