A computational study of the reactivity of diethenylnaphthalenes towards anionic polymerization

Diethenyl, di(1-methylethenyl), and di(1-phenylethenyl) naphthalenes are kn own to be difunctional initiators used in the synthesis of thermoplastic el astomers. Semiempirical (AM1, PM3) and ab initio calculations (HF/6-31G, HF /6-31G*) have been carried out to determine the reactivity of these compoun ds towards anionic polymerization. For this purpose, geometrical parameters , electrostatic potentials, and frontier orbitals have been analyzed. React ion 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 conf ormational 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 th e most suitable difunctional initiators for anionic polymerization are the compounds where the substituents lie away from the naphthalene bridge. We h ave also found that in some cases the substituents are conjugated with each other and di(1-phenylethenyl)naphthalenes are more reactive th an dietheny lnaphthalenes which in turn are more reactive than di(1-methylethenyl)napht halenes towards anionic polymerization.