Unsaturated fatty acids, esters

When a-sulfo fatty acid esters are used as the major active component in detergents they can cause problems because of their foaming properties. In European horizontal drum-type automatic washers they produce too much foam, and in the rinse cycle of the American and Japanese pulsator-type washers the foam cannot be completely rinsed out [38]. The problem of inefficient rinsing can be solved by the addition of soap [63] or sulfonated unsaturated fatty acid esters [64]. For European applications special foam inhibitors are needed. 

Polymers Catalytic reactions involving C=C bonds are widely used for the conversion of unsaturated fatty compounds to prepare useful monomers for polymer synthesis. Catalytic C-C coupling reactions of unsaturated fatty compounds have been reviewed by Biermann and Metzger [51]. Metathesis reactions involving unsaturated fatty compounds to prepare co-unsaturated fatty acid esters have been applied by Warwel et al. [52], Ethenolysis of methyl oleate catalyzed by ruthenium carbenes developed by Grubb yields 1-decene and methyl 9-decenoate (Scheme 3.6), which can be very useful to prepare monomers for polyolefins, polyesters, polyethers and polyamide such as Nylon 11. 

Recently, we reported that the rhodium/BIPHEPHOS-catalyzed hydroformylation of trans-4-octene (Scheme 6) provides an interesting approach for the synthesis of n-nonanal [23]. In this context trans-4-octene can also be seen as a model substance for hydroformylation of internally unsaturated fatty acid esters. This could open up access to the use of renewable resources for the synthesis of valuable n-aldehydes. 

Arai, M. and Fukuda, H. (1989) Concentration and separabon of unsaturated fatty acid esters. )pn Patent 63264555. 

Although in general functionally-substituted olefins are unreactive, the disproportionation of acrylonitrile with propylene and of certain unsaturated fatty acid esters have been recently reported (8, 9). The disproportionation of acetylenes has been observed over heterogeneous catalysts (10). 

The application of hydroformylation is not limited to unfunctionalized petrochemicals. Also, renewables are of interest for industrial applications. One good available resource is oleocompounds which possess C=C-double bonds [16]. Ucciani and Lai first investigated the hydroformylation of unsaturated fatty acid esters using cobalt catalysts such as cobalt laurate or dicobalt octacarbonyl (Scheme 6) [17, 18]. 

Also, bulky phosphite-modified rhodium catalysts are highly reactive for the hydroformylation of unsaturated fatty acid esters [23]. The catalyst was able to yield turnover numbers (TON) of 400-500 when moderate conditions with 20 bar synthesis gas pressure and 100°C were applied. These phosphites, like tris (2-ferf-butyl-methyl) phosphite, have higher activity than phosphines like triphenylphosphine. 

Muilwijk KF, Kamer PCJ, van Leeuwen PWNM (1997) A bulky phosphite-modified rhodium catalyst for the hydroformylation of unsaturated fatty acid esters. J Am Oil Chem Soc 74 223-228... 

Applied pressure during CEC can decrease the separation time [30]. In this study the pressurized capillary electrochromatography (pCEC) coupled to NMR separated and identified a mixture of unsaturated fatty acid esters. The analysis time has been reduced by factor of 10 compared to nonpressurized CEC. 

Silver nitrate-impregnated silica gel has also been used successfully in the separation of some classes of compounds that contain double bonds in their structures. Thus it was used in the separation of glycerides and isomers of unsaturated fatty acid esters. The 2-D TLC on adjacent layers of silica gel G and sihca G impregnated with 5% of silver nitrate was used for development. The silica gel G layer covered a surface of 3 x 20 cm and the difference of the surface of 17 x 20 cm was covered with silica gel G impregnated with 5% AgNOs. The first direction was performed on silica gel G with petroleum ether-diethyl ether (9 1, v/v) as eluent. The second direction was carried out on the impregnated silica gel G and developed twice with the same eluent as in the first direction. After the first direction, the mixture was... 

Metathesis of olefins, through the use of transition metal catalysis, is an important application in the petrochemical as well as in the polymer chemical industry for the production of special olefins and polymers (cf. Section 2.3.3). This chemistry is also applicable to unsaturated fatty acid esters, such as acetic acid methyl ester. However, the high price and unsustainability of the catalysts, compared with the fatty acids as substrates, have made commercial utilization not yet possible nevertheless they are of great interest for researchers in this field. 

