The homogeneous catalyst CpTiCl(3)-MAO is able to produce a random copolymer of 4-methyl-1, 3-pentadiene with ethylene. C-13 NMR analysis of the copolymers shows that after insertion of ethylene units, the next 4-methyl-1,3-pentadiene unit can be inserted in either 1,2 or 1,4 arrangement. The high chemoselectivity observed in the 1,2-syndiotactic homopolymerization of 4-methyl-1,3-pentadiene with respect to the lower one observed in the copolymerization with ethylene is attributed to a back-biting coordination to the Ti of the active species of the penultimate monomer unit of the growing chain.
Chemoselectivity in 4-methyl-1,3-pentadiene polymerization in the presence of homogeneous Ti-based catalysts.
LONGO, Pasquale;GRISI, Fabia;PROTO, Antonio;ZAMBELLI, Adolfo
1997
Abstract
The homogeneous catalyst CpTiCl(3)-MAO is able to produce a random copolymer of 4-methyl-1, 3-pentadiene with ethylene. C-13 NMR analysis of the copolymers shows that after insertion of ethylene units, the next 4-methyl-1,3-pentadiene unit can be inserted in either 1,2 or 1,4 arrangement. The high chemoselectivity observed in the 1,2-syndiotactic homopolymerization of 4-methyl-1,3-pentadiene with respect to the lower one observed in the copolymerization with ethylene is attributed to a back-biting coordination to the Ti of the active species of the penultimate monomer unit of the growing chain.File in questo prodotto:
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