1,1,1,2-tetrafluoroethane

Structural formula
General
Non-proprietary name	Norflurane
other names	R-134a HYDROFLUOROCARBON 134A ( INCI )
Molecular formula	C 2 H 2 F 4
Brief description	colorless gas with a faint ethereal odor
External identifiers / databases
CAS number 811-97-2 EC number 212-377-0 ECHA InfoCard 100.011.252 PubChem 13129 ChemSpider 12577 DrugBank DB13116 Wikidata Q423029
properties
Molar mass	102.04 g mol −1
Physical state	gaseous
density	4.24 kg m −3 (20 ° C, gaseous)
Melting point	−101 ° C
boiling point	−26.1 ° C
Vapor pressure	570 k Pa (20 ° C)
solubility	poor in water (1 g l −1 at 25 ° C)
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 280 P: 410 + 403
MAK	DFG : 1000 ml m −3 or 4200 mg m −3 Switzerland: 1000 ml m −3 or 4200 mg m −3
Global warming potential	1549 (based on 100 years)
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

1,1,1,2-Tetrafluoroethane (often short but imprecise tetrafluoroethane , trade name R-134a ) is a fluorocarbon (a hydrofluoroalkane ) that is used as a propellant and refrigerant and as an alternative to fluorochlorohydrocarbons .

In addition to 1,1,1,2-tetrafluoroethane, there is also its isomer 1,1,2,2-tetrafluoroethane , which is also known as tetrafluoroethane.

properties

If liquid tetrafluoroethane is taken from a pressure vessel and exposed to normal pressure, it boils at −26.1 ° C

Tetrafluoroethane is a colorless and almost odorless gas that can be easily liquefied by pressure. The critical point is 101.15 ° C and 41 bar. When degraded in the environment, the very persistent trifluoroacetic acid ( TFA ) is formed through photooxidation .

In contrast to CFCs, tetrafluoroethane does not have a destructive effect on the ozone layer , but is a powerful greenhouse gas . Its greenhouse effect is 1430 times the same amount of carbon dioxide based on a time horizon of 100 years (see global warming potential ).

application

Because of its favorable properties, tetrafluoroethane is used in refrigeration machines such as refrigerators , air dehumidifiers and when operating steam turbines in the Organic Rankine Cycle without water vapor as a working medium.

Many air conditioning systems are based on R-134a as a refrigerant. Since 2011, however, this may no longer be used in the EU for air conditioning systems in new cars. It is also used as a test / inspection device for optical smoke detectors . Tetrafluoroethane is the main component in cold sprays in the electronics industry.

Tetrafluoroethane is also used to protect magnesium melts. A gas mixture with nitrogen is usually used for this purpose. The mixing ratio is around 99.5–99.8% nitrogen and 0.5–0.2% tetrafluoroethane, depending on the area of ​​application. In combination with air humidity, tetrafluoroethane forms hydrofluoric acid in the heat , which leads to increased corrosion in steel.

In medicine, it is used as a propellant for metered-dose aerosols, for example in a number of drugs with active ingredients such as salbutamol or fluticasone .

future

Since 2011, an EU directive has banned the use of HFCs with a global warming potential greater than 150 (including R-134a) in the air conditioning systems of cars with new type approval. From 2017 onwards, new vehicles with such refrigerants may no longer be sold. In the future, refrigerants with little or no climate impact such as B. carbon dioxide (R-744) , ammonia , propane or 2,3,3,3-tetrafluoropropene (R1234yf) can be used.

Web links

Commons : Tetrafluoroethane  album with pictures, videos and audio files

• Safety data sheet tetrafluoroethane (R134a) from Air Liquide

Individual evidence

1. ↑ Entry on HYDROFLUOROCARBON 134A in the CosIng database of the EU Commission, accessed on December 17, 2019.
2. ↑ ^{a b c d e f g h} Entry on 1,1,1,2-tetrafluoroethane in the GESTIS substance database of the IFA , accessed on February 9, 2017(JavaScript required) .
3. ↑ Data sheet refrigerant R134a from Agatex, accessed on March 19, 2018.
4. ↑ Swiss Accident Insurance Fund (Suva): Limits - Current MAK and BAT values (search for 811-97-2 or 1,1,1,2-tetrafluoroethane ), accessed on May 14, 2020.
5. ↑ G. Myhre, D. Shindell et al .: Climate Change 2013: The Physical Science Basis . Working Group I contribution to the IPCC Fifth Assessment Report. Ed .: Intergovernmental Panel on Climate Change . 2013, Chapter 8: Anthropogenic and Natural Radiative Forcing, pp. 24-39; Table 8.SM.16 ( PDF ).
6. ^ EH Christoph: Balancing and biomonitoring of trifluoroacetate and other halogen acetates , dissertation, 2002, University of Bayreuth
7. ↑ Forster, P .; et al. (2007). Changes in Atmospheric Constituents and in Radiative Forcing. . Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Table p. 212
8. ↑ heise.de: Air conditioning systems divide European car manufacturers , January 24, 2008.
9. ↑ Directive 2006/40 / EC of May 17, 2006 (PDF) .
10. ↑ Federal Environment Agency: Car air conditioning systems with fluorinated refrigerants | Federal Environment Agency , accessed on March 25, 2018.