Transparent carbon-fluorine compounds prepared by the heat treatment of pitch fluoride under a fluorine atmosphere

Abstract

Pitch fluoride prepared from mesophase pitch at 70 °C was heat treated in a fluorine atmosphere over the temperature range from 200 to 400 °C. The compounds obtained were a colorless transparent solid with a composition between CF 1.38 and CF 1.50, and a liquid fluorocarbon which was colorless and transparent. The yields of both compounds depended on the heat-treatment temperature. From 200 to 280 °C, the solid compound was obtained as the main product, together with the liquid fluorocarbon as a by-product. Above 280 °C, the liquid compound was the main product and the solid the by-product. The liquid compound was selectively obtained at 400 °C. These compounds are composed of chair-type condensed cyclohexane rings with CF 2, CF 3CF 2- and CF 3CF- groups in the periphery of the rings. The difference between these compounds is mainly in their molecular weights.