Metathesis methyl oleate

Polar-substituted alkenes where the functionality is not attached to a strained ring are considerably more discriminating in their compatibility with metathesis catalysts and as a rule require relatively high catalyst charges. In the aliphatic series, unsaturated esters have received the most attention. Boelhouwer reported in 1972 the metathesis of the ester methyl oleate and its trans isomer, methyl elaidate, with a homogeneous catalyst based on a 1/1.4 molar combination of WCl6/(CH3)4Sn (23). At 70°C and an ester/W molar ratio of 33, near-thermodynamic equilibrium was attained, and 49 and 52% of the respective esters were converted to equal amounts of 9-octadecene and the dimethyl ester of 9-octadecene-1,18-dioic acid. 

Cross-metathesis of methyl oleate with 3-hexene under similar conditions led, in addition to the above products [Eq. (54)], to 3-dodecene and the methyl ester of 9-dodecenoic acid. 

Initial reports of cross-metathesis reactions using well-defined catalysts were limited to simple isolated examples the metathesis of ethyl or methyl oleate with dec-5-ene catalysed by tungsten alkylidenes [13,14] and the cross-metathesis of unsaturated ethers catalysed by a chromium carbene complex [15]. With the discovery of the well-defined molybdenum and ruthenium alkylidene catalysts 3 and 4,by Schrock [16] and Grubbs [17],respectively, the development of alkene metathesis as a tool for organic synthesis began in earnest. 

It has been noted in a recent review that 4 successfully catalyses the cross-metathesis reactions of methyl oleate 1 or oleic acid with ethene see [1]... 

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. 

Cross-metathesis of ethylene and methyl oleate (ethenolysis) and associated... 

Tabie 3.5 initial rate of propene and methyl oleate transformation by metathesis. 

Table 3.6 Comparison of homogeneous and heterogeneous Re-based catalysts in methyl oleate metathesis.

Noteworthy is the surface-complex [ iORe( Bu)(=CH Bu)(CH 2Bu)], which displays catalytic activities much higher than both its homogeneous or heterogeneous homologues [68]. In fact, it is possible to achieve the metathesis of functional olefins such as methyl oleate with good activities (TOP and TON) (Table 3.6). 

One of the latest compounds of this class is the phoban-indenylidene complex XXVII, synthesized by Forman et al. in 2006 [60]. This robust catalyst was tested in self-metathesis and ethenolysis reactions of methyl oleate, giving rise to significantly... 

The application of olefin metathesis to fatty acids and related compounds has its starting point in 1972 with the selective transformation of methyl oleate into equimolar amounts of 9-octadecene and dimethyl 9-octadecene-l,18-dioate by Van Dam, Mittelmeijer, and Boelhouwer (Scheme 1) [29]. In this early work, 1-2 mol% of a... 

As already mentioned, the development of metathesis catalysts that can be easily accessed from simple precursors is necessary if a large-scale application is desired. With this in mind, Forman et al. developed a robust ruthenium-based phoban-indenylidene complex through a simple and relatively inexpensive procedure, if compared to the preparation of C3 [40]. This mthenium alkylidene was tested in the bulk SM of methyl oleate. As a result, they could reach up to 50% conversion with 0.005 mol% catalyst at 50°C. 

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%. 

Brandli and Ward prepared a library of internal olefins through self-metathesis and CM of a variety of derivatives of oleic acid, namely, methyl oleate, oleic acid, oleyl amine (which did not react), oleyl alcohol, and other olefins [42], These reactions were performed using 1 mol% of C3 and led to statistical product mixtures that were analyzed by GC-MS and NMR. 

Scheme 7 Cross metathesis with symmetric olefins, (a) methyl oleate with m-2-butene-1,4-d iyl diacetate [67], and (b) 10-undecenoate with diethyl maleate [68]...

Ferulic acid, a phenolic acid that can be found in rapeseed cake, has been used in the synthesis of monomers for ADMET homo- and copolymerization with fatty acid-based a,co-dienes [139]. Homopolymerizations were performed in the presence of several ruthenium-based olefin metathesis catalysts (1 mol% and 80°C), although only C5, the Zhan catalyst, and catalyst M5i of the company Umicore were able to produce oligomers with Tgs around 7°C. The comonomers were prepared by epoxidation of methyl oleate and erucate followed by simultaneous ring opening and transesterification with allyl alcohol. Best results for the copolymerizations were obtained with the erucic acid-derived monomer, reaching a crystalline polymer (Tm — 24.9°C) with molecular weight over 13 kDa. 

Figure 3.15 Transformation of a seed oil based feedstock, methyl oleate, using catalytic olefin metathesis...

Burdett, K.A., L.D. Harris, P. Margl, B.R. Maughon, T. Mokhtar-Zadeh, P.C. Saucier and E.P. Wasserman, Renewable Monomer Feedstocks Via Olefin Metathesis Fundamental Mechanistic Studies of Methyl Oleate Ethenolysis with the First-Generation Grubbs Catalyst, Organometallics, 23, 2027-2047 (2004). 

Self-metathesis describes the reachon of an unsaturated fatty acid with itself. For example, methyl oleate gives a mixture of starting material (50%), unsaturated hydrocarbon (25%), and long-chain unsaturated diester (25%), aU as a mixture of T-and trani-isomers. (Figure 18). The diester can be converted to the musk component civetone, but a more efficient route is through self metathesis of the ketone oleon derived from methyl oleate by Claisen condensation (104) (Figure 18). 

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)). 

Tungsten hexachloride reacts with dry silica gel to form a surface complex with average composition ( i02)WCl4. Van Roosmalen and associates reported that with tetramethyltin the complex yields a solid catalyst for the metathesis of alkenes with the same activity as the WOQ4-SnMe4 system, but is less active for the metathesis of methyl oleate. The supported complex can be used several times without additional SnMe4. ... 

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... 

Metathesis has been applied in oleochemistry for many years, but only fairly recently technical realization comes within reach [33, 34]. As typical catalysts, ruthenium carbene complexes of the Grubbs type are applied because of their very high activity (turnover numbers up to 200 000). In principle, oleochemical metathesis can be divided into two different types in self-metathesis the same fatty substrate reacts with itself and in cross-metathesis a fatty substrate reacts with, for example, a petrochemical alkene. The simplest case, the self-metathesis of methyl oleate forms 9-octadecene and dimethyl 9-octadecenedioate. The resulting diester can be used along with diols for the production of special, comparatively hydrophobic, polyesters. An interesting example of cross-metathesis is the reaction of methyl oleate with an excess of ethene, so-called ethenolysis. This provides two produds, each with a terminal double bond, 1-decene and methyl 9-decenoate (Scheme 3.3). 

Other exemplary reactions are the cross-metathesis of methyl oleate with allylam-ine, methyl acrylate and dimethyl maleate. In just a single reaction step, very different multifundional products can be produced in this way. 

Scheme 3.3 Cross-metathesis of methyl oleate with ethene and the follow-up chemistry.

Olefin metathesis has been used by a number of workers to produce macrocyclic musks. One of the earliest examples is Mol s synthesis of civetone from methyl oleate. This takes advantage of the ideally placed double bond in the starting oleic acid. Unfortunately, the ds-geometry of the olefin is lost on metathesis and a mixture of isomers results. Furthermore, almost half of the weight of the starting material is lost as the unwanted 9-octadecene. Dieckmann cyclisation of the metathetical diester, followed by hydrolysis and decarboxylation, gives a mixture of E- and Z-civetone. The synthesis is shown in Figure 4.59. 

Methyl oleate (methyl c -q-octadecenoate) is an attractive functionalized olefin for metathesis because of its ready availability and the utility of the metathesis products. An early example is the proposed route to civetone by metathesis of methyl oleate followed by cyclocondensation (Eqs. lla,b). Civetone is a seven-teen-membered unsaturated macrocyclic ketone (d5-9-cycloheptadecen-l-one) identical with the natural compound (civet cat). It has an intense musk odour, and is therefore an attractive perfume component. 

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