RING-OPENING POLYMERIZATION OF ACTIVATED CYCLOPROPANES - POLYMERIZATION OF DIETHYL 1,1-CYCLOPROPANEDICARBOXYLATE BY METALLIC SODIUM

Diethyl 1,1-cyclopropanedicarboxylate undergoes ring-opening polymeriz ation under anionic conditions. If the cyclopropane is contaminated by diethyl malonate CH2(COOEt)2, polymerization can be initiated by meta llic sodium. The mechanism of this initiation was found to involve an initial reduction of the malonate by sodium to give the salt (EtOOC)2C H(-) Na(+) which acts as the real initiator. Poly(diethyl 1,1-cyclopro pane dicarboxylate) is soluble in halogenated solvents and was charact erized by GPC, IR, H-1- and C-13-NMR. Molecular weights are low to mod erate (typically 10(3)-10(4)) and are compatible with the low monomer / initiator ratios used in these experiments.