Unsaturated natural molecules made from hydrogen, fluorine, and carbon are called hydrofluoroolefins (HFOs). The Air Conditioning (AC) systems in homes and automobiles employ these organofluorides as refrigerants. HFO refrigerants provide a more ecologically friendly alternative to CFCs (chlorofluorocarbons), HCFCs (hydrochlorofluorocarbons), and HFCs (hydrofluorocarbons) considering they’re labeled as having 0 ODP (ozone depletion potential) and coffee GWP (global-warming potential). They have at least one double bond and are hence unsaturated. Olefins or alkenes are the names of these molecules. The term “HFOs” is now most frequently used to refer to refrigerants containing a double bond of carbon.
Despite being generally stable, HFOs are more reactive than HFCs because of the carbon-carbon bond’s reactivity. Due to the decreased global warming potential, this became a desirable attribute given the growing worries about climate change.As “fourth generation” refrigerants, HFOs are currently being developed and have 0.1% the global warming potential of HFCs.2,3,3,3-tetrafluoropropene (HFO-1234yf) and 1,3,3,3-tetrafluoropropene (HFO-1234ze) are HFOs which are presently in use. Also under development is 1-chloro-3,3,3-trifluoropropene (HFO-1233zd).
The Production Of Hydrofluoroolefins.
Ethylene and methane are the usual starting materials for HFO production. Chlorofluoroethene (CCIF=CF2) and chlorofluoromethane (CH2CIF) are produced by selectively chlorinating (or oxychlorinating) ethylene and fluorinating (or oxyfluorinating) methane. Catalysts include metallic fluorides or metallic chlorides. The procedures include the addition of an aluminum halide to a reaction zone where chlorofluoroethene and chlorofluoromethane are combined to generate (chloro)fluoropropanes. The procedures include the formation of HFOs by dehydrofluorination, or the elimination of HF, when heated in the presence of a catalyst, typically made of aluminum.