CATIONIC POLYMERIZATION OF METHOXYALLENE WITH LEWIS-ACIDS

The cationic polymerization of methoxyallene (1) was carried out with some Lewis acids at -50-degrees-C in dichloromethane. BF3OEt2 was found to be an effective catalyst for the cationic polymerization of 1. From analyses of H-1 and C-13 NMR spectra, the obtained polymers consist of units with the 1,2-double bond of 1 being opened, although the 2,3-double bond is consumed also to an amount of 24 to 43 mol-%. This decrease in 2,3-double bond content in the polymer may be attributed to intramolecular cyclization of the propagating cation and/or the intermolecular reaction of the propagating cation with polymer to produce a graft polymer. Moderately polar solvents such as dichloromethane proved to be best suited for obtaining polymers with high double bond content.