Ring‐opening polymerization of cyclic compounds with bifunctional groups. V. Polymerization of 7‐oxo‐4‐phenyl‐1,4‐azaphosphepane (phospha‐caprolactam)

Abstract 7‐Oxo‐4‐phenyl‐1,4‐azaphosphepane (II) (phospha‐caprolactam) and its 3,5‐tetramethyl derivative (IV) containing an amide group and a phosphorus atom in the same ring, have been synthesized and polymerized in the presence of various catalysts. II polymerized with Al(C2H5)2Cl or SnCl4 as catalysts to give polyamide of low molecular weight, whereas IV did not polymerize with satisfactory results. On the other hand, the copolymerization of the tetramethyl substituted “phospha‐caprolactam” IV with other cyclic compounds including lactams, lactones or cyclic ethers took place in the presence of cationic catalysts.