Unsaturated fatty compounds

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. 

Unsaturated fatty compounds are the preferred educts in industrial epoxidation. Numerous methods are available to transform then to the corresponding epoxides. Epoxidation with molecular oxygen [3], dioxiranes [4], hydrogen peroxide with methyltrioxorhenium as catalyst [5, 6], the Halcon process [7], or enzymatic reactions [8] are the most important industrial processes (cf. Section 2.4.3). 

Furthermore, oxidation of fatty acids to vicinal diols, as well as their oxidative cleavage, are important industrial applications. Vicinal diols of unsaturated fatty compounds can be prepared by nucleophilic ring opening of the epoxides after epoxidation, but difficult technical conditions are necessary to achieve this ring opening [9]. The use of Re- [10], W- [11], or Mo [l]-based catalysts with hydrogen peroxide can give a jyn-diol via the epoxide as intermediate (eq. (2)). 

From the industrial point of view the co-metathesis of unsaturated fatty compounds, especially methyl oleate, with ethylene to form methyl 9-decenoate and 1-decene is becoming more important (eq. (3)). 

In fat chemistry ( oleochemistry ) no considerable application of homogeneous catalysis and of industrial importance is known so far [1], One reason for this is the modest reactivity of the starting chemicals. Oleochemicals are molecules with a long carbon chain. The double bonds of unsaturated fatty compounds are always in internal positions. Hence, the steric hindrance of oleochemicals is often very high, and the coordination to metal complexes is made difficult. In addition all fatty compounds contain a substituent with a heteroatom such as carboxyl, ester, aldehyde, alcohol, or amine groups. These substituents often react with organome-tallic compounds and can inactivate the catalyst. 

One important aim in oleochemistry hydrogenations is the selective hydrogenation of multiply unsaturated fatty compounds to singly unsaturated products. A typical example is the selective hydrogenation of linoleic acid (C18 2) to oleic acid (C181) without significant formation of stearic acid (D18 0) as shown in Eq. (1). This... 

The kinetics of the selective hydrogenation with palladium SSCs is shown in Figure 1. At room temperature the linoleic acid (C18 2) is completely hydrogenated after 45 min. During this time no additional stearic ester is formed. This result is characteristic of the high selectivity of the palladium SSC. Obviously, the double unsaturated fatty compound coordinates essentially better than the monounsatu-rated compounds to the palladium. 

The hydrosilylation of unsaturated fatty compounds yields interesting chemicals with a new C Si bond. As a model reaction the conversion of 10-undecenoic acid... 

The reason for autoxidation is the presence of double bonds in the chains of many fatty compounds. The autoxidation of unsaturated fatty compounds proceeds... 

Synthesis of New Oleochemicals Products of Friedel-Crafts Reactions of Unsaturated Fatty Compounds... 

Unsaturated fatty compounds are of interest as renewable raw materials (1). These compounds can be functionalized at the C,C-double bond by electrophilic addition reactions to give new oleochemicals with potentially new and interesting properties. The alkylaluminum chloride-induced Friedel-Crafts acylation of unsaturated fatty compounds (Fig. 1), such as oleic acid [la], 10-undecenoic acid [2a], petroselinic acid [3a], and erucic acid [4a], and the respective esters and alcohols yield the corresponding P,y-unsaturated ketones (2,3). 

Fig. 1. Unsaturated fatty compounds oleic acid [1a], 10-undecenoic acid [2a], petroselinic acid [3a], erucic acid [4a], and the respective esters [1b]-[4b] and alcohols [1c]-[4c]...

The Lewis acid-induced acylation of unsaturated fatty compounds combined with the following reactions allows the synthesis of natural products derived from fats. Acylation of 10-undecenoic acid [2a] with heptanoyl chloride gave 12-oxo-9-octadecenoic acid reduction with NaBHq afforded the racemate of ricinelaidic acid [6], a natural product (Fig. 2). 

Further acylations of unsaturated fatty compounds were carried out with aromatic and heteroaromatic carboxylic acid chlorides such as benzoyl chloride and thiophene-2-carboxylic acid chloride. The benzoylation of 10-undecenoic acid [2a], induced by EtAlCl2, was already complete after a reaction time of 30 min (Scheme 6). Product [14], a phenyl allyl ketone, was obtained as a mixture of ( )/(Z)-stereoisomers in an isolated yield of 49%. The reaction occurred regioselectively at C-11 of the molecule chain. 

