2-(Hydroquinon-2-yl)-5,10,15,20-tetraphenyl porphyrin and its metal complexes I were synthesized by the direct reaction of 2-nitro-5,10,15,20-tetraphenyl porphyrin with neutral hydroquinone in 60%～80% yields. 2-Substituted porphyrin tautomers II were also obtained as byproduct and characterized by MS, IR, ¹H NMR and 2D NMR as precursor and dynamic isomer of I. In applications of water and O₂ intrusion at high temperature, both the rate and the yield of the system were increased obviously. The O₂ intrusion would be the key for the increase of the rate and the water intrusion would lead to the more acidic environment resulting in the isomerization of II to I. From these experiments it was concluded that single-electron transfer free radical reaction mechanism was involved in the reaction.

Key words: 2-hydroquinon-2'-yl porphyrin, synthesis, single-electron transfer, free radical mechanism