Chemistry of pyrrolic compounds. XXVII. Some aspects of the mass spectra and chemistry of meso-substituted porphyrins.

Characteristic fragmentations have been observed in the mass spectra of some meso-substituted porphyrins, and especially in some meso-oxy derivatives. meso-Substituted octaethylporphyrins generally underwent thermal decomposition in the mass spectrometer; this resulted in the formation of the parent porphyrin from which the successive loss of eight methyl radicals was observed. Attempts to prepare meso-carboxyoctaethylporphyrin by oxidation of the formyl derivative or by hydrolysis of the meso-cyano compound failed. As a by-product of the preparation of meso-cyano- octaethylporphyrin a porphyrin isocyanide was obtained. Some aspects of the chemistry of this novel porphyrin derivative are reported together with the preparation and properties of an oxyporphyrin substituted with acetic ester side chains.