Polyhalogenoheterocyclic compounds. Part 33. Mechanism of thermal rearrangements of perfluoropyridazine and perfluoroalkylpyridazines

Abstract

Rearrangement of perfluoro-4,5-di-s-butylpyridazine (4) to a mixture of perfluoro-4,5-di-s-butylpyrimidine (13) and -2,5-di-s-butylpyrazine (20), occurs at 300 °C, in a sealed tube. Cross-over experiments between various fluorinated pyridazine derivatives and, also, doubly ¹⁵N-labelled derivatives, rule out any rearrangement mechanism involving a cycloaddition process. Compound (4) and other fluorinated compounds act as promoters for the rearrangement of various fluorinated pyridazine derivatives and this process is now most reasonably regarded as a free-radical promoted formation of valence isomers.