Catalysis of Water-soluble Porphyrins for Oxidation of 1,5-Dihydroxynaphthalene

A series of water-soluble free base porphyrins(H2TPPS, H2TCPP and H2TMPyP) and their metal complexes(FeTPPS, ZnTPPS, CoTPPS) were efficiently synthesized and characterized. As photosensitizers, these porphyrins were used to catalyze the oxidation of 1,5-dihydroxynaphthalene under visible light irradiation. The main product were identified as 1,5-dihydroxynaphthalene. The catalytic process was monitored by UV-Vis method and the optical catalytic conditions were established. The water phase system and water-dichloromethane double phase system were explored. The effects of various factors such as substituent groups, central metal ions were investigated. The catalytic results show that anionic porphyrins have efficient catalytic activity; At the beginning of the reaction, high catalytic acitivity can be obtained for iron porphyrin, while it decreases greatly because of catalyst photolysis; The sodium sulfonic porphyrin is the most stable catalyst in the reaction system and has the best catalytic activity.