ACID CATALYZED SOLVOLYSIS KINETICS OF ZINC(II), COBALT(II), COPPER(II) AND NICKEL(II)N-METHYL-TETRA-(4-SULFONATOPHENYL)PORPHYRINS

Abstract A kinetic study of the acid solvolysis reactions of divalent nickel, cobalt, zinc and copper complexes of N-methyl-tetra(4-sulfonatophenyl)porphyrin was done at 25°C in aqueous solution. All reactions were first order in metalloporphyrin and first order in [H+]. Only the ZnII and CuII derivatives had a second term proportional to [H+][Ac−]. Calculated formation constants of the uncatalyzed reactions are in the order Ni > Cu ∼ Zn > Co > Cd. The results show that kinetically N-alkylated metalloporphyrins require one less proton for acid solvolysis than do the corresponding metalloporphyrins.