Basic Trends in the Development of Methods for Obtaining Polyfluoroolefins

Analysis of the new approaches to the synthesis of perfluoroolefins and the conditions for performing thermal decomposition of difluorochloromethane and perfluoroalkyl iodides for the synthesis of tetrafluoroethylene and hexafluoropropylene is carried out. Essential simplifications of the technology are stressed. It is established that the production of tetrafluoroethylene is affected by the presence of chlorine and oxygen, the material of reactor walls (quartz glass) and diluter (overheated water vapour). The mechanism of thermolysis is discussed from the viewpoint of the decisive role of difluorocarbene. The possibilities of dehalogenation and dehydrohalogenation of polyfluorohalogenoalkanes in the synthesis of perfluoroolefins and perfluorobutadiene are demonstrated. Decarboxylation of perfluorocarboxylic acids in the production of terminal perfluoroolefins are discussed.