RING-OPENING CLOSING ALTERNATING COPOLYMERIZATION OF CYCLIC PHOSPHONITES WITH DIALDEHYDES

The present paper describes the ring-opening-closing alternating copolymerization (ROCAC) of four cyclic phosphonites (1) with four dialdehydes (2) including aliphatic and aromatic dialdehydes. The reaction of a 1:1 monomer feed ratio proceeded without any added catalyst to give an alternating copolymer 3 involving ring opening of 1 and ring closing of 2. The structure of copolymer 3 was determined by H-1, C-13, and P-31 NMR and IR spectroscopies as well as elemental analysis. The copolymerization is reasonably explained by a mechanism of propagation via zwitterion intermediates. The electrophilic reactivity of a carbonyl carbon in 2a and 2b toward monomer 1a was quantitatively examined.