Polymer and Materials Science
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
The interaction between AlEt3 and silyl ethers, PhnSi(OMe)4-n (n = 0-3), was followed by 13C- and 29Si-NMR techniques in conditions close to those typical for an olefin polymerization reaction with supported Ziegler-Natta catalysts (A1Et3:silyl ether ratios from 1 to 10, temperature range 25-75°C). A1Et3 and silyl ethers form instantaneously at ambient temperature a donor-acceptor complex, which is stable at a 1:1 molar ratio. In the presence of excess A1Et3 the complex decomposes via a mechanism consisting, in the case of PhSi(OMe)3, of five consecutive steps: alternating complexation and ether reductions with the formation of alkylated silyl ethers, Ph(Et)nSi(OMe)3-n (n = 1,2), and dialkyl-aluminum alkoxides, (Et2A1OMe3)n (n = 2,3). The rate of decomposition was enhanced by the increasing number of methoxy groups present in the silyl ether, heating, or a high A1Et3:silyl ether ratio. The decomposition was not inhibited by the presence of 1-hexene.
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