Codimerization of ethylene

Further examples which show that the direction of Ni—C addition to propene can be changed from Ni — C2 to Ni — Cj by introducing P(i-C3H7)3 are to be found in the codimerizations of ethylene with propene (4, 12, 29) and of 1,3-cyclooctadiene with propene (4, 79). The last example is particularly informative, for in this case no ambiguity as to the assignment of the products to Ni - C4 or Ni - C2 type addition exists. 

The codimerization reaction we will discuss in this chapter belongs to the last type. The reaction and the reactants involved will be the simplest of them all, i.e., a 1 1 codimerization of ethylene and butadiene to form C dienes. 

Typical Isomer Distributions in 1 1 Codimerization of Ethylene and Butadiene by Various Transition Metal Catalysts... 

Scheme 2. Catalytic cycle for Rh catalyst for 1 1 codimerization of ethylene and butadiene to form 1,4-hexadiene.

Codimerization of ethylene and 1,3-butadiene is also of commercial significance since the product 1,4-hexadiene is used as a comonomer in the manufacture of ethylene-propylene-diene elastomers. Rhodium and nickel catalysts are used since they are the most active and selective, bringing about the formation of the required... 

A recent study by Yamamura and Nakatomi (126) shows that phospho-tungstic acid impregnated on alumina is more active than alumina for codimerization of ethylene with propylene. The authors concluded that the newly formed acid sites (H0 s - 5.6) increased the yield of pentenes. 

Nickel allyl complexes in the presence of chiral bidentate ligands catalyze the enantioselective codimerization of ethylene with norbornene and with styrene 129... 

Olehns with four to eight carbon atoms can be obtained by dimerization and codimerization of ethylene, propylene and butenes. 

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