Synthesis of α-Tetralone from Tetralin by Metalloporphyrin and Transition Metal Salt Tandem Catalysis and the Reaction Mechanism

An efficient two-step preparation of α-tetralone from tetralin was studied.First,tetralin was oxidized to α-tetralin hydroperoxide with air in the presence of a metalloporphyrin catalyst.Second,a catalytic amount of either water-soluble iron salts or copper salts was added to the resultant α-tetralin hydroperoxide solution to convert α-tetralin hydroperoxide into α-tetralone.The major product of oxidation catalyzed by metalloporphyrin was α-tetralin hydroperoxide,and only a minor amount of α-tetralone and trace of α-tetralol were formed.Simple salts such as CuⅠand FeⅡcould efficiently decompose α-tetralin hydroperoxide to α-tetralone,and best result was obtained with ferrous ion.The influence of the metal ions,catalyst amount,and reaction temperature on both the tetralin aerobic oxidation and the decomposition of α-tetralin hydroperoxide was studied.Possible mechanisms for the oxidation of tetralin and the decomposition of α-tetralin hydroperoxide were proposed.