Nucleophilic aromatic substitution polymerization: evaluation of monomer reactivity by ¹⁹F NMR

Abstract

It has been demonstrated that some weakly activated aryl-fluorides can undergo nucleophilic aromatic substitution. In these cases, certain heterocycles and other functional group (eg. the azine group) can effectively activate aryl-fluorides and reports of the use of these nonconventionally activating groups in polymer forming reaction have appeared recently. It was of interest to find a spectroscopic probe that would allow the evaluation of potential monomers in these polymerization reactions. The series of monomers studied is listed, and in some cases, the 13C NMR chemical shift of the ipso carbon is also given. The monomers are listed in order to decreasing chemical shift. The relative rates of reaction, as estimated by the time needed to form high molecular weight polymer, is followed by the magnitude of the 19F NMR chemical shifts; the lower the chemical shift, the lower the reactivity of that monomer. Competitive relative reactivity studies were conducted in order to corroborate these observations.