Synthesis of High Molar Mass Poly(alkylene phosphate)s by Polyaddition of Diepoxides to Difunctional Phosphoric Acids: Unusual Elimination of the Side Reactions

The reaction between diepoxides and difunctional acids of phosphorus was studied as a potential route to linear polyesters of phosphoric acid. The reaction between diepoxide and P-OH groups in H3PO4 and related acids leads to linear phosphates, but cyclic phosphates are also formed as side products. The formation of such unreactive groups terminates polyaddition. However, cyclization is practically eliminated when the epoxide ring is fused to another ring, such as in cyclohexene oxide. A commercially available diepoxide containing two cyclohexene oxide moieties, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (ERL), was, therefore, used for polyaddition studies. Indeed, in the polyaddition of ERL with ethylphosphoric acid, high molecular weight (number-average molecular weight up to 10^4) linear polyphosphates were obtained