2,3,3,3-tetrafluoropropene

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Structural formula
Structural formula of 2,3,3,3-tetrafluoropropene
General
Surname 2,3,3,3-tetrafluoropropene
other names
  • HFO-1234yf
  • R1234yf
  • 2,3,3,3-tetrafluoropropylene
Molecular formula C 3 H 2 F 4
Brief description

Colorless gas

External identifiers / databases
CAS number 754-12-1
EC number 468-710-7
ECHA InfoCard 100.104.879
PubChem 2776731
Wikidata Q179088
properties
Molar mass 114 g mol −1
Physical state

gaseous

density

1.1 g cm −3 at 25 ° C (liquid)

Melting point

−152.2 ° C

boiling point

−30 ° C

Vapor pressure
  • 6067 h Pa (21.1 ° C)
  • 14203 hPa (54.4 ° C)
solubility

very bad in water (198.2 mg l −1 at 24 ° C)

safety instructions
GHS labeling of hazardous substances
02 - Highly / extremely flammable 04 - gas bottle

danger

H and P phrases H: 220-280
P: 210-377-381-410 + 403
Global warming potential

<1 (based on 100 years)

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

2,3,3,3-Tetrafluoropropene or HFO-1234yf (according to ASHRAE nomenclature R1234yf , trade name e.g. Solstice ) is a chemical compound from the hydrofluoroolefin group .

Extraction and presentation

The compound can be prepared in several stages, starting from 1,2,3-trichloropropane . First of all, the middle fluorine atom is introduced via elimination and subsequent addition . After the formation of a tetrachlorofluoropropane by chlorination in sunlight, the compound is partially fluorinated. In the last steps, 3-chloro-2,3,3-trifluoropropene and 3,3-dichloro-2,3-difluoropropene are first prepared by dehydrohalogenation , which are reacted with antimony pentafluoride to give 2,3,3,3-tetrafluoropropene.

R1234yf is manufactured exclusively by Chemours (formerly DuPont ) and Honeywell , who have a patent .

properties

2,3,3,3-Tetrafluoropropene is a flammable, colorless gas with a faint odor. In contrast to chlorine-containing hydrocarbons , it does not deplete the ozone layer and therefore does not damage the ozone layer . Its global warming potential is also low and is <1 (based on 100 years, carbon dioxide = 1). It is in contrast to other fluorocarbons such as 1,1,1,2-tetrafluoroethane with a global warming potential of around 1500. The reason for this lies in the rapid degradation of 2,3,3,3-tetrafluoropropene, which has an average lifetime in the atmosphere only about 12 days. It reacts primarily with the reactive hydroxyl radicals in the atmosphere, initially degrading to trifluoroacetyl fluoride and, through hydrolysis, finally to the stable trifluoroacetic acid .

According to Antoine, the vapor pressure function results from log 10 (P) = A− (B / (T + C)) (P in bar, T in K) with A = 4.555, B = 1099 and C = −2.180 in the temperature range from - 50 to 30 ° C.

Vapor pressure function of 2,3,3,3-tetrafluoropropene

use

In addition to carbon dioxide , 2,3,3,3-tetrafluoropropene is used as a substitute for 1,1,1,2-tetrafluoroethane as a refrigerant in air conditioning systems. It is controversial because of its flammability and the dangerous combustion products hydrogen fluoride and carbonyl fluoride .

safety

2,3,3,3-Tetrafluoropropene forms flammable gas-air mixtures and is classified as extremely flammable. The explosion range is between 6.2 vol.% As the lower explosion limit (LEL) and 12.3 vol.% As the upper explosion limit (UEL). A second source gives a range from 6.7% to 11.7% by volume. The auto-ignition temperature is between 400 ° C and 405 ° C. When burned, toxic and corrosive hydrogen fluoride and carbonyl fluoride (COF 2 ) are released.

For the Association for the Promotion of German Fire Protection as well as for the German Fire Brigade Association , nothing has changed in terms of the risk posed by the new refrigerant in the vehicle. On the other hand, the professional association fire brigade , which was founded a few years ago, demands a ban on use because of the dangers associated with this substance. In Switzerland, the Federal Council rejected a ban on use on the grounds that other comparable substances carry similar risks, but have been used safely for decades thanks to technical protective measures; this also applies to tetrafluoropropene. A single country could not force a technology change on the international automotive industry and the high price and the risks of tetrafluoropropene would ensure that it is only used where there is no alternative.

In September 2012, Daimler announced that it no longer wanted to use the new refrigerant R1234yf because it was too dangerous. In our own investigations according to in-house standards, it was found that the agent ignites in the hot engine compartment. This can be demonstrated reproducibly at any time. At the beginning of October 2012, Daimler underscored the importance of these results by calling the workshops back for all vehicles filled with R1234yf. It was refilled with R134a , for which the EU had issued an exemption due to delivery bottlenecks until December 31, 2012.

