Butadiene oligomerization products

One other reaction deserves mention. From bis(cyclooctadiene)nickel and butadiene (31), and in the presence of an isocyanide (RNC, R = cyclohexyl, phenyl, tcrt-butyl) two organic oligomeric products are obtained, 1 -acylimino-11 -vinyl-3,7-cycloundecadiene and 1 -acylimino-3,7,11 -cyclo-dodecatriene. In each, one isocyanide has been incorporated. An analogous reaction with carbon monoxide had been reported earlier. The proposed mechanism of these reactions, via a bis-7r-allyl complex of nickel, is probably related to the mechanism described for allylpalladium complexes above. 

Oligomeric products, obtaining, 16 106 Oligomeric titanates, pyrolysis of, 25 121 Oligomerization, 23 329 acetylene, 1 181 butadiene, 4 373-374 in higher olefins, 17 712 ionic liquids in, 26 885-887 olefin, 16 111... 

Allylic Grignard reagents also react with dienes such as butadiene or isoprene. However, the reaction tends to produce oligomeric products. Otsuka and Akutagawa have... 

Homogeneous nickel complexes proved to be versatile catalysts in dimerization and trimerization of dienes to yield different oligomeric products.46-55 Depending on the actual catalyst structure, nickel catalyzes the dimerization of 1,3-butadiene to yield isomeric octatrienes, and the cyclodimerization and cyclotrimerization to give 1,5-cyclooctadiene and all-trans-l,5,9-cyclododecatriene, respectively46 56 [Eq. (13.13)]. Ziegler-type complexes may be used to form cis,trans,trans-1,5,9-cyclododecatriene37,57 58 [Eq. (13.14)], which is an industrial intermediate ... 

As a second example, there is a wide variety of breakdown products and oligomeric products that may be formed from the reactive monomers that are the building blocks of plastics. For plastics, the general assumption has been that any side-reaction products and breakdown products are likely to be significantly less toxic than the monomers, and so restricting the migration of the monomer was accepted as an indirect way to limit any hazard from the oligomers also. Whilst this approach is probably acceptable for addition polymers, such as those made from the unsaturated monomers vinyl chloride, butadiene and acrylonitrile where the unsaturated monomer is far more noxious than their products, the validity of this means of indirect control is questionable for condensation polymers such as polyesters and for polyethers formed from epoxide monomers. 

Table 1. Composition of the oligomerization products of butadiene with nickel-ligand catalysts .

A bis(dicyclohexylphosphino)butane (DCPB)-based palladium catalyst was found to catdyze the analogous reaction between isoprene and CO2 [11]. A mixture of lactones 7 and 8 is obtained but the yield of co-oligomerization products is significantly lower (8%) than for the reaction of 1,3-butadiene. 

Figure 2.8. Ligand control charts or titration curves for butadiene oligomerization by nickel with L = PPha A, product distribution among cyclotrimers and cyclodimers B, distribution among the cyclotrimers. From Reference 215.

The nickel(o)-catalysed oligomerization of butadiene has been further studied. Cyclo-octa-1,5-diene is a major product in hydroxylic solvents, and a minor product in the presence of secondary amines." The oligomerization of butadiene in the presence of nickel(ii)acetylacetonate, triethylamine, alkyl cyanamides, and miscellaneous heterocycles has also been studied, and catalyst systems causing an almost quantitative conversion into trans,trans,trans-, cis,trans,trans-, or cis,cis,trans-cyclododeca-l,5,9-triene were found." The ability of some hydrides, trans-MHX-(PR3)2 (M = Ni or Pd), to act as catalysts for butadiene oligomerization has been found to depend upon the substituent, X, and the solvent the reactions of some cationic palladium hydrides with butadiene was also examined. Unlike other organo-cobalt catalyst systems, CoCUPPhjjj has been found to catalyse the dimerization... 

The hydroesterification of butadiene is not well developed, although much effort in many industrial laboratories has been spent to develop this process as a method to prepare adipic add and caprolactam. Because little information on this process has been disclosed in 1he academic literature, this topic is not presented in detail here. Challenges encountered in developing this reaction include the regioselectivity for formation of terminal esters, the potential to form stable allyhnetal intermediates, and the potential to form polymeric or oligomeric products containing multiple diene units. 

Another supported nickel(O) species has been prepared by the reaction of bis-(cyclooctadiene)nickel with a phosphinated macroreticular polystyrene. This has a very low activity toward butadiene oligomerization [34e], which is somewhat reminiscent of the deactivated catalyst previously described. However, the addition of AlEjCOEt) promotes the activity to about 60-100 g of product/g Ni/h. Cyclo-dodecatriene is not found among the products, which consists of 70% COD and 30% VCH, a repartition similar to that obtained with the classical homogeneous systems. 

The structure of the terpene limonene is shown below (see also Exercise 5-29). Identify the two 2-methyl-l,3-butadiene (isoprene) nnits in limonene. (a) Treatment of isoprene with catalytic amonnts of acid leads to a variety of oligomeric products, one of which is limonene. Devise a detailed mechanism for the acid-catalyzed conversion of two molecules of isoprene into limonene. Take care to nse sensible intermediates in each step, (b) Two molecnles of isoprene may also be converted into fimo-nene by a completely different mechanism, which takes place in the strict absence of catalysts of any kind. Describe this mechanism. What is the name of the reaction ... 

This strategy is used for the synthesis of three different exact-mass telechelic oligomers. GPC, NMR, and GC/MS evidence indicates that clean depolymerization chemistry occurs for all three samples. Poly( 1,4-butadiene) (38) is broken down into oligomeric units with two, three, and four repeat units using catalyst 23. Catalyst 14 is more efficient and produces even lower molecular weight oligomers, primarily one and two repeat units. When allylchlorodimethylsilane is used instead of ethylene with 14, telechelic dimers are the only product. 

Scheme 1. Catalytic cycle of the [Ni°L]-catalyzed cyclo-oligomerization of 1,3-butadiene affording Cg-cyclo-oligomer products (according to Wilke et al.) 14...

Scheme 6. Interplay of the C8- and C -production channels for the cyclo-oligomerization of 1,3-butadiene with zero valent PR3/P(OR)3-stabilized nickel complexes as the catalyst. Free energies (AG, AGJ in kcalmol-1) are given relative to the favorable rf-synrfiC A-cis isomer of 2a for catalysts bearing strong a-donor ligands namely I (L = PMe3), III (L = PPrj), VI (L = PBU3), and -acceptor ligands namely V (L = P(OMe)3), IV...

A more recent raw material for plasticizer alcohols is crack-C4 as a byproduct of steamcrackers in ethene/propene production. After extraction of butadiene for use and etherification of isobutene with methanol to methyl-tertiary-butylether MTBE as an octane enhancer, a stream is left containing 1-butene, 2-butene, and butanes, so-called raffinate II. Oligomerization of the butenes yields C8 olefin mixtures ( dibutene ) as the main product and the corresponding C12 olefins as the main byproduct (tributene). They are the... 

Solutions of the nickel(O) and palladium(O) complexes of 1,3,5-triaza-7-phosphaadamantane, PTA (82) and tris(hydroxymethyl)phosphine (98) in water catalyze the oligomerization and telomerization of 1,3-butadiene at 80 °C. Although high yields and good selectivities to octadienyl products (87 %) were obtained, the complexes (or the intermediate species formed in the reaction) dissolve sufficiently in the organic phase ofthe monomer and the products to cause substantial metal leaching [17],... 

Nakazaki s synthetic approach is conspicuous by its remarkable straightforwardness it has been proved to be so far the simplest synthetic route to the target compounds. In their first synthesis of 61a54a), Nakazaki and coworkers started from cyclododecyne (62a), whose oligomerization with two molecules of butadiene afforded the bicyclic 63a. The cis[10.8] precursor 64a, obtained by partial catalytic hydrogenation with Raney nickel catalyst, was dissolved in cyclohexane, which contained xylene as photosensitizer, and the solution was irradiated with a medium pressure Hg lamp for 12 h. Examination of the reaction mixture by means of GLC indicated that the product was a 2.4 1 mixture of (Z) 64a and (E) 61 a, and the further study54b) showed that this ratio could be raised to 1 2 by irradiation of a hexene solution with a low pressure Hg lamp. 

Dimerization and Oligomerization Reactions. Besides Diels-Alder-type dimerization reactions, butadiene undergoes a number of other dimerization or oligomerization reactions to produce cyclic or linear products. With the proper catalysts these reactions proceed quite selectivity. Noncatalyzed or photocatalyzed dimerizations produce compounds like divinylcyclobutanes and have been studied in detail (137,138). 

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