2,3,3,3-Tetrafluoropropene

HFO-1234yf was developed by a team at DuPont, led by Barbara Haviland Minor, jointly with researchers at Honeywell.{{cite web |title=Recognizing excellence: Development of HFO-1234yf as the next generation refrigerant for the automotive industry |url=http://www2.dupont.com/Sustainability/en_US/assets/downloads/2010_sg_award_brochure.pdf |website=2010 DuPont Excellence Awards Sustainable Growth |access-date=31 July 2018|page=3|date=2010}}{{cite press release |title=DuPont Names Seven New DuPont Fellows |url=http://www.dupont.com/corporate-functions/media-center/press-releases/dupont-names-seven-new-dupont-fellows.html |access-date=30 July 2018 |work=DuPont Media Center |date=July 17, 2014|archive-url=https://web.archive.org/web/20180730170851/http://www.dupont.com/corporate-functions/media-center/press-releases/dupont-names-seven-new-dupont-fellows.html|archive-date=30 July 2018|url-status=dead}} 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.{{cite web |title=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 |url=https://www.fluorocarbons.org/mac-directive-402006/ |website=EFCTC |access-date=26 July 2018 |archive-date=26 July 2018 |archive-url=https://web.archive.org/web/20180726234049/https://www.fluorocarbons.org/mac-directive-402006/ |url-status=dead }} 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).{{cite news |title=IPCC confirms HFO GWPs are less than 1 |url=https://www.coolingpost.com/world-news/ipcc-confirms-hfo-gwps-are-less-than-1/ |access-date=26 July 2018 |work=Cooling Post |date=3 Feb 2014}}{{cite book |title=Scientific Assessment of Ozone Depletion: 2014 Full Report |date=2014 |publisher=World Meteorological Organization Global Ozone Research and Monitoring Project—Report No. 55 |page=551 |url=https://www.wmo.int/pages/prog/arep/gaw/ozone_2014/full_report_TOC.html}}

Among the alternatives developed to comply with 2006/40/EC, HFO-1234yf had the lowest switching cost for automakers.{{cite journal |last1=Ansari |first1=Naushad A. |last2=Yadav |first2=Bipin |last3=Kumar |first3=Jitendra |date=August 2013 |title=Theoretical exergy analysis of HFO-1234yf and HFO-1234ze as an alternative replacement of HFC-134a in simple vapour compression refrigeration system |journal=International Journal of Scientific & Engineering Research |volume=4 |issue=8 |citeseerx=10.1.1.415.9796}}{{cite press release |title=HFO-1234yf, New Dawn of Refrigerant Alternatives |url=https://www.honeywell-refrigerants.com/india/?document=japan-air-conditioning-heating-refrigeration-news-april-2008&download=1 |access-date=1 August 2018 |work=JARN: Japan Air Conditioning, Heating & Refrigeration News |date=April 25, 2008 |volume=40 |issue=4 |pages=1, 6, 24}} It can be used as a "near drop-in replacement" for R-134a,{{cite press release|title=Honeywell's low-global-warming refrigerant for vehicles approved for import, use by Japan regulators |url=http://www51.honeywell.com/honeywell/news-events/press-releases-details/8.4.09Low-Global-WarmingRefrigerantforVehicles.html?c=31 |access-date=26 July 2018 |work=Honeywell |date=August 4, 2009}} the previous automobile AC refrigerant, which has a 