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2,3,3,3-Tetrafluoropropene molecule
Preferred IUPAC name
Other names
HFO-1234yf; R1234yf; R-1234yf; 2,3,3,3-Tetrafluoropropylene
3D model (JSmol)
ECHA InfoCard 100.104.879 Edit this at Wikidata
EC Number
  • 468-710-7
UN number 3161
  • InChI=1S/C3H2F4/c1-2(4)3(5,6)7/h1H2 checkY
  • InChI=1/C3H2F4/c1-2(4)3(5,6)7/h1H2
  • C=C(F)C(F)(F)F
  • FC(=C)C(F)(F)F
Molar mass 114 g/mol
Appearance Colorless gas
Density 1.1 g/cm3 at 25 °C (liquid); 4 (gas, relative, air is 1)
Boiling point −30 °C (−22 °F; 243 K)
198.2 mg/L at 24 °C, 92/69/EEC, A.6
log P 2.15, n-octanol/water, 92/69/EEC, A.8
Vapor pressure 6,067 hPa at 21.1 °C; 14,203 hPa at 54.4 °C
GHS labelling:
GHS02: FlammableGHS04: Compressed Gas
H220, H280
P210, P260, P281, P308+P313, P410+P403
405 °C (761 °F; 678 K)
Explosive limits 6.2% vol.; 12.3% vol.
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

2,3,3,3-Tetrafluoropropene, HFO-1234yf, is a hydrofluoroolefin (HFO) with molecular formula CH2=CFCF3. Its primary application is as a refrigerant with low global warming potential (GWP).[1][2]

As a refrigerant, it is designated R-1234yf[1] and marketed under the names Opteon YF by Chemours and as Solstice YF by Honeywell.[3] R-1234yf is also a component of zeotropic refrigerant blend R-454B.

HFO-1234yf has a GWP less than carbon dioxide,[4][2] itself 1,430 times less potent than R-134a.[5] For this reason, 2,3,3,3‑tetrafluoropropene is the pre-eminent replacement for R-134a in vehicular air conditioners. As of 2022, 90% of new U.S. vehicles are estimated to use HFO-1234yf.[6] Unlike previous vehicular refrigerants, 2,3,3,3‑tetrafluoropropene is flammable, but does not increase fire risk in internal combustion engines.

One drawback is it breaks down into short-chain perfluorinated carboxylic acids (PFCAs), which are persistent organic pollutants.[7]

Adoption by automotive industry[edit]

HFO-1234yf was developed by a team at DuPont, led by Barbara Haviland Minor, jointly with researchers at Honeywell.[8][9] Their goal was to meet European directive 2006/40/EC, which went into effect in 2011 and required that all new car platforms for sale in Europe use a refrigerant in its AC system with a global warming potential (GWP) less than 150 times more potent than carbon dioxide.[10][11] HFO-1234yf was initially considered to have a 100-year GWP of 4, and is now considered to have a 100-year GWP lower than 1 (carbon dioxide has a GWP of 1.0).[2][4]

Among the alternatives developed to comply with 2006/40/EC, HFO-1234yf had the lowest switching cost for automakers.[12][13] It can be used as a "near drop-in replacement" for R-134a,[14] the previous automobile AC refrigerant, which has a 100-year GWP of 1430.[5][15] HFO-1234yf can be handled in repair shops in the same way as R-134a, although it requires some different, specialized equipment to perform the service. One of the reasons for that is the flammability of HFO-1234yf.[16] Another issue affecting the compatibility between HFO-1234yf and R-134a-based systems is the choice of lubricating oil.[17]

On July 23, 2010, General Motors announced that it would introduce HFO-1234yf in 2013 Chevrolet, Buick, GMC, and Cadillac models in the U.S.[18] Shortly thereafter, Honeywell and DuPont announced that they would jointly build a manufacturing facility in Changshu, Jiangsu Province, China to produce HFO-1234yf.[19] In 2012, Cadillac produced the first American car using R-1234yf.[20] Since then, Chrysler,[21] GMC[22] and Ford[23] have all begun transitioning vehicles to R1234yf.[16]