The Volkswagen Group also announced at an industry conference in Berlin that it preferred carbon dioxide and wanted to use the old refrigerant R134a in a transitional period. When testing an Opel compact car, however, R1234yf did not ignite despite leaks in the cooling system near the hot exhaust manifold . The Federal Motor Transport Authority ( Kraftfahrtbundesamt ) is conducting tests on various types of car to determine whether R1234yf escaping from defective air conditioning systems can ignite on hot parts.

SAE investigation

The debate about the safety of tetrafluoropropene, reignited by the Daimler tests, did not result in Daimler being left alone and isolated with its view, as the most important association of automotive engineers, the SAE, pointed out at the end of 2012. A team of experts (CRP-1234-4 Team) deployed within the SAE should re-examine the reservations and report them provisionally at the end of February 2013 and final in the summer. Because of apparently insurmountable opposing views, both Daimler, BMW and Audi announced at the beginning of February 2013 that they would leave the SAE group of experts prematurely.

In April 2013, as a result of investigations carried out, the SAE announced that R1234yf was safe for use in vehicles. The test used by Daimler is unrealistic because some factors in a real accident were not taken into account. The final report was published in June 2013. According to this, the risk of a vehicle occupant being exposed to a fire due to an ignition of R1234yf is almost six orders of magnitude lower than the risk of a vehicle fire at all.

KBA investigation

The new situation regarding the flammability of R1234yf in an accident, which emerged after the tests by Daimler, also put the federal government under pressure due to the subsequent refusal to fill this refrigerant. The responsible EU Commission requested evidence for this claim. Safety guidelines for the registration of motor vehicles are regulated by a product safety code of the KBA . A decision had to be made after weighing up the two legal interests of product safety and EU conformity. For this purpose, the KBA commissioned TÜV Rheinland with the assistance of BAM , BASt and UBA to carry out further tests.

The preliminary interim report submitted for the report in August 2013 confirms that R1234yf does not have an increased risk after two test procedures, which would have to result in measures from the point of view of product safety.

However, after carrying out an extended scenario, both ignition in the engine compartment and the formation of hydrogen fluoride were found in considerable concentrations. Since hazards to rescuers and inmates cannot be ruled out in both cases, the KBA strongly recommends carrying out further investigations. A regulated future safety assessment of vehicle air conditioning is also conceivable. Overall, the safety of vehicles with R1234yf as a cold filling is worsened in comparison with R-134a.

On March 7, 2014, the Joint Research Center (JRC) of the European Commission announced the results of its scientific study on the use of the refrigerant R1234yf or HFO-1234yf. The review of the tests carried out by the Federal Motor Transport Authority (KBA) showed that there is no danger for use in motor vehicles.

Investigation by the LMU Munich

In the course of investigations of the refrigerant R1234yf at the Institute for Inorganic Chemistry at the Ludwig Maximilians University in Munich, it was proven that, in addition to the toxic hydrogen fluoride, around 20 percent of the combustion gases consist of the even more toxic carbonyl fluoride . For this reason, the scientists suggested a reassessment of the risk potential of the refrigerant.

2,3,3,3-tetrafluoropropene in the atmosphere

At the beginning of 2015, Empa Swiss environmental chemists Martin K. Vollmer, Stefan Reimann, Matthias Hill and Dominik Brunner demonstrated in initial analyzes at the Jungfraujoch and Dübendorf measuring points that compounds of fluoroolefins (yf and ze isomers as well as 1233zd) even existed a few years ago are not analytically detectable and meanwhile with a significant increase in the atmosphere.

Health hazards

2,3,3,3-Tetrafluoropropene was included by the EU in 2012 in accordance with Regulation (EC) No. 1907/2006 (REACH) as part of substance evaluation in the Community's ongoing action plan ( CoRAP ). The effects of the substance on human health and the environment are re-evaluated and, if necessary, follow-up measures are initiated. Ingestion of 2,3,3,3-tetrafluoropropene was caused by concerns about environmental exposure , high (aggregated) tonnage, other hazard-related concerns and widespread use. The re-evaluation has been running since 2012 and is carried out by Germany . In order to be able to reach a final assessment, further information was requested.

