The chemistry of pyrrolic compounds. X. A contribution to the chemistry of the oxyporphyrins

The preparation of a number of new oxyporphyrins is described and the spectroscopic and tautomeric properties of these tetrapyrroles and their metal ohelates examined in terms of substituent and steric effects. In selected cases oxyporphyrins and their acetates can be prepared in fair yield by condensation of the appropriate dipyrrylketone and diformyldipyrrylmethane in the presence of acetic anhydride. The zinc chelates of oxyporphyrins like the parent compounds are paramagnetic. Phosphorus pentasulphide has been shown to deoxygenate some oxyporphyrins.