The metathesis of unsaturated fatty-acid esters has received considerable attention. Aspects of the metathesis of fatty-acid esters and related compounds were recently reviewed by Boelhouwer.With the WCl6/Me4Sn system, both self-metathesis and co-metathesis (with symmetric alkenes) of unsaturated esters occur, provided that the double bond and the ester group are separated by at least one methylene group.As an example, conversion of C8-C=C-C7-COOC of 50% for self-metathesis and 70% for co-metathesis... 

To prepare 9-decenoic and 13-tetradecenoic acid methylester, we used the transition-metal catalysed olefin metathesis [6, 7], actually applied in petro- and polymerchemistry in seven industrial processes [8], As stated first by C. Boelhouwer et al. [9, 10], this reaction is valid not only for olefins, but for unsaturated fatty acid esters, too. 

Table 2. Ketonisation of co-unsaturated fatty acid esters with PdCl2/CuCl or RhCl3/FeCl3...

Subbaram, M. R., Separation of saturated and unsaturated fatty acid esters of cholesterol by gas-liquid chromatography. J. Chromatog. 16, 79-80 (1964). 

Various Pt(IV), Pt(II), and Pt(0) catalysts were screened for the hydrosilylation of fatty acid esters (Eq. 7) containing terminal as well as internal double bonds. The reaction of terminally unsaturated fatty acid esters proceeds smoothly with short reaction times for nearly all catalysts examined, whereas the Pt(IV) and Pt(II) or Pt(0) species with labile ligands are sufficiently active in the reaction of internally unsaturated compounds. For methyl linoleate, a conjugation of the two internal double bonds before the hydrosilylation was observed. The reaction can be carried out in solid as well as in solvent systems, permitting catalyst recycling and reuse. In these systems, however, hydrogenation and double-bond isomerization are found as side reactions [22]. 

The manufacture of epoxy stabilizers begins with soya and linseed oils or oleate and other unsaturated fatty acid esters. When epoxidation is incomplete, residual unsaturation remains, leading to poor compatibility-stability. This results in exudation on products in the marketplace. Makers of epoxldized fatty acid esters strive to prevent such failure by ensuring more complete epoxidation and supplying products with the lowest possible iodine number. Vinyl formulators further protect themselves by diminishing the proportion of epoxidized stabilizer to an amount ca. 3% while maintaining plasticizer concentration at ca. 35%. 

Medium-chain unsaturated fatty acid esters (C12-C16) are also starting materials for the synthesis of pheromones of the general formula Me(CH2)nCH=CH(CH2)7X, where X is CH2OAC, CH2OH or CHO, and n = 1-5. 

Berezin, M. Y., Ignatov, V. M., Belov, P. S., Elev, I. V., Shelimov, B.N., Kazansky, V. B. (1991) Mechanism of Olefin Metathesis and Active Site Formation on Photoreduced Molybdenum Catalysts. 5. Metathesis of Unsaturated Fatty Acid Esters, Kinet. Ratal. 32, 379-389. 

Dialkylhydridoaluminums often have a more selective reducing action than LiAlH4. Thus unsaturated aldehydes can be prepared in 60-95% yield by reducing the corresponding unsaturated fatty acid esters with diethyl- or diisobutyl-hydridoaluminum in benzene at 80°.539... 

Isomers of the unsaturated fatty acid esters (55) and uhsatnrated normal aldehydes (59) which differ only in the position of a double bond in the alkyl chain are surprisingly well separated on silver-impregnated silica but not on normal silica. The basis for these effects is somewhat more complicated than simple steric hindrance to silver ion complexation, however. TV"... 

For some time the hardening action of sulfur dioxide on several fatty oils has attracted the attention of many investigators. However, the cis-trans conversion involved was not studied systematically imtil 1940 (9). This isomerization is of special interest for the treatment of nondrying and semidrying oils, since it raises the melting point considerably by the conversion of oleic (and other mono-unsaturated) fatty acid esters into the higher melting elaido forms. 

Unsaturated fatty acid esters as obtained by Wittig reactions as well as saturated ones have been dimerized to gemini-diesters by deprotonation and subsequent oxidation to radicals (Scheme 2.3.4). 

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