Individual evidence

  1. ↑ a b c d e f g h i j data sheet 2,3,3,3-tetrafluoropropene ( Memento from April 25, 2012 in the Internet Archive ) (PDF; 61 kB) from Honeywell.
  2. ↑ a b Entry on 2,3,3,3-tetrafluoroprop-1-ene in the GESTIS substance database of the IFA , accessed on January 10, 2017(JavaScript required) .
  3. ↑ 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 ).
  4. ↑ Albert L. Henne, T. Phillip Waalkes: Fluorinated Derivatives of Propane and Propylene. VI. In: J. Am. Chem. Soc. 68, 3, 1946, pp. 496-497, doi: 10.1021 / ja01207a041 .
  5. ↑ a b Christoph Ruhkamp: Refrigerant R1234yf: Good for the climate - but also extremely corrosive . In: Frankfurter Allgemeine Zeitung . April 7, 2011 ( faz.net ).
  6. ↑ OJ Nielsen, MS Javadi, MP Sulbaek Andersen, MDHurley, TJ Wallington, R. Singh: Atmospheric chemistry of CF 3 CFCH 2 : Kinetics and mechanisms of gas-phase reactions with Cl atoms, OH radicals, and O 3 . In: Chemical Physics Letters. 439, 1-3, 2007, pp. 18-22, doi: 10.1016 / j.cplett.2007.03.053 .
    Vassileios C. Papadimitriou, Ranajit K. Talukdar, RW Portmann, AR Ravishankara, James B. Burkholder: CF 3 CF = CH 2 and (Z) -CF 3 CF = CHF: temperature dependent OH rate coefficients and global warming potentials. In: Phys. Chem. Chem. Phys. 10, 2008, pp. 808-820, doi: 10.1039 / b714382f .
  7. ↑ G. Di Nicola, F. Polonara, G. Santori: Saturated Pressure Measurements of 2,3,3,3-Tetrafluoroprop-1-ene (HFO-1234yf). In: J. Chem. Eng. Data . 55, 2010, pp. 201-204, doi: 10.1021 / je900306v .
  8. ↑ Refrigerant R1234yf again under criticism. August 27, 2019, accessed May 19, 2020 .
  9. ↑ Shigeo Kondo, Kenji Takizawa, Akifumi Takahashi, Kazuaki Tokuhashi, Junji Mizukado, Akira Sekiya: Flammability limits of olefinic and saturated fluoro compounds. In: J. Hazard. Mat. 171, 2009, pp. 613-618, doi: 10.1016 / j.jhazmat.2009.06.042 .
  10. ↑ Martin Graz, Uwe Wuitz: Flammability Investigation of Different Refrigerants using an operating MAC system in a simulated front end collision situation.
  11. ↑ Federal Institute for Materials Research and Testing: Final Test Report: Ignition behavior of HFO1234yf ( Memento from August 16, 2012 in the Internet Archive ) (PDF; 2.4 MB) from October 8, 2009, accessed on June 10, 2013.
  12. ↑ bv-feuerwehr.eu: PRESS RELEASE from BV September 27, 2011 , accessed on June 10, 2013.
  13. ↑ Answer of 5 March 2012 to parliamentary question 12.5013
  14. ↑ Automotive industry: Mercedes: New refrigerant too dangerous ; dated September 25, 2012, accessed June 10, 2013.
  15. ↑ autoservicepraxis.de: New air conditioning refrigerant .
  16. ↑ Tests with R1234yf: In August there should be clarity in the refrigerant dispute. In: Spiegel online. June 6, 2013, Retrieved June 21, 2013.
  17. ↑ Automobilwoche: Daimler and Audi leave the refrigerant expert group on February 6, 2013, accessed on June 10, 2013.
  18. ↑ SAE International CRP1234-4 Analysis of R-1234yf Nears Completion on sae.org
  19. ↑ SAE International Cooperative Research Project CRP1234-4 on R-1234yf Safety, Finishes Work and Presents Conclusions on sae.org
    SAE International Cooperative Research Project CRP1234-4 on R-1234yf Safety: Executive Summary. (PDF; 58 kB) SAE International, June 21, 2013, p. 2 , accessed on July 18, 2013 (English): “Based on the updated analysis, the estimated overall risk of vehicle fire exposure attributed to use of R-1234yf is conservatively estimated at 3 × 10 −12 events per vehicle operating hour. This is nearly six orders of magnitude less than the current risk of vehicle fires due to all causes (approximately 1 × 10 −6 per vehicle operating hour) and also well below other risks accepted by the general public. "
  20. ↑ Preliminary report on tests with vehicles for ignition and HF exposure with vehicle air conditioning systems when using R1234yf. (pdf, 37 kB) Federal Motor Transport Authority, August 7, 2013, accessed on June 26, 2018 .
  21. ↑ Mobile air-conditioning systems (MACs). European Commission, September 25, 2014, archived from the original on August 13, 2015 ; accessed on June 26, 2018 (English). JRC technical and scientific support to the research on safety aspects of the use of refrigerant R1234yf on MAC systems. (pdf, 329 kB) European Commission, March 3, 2014, accessed on June 26, 2018 (English).
  22. ↑ Refrigerants in cars: air conditioning with highly toxic potential. Ludwig Maximilians University Munich , April 8, 2014, accessed on June 26, 2018 .
  23. ↑ Martin K. Vollmer, Stefan Reimann, Matthias Hill, Dominik Brunner: First Observations of the Fourth Generation Synthetic Halocarbons HFC-1234yf, HFC-1234ze (E), and HCFC-1233zd (E) in the Atmosphere . In: Environmental Science & Technology . tape 49 , no. 5 , 2015, p. 2703 , doi : 10.1021 / es505123x .
  24. ↑ Community rolling action plan ( CoRAP ) of the European Chemicals Agency (ECHA): Polyhaloalkene , accessed on March 26, 2019.Template: CoRAP status / 2012