CATALYTIC SYNTHESIS OF CHLOROFLUOROCARBON ALTERNATIVES

This chapter describes the synthetic routes available to several of the hydrofluorocarbon (HFC) and hydrochlorofluorocarbon (HCFC) alternatives to chlorofluorocarbons (CFCs) under consideration for commercial development, as well as some that have already been commercialized. The need for retention of hydrogen in the molecule has led to the development of a wide variety of catalysts and processes that are selective in this regard. Starting materials for such processes have included hydrocarbons, halohydrocarbons, olefins and haloolefins. The general processes of HF addition to olefins, halogen exchange, isomerization, disproportionation, chlorofluorination, and hydrogenolysis constitute the majority of the approaches. The chapter discusses the catalytic synthesis of key CFC alternatives. An ideal CFC substitute is one that offers identical performance properties of the CFC it replaces with the added stipulation that it does not destroy the ozone layer and has low global warming potential. Because CFCs are in such widespread use and realistic HFCs for every need is not been identified, HCFCs, when available, is suggested as bridging molecules to fulfill a short-term need. © 1993, Academic Press Inc.