Intramolecular acylations are also possible with unsaturated fatty compounds (2). The intramolecular reaction of petroselinic acid chloride and EtAlCl2 gave the cyclic product [20] with an exocyclic double bond (Scheme 9). The ring closure took place regioselectively at C-6. The pure ( )-adduct was isolated in a yield of 58%. The unsaturated ketone [20] could be easily hydrogenated to give 2-dodecylcyclohexanone [21]. 

The alkylaluminum halide-induced Friedel-Crafts acylation is a very general and synthetically useful reaction that allows the functionalization of unsaturated fatty compounds. Acylations were carried out with different acylating agents such as acyl chlorides, dicarboxylic acid dichlorides, cyclic anhydrides, unsaturated acyl chlorides, and aromatic and heteroaromatic carboxylic acid chlorides, yielding a large... 

Metzger, J.O., and U. Biermann, Lewis Acid Induced Addition to Unsaturated Fatty Com-poimds rV Synthesis of Cyclopentenones from Friedel-Crafts Acylation Products of Unsaturated Fatty Compounds with a,P-Unsaturated Chlorides, Fett/Lipid 100 2-6 (1998). 

Unsaturated fatty compounds such as oleic acid [la], 10-undecenoic acid [2a], pet-roselinic acid [3a], erucic acid [4a], and the respective esters, alcohols, and native oils (Fig. 1) are alkenes and contain an electron-rich double bond that can be functionalized in many different ways by reactions with electrophilic reagents. It is therefore remarkable that >90% of oleochemical reactions have been focused on the carboxylic acid functionality and < 10% have been reactions of the alkyl chain and the C,C-dou-ble bond (1). A review on radical additions to unsaturated fatty compounds that appeared in 1989 (2) quoted only very few C,C-bond-forming reactions giving branched and chain-elongated fatty compounds. Since then, modem preparative radical chemistry has been developing and has been applied also to fat chemistry (3-5). We report here on radical additions of activated haloalkanes such as alkyl 2-haloalka-noates and 2-haloalkanenitriles to unsaturated fatty compounds [l]-[4] initiated by electron transfer from copper in solvent-free systems. These additions were also car-... 

New fatty compounds have been synthesized in high yields using radical addition reactions. Alkyl 2-haloalkanoates have been added to the double bond of unsaturated fatty compounds to give y-lactones. 2-Haloalkanenitriles have been added as well to give 4- haloalkanenitriles. 2-Halo fatty compounds, e.g., methyl 2-bromopalmitate, have been added to alkenes, allyl alcohol, vinyl esters, and trimethylsilyl enol ethers to give interesting branched and functionalized compounds. Key features of the re-... 

Metzger, J.O., and U. Linker, New Results on Free Radical Additions to Unsaturated Fatty Compounds, Fat ci. Technol 93 244-249 (1991). 

Biermarm, U., and J. Metzger, Lewis Acid Induced Additions to Unsaturated Fatty Compounds, Fat Set Technol. 9 326-328 (1993). 

Unsaturated fatty compounds such as oleic acid, petroselinic acid, erucic acid, ricinoleic acid, linoleic and linolenic acid, andlO-undecenoic acid and also the respective esters, alcohols and native oils are alkenes, and contain an electron-rich C—C double bond that can be functionalized in many different ways by reactions with electrophilic reagents [287]. 

Biermann U, Metzger JO. 2004. Catalytic C,C-Bond Forming Additions to Unsaturated Fatty Compounds. Topics in Catalysis 38 3675-3677. 

The reason for auto-oxidation is the presence of double bonds in the chains of many fatty compounds. The auto-oxidation of unsaturated fatty compounds proceeds with different rates depending on the number and position of double bonds (Frankel, 2005). The positions allylic to double bonds are especially susceptible to oxidation. The bix-aUylic positions in common polyunsaturated fatty acids, such as linoleic add (double bonds at C-9 and C-12, giving one te-allylic position at C-11) and linolenic add (double bonds at C-9, C-12, and C-15, giving two te-allylic positions at C-11 and C-14), are even more prone to autoxida-tion than allylic positions. The relative rates of oxidation given in the literature (Frankel, 2005) are 1 for oleates (methyl, ethyl esters), 41 for Unoleates, and 98 for linolenates. This is essential because most biodiesel fuels contain significant... 

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