Trifluorobromo-methane and difluorochlorobromo-methane prepn. - from carbon tetrachloride or fluorotri chloro-methane, hydrogen fluoride and hydrogen bromide

摘要

and CF2ClBr are prepd. by introducing CCl4 or CCl3F together with HF and HBr into a reaction tube packed with a Friedel-Crafts catalyst and heated to 200-400 degrees C, and reacted at normal or increased press. The end prods. are recovered from mixt. obtd., after sepn. of unconverted acid constituents, by cooling and fractionated evaporation. The polyhalogenated fluoroalkanes obtd. are used as fire-extinguishing media, esp. in fuel fires, and as blowing agents in plastic foam prepn., esp. so that they remain enclosed within foam cells and act as fireproofing agents in case of fire. CF3Br and CF2ClBr can be obtd. in 1 step, from easily available raw materials, at low temps.