Demetallation of ?,?,?,?-tetrakis(p-sulfophenyl) porphiniron(III) in mineral acid-alcohol-water media

Autor: Warren L. Reynolds, Kevin Kooda, Brent L. Florine, Nancy Collins Johnson, Kenneth Thielman
Rok vydání: 1980
Předmět:
Zdroj: International Journal of Chemical Kinetics. 12:97-105
ISSN: 1097-4601
0538-8066
DOI: 10.1002/kin.550120203
Popis: Demetallation rates of α,β,γ,δ-tetrakis(p-sulfophenyl)porphiniron(III) in hydrochloric acid–ethanol–water, perchloric acid–ethanol–water, and sulfuric acid–alcohol–water media were determined. For a given acidity value H0 the order of the rates for the three acids was HCl > H2SO4 > HClO4. This is also the order for complex formation between acid anion and iron(III). Consequently ligands as well as protons are involved in the breaking of bonds between the metal and the porphyrin leading to the formation of the activated complex. The log k values for HCl and HClO4 media were not linearly related to the Hammett acidity function as they were for sulfuric acid–ethanol–water media. The average ΔH‡ and ΔS‡values for the HCl media were 18.4 ± 1.4 kcal/mol and 19 ± 3 cal K mol, respectively, in very close agreement with those for H2SO4 media despite the difference in H0 dependence. For H2SO4–alcohol–water media the order of the rates was butanol > propanol > ethanol with little difference between isomeric alcohols.
Databáze: OpenAIRE
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