Synthesis of poly-p-oxyperfluorobenzylene and related polymers. A novel synthesis of the monomer 2,3,5,6-tetrafluoro-4-trifluoromethylphenol

The synthesis and polymerization of 2,3,5,6-tetrafluoro-4-trifluoromethylphenol (heptafluoro- p -cresol) is described. The polymer, poly- p -oxyperfluorobenzylene (polyperfluoro- p -benzylene oxide), is probably formed through the perfluoro- p -quinonemethide intermediate obtained by the intramolecular loss of either hydrogen fluoride or a metal fluoride. The polymer has a structure analogous to that reported for the polymer derived from p -trifluoromethylphenol under similar conditions. In the course of the synthesis of the monomer, heptafluoro- p -cresol, a novel synthetic method was discovered. The synthesis consists in the prior preparation of 1- t -butoxy-2,3,5,6-tetrafluoro-4-trifluoromethylbenzene and its subsequent thermal decomposition into the isobutylene and the desired cresol. Similarly, N-t -butyl-2,3,5,6-tetrafluoro-4-trifluoromethylaniline undergoes a similar liquid phase pyrolysis into isobutylene and 2,3,5,6-tetrafluoro-4-trirluoromethylaniline. However, during the course of this pyrolysis, practically all of the aniline undergoes polymerization with the concomitant loss of hydrogen fluoride. The polymer is formed by the same mechanism operative in the thermal polymerization of p -heptafluorocresol except that additional quantities of hydrogen fluoride can be eliminated from the - NHCF 2 - segments of the polymer chain thereby introducing - N = CF - units into the polymer backbone. Other t -butyl derivatives were synthesized and their thermal decomposition studied. Several possible mechanisms for the decomposition of these t -butyl compounds are considered.