Japanese automakers are also transitioning to R1234yf. Honda and Subaru began to introduce the new refrigerant with the 2017 models.[20] From 2017 to 2018, BMW changed all of its models to R-1234yf. As of 2018, 50% of new vehicles from original equipment manufacturers (OEMs) are estimated to use R-1234yf.[24]

In 2017, Honeywell opened a new plant in Geismar, Louisiana, to handle increased demand for the compound.[25][26] Honeywell and DuPont hold most patents issued for HFO-1234yf[19] and remained the pre-eminent manufacturers in 2018.[27]


Although the product is classified slightly flammable by ASHRAE, several years of testing by SAE International proved that the product could not be ignited under conditions normally experienced by a vehicle.[10] Tests conducted in 2008 indicated that ignition requires temperatures exceeding 900 °C (1,650 °F) and mixture with PAG oil.[28] Once in flame, 2,2,3,3‑trifluoropropene releases highly corrosive and toxic gaseous hydrogen fluoride and carbonyl fluoride.[29]

In August 2012, Mercedes-Benz showed that the substance ignited in simulated head-on collisions. A senior Daimler engineer who ran the tests, stated "We were frozen in shock, I am not going to deny it. We needed a day to comprehend what we had just seen." When researchers sprayed 2,2,3,3‑trifluoropropene and A/C compressor oil onto a car's hot engine, the mixture burned in two out of three times.[30] In September, Daimler issued a press release,[10] proposed a recall of cars using the refrigerant, and continued to use older refrigerants in its own designs.[31] The German automakers argued for development of carbon dioxide refrigerants, which they argued would be safer.[30]

In October 2012, SAE International established a new Cooperative Research Project, CRP1234-4, to extend its previous testing and investigate Daimler's claims.[10] The investigation concluded that R-1234yf did not increase the estimated risk of vehicle fire exposure, because "the refrigerant release testing completed by Daimler was unrealistic" and "created extreme conditions that favored ignition".[10][32] Germany's Kraftfahrt-Bundesamt (KBA, Federal Motor Transport Authority) [de] also conducted its own tests. In their August 2013 report to the European Union, the KBA concluded that while R-1234yf was potentially more hazardous than R-134a, it did not comprise a serious danger.[31]

Writing for Auto Service Professional, Gordon Jacques summarized the controversy:

"The flammability issue has attracted a lot of attention, prompting the industry to conduct some serious third-party testing. The bottom line is this: The refrigerant will burn, but it takes a lot of heat to ignite it and it burns slowly. Almost every other fluid under the hood will light more easily and burn hotter than R1234yf, so the industry has determined that with proper A/C system design, it does not increase the chances of fire in the vehicle."[16]

Mixing HFO-1234yf with 10–11% R-134A is in development to produce a hybrid gas under review by ASHRAE for classification as A2L which is described as "virtually non-flammable". These gases are under review with the names of R451A and R451B. These mixes have GWP of ~147.[33]

Other additives have been proposed for lowering the flammability of HFO-1234yf, such as trifluoroiodomethane, which has a low GWP due to its short atmospheric lifetime, but is slightly mutagenic.[34]

In the environment[edit]

HFO-1234yf has been shown to atmospherically transform into trifluoroacetic acid (TFA), leading to a potential for wet and dry atmospheric deposition.[35][36]

See also[edit]


