A computational study of the reactivity of diethenylnaphthalenes towards anionic polymerization

Abstract

Diethenyl, di(1-methylethenyl), and di(1-phenylethenyl) naphthalenes are known to be difunctional initiators used in the synthesis of thermoplastic elastomers. Semiempirical (AM1, PM3) and ab initio calculations (HF/6-31G, HF/6-31G*) have been carried out to determine the reactivity of these compounds towards anionic polymerization. For this purpose, geometrical parameters, electrostatic potentials, and frontier orbitals have been analyzed. Reaction paths starting from the diethenylnaphthalenes and reaching the proposed products have been studied, and transition structures along the paths have been located. The minimum energy conformers were determined through a conformational search around single bonds for a series of diethenylnaphthalenes. We have attempted to predict how the location of the vinyl groups affects the reactivity of diethenylnaphthalenes. Our results have revealed that the most suitable difunctional initiators for anionic polymerization are the compounds where the substituents lie away from the naphthalene bridge. We have also found that in some cases the substituents are conjugated with each other and di(1-phenylethenyl)naphthalenes are more reactive than diethenylnaphthalenes which in turn are more reactive than di(1-methylethenyl)naphthalenes towards anionic polymerization.