Novel Isomerization Polymerization of Glycidyl Acetate To Produce a Poly(ortho ester)

A new mode of polymerization of glycidyl acetate (1a) to yield a poly(ortho ester), i.e., poly[(2-methyl-1,3-dioxolane-4,2-diyl)oxymethylene] (3a), was explored. This new polymerization exclusively proceeded when a bulky Lewis acid, methylaluminium bis(2,6-di-tert-butyl-4-methylphenoxide) (2a), was employed as the catalyst. The polymerization of 1a with 4 mol % of 2a proceeded smoothly in toluene at 0 °C and gave 3a in 82% after 1 h. The time-trace of the polymerization system revealed that this polymerization was completed within 3 min under these conditions. The polymerization mechanism is tentatively assumed as polyaddition of zwitterionic species produced from 1a with the assistance of 2a. The polymerization of glycidyl methacrylate (1b) with 2a gave poly(ortho ester) 3b in a similar manner.