N-fluoro-compounds. Part V. Photochemical reactions of perfluoro-N-fluoromorpholine, and a re-investigation of its thermal decomposition; preparation and properties of perfluoromorpholin-N-oxyl

Abstract

U.v. irradiation of perfluoro-N-fluoromorpholine in the presence of perfluorocyclobutene yields perfluorobicyclobutyl, perfluoro-NN′-bimorpholyl, and perfluoro-(N-cyclobutylmorpholine). Pyrolysis of the last product gives perfluoro-(N-vinylmorpholine), photochemical bromination of which provides perfiuoro-[N-(1,2-dibromoethyl)-morpholine], a compound also formed, together with N-(2-bromo-1,2,2-trifluoroethyl)octafluoromorpholine, when the vinyl derivative is subjected to photochemical hydrobromination. U.v. irradiation in silica–Pyrex apparatus of perfluoro-N-fluoromorpholine, either alone or in the presence of oxygen, yields, inter alia, the N–O–N compound perfluoro-[N-(morpholino-oxy)morpholine]. Pyrolysis of this product gives perfluoromorpholin-N-oxyl, perfiuoro-NN′-bimorpholyl, perfiuoro-(6-morpholino-oxy-2-aza-5-oxahex-1-ene), perfiuoro-(6-morpholino-oxy-2-aza-5-oxahex-2-ene), perfluoro-5,6-dihydro-2H-1,4-oxazine, perfluoro-N-fluoromorpholine, and, if the decomposition is carried out at low pressure, a compound believed to be perfluoro-[N-(morpholino-oxymethyl)oxazolidine]. Perfluoro-(4-morpholino-oxy-3-oxabutyric) acid and its amide can be obtained via hydrolysis of the azahexenes. Perfluoromorpholin-N-oxyl reacts with nitric oxide, tetrafluoroethylene, and perfluorobut-2-yne to give perfluoromorpholyl nitrite, perfiuoro-[1,2-bis(morpholino-oxy)ethane], and perfiuoro-[N-(morpholino-oxy)morpholine] and perfluorobiacetyl, respectively. Flow pyrolysis of perfluoro-N-fluoromorpholine in platinum yields carbonyl fluoride, carbon tetrafluoride, hexafluoroethane, perfluoro-2-azapropene, perfluoro-2-azabut-2-ene. perfluoro-(N-methyloxazolidine), perfluoro-5,6-dihydro-2H-1,4-oxazine, and, possibly, N-fluorodifluoromethyleneamine, but apparently not perfluoro-4-oxa-2-azahex-2-ene, as proposed previously; this can be rationalised by a breakdown mechanism that is consistent with the formation of the azahexenes when perfiuoro-[N-(morpholino-oxy)-morpholine] is pyrolysed and with the production of 6-chloro-octafluoro-5-oxa-2-azahex-2-ene when perfluoromorpholine is heated with chlorine in the presence of potassium fluoride.

E.s.r. data for perfluoromorpholin-N-oxyl are presented.