  1. ^ a b Sciance, Fred (October 29, 2013). "The Transition from HFC- 134a to a Low -GWP Refrigerant in Mobile Air Conditioners HFO -1234yf" (PDF). General Motors Public Policy Center. Retrieved 1 August 2018.
  2. ^ a b c "IPCC confirms HFO GWPs are less than 1". Cooling Post. 3 Feb 2014. Retrieved 26 July 2018.
  3. ^ "Honeywell and Chemours Announce New Manufacturing Plants for HFO 1234yf". Aspen Refrigerants. June 12, 2017. Archived from the original on 4 August 2020. Retrieved 26 July 2018.
  4. ^ a b Scientific Assessment of Ozone Depletion: 2014 Full Report. World Meteorological Organization Global Ozone Research and Monitoring Project—Report No. 55. 2014. p. 551.
  5. ^ a b P. Forster; V. Ramaswamy; P. Artaxo; T. Berntsen; R. Betts; D.W. Fahey; J. Haywood; J. Lean; D.C. Lowe; G. Myhre; J. Nganga; R. Prinn; G. Raga; M. Schulz; R. Van Dorland (2007). "Chapter 2: Changes in atmospheric constituents and in radiative forcing". In Solomon, S.; Miller, H.L.; Tignor, M.; Averyt, K.B.; Marquis, M.; Chen, Z.; Manning, M.; Qin, D. (eds.). Climate Change 2007: the physical science basis. Contribution of Working Group I to the fourth assessment report of the Intergovernmental Panel on Climate Change. Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press. Archived from the original on 1 December 2016. Retrieved 9 October 2016.
  6. ^ "StackPath". www.vehicleservicepros.com. 23 March 2022. Retrieved 2022-05-28.
  7. ^ Wang, Ziyuan; Wang, Yuhang; Li, Jianfeng; Henne, Stephan; Zhang, Boya; Hu, Jianxin; Zhang, Jianbo (30 January 2018). "Impacts of the Degradation of 2,3,3,3-Tetrafluoropropene into Trifluoroacetic Acid from Its Application in Automobile Air Conditioners in China, the United States, and Europe". Environmental Science & Technology. 52 (5): 2819–2826. Bibcode:2018EnST...52.2819W. doi:10.1021/acs.est.7b05960. PMID 29381347.
  8. ^ "Recognizing excellence: Development of HFO-1234yf as the next generation refrigerant for the automotive industry" (PDF). 2010 DuPont Excellence Awards Sustainable Growth. 2010. p. 3. Retrieved 31 July 2018.
  9. ^ "DuPont Names Seven New DuPont Fellows". DuPont Media Center (Press release). July 17, 2014. Archived from the original on 30 July 2018. Retrieved 30 July 2018.
  10. ^ a b c d e Lewandowski, Thomas A. (July 24, 2013). "Additional risk assessment of alternative refrigerant R-1234yf prepared for SAE International cooperative research program CRP1234-4" (PDF). SAE International. Retrieved 26 July 2018.
  11. ^ "Directive 2006/40/EC of the European Parliament and of the Council of 17 May 2006 relating to emissions from air-conditioning systems in motor vehicles and amending Council Directive 70/156/EEC". EFCTC. Archived from the original on 26 July 2018. Retrieved 26 July 2018.
  12. ^ Ansari, Naushad A.; Yadav, Bipin; Kumar, Jitendra (August 2013). "Theoretical exergy analysis of HFO-1234yf and HFO-1234ze as an alternative replacement of HFC-134a in simple vapour compression refrigeration system". International Journal of Scientific & Engineering Research. 4 (8). CiteSeerX
  13. ^ "HFO-1234yf, New Dawn of Refrigerant Alternatives". JARN: Japan Air Conditioning, Heating & Refrigeration News (Press release). April 25, 2008. pp. 1, 6, 24. Retrieved 1 August 2018.
  14. ^ "Honeywell's low-global-warming refrigerant for vehicles approved for import, use by Japan regulators". Honeywell (Press release). August 4, 2009. Retrieved 26 July 2018.
