Kinetics of Magnesium Incorporation into Water Soluble Porphyrins
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Sabrina L. Bailey
Abstract
The kinetics of Mg2+ incorporation into the three water soluble porphyrin isomers of the relatively planar cationic tetrakis(N-Methyl-X-pyridyl)porphyrins (X = 2,3, or 4) were studied from pH 6.5 to 8.9 at 25 °C, I = 2.6. The reactions were first order in both porphyrin and magnesium ion concentrations, and the specific rate constants increased with an increase in pH. The proposed mechanism involves Mg2+ reacting with the differing centrally protonated forms of these porphyrins, in the order Ρ 2-> H-P-" > H2-P. Various other porphyrins were substantially less reactive. In contrast, Mg reacts orders of magnitude faster with the non-planar ß-octabromo-tetra(N-methyl-4-pyridyI) porphyrin, where the reaction proceeds almost exclusively through the Mg2+ + P2- pathway. As compared to other metal ions, the relatively slow incorporation of Mg2+ into porphyrins is in part a consequence of the comparatively slow water exchange rate constant for the aquo Mg2+ ion.
© 2014 by Walter de Gruyter Berlin/Boston
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Articles in the same Issue
- Introducing The New Co-Editor Of Inorganic Reaction Mechanisms
- Kinetic and Mechanistic Studies of Substitution Reactions of Solvated Cobalt(II), Nickel(II), Copper(II) and Zinc(II) Ions with 2,2′:6′,2″-Terpyridine and Several 2,2′:6′,2″-Terpyridine Derivatives. Evidence for the Formation of Intermediates
- Activation Volumes for a Series of Spontaneous, Acidand Base-Catalysed Aquation Reactions of Aniono trans- [Co(MeNH2)(NH3)4X]2,1+ Complexes (X=Cl-, Br-,ΝO3-,SO42-)
- Interactions of the Aminoglycoside Neamine and 2-Deoxystreptamine with Copper(II) and Zinc(II)
- Kinetics of Oxidative Deamination and Decarboxylation of L-Asparagine by Alkaline Permanganate: a Mechanistic Approach
- Kinetics of Magnesium Incorporation into Water Soluble Porphyrins
- Micellar Effect on Chromium(VI) Oxidation of D-Glucose in the Presence and Absence of Picolinic Acid in Aqueous Media: A Kinetic Study
- Kinetics of Oxidation of Antimony(III) by Tetrachloroaurate(III) in Aqueous Hydrochloric Acid Media
