Tetralin autoxidation products

Tetralyl hydroperoxide was isolated as the product of tetralin autoxidation... 

Two very curious but heretofore unexplained phenomena relate to the interaction of reduced polyoxometalates with O2 and are addressed by our experiments described right below. The first involves the lack of oxygenated products seen in the photochemical functionalization of heptacyclotetradecane (HCTD) in the presence of O2 by Christina Prosser-McCartha. The second involves two observations by Neumann and Levin, namely, the suppression of tetralin autoxidation and the clean conversion of a-terpinene to p-cymene in the presence of O2 without formation of oxygenated products. 

Autoxidation may in some cases be of preparative use thus reference has already been made to the large-scale production of phenol+ acetone by the acid-catalysed rearrangement of the hydroperoxide from 2-phenylpropane (cumene, p. 128). Another example involves the hydroperoxide (94) obtained by the air oxidation at 70° of tetrahydro-naphthalene (tetralin) the action of base then yields the ketone (a-tetralone, 95), and reductive fission of the 0—0 linkage the alcohol (a-tetralol, 96) ... 

The known examples of catalytic oxygenations involve substrates that undergo relatively facile autoxidation to hydroperoxides often even without an added catalyst. For example tetraline is converted to a-tetralone in the presence of ClFeTPP at 25 °C [96]. CoTTP catalyzes the oxidation of 2,5-dihydrofuran to 2-hydrofuran-5-one and 2-hydrofuran-5-ol in ethyl acetate at 30 C [97]. Furan and 2,3-dihydrofuran were also oxidized but the products were not determined. Tetraline and cumene did not react. The kinetics of autoxidation were interpreted in terms of chain initiation by the dioxygen adduct of CoTTP ... 

Kinetic results were consistent with a bimolecular termination reaction whereas reaction products and mechanisms were something of a mystery. At that time it was known that the termination rate constant for autoxidation of cumene ( ) is about three orders of magnitude smaller than the termination rate constant for autoxidation of tetralin (7.). It was, however, generally accepted that the tennination rate constants for tertiary ( ) and secondary (9 ) alkylperoxy radicals are insensitive to the structure of the hydrocarbon residue in the radical. 

---