135256-53-0Relevant academic research and scientific papers
Self-Initiated Autoxidation of a Sterically Crowded Cycloheptatriene Derivative via Norcaradienyloxyl Radicals
Kitagawa, Toshikazu,Miyabo, Atsushi,Fujii, Hideki,Okazaki, Takao,Mori, Tetsuya,Matsudou, Masaki,Sugie, Takeshi,Takeuchi, Ken'ichi
, p. 888 - 892 (1997)
An extremely crowded cycloheptatriene derivative, 1,3,5-tri-tert-butyl-7-(9-phenyl-9-fluorenyl)-l,3,5-cycloheptatriene (1), underwent autoxidation at 25 °C in cyclohexane to give 4-tert-butyl-2-pivaloylphenol (3) (33%), 5-tert-butyl-2-pivaloylphenol (4) (11%), 1,3,5-tri-tert-butylbenzene (5) (5%), tert-butyl 9-phenyl-9-fluorenyl peroxide (6) (44%), bis(9-phenyl-9-fluorenyl) peroxide (7) (7%), 1,1′,3,3′,5,5′-hexa-tert-butyl-7,′-bicycloheptatriene (8) (2%), and carbon monoxide (4%). ESR studies showed that 1 dissociates into l,3,5-tri-tert-butyltropyl radical (11) and 9-phenylfluorenyl radical (12) at 25-85 °C. The enthalpy and entropy of dissociation were determined to be 23.3 kcal/mol and 22.0 cal/mol·K, respectively. The formation of 3-5 can be explained by a mechanism involving attack of molecular oxygen to 11 and subsequent valence tautomerism of cycloheptatrienyloxyl radicals to norcaradienyloxyl radicals.
