Cw CO2 laser driven oxidation of some perhalogenocycloalkenes

The title reaction of hexafluorocyclobutene, 1,2-dichloro-3,3,4,4-tetrafluorocyclobutene and decafluorocyclohexene studied at total pressure 13.3 and 16 kPa yield oxalyl halides COX.COX (X = F, Cl) and C 2 F 4 that undergo consecutive reactions to COF 2 , CO and X 2 . The oxidation of decafluorocyclohexene is preceded by retro-Diels-Alder decomposition affording hexafluorocyclobutene and C 2 F 4 . Two alternative mechanisms for the oxidation of the cyclobutenes are presented, one involving a novel cleavage of intermediary bicyclic dioxetanes. The decomposition of oxalyl fluoride into COF 2 and CO is favored over its oxidation.