Polymerization and copolymerization of 1‐ and 9‐vinylanthracenes and 9‐vinylphenanthrene

Abstract

AbstractThe free radical polymerization and copolymerization with styrene of 1‐ and 9‐vinylanthracenes and 9‐vinylphenanthrene was studied. The highest reactivity was shown by 9‐vinylphenanthrene and the lowest by 9‐vinylanthracene. From the experimental data on the copolymerization reactions the reactivity ratios r1 and r2 were calculated and for the two vinylanthracenes the values of Q2 (general reactivity) were obtained after application of the Price‐Alfrey scheme for correlating reactivities of vinyl compounds in copolymerization. The scheme was not used for 9‐vinylphenanthrene as the product of r1 × r2 was in this case greater than unity. It appears that the rates of polymerization (and copolymerization) of the three monomers are influenced by two factors: the steric hindrance to conjugation between the anthracene or phenanthrene system and the exocyclic double bond, and the nonaromatic character of the 9,10 double bond in phenanthrene. In 9‐vinylanthracene the conjugation between the anthracene system and the vinyl group is sterically more hindered that in the 1‐isomer, the resonance stabilization of the radical adduct of 1‐vinylanthracene is greater than in the case of the 9‐isomer and the latter is less reactive. In 9‐vinylphenanthrene and 1‐vinylanthracene the steric hindrance is the same and the higher reactivity of the first monomer as compared with the second seems to be due to the non‐aromatic character of the 9, 10 double bond in phenanthrene, which makes the 9‐vinylphenanthrene and almost aliphatic diene.