Copolymerization reactivities, electron structure and nuclear magnetic resonance spectra of vinylazoles

Abstract

AbstractData obtained on the electronic structure of a series of C‐ and N‐vinylazoles using the SCF MO method in MNDO approximation and analysis of the 13C and 1H NMR data as well as their copolymerization reactivity ratios in the copolymerization with styrene have shown individual correlations between the relative activity 1/r (r is the copolymerization reactivity ratio of styrene) and the chemical shifts of the terminal vinyl carbon atoms in 13 C NMR spectra, between 1/r and chemical shifts of the protons in trans‐position towards the substituent in 1H NMR spectra, and between 1/r and the net effective charges on the terminal vinyl carbon atoms for each type of monomers considered. The correlations obtained and the analyses obtained from the monomers studied within the modified Alfrey‐Price scheme indicate that the reactivity of vinylazoles in copolymerization is mainly influenced by two factors: the acceptor inductive effect of a substituent in the vinyl bond and the conjugation effect. These factors operate in a different manner for C‐ and N‐vinylazoles and determine their different reactivity in radical copolymerization with styrene.