Synthesis and Acid-base Properties of Isomeric Tetrachlorooctabromo- and Tetrabromooctachlorotetraphenyl-porphyrins

Reactions of Co(II)-5,10,15,20-tetra(4-bromophenyOporphyrin chlorination with excess of the thionyl chloride and Co(II)-5,10,15,20-tetra(4-chlorophenyl)porphyrin bromination with N-bromosuccinimide were investigated. Co(II)-2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetra(chlorophenyl)porphyrin and Co(H)-2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetra(4-bromophenyl)porphyrin were synthesized and identified by UV-Vis, H-1 NMR spectroscopy and mass-spectrometry. When the halogen substituted Co(II) porphyrins were treated with a chloric and sulfuric acids mixture, corresponding porphyrin-ligands were obtained. The acid-base properties of the 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetra(4-chlorophenyl)porphyrin and 2,3,7,8, 12, 13, 17, 18-ociachloro-5, 10, 1 5, 20-tetra(4-bromophenyl) porphyrin in acetonitrile were studied. Acidity and basicity constants of the synthesized porphyrin ligands were determined and the concentration intervals for their ionized forms existence were established.