Pyrolysis/gas chromatography/mass spectrometry analysis of 5,10,15,20-tetraphenyl-21H,23H-porphyrin and some of its derivatives

A coupled on-line pyrolysis/gas chromatography/mass spectrometry technique (Py/GC/MS) was applied to identify products of pyrolysis of 5,10,15,20-tetraphenyl-21H,23H-porphyrin (1a) and its methyl and hydroxyl substituted derivatives (1b and 1c). The mass spectra of some important pyrolitic products are presented and mass fragmentation of this type compounds is discussed. From the investigation it can be concluded that the direction of the main thermal (pyrolytic) reactions is similar for all compounds studied: namely breaking of the porphyrin macrocycle followed by splitting of molecule fragments containing one, two or three pyrrole and/or benzene rings. The products of pyrolysis can be simply correlated with the structures of porphyrins.