Polyfluoroheterocyclic compounds. Part XXV. Thermal reactions of perfluoroalkylpyridazines

Abstract

Flow pyrolysis of perfluoro-4,5-diethylpyridazine gave mainly perfluoro-4,5-diethylpyrimidine and some perfluoro-2,6-diethylpyrazine; perfluoro-4-ethylpyridazine gave a mixture of perfluoro-4- and -5-ethylpyrimidines; and perfluoro-4-isopropylpyridazine gave a mixture of perfluoro-isopropyl- and -ethyl-pyrimidines. Pyrolysis of perfluoro-4,5-di-isopropylpyridazine has been re-examined under flow and static conditions and a correction to previous conclusions is made. These reactions are explained in terms of formation and rearrangement of diazabenzvalenes. Perfluoro-4,5-diethyl-3,6-di-isopropylpyridazine has been synthesised; pyrolysis led to products arising from both nitrogen elimination and rearrangement. Vacuum pyrolysis of perfluoro-4,5-di-isopropylpyridazine gave significant amounts of fragmentation products.