Radiation Chemistry of Some Cyclic Fluorocarbons^1,2

Abstract

Radiolysis experiments have been carried out on a series of highly purified cyclic fluorocarbons-hexafluorobenzene, perfluorobiphenyl, and perfluoronaphthalene, and their saturated analogs perfluorocyclohexane, perfluorobicyclohexyl, and perfluorodecalin (perfluorodecahydronaphthalene). Irradiations were done in nickel cells using a 1.5-Mev. Van de Graaff electron beam. Temperatures were chosen so that materials were irradiated in the liquid phase and were room temperature where possible, otherwise around 100°. Radiation doses were of the order of 109 rads. Radiation stability of the aromatic compounds is less than that of the corresponding hydrocarbons, whereas the alicyclic fluorocarbons are more stable than their hydrocarbon analogs. Total G values for destruction of starting material range from 1.3 to 2.4 and are very similar for aromatic and alicyclic compounds. The aromatic fluorocarbons under irradiation yield polymeric material almost exclusively. Only traces of gaseous and low molecular weight compounds are formed. Polymeric material is colored yellow to dark brown depending on the dose. Radiolysis of the alicyclic fluorocarbons causes appreciable breakdown into gases and products of lower molecular weight than the starting material, as well as polymer formation. Polymeric material is colorless. No free fluorine has been detected in any of the irradiations.

Etude par résonance paramagnétique électronique de la radiolyse en phase solide de composés cycliques perfluorés

“…De plus, les produits de radiolyse en phase gazeuse du perfluorocyclohexane ont Ct C identifiCs par chromatographie (12) et par spectromttrie de masse (13) ce qui permet de recouper certains rtsultats que nous avons obtenus.…”

Effects of iodine and other scavengers on the .gamma. radiolysis of liquid perfluorocyclohexane

“…Although the results of our scavenging experiments indicate that the major radiolysis products of F-cyclohexane are formed by radical-radical combination reactions, the initial radiolytic processes must involve ionized and excited species. The principal positive ions could be CgFn+ and CgFi2+ c-C6F12 -C6F12+ + e~ (5) c-C6F12-*-C6Fn+ + F + e~(or F~) (6) While the abundance of the parent ion is very low in the mass spectrum of F-cyclohexane, this does not necessarily rule out its importance in the liquid phase. Carbon tetrachloride also does not give a parent ion in the mass spectrometer, but evidence has been reported that the CCU+ ion is produced by irradiation of the liquid.18 Natalis19 has suggested that the structure of the CgFn+ ion is an open chain, suggesting a route to formation of the F-hexenyl radical.…”