  15. ^ "Air conditioning in new vehicle models requires a greener gas". Autodata. 2017. Retrieved 26 July 2018.
  16. ^ a b c Gordon, Jacques (April 12, 2017). "Real world experience with R1234yf: The new refrigerant is finally here; are you ready?". Auto Service Professional. Retrieved 26 July 2018.
  17. ^ Johnson, Alec (October 13, 2017). "Understanding refrigerant oils". Refrigerant HQ. Retrieved 26 July 2018.
  18. ^ "GM first to market greenhouse gas-friendly air conditioning refrigerant in U.S." GM Corporate Newsroom (Press release). 2010-07-23. Retrieved 26 July 2018.
  19. ^ a b "Automakers Go HFO", Chemical & Engineering News, July 26, 2010
  20. ^ a b Schaeber, Steve (February 27, 2017). "R-1234yf at the 2017 PHL Auto Show". MACS Worldwide. Retrieved 26 July 2018.
  21. ^ Zatz, David (October 1, 2013). "Chrysler adopting R1234YF". Allpar News (Press release). Retrieved 2018-06-16.
  22. ^ "GMC hits the road with R-1234yf". MACS Worldwide. September 22, 2016. Retrieved 26 July 2018.
  23. ^ Schaeber, Steve (August 17, 2016). "Ford dealers selling their first MPVs with R-1234yf". MACS Worldwide. Retrieved 26 July 2018.
  24. ^ "Ask the expert: How many light duty OEs use HFO-1234yf refrigerant?". Vehicle Service Pros. May 15, 2018. Retrieved 26 July 2018.
  25. ^ "Honeywell announces major investments to increase HFO-1234yf production in the United States". Honeywell (Press release). December 10, 2013. Archived from the original on 26 July 2018. Retrieved 26 July 2018.
  26. ^ "Honeywell starts up $300 million automotive refrigerant production facility in Louisiana". Honeywell (Press release). May 16, 2017. Retrieved 26 July 2018.
  27. ^ Marwa, Stefen (July 26, 2018). "HFO-1234yf market 2018 global share and projections: Honeywell and Chemours". The Aerospace News. Archived from the original on 26 July 2018. Retrieved 26 July 2018.
  28. ^ Spatz, Mark; Minor, Barbara (July 2008). "HFO-1234yf Low GWP Refrigerant Update" (PDF).
  29. ^ "Refreshingly cool, potentially toxic". Ludwig-Maximilians-Universität (LMU) Munich. 2014. Retrieved 26 July 2018.
  30. ^ a b Hetzner, Christiaan (December 12, 2012). "Coolant safety row puts the heat on Europe's carmakers". Reuters. Retrieved 26 July 2018.
  31. ^ a b Bolduc, Douglas A. (August 8, 2013). "German officials provide mixed ruling on Honeywell refrigerant Despite fire risk, agency does not seek recall of cars using HFO-1234yf". Automotive News Europe. Retrieved 26 July 2018.
  32. ^ "A heated row over coolants". The Economist. August 31, 2013. Retrieved 26 July 2018.
  33. ^ "R134a alternative is "virtually non-flammable"". Cooling Post. 30 November 2014. Retrieved 2017-06-09.
  34. ^ "US6969701B2 Azeotrope-like compositions of tetrafluoropropene and trifluoroiodomethane". Google patents. Retrieved 26 July 2018.
  35. ^ Luecken, Deborah J.; Waterland, Robert L.; Papasavva, Stella; Taddonio, Kristen N.; Hutzell, William T.; Rugh, John P.; Andersen, Stephen O. (2010). "Ozone and TFA Impacts in North America from Degradation of 2,3,3,3-Tetrafluoropropene (HFO-1234yf), A Potential Greenhouse Gas Replacement". Environmental Science & Technology. 44 (1): 343–348. Bibcode:2010EnST...44..343L. doi:10.1021/es902481f. PMID 19994849.
  36. ^ Hurley, M.D; Wallington, T.J; Javadi, M.S; Nielsen, O.J (2008). "Atmospheric chemistry of CF3CF=CH2: Products and mechanisms of Cl atom and OH radical initiated oxidation". Chemical Physics Letters. 450 (4–6): 263–267. doi:10.1016/j.cplett.2007.11.051.