Codimerization of olefins

Other Dimer Olefins. Olefins for plasticizer alcohols are also produced by the dimerization of isobutene [115-11-7] 4 8 codimerization of isobutene and / -butene [25167-67-3]. These highly branched octenes lead to a highly branched isononyl alcohol [68526-84-1] product. BASE, Ruhrchemie, ICl, Nippon Oxocol, and others have used this source. 

Propjiene (qv) [115-07-1] is the predominant 0x0 process olefin feedstock. Ethylene (qv) [74-85-1J, as well as a wide variety of terminal, internal, and mixed olefin streams, are also hydroformylated commercially. Branched-chain olefins include octenes, nonenes, and dodecenes from fractionation of oligomers of C —C olefins as well as octenes from dimerization and codimerization of isobutylene and 1- and 2-butenes (see Butylenes). 

Included are the dimerization, codimerization, oligomerization, double-bond isomerization, and cyclization of olefins. 

Nickel(0)-catalyzed codimerization of methylenecyclopropanes with electron-deficient olefines are highly regiospedfic, but show a rather poor stereoselectivity. Thus the asymmetric nickel(0)-catalyzed codimerization of methylenecyclopropanes with the chiral bomane derivatives of acrylic acid leads to the optically active 3-methylenecyclopen-... 

This principle may also be illustrated by some real cases. In the codimerization of propene and hexene it is important primarily to minimize the dimerization of the reactive propene. In order to favor the codimerization, a stage injection of propene according to the principle in Fig. 1 was therefore performed [2]. A similar process design with distributed additions of chlorine was applied in the chlorination of propene to allyl chloride in order to suppress different side reactions [3]. For liquid-phase processes, a distributed feed to the cascade of stirred reactors was a more natural variant. This was applied in the sulfuric acid alkylation of / obutane, where the olefin feed has to be subdivided due to selectivity reasons and the goal was to reach a desired octane number of the product [4]. 

Table 4. Codimerization of hexylidenecyclopropane with electron deficient olefines...

Table 6. Codimerizations of isopropylidenecyclopropane with electron deficient olefines IsJ... 

While rare-earth metals are proven powerful olefin polymerization catalysts [21-24], there are only limited reports on controlled olefin oligomerizations or selective olefin dimerizations utilizing these elements [204,207,208], An ansa-scandocene [207] and the bis(indenyl)yttrium complex 41 (Fig. 25) [204] were reported to produce head-to-tail dimers from monosubstimted aliphatic alkenes (57). Complex 41 produces predominantly the tail-to tail adduct with styrene. The codimerization of an aliphatic alkene (including substrates containing various functionalities) with styrene affords tran -tail-to-tail dimers, apparently as a result of 1,2-insertion of the a-olefin followed by 2,1-insertion of styrene directed by the phenyl group (58). 

Asymmetric Codimerizations. The use of Ni catalysts modified by an optically active phosphine in catalytic asymmetric syntheses, e.g., of the type [ NiX(rj -C3Hs) ij]/ Al2Cl3Et3/PR3, is important . Phosphines bearing the optical activity in the substituents such as 7 are most effective. Particularly high optical yields occur in the codimerization of C2H4 with a strained cyclic olefin such as norbomene [equation (a)] ... 

These olefins are present in light gasolines produced by catalytic cracking, steam cracking or resid coking, from which they can be extracted. However, they are usually produced by the dimerization or codimerization of propvlene and butenes (see Section... 

Asymmetric modifications of hydrovinylation are one of the earliest examples of successful asymmetric transition metal catalysis. After optimization of various dimerization and codimerization reactions using phosphane modified nickel catalysts, the first examples of asymmetric olefin codimerization were reported with n-allylnickel halides activated by organoaluminum chloride and modified by chiral phosphanes7. Thus, codimerization of 2-butene with propene using n-allylnickel chloride/A]X, (X = Cl, Br) in the presence of tris(myrtanyl)phosphane gives low yields of (—)-( )-4-methy 1-2-hexene (I) with 3% ee7,7 . 

The regiochemistry of codimerization of methylenecyclopropanes with olefins is very dependent on the nature of the metal species used to effect the cyclization. The extent of substitution on the substrate skeleton can also play a role. 

As alluded to above, codimerizations of methylenecyclopropanes with olefins can be mediated with nickel(0)-based catalysts. The discussion now turns to the extent to which regioselectivity and stereoselectivity may be influenced by the nature of the catalyst, as well as by the degree of substitution on the substrate. 

Substrate-controlled stereoselective codimerizations of unsubstituted and substituted methylenecyclopropanes with electron-deficient olefins have been described. Thus, as depicted in the following scheme, (diphenylmethylene)cyclopropane and isopropylidenecyclopropane undergo clean product A formation (distal C—C cleavage) with 2-substituted cyclopcntcnones under palladium(O) mediation63. 

The nickel(0)-mediated codimerization of methylenecyclopropane, as well as 2,2-disubstituted derivatives with electron-deficient olefins, has proven to be an excellent system for auxiliary controlled selectivity. As described in Section 1.6.1.2.3.1, the combination of methylenecyclopropane with alkyl acrylates and Ni(cod)2 catalysis results in the clean formation of typeB cycloadducts under mild conditions. These systems allow facile chiral modification in the form of acrylate esters or amides involving nonracemic residues and employment of the chiral camphorsultam7n as the auxiliary leads to impressive diastereoselectivity 1. The stereoselectiv-... 

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