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Ethylalumoxanes and ethylchloroalumoxanes as components of catalyst for propylene polymerization
Author(s) -
Pasynkiewicz S,
Mańk B
Publication year - 1992
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.590060604
Subject(s) - chemistry , catalysis , hydrolysis , polymerization , stereospecificity , degree of polymerization , natta , polymer chemistry , chlorine , ziegler–natta catalyst , alkyl , organic chemistry , polymer , ethylene
Ethylalumoxanes and ethylchloroalumoxanes as components of Ziegler‐Natta catalysts for polymerization of propylene have been studied. The influence of the degree of hydrolysis of triethyl aluminium [(Et 3 Al) and diethylaluminium chlorilp (Et 2 AlCl) 2 ] in the range 0.5–1.5:1 on the activity and the stereospecificity of the catalytic systems was determined (the degree of hydrolysis is defined as the molar ratio H 2 O/organoaluminium compound). It was found that the activity of the catalytic system ethylalumoxane‐ TiCl 4 is a little higher than the activity of the Et 2 AlCl‐TiCl 4 system. The ethylchloroalumoxane‐TiCl 4 system is about six times more active than the classical Ziegler‐Natta system. Our studies showed that alumoxanes react with TiCl 4 as follows: (a) to form compounds of the AlOTiCl 3 type; (b) to exchange alkyl groups for chlorine; (c) to form donor‐acceptor complexes. Reactions of types (b) and (c) occur mainly in the cases of alumoxanes of low degree of hydrolysis (0.5–0.7). In cases of alumoxanes of a degree of hydrolysis equal to 0.7–1.0, reactions of all three types occur, and for alumoxanes of degree of hydrolysis >1.0 reactions of types (a) and (c) are preferred.