Metathetic alkenolysis of unsaturated units in polymers and copolymers––application to the synthesis of epoxy-functionalized oligomers and organic compounds

Depolymerization of 20% epoxidized cis-1,4-polybutadiene was carried out through alkenolysis of the butadiene repeat units (B) using 4-octene as depolymerizing agent (DA) and bis(tricyclohexyl phosphine)benzylidene ruthenium (IV) dichloride (1) as catalyst. The average molecular weight of the depolymerization products was determined by NMR, and SEC, and their constituents were identified by GC MS. Cis-4-octene was found more efficient in performing the depolymerization as compared to its trans isomer. Besides dodeca-4,8-diene and hexadeca-4,8,12-triene, 2,3-di[3-heptenyl]-oxirane with a cis oxirane configuration was clearly characterized. Beside the DA to B mole ratio, the catalyst to double bond mole ratio was observed as the major factor controlling the molecular weight of the depolymerization products and the 2,3-di[3-heptenyl]-oxirane yields.