Hydrofluoroolefins (HFOs) are unsaturated

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

s composed of

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

fluorine Fluorine is a chemical element; it has Chemical symbol, symbol F and atomic number 9. It is the lightest halogen and exists at Standard temperature and pressure, standard conditions as pale yellow Diatomic molecule, diatomic gas. Fluorine is extre ...

and

carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

. These organofluorine compounds are of interest as refrigerants. Unlike traditional hydrofluorocarbons (HFCs) and

chlorofluorocarbon Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are fully or partly Halogenation, halogenated hydrocarbons that contain carbon (C), hydrogen (H), chlorine (Cl), and fluorine (F). They are produced as volatility (chemistry), volat ...

s (CFCs), which are saturated, HFOs are olefins, otherwise known as alkenes. HFO refrigerants are categorized as having zero ozone depletion potential (ODP) and low

global warming potential Global warming potential (GWP) is a measure of how much heat a greenhouse gas traps in the atmosphere over a specific time period, relative to carbon dioxide (). It is expressed as a multiple of warming caused by the same mass of carbon dioxide ( ...

(GWP) and so offer a more environmentally friendly alternative to CFC, HCFC, and HFC refrigerants. Compared to HCFCs and HFCs, HFOs have shorter tropospheric lifetimes due to the reactivity of the C=C bond with hydroxyl radicals and chlorine radicals. This quick reactivity prevents them from reaching the stratosphere and participating in the depletion of good ozone, leading to strong interest in the development and characterization of new HFO blends for use as refrigerants. Many refrigerants in the HFO class are inherently stable chemically and inert, non toxic, and non-flammable or mildly flammable. Many HFOs have the proper freezing and boiling points to be useful for refrigeration at common temperatures. They have also been adopted as blowing agents, i.e. in production of insulation foams, food industry, construction materials, and others. However, HFOs degrade to produce trifluoroacetic acid, a persistent toxic chemical which can lead to acidification of water bodies, and which can accumulate in wetlands, a sensitive ecosystem. HFOs are being developed as "fourth generation" refrigerants with 0.1% of the GWP of HFCs.

Examples

HFOs in use include: * 2,3,3,3-tetrafluoropropene (HFO-1234yf, trademarked as Opteon YF) and 1,3,3,3-tetrafluoropropene (HFO-1234ze). * ''cis''-1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz-Z; DR-2) shows also a promise in high temperature applications like cogeneration, heat recovery and medium temperature heat pumps. * ''trans''-1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz-E) also has good properties, and is being investigated. The largest brand of HFOs is Opteon, produced by Chemours (a

DuPont Dupont, DuPont, Du Pont, duPont, or du Pont may refer to: People * Dupont (surname) Dupont, also spelled as DuPont, duPont, Du Pont, or du Pont is a French surname meaning "of the bridge", historically indicating that the holder of the surname re ...

spin-off).

References

{{reflist Fluoroalkenes Organofluorides Refrigerants

Examples

See also

References