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 Zn^II and Cu^II 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.

Key Words:

• porphyrins
• acid catalyzed solvolysis
• kinetics
• zinc(II)