Decenes metathesis

Fig. 5 Product distribution of 1-decene metathesis with [(=SiO-)WMe5] catalyst...

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 key step in Fiirstner s elegant synthesis of racemic 153 furnishing a Z E=7 3 mixture, used an intramolecular metathesis reaction of the ester A [292]. Employing optically active 9-decene-2-ol will certainly produce the desired enantiomer (Fig. 7). 

Decarboxylation catalysts for, 19 89 cycloamylose-catalyzed, 23 242-244 Decationation, 33 264-272 1,5,9-Decatriene, metathesis of, 24 134 1-Decene... 

A number of new processes exploiting metathesis have been developed by Phillips. A novel way to manufacture lubricating oils has been demonstrated.145 The basic reaction is self-metathesis of 1-octene or 1-decene to produce Ci4-C28 internal alkenes. The branched hydrocarbons formed after dimerization and hydrogenation may be utilized as lubricating oils. Metathetical cleavage of isobutylene with propylene or 2-butenes to isoamylenes has a potential in isoprene manufacture.136,146 High isoamylene yields can be achieved by further metathesis of C6+ byproducts with ethylene and propylene. Dehydrogenation to isoprene is already practiced in the transformation of isoamylenes of FCC C5 olefin cuts. 

WC16 Na[Re04] [C4C im][BF4] [C4C1im]Cl-AlCl3 Cross-metathesis of linear olefins, e.g. conversion of 1-hexene to 4-octene and 5-decene rather low conversions (<15-30%) addition of 10-30% SnBu4 significantly increases the yield and the selectivity for 4-octene (> 95%). [25]... 

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)). 

Pheromones are chemicals that are used by animals and plants for communication. Insects utilize pheromones extensively to indicate their availability for reproduction, to sound alarms, and to make known the presence of food. The use of pheromones in small amounts in traps can interfere with the reproduction of harmful insects in an environmentally friendly manner. Recently, Grubbs second-generation catalyst (24) was used to synthesize on an industrial scale the sex attractant pheromone of the peach twig borer, a pest that attacks peach, plum, nectarine, and almond crops.46 Equation 11.16 shows how Ru-catalyzed metathesis of 5-decene and l,10-diacetoxy-5-decene produces a 50% yield of E-Z mixture (the desired E-isomer predominates, and the presence of small amounts of Z-isomer does not lower the activity of the pheromone) of the desired pheromone at low temperature. The unreacted starting materials are recovered by vacuum distillation and recycled. 

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). 

Cross-metathesis reactions are useful for the production of fine chemicals such as synthetic perfumes, prostaglandin intermediates, and insect pheromones. An example of the last is the cross-metathesis of ethyl oleate with 5-decene in the presence of a MoCl5/Si02/Me4Sn catalyst at 90 °C [14], or a Mo03/Si02/cyclopropane catalyst at 50 °C [16], resulting in a cisitrans mixture of ethyl 9-tetradecenoate, an insect pheromone precursor (Eq. 12). 

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. 

The two-step-process via metathesis of oleic acid methyl ester with ethylene, yielding 9-decenoic acid methyl ester and 1-decene (65,66), has the advantage that the production of the two products of direct cleavage can be decoupled. 1-Decene will be submitted to Oxidative cleavage only if there is a market for pelargonic acid. Be-... 

Another example of organic synthesis via cross-metathesis is the synthesis of biologically active compounds such as insect pheromones. Use of such pheromones offers an effective and selective pest control method. Thus, cross-metathesis of ethyl oleate with 5-decene results in a cis-trans mixture of ethyl 9-tetradecenoate, an insect pheromone precursor [15]. Cross-metathesis of methyl d.y-5-eicosenoate (obtained from meadowfoam oil) with excess 5-decene gives methyl tm 5-decenoate, which can be transformed into a 83 17 mixture of trani -5-decenylacetate and tran.y-5-decenol (in total 90% trans), the sex pheromone of the Peach Twig Borer moth, a major pest in Northern Hemisphere fruit orchards. The isomeric mixture was active in mating disruption [16]. Other examples of organic synthesis via cross-metathesis are summarised elsewhere [17 18]. 

Ar = C6H3-(Ph)2-2,6 Np = CH2CMe3. Cross-metathesis with 5-decene. 

Cross-metathesis of allylsilanes with alkenes also occurs via their preliminary isomerization followed by the reaction of l>propenylsilane with exemplary olefin - 1-decene resulting in l-(triethoxysilyl)-l-decene as a product (equation 13b). If crossmetathesis took place, one could expect l-silyl-2-undecene as a product of this reaction (equation 13a). 

Further investigation on the metathesis of 1-decene (an expected olefin during the alkane metathesis of -decane) and the hydrogenation of the products formed clearly demonstrated that the distribution resulting from alkane and olefin metathesis completely differs with the same catalyst. If there is no double-bond migration, 9-octadecene and ethylene are expected to be the major primary products. Indeed, these primary products are observed, as the temperature reaches 150°C. However, after just 15 min, Cj to C12 and C13 to C20 olefins are also observed, clearly indicating that some isomerization of double bond occurs leading to several competitive metatheses (Fig. 5). 

While in alkane metathesis mechanism (Scheme 20, b), the n-decane undergoes o-bond metathesis to generate methane and the W-bis-decyl species which, upon P-H elimination, produces the W-H with a coordinated olefin. Further, the a-hydrogen transfer from the alkyl to alkylidyne forms the hydrido W-bis-carbene [55, 76]. This upon [2-1-2] cycloaddition and cycloreversion gives an internal olefin and hydrido W-bis-carbene. Successive insertion/elimination steps (by chain walking) [77] give the terminal alkene, which reacts to a new W-alkylidene. The CH activation of the pendant W-hydride with -decane followed by p-H elimination provides 1-decene. A second metathesis between 1-decene and newly formed W-alkylidene followed by hydrogenolysis produces the alkane. 

Starting with -hexane (Cg) metathesis, dehydrogenation should give the corresponding 1-hexene, followed by its homo-metathesis to yield ethylene and decene, which upon hydrogenation, should ideally produce ethane and decane (Cj q products) as the major products (Scheme 2.18, path a). However, this tandem reaction process was not selective since -decane represented <50% of the total primary products of heavy alkanes when the reaction was catalyzed with Ir-2(H2). The authors attributed this unexpected distribution of alkanes to the isomerization of the (x-olefin prior its metathesis, as depicted in pathway b (Scheme 2.18). 

Stereospecificity in degenerate metathesis reactions provided the first clue to unmask the chain-carrying species. The assay published by Casey and Tuinstra [12] is shown in Scheme 10.8 octene-l,l-ii2 and (Z)-decene-l-ii2 were subjected... 

Vinylsiloxanes of the type illustrated in Figure 3 are model compound for poly(vinyl)siloxanes. Therefore, a series of vinylsiloxanes (Figure 3) was synthesized and the reactivity of these compounds in cross-metathesis with styrenes and 1 -decene was studied [21],... 

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