Ž . Journal of Molecular Catalysis A: Chemical 160 2000 323–330 www.elsevier.comrlocatermolcata Structural stabilities of sulfonated manganese tetramesitylporphyrin and its b-brominated analogue toward ž / NaOCl, H O and CH COOH 2 2 3 3 Hayrettin Turk ) , Turgay Tay, Huseyin Berber ¨ ¨ Department of Chemistry, Faculty of Sciences, Anadolu UniÕersity, 26470 Eskis ¸ehir, Turkey Received 2 March 2000; received in revised form 5 June 2000; accepted 5 June 2000 Abstract Ž . Ž . This article gives the degradation rate constants of meso-tetrakis 3,5-disulfonatomesityl porphinatomanganese III X Ž y .Ž . Ž . where X sH O andror OH depending on pH MnTMSP and its b-brominated analogue MnTMSPBr toward the 2 8 Ž . oxidants NaOCl, H O , and CH COOH at various pHs, I s0.2 M and 308C. In addition, the degradation rate constants 2 2 33 Ž of MnTMSP was determined when it was bound to cationic supports — namely, CTAB, a poly vinylbenzyltrimethylam- . monium chloride latex, 2,6-ionene and 2,10-ionene. MnTMSP showed high structural stability toward the peroxides in strong acidic medium and the degradation rate constants were found as low as 10 y4 min y1 at pH -1.50. When NaOCl was employed as the oxidant, the pH dependence of the stability of MnTMSP was vice versa and its degradation rate constant was determined as 1.43 =10 y4 min y1 at pH 14.10. In strong acidic solution, the supports CTAB and latex made the stability of MnTMSP toward the peroxides improve significantly. In strong basic solution, only latex-bound MnTMSP showed higher stability toward NaOCl than the homogeneous MnTMSP. Because MnTMSPBr was not stable in solutions 8 having pH higher than 9 and containing no oxidant, its stability was investigated at pH -9 and it showed slightly lower stability toward the peroxides than the non-brominated analogue. q 2000 Elsevier Science B.V. All rights reserved. Keywords: Porphyrin stability; Porphyrin degradation; Tetramesitylporphyrin Supported porphyrin 1. Introduction After the discovery of the cyctochrome P-450 monooxygenese-like activity of meso-tetraphen- Ž . ylporphinatoiron III chloride in 1979, a large class of metalloporphyrins were synthesized and ) Corresponding author. Tel.: q 90-222-335-0581, ext. 5122; fax: q 90-222-320-4910. Ž . E-mail address: hturk@anadolu.edu.tr H. Turk . ¨ used as catalysts for epoxidation and hydroxyl- w x ation reactions 1–6 . Although many advances have been made concerning the selectivities and w x mechanisms of these oxidations 3–22 , it was found that metalloporphyrin catalysts are not very stable during the reactions. They act fre- quently as a substrate and self-destruct in an intermolecular process. Also, it has been well established that the stability of a porphyrin de- pends on the substituents on the phenyl and pyrrole moities of the macrocycle as well as the 1381-1169r00r$ - see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž . PII: S1381-1169 00 00308-3