Copolymerization of 2-phenoxy-1,3,2-dioxaphosphorinanes with α-keto acids involving deoxygenation of the keto oxygen atom: deoxy-copolymerization

Summary

The copolymerization of 2-phenoxy-1,3,2-dioxaphosphorinanes (4) with α-keto acids (2) took place at room temperature without added catalyst to produce copolymers (5). The copolymer 5 is composed of phosphoric acid triester unit (5 α) and of α -hydroxy-carboxylic acid ester unit (5 β). Unit 5 α is an alternating unit of monomers 4 and 2 whereas unit 5β is formed by deoxygenating 2 by 4. 5 can be taken as copolymers of units 5 α and 5 β, the formation of the latter involving a deoxygenation process (“Deoxy-Copolymerization”). The ratio of 5 β /5α (m-value in 5) increased in the order of unsubstituted (4a)-, 5,5-dimethyl (4b)-, and 5-t-butyl (4c)-phosphorinane systems. The reaction mechanism is also discussed.