Reactions of perfluoronitroxides with sulphur dioxide

Abstract

Perfluoro-2,5-diazahexane 2,5-dioxyl reacts with sulphur dioxide and with sulphur tetrafluoride to give the 1 : 1 cyclic adducts perfluoro(4,7-dimethyl-1,3-dioxa-2-thia-4,7-diazacycloheptane 2,2-dioxide) and perfluoro(4,7-dimethyl-1,3-dioxa-2-tetrafluorothia-4,7-diazacycloheptane), respectively. Perfluoro(4,7-dimethyl-1,3-dioxa-2-thia-4,7-diazacycloheptane 2,2-dioxide) which oxidises iodide ion to iodine at room temperature, is stable to hydrolysis by aqueous potassium hydroxide at 120 °C. It is stable to u.v. irradiation, but flow pyrolysis at 350 °C and ca. 1 mmHg pressure gives trifluoronitrospmethane, perfluoro(2-methyl-1,2-oxazetidine), carbonyl fluoride, perfluoro(N-methylenemethylamine), and sulphur dioxide. It reacts with triphenylphosphine to give perfluoro(3,6-dimethyl-1-oxa-2-thia-3,6-diazacyclohexane 2,2-dioxide), perfluoro(2,5-dimethyl-1-thia-2,5-diazacyclopentane 1,1-dioxide) and triphenylphosphine oxide. Bis(trifluoromethyl) nitroxide reacts with sulphur dioxide to give the 2 : 1 adduct perfluoro(2,6-dimethyl-3,5-dioxa-4-thia-2,6-diazaheptane 4,4-dioxide), flow pyrolysis of which at 350 °C and ca. 1 mmHg gives only bis(trifluoromethyl) nitroxide and sulphur dioxide. Perfluoro(2,4-dimethyl-3-oxa-2,4-diazapentane) reacts with sulphur dioxide giving perfluoro(2,5-dimethyl-3-oxa-4-thia-2,5-diazahexane 4,4-dioxide).