Premium
Mechanism of anionic ring‐opening polymerization of silacyclopent‐3‐enes
Author(s) -
Weber William P.,
Park Young Tae,
Zhou Stephen Q.
Publication year - 1991
Publication title -
makromolekulare chemie. macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 0258-0322
DOI - 10.1002/masy.19910420121
Subject(s) - isoprene , polymerization , chemistry , stereospecificity , anionic addition polymerization , yield (engineering) , cationic polymerization , polymer chemistry , ring opening polymerization , ring (chemistry) , living anionic polymerization , ene reaction , polymer , living polymerization , radical polymerization , stereochemistry , copolymer , materials science , catalysis , organic chemistry , metallurgy
Anionic ring‐opening polymerization of silacyclopent‐3‐enes has characteristics which are different from those of anionic living polymerizations of 1,3‐dienes. High molcular weights are obtained in most cases but generally with most probable molecular weight distributions M w /M n ≅ 2. The polymerization is stereospecific. Poly(1‐sila‐cis‐pent‐3‐enes) are obtained. Ring opening polymerization of 1,1,3‐trimethyl‐1‐sila cyclopent‐3‐ene is found to be regioselective at −78°C to yield a polymer in which cis‐1,4‐isoprene units are joined to dimethylsilylene units almost exclusively in a head to tail orientation. Finally, anionic polymerization of 1‐methyl‐1‐silacyclopent‐3‐ene is found to yield poly(1‐methyl‐1‐sila‐cis‐pent‐3‐ene) of low molecular weight. This permits end group analysis by 1 H, 13 C and 29 Si NMR spectroscopy, signals are observed which are consistent with the presence of 1‐methyl‐1‐silacyclopent‐3‐ene rings. These are probably end groups. A mechanism consistent with the above is discussed.