Ethylene codimerization with 1-butene

A wide variety of acid-catalyzed reactions besides those described above have been investigated with heteropoly compounds as catalysts. Al203-supported H3PW12O40 (probably decomposed) catalyzed propylene-ethylene codimerization at 573 K to form pentenes with a selectivity of 56% (butenes 17%, hexenes 27%) (224). Propylene oligomerization proceeded on various kinds of salts of H3PWl204o (225). The activities of the salts decrease in the order A1 > Co > Ni, NH4 > H, Cu > Fe, Ce > K. The A1 salt gave trimers with 90% conversion at 503 K. The selectivities to trimer are about 40% for Al, Ce, Co, and Cu, while that of the acid form is 25%. 

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

Finally, in the codimerization of styrene with ethylene to optically active 3-phenyl-1-butene (52) (Table XI), it has been shown that the complex anion (Y) can exert a strong influence on the optical yield 103, 105). 

Codimerization of styrene and ethylene giving 3-phenyl-l-butene is another example of asymmetrically induced hydrovinylation. With catalyst precursors obtained from (jt-allyl)NiX or (> 3-cyclooct-5-enyl)NiX (X = various anions) modified with bis(menthyl)methylphosphane. ]<)- and (S)-3-phenyl-1 -butene in up to 37% ee is obtained, depending on the counterion X of the catalytic system13. 

This is to be compared with the products of codimerization of ethylene with 1-butene (R = Et vide supra). As for tantalum, the /3-substituted metallacycle preferentially forms over the a-derivative. 

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