Olefin also codimerization

The use of triphenylphosphane- or triarylphosphite-modified Ni(0) catalysts (e.g. Ni(cod)2/PPh3) demands higher reaction temperatures and leads to a decrease in stereoselectivity189) e.g. pure trans-alkenes give stereoisomeric mixtures of methyl-enecyelopentanes (Eq. 81). On the other hand more electron deficient olefines, e.g. crotonaldehyde, also codimerize in the presence of these catalysts. 

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). 

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]. 

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. 

Thus reaction occurs at both the electron-deficient and nonactivated olefin moieties of the norbornadiene diester32. Noteworthy also is the much higher exo selectivity compared with the chemoselective TMM-Pd process24. When the olefin is too electron-deficient, as in maleic anhydride, acrolein or acrylonitrile, bonding to the palladium center is so strong that no codimerization occurs. Conversely, if the initial /[-interaction is too weak, then a common side reaction becomes apparent, cyclodimerization of the methylenecyclopropane. 

During our investigation of these codimerizations it turned out that with Ni(0) catalysts not only the metal determines the course of the reaction, but also several other factors e.g. the kind and number of the ligands bonded to the nickel, the kind, number and position of substituents on the methylenecyclopropane and the electronic properties of the second olefine. These observations make it nearly impossible to predict, whether methylenecyclopentanes of Type A or B will be the products. 

The codimerization of a functional olefin with a non-functional olefin is an interesting possibility for the synthesis of longer-chain monofunctional products. One example is the rhodium or rutheniixm chloride catalyzed codimerization of methyl acrylate with ethylene yielding linear monounsat-urated acids [48]. The main product is methyl-3-pentenoate (47%), but also esters of acids containing seven and nine carbon atoms were isolated in yields of 12 and 9%, respectively (Equation 49). 

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