Ethenolysis, of methyl oleate

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. 

The metathesis of oleochemicals in the presence of ethylene, also called ethenolysis, provides an efficient way to a-oleftns and 0)-unsaturated esters, which are useful intermediates for the synthesis of polymers, fragrances, surfactants, lubricants, and others [51, 52], The ethenolysis of methyl oleate was demonstrated in 1994 by Grubbs et al. using C3 [32], They could reach productive turnovers of 130-140. In 2001, Warwel et al. carried out the ethenolysis of the methyl esters of oleic, erucic, 5-eicosenoic, and petroselinic acids also in the presence of C3 [53]. The reactions were performed at 50°C and 10 bar using 0.025 mol% of catalyst and gave conversions from 58% to 74%. 

The bulk ethenolysis of methyl oleate was performed by Forman et al. using a phoban-indenylidene catalyst [38]. As for the SM of methyl oleate, this readily available catalyst demonstrated to be a suitable alternative to C3, affording the desired products in 64% conversion with a catalyst load of 0.005 mol%, at 50°C and 10 bar of ethylene. Using the same conditions, C3 led to a conversion of 43%. 

Scheme 4 Products of the ethenolysis of methyl oleate and highly efficient catalysts for this transformation developed by Gmbbs [56], and Schrock and Hoveyda [59]...

In an application-focused work, Gmbbs and coworkers developed a microreactor for the continuous-flow ethenolysis of methyl oleate [59], This... 

The ene-yne CM of fatty acid-derived terminal alkenes with several alkyne derivatives was shown by Bruneau et al. [75], These reactions, which led to renewable conjugated dienes, were performed in a one-pot two-step procedure. In the first step, the ethenolysis of methyl oleate was performed in the presence of the first-generation Hoveyda-Grubbs catalyst (2.5 mol%) using dimethyl carbonate as solvent at room temperature. After completion of the ethenolysis (90% conversion), C4 (1 mol%) and the corresponding alkyne (0.5 equivalents with respect to olefins) were added and the reaction was run at 40°C for 2 h (Scheme 9). The desired dienes were thus obtained in high yields close to the maximum theoretical value (50%). Moreover, in order to maximize the formation of functional dienes, the same reaction sequence was applied to the diester obtained by SM of methyl oleate. In this way, the yield of functional dienes was increased up to 90% depending on the... 

Naturally-occurring fatty acids, such as oleic acid, could serve as feedstocks for metathesis-centered transformations. For example, workers at Dow Chemical Company explored the use of Grubbs first-generation catalyst (23) to promote ethenolysis of methyl oleate (equation 11.18) to form C10 alkenes, which might serve as feedstocks for some of the processes that have already been mentioned in this section.49... 

Ethenolysis of unsaturated esters results in the synthesis of shorter-chain w-unsaturated esters, compounds with a broad range of application. Excess ethene can easily be used (e. g. by use of ethene pressures of 30-50 bar) to suppress self-metathesis of the ester and to force the conversion to completion. Ethenolysis of methyl oleate produces methyl 9-decenoate and 1-decene (Eq. 13) [37,38]. High conversion of methyl oleate can be obtained at room temperature by use of a Re207 catalyst promoted with tetraalkyltin. 

Sibeijn, M. and Mol, J.C. (1992) Ethenolysis of Methyl Oleate over supported Re-based catalysts, J. Mol Catal 76 345-358. 

Alternatively, monoaryloxide-pyrrolide (MAP) complexes of Mo and W have been developed. It was found that the methyUdene species of these complexes were quite stable toward bimolecular decomposition, yet very reactive [20]. As such, MAP catalysts are very efficient in reactions, including the ethenolysis of methyl oleate [21], enantioselective RCM [22], and Z-selective homocouplings and cross metatheses [23, 24]. MAP catalysts are further discussed in detail in Chapters 1, 6, and see Grubbs, Handbook of Metathesis, 2nd Edition, Volume 2, Chapter 7. 

Scheme 5.17 Ethenolysis of methyl oleate catalysed by 66-68 (0.01 mol% [Ru], 10 bar ethylene, 40 °C).

Catalysts 66-68 also displayed high selectivities for the formation of terminal olefins in the ethenolysis of methyl oleate (Seheme 5.17). Notably, at low catalyst loadings (10 ppm) 68 achieved the highest TONs (35 000) reported to date. 

Ethenolysis of Methyl Oleate in Room-Temperature Ionic Liquids. ChemSusChem 2008,1 (1-2), 118-122. 

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