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Conjugated dienes oligomerization

Table 5 gives typical results of the wax cracking process to surfactant olefins. Compared with the pure a-olefins produced by the oligomerization reactions of ethylene the crack olefins are decreased in quality, especially due to the conjugated diene part (2-4%). Moreover, there are some problems in guaranteeing the wanted amounts of C20-C30 n-alkanes. Therefore in industrially de-... [Pg.10]

Nickel(O) complexes are extremely effective for the dimerization and oligomerization of conjugated dienes [8,9]. Two molecules of 1,3-butadiene readily undergo oxidative cyclization with a Ni(0) metal to form bis-allylnickel species. Palladium(O) complexes also form bis-allylpalladium species of structural similarity (Scheme 2). The bis-allylpalladium complexes show amphiphilic reactivity and serve as an allyl cation equivalent in the presence of appropriate nucleophiles, and also serve as an allyl anion equivalent in the presence of appropriate electrophiles. Characteristically, the bis-allylnickel species is known to date only as a nucleophile toward carbonyl compounds (Eq. 1) [10,11],... [Pg.183]

Beyond dimerization and oligomerization, [2 + 2]- and [4+ 2]-cycloadditions with conjugated dienes and styrenes and the addition of nucleophiles are typical reactions of strained cyclic allenes. These transformations have been studied most thoroughly with 1,2-cyclohexadiene (6) and its derivatives [1, 2]. Concerning the cycloadditions, a theoretical study had the surprising result that even the [4+ 2]-cycloadditions should proceed in two steps via a diradical intermediate [9]. In the case of nucleophiles, the sites of attack at several 1,2-cyclohexadiene derivatives having an... [Pg.243]

Catalyzed oligomerization and co-oligomerization of conjugated dienes have been performed with a wide range of transition-metal complexes. Catalytic cyclodimerizations of conjugated dienes have also been performed selectively [27]. Thus, a catalytic amount of CpRuCl(diene) and Ag(0S02CF3) led to the formation of 1,5-cyclooctadiene, dimethylcyclooctadienes, and 6-methyl-... [Pg.9]

Recent Developments in Theoretical Organometallic Chemistry. 15, I Redistribution Equilibria of Organometallic Compounds, 6, 171 Redistribution Reactions of Transition Metal Organometallic Complexes, 23, 9S Redistribution Reactions on Silicon Catalyzed by Transition Metal Complexes, 19, 213 Remarkable Features of (7] -Conjugated Diene) zirconocene and -hafnocene Complexes, 24, I Selectivity Control in Nickel-Catalyzed Olefln Oligomerization, 17, lOS Silyl. Germyl, and Stannyl Derivatives of Azenes. N H Part I. Derivatives of Diazene, N,H2, 23, 131... [Pg.470]

The oligomerization and cooligomerization of conjugated dienes are representative reactions that proceed via transition-metal Jt-allyl intermediates. When (CsMesjRuCljt/ -butadiene) in dichloromethane was treated with an acetone solution of an equimolar amount of silver trifluoromethanesulfonate (AgOTf) in the presence of excess butadiene at ambient temperature, after which the mixture was allowed to react with carbon monoxide (1 atm), a cationic 1,5-cyclooctadiene carbonyl complex, [(C5Me5)Ru(CO)( -l,5-C8Hi2)]OTf, was isolated in 95% yield (Eq. [Pg.147]

In this account, an overview of the methods employed for the synthesis of conjugated dienes and polyenes is presented. Dienes and polyenes with isolated double bonds are excluded, as they are accessed through methods usually employed for alkene synthesis. Oligomerizations and polymerization reactions leading to polyenes are also not covered. Synthesis of 1,2-dienes, i.e. allenes, is excluded from the purview as there is a volume in the present series devoted to this functional group. Synthesis of heterodienes, conjugated enol ethers, [n]-annulenes and related compounds are also not covered here. However, enynes, dienynes and enediynes syntheses have been included in a few cases in view of their emerging importance. [Pg.361]

The TT-allyl complexes of Pd , e.g. [Pd( j -C3Hs)X]2 (X = Cl, Br, I), are very stable and more numerous than for any other metal, and neither Ni nor Pt form as many of these complexes. Indeed, the contrast between Pd and Pt is such that in reactions with alkenes, where a particular compound of Pt is likely to form an alkene complex, the corresponding compound of Pd is more likely to form a rr-allyl complex. The role of the Pd and Ni complexes as intermediates in the oligomerization of conjugated dienes (of which 1,3-butadiene, C4H6, is the most familiar) have been extensively studied, particularly by... [Pg.1171]

By eliminating the volatile components under vacuum, the reaction mixture yields oleous products which have been subjected to elemental and physico-chemical analyses (Table 26). The viscous oil products show an oligomeric character and a structure originating from the alternating copolymerization of an 02 molecule with the conjugated diene system. In fact, the absorption bands of the dienic systems are... [Pg.62]

S. 7c-Allyl Metal Complexes by Oligomerization of Conjugated Dienes. [Pg.157]


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1,3-Diene, conjugated

Conjugate 1,3 dienes

Conjugation Dienes, conjugated)

Dienes conjugated

Oligomerization dienes

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