Bromination of tetraazaporphine and its beta-substituted derivatives usingpyridine as solvent and catalyst

The selectivity and degree of bromination of pyrrole rings in porphyrazine strongly depends on the brominating agent and solvent nature. The reaction of porphyrazine magnesium complex with molecular bromine and N-bromosuccini mide in pyridine gave magnesium complex of dibromotetraazaporphine. Increas ing bromine substitution in porphyrazine enhances its acidic properties.