Anionic polymerization of 2-substituted cyclopropane-1,1-dicarbonitriles

Abstract

To investigate the anionic ring-opening polymerization of substituted cyclopropanes further, 2-phenylcycloprepane-1,a-dicarbonitrile(I), 2-ethylcycloprepane-1,1-dicarbonitrile(II) and 2,2-dimethylcycloprepane-1,1-dicarbontrile(III) were prepared and the polymerization behavior along with various other chemical reactions of these substituted cyclopropanes were investigated. The polymerizations of 2-substituted cyclopropanes were initiated with sodium cyanide in N,N-dimethylformamide. Under these conditions only compound I polymerized efficiently. The polymer from I was insoluble in common solvents including DMF, DMSO and HMPA. However it was slightly soluble in hot sulfolane in which the inherent viscosity was measured, 0.5dl/g (conc. 0.5 g in 100 ml). The polymer of 2-phenylcyclopropane-1,1-dicarbonitrile exhibited good thermal stability and started to decompose around $330^\circ C$. No significant transitions were detected on thermal analysis. The results of present investigation support the mechanism that a cyclopropane ring with properly positioned electron-donating and electron-withdrawing substituents can polymerize by opening the bond activated by a "push-pull" system. The present investigation has also shown that the tendency of the substituted cyclopropanes to polymerize anionically is in the order of 2-ethoxycycloprppane-1,1- dicarbonitrile $>$ 2-phenylcyclopropane-1,1-dicarbonitrile $>$ 2-vinylvyvlopropane- 1,1-dicarbonitrile $>$ Ethyl 1-cyano-2-vinylcyclopropanecarboxylate $>>$ 2-ethylcyclopropane-1,1-dicarbonitrile, 2,2-dimthylcyclopropane-1,1-dicarbonitrile$.