Demetallation of α,β,γ,δ-tetrakis(p-sulfophenyl) porphiniron(III) in mineral acid–alcohol–water media

✍ Scribed by Warren L. Reynolds; Kevin Kooda; Brent Florine; Nancy Johnson; Kenneth Thielman

• Publisher: John Wiley and Sons
• Year: 1980
• Tongue: English
• Weight: 420 KB
• Volume: 12
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550120203

✦ Synopsis

Demetallation rates of cu,P,y,d-tetrakis(p-sulfophenyl)porphiniron ( 111) in hydrochloric acid-ethanol-water, perchloric acid-ethanol-water, and sulfuric acid-alcohol-water media were determined. For a given acidity value Ho the order of the rates for the three acids was HCl > &So4 > HC104. This is also the order for complex formation between acid anion and iron(II1). 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 HC1 and HC104 media were not linearly related to the Hammett acidity function as they were for sulfuric acid-ethanol-water media. The average AH* and AS* values for the HC1 media were 18.4 f 1.4 kcal/mol and -19 f 3 cal K mol, respectively, in very close agreement with those for HzS04 media despite the difference in Ho dependence. For HzS04-alcohol-water media the order of the rates was butanol > propanol > ethanol with little difference between isomeric alcohols.