The polyaddition of 1,4-bis [(3-ethyl-3-oxetanyl)methoxymethyl] benzene with 2,2'-bis [(4-chloroformyl)oxyphenyl] propane was examined with quaternary onium salts as catalysts. When the polyaddition was carried out with tetrabutylphosphonium bromide in chlorobenzene at 120 degreesC for 24 h, the corresponding poly(alkyl aryl carbonate) with a high molecular weight (number-average molecular weight = 16,700) was obtained in an almost quantitative yield. It was found from the H-1 NMR and C-13 NMR spectra of the obtained polymer that the addition reaction proceeded without any side reactions, providing the polycarbonate with pendant chloromethyl groups in the side chain. The polyaddition of bis{[3-(3-ethyloxetanyl)]methyl}terephthalate also proceeded smoothly and gave the corresponding polycarbonate with high molecular weight in a good yield. (C) 2003 Wiley Periodicals, Inc.