Molecular modeling of metathesis degradation of polyalkenamers - 1. Degradation of polynorbornene via cross-metathesis with linear olefins

The molecular modeling of polynorbornene (PNB) degradation via cross-metathesis with ethylene, 2-butene, and 1,4-dichloro-2-butene as chain-transfer agents (CTAs) at 25 degreesC using the B3LYP/6-3IG(d,p) level of theory reveals that chain-chain equilibrium constants depend on the nature of linear olefins used as CTAs. The cross-metathesis of PNB with trans- 1,4-dichloro-2-butene as a CTA proceeds with high selectivity. The yield of bis(allyl chloride) functionalized diene reaches 92 mol%. The results of calculations are in agreement with experimental data obtained for the cross-metathesis of PNB with trans- 1,4-dichloro-2-butene using highly active ruthenium-based catalyst, (1,3-dimesityl-4,5-dihydroimidazol-2-ylidene) (PCy3)CI2Ru=CHPh. (C) 2004 Elsevier Ltd. All rights reserved.