Polymer and group interactions. VII. Lactonization of polyethyl α‐chloroacrylate

Polyethyl α‐chloroacrylate (PCA) has been condensed in the presence of aluminum chloride and aromatic hydrocarbons; the molar ratio AICl3/PCA was usually higher than unity. Although the halogen content decreases with a higher degree of conversion, no aromatic hydrocarbons are incorporated into the polymer. The reaction proceeds through a nucleophilic substitution mechanism with intramolecular lactonization; the polymer composition has been calculated from the halogen content and the conductometric titration of free acid and lactone rings after opening. The degrees of polymerization of the reaction products were determined by the osmotic method in order to evaluate the importance of the chain degradation during the condensation. In spite of the high condensation temperature and the high degree of conversion, the degrees of polymerization are about 40–50% of that of the initial PCA. While the limited viscosity numbers vary only slightly, the Huggins‐Schulz k′ constant values decrease regularly with an increasing degree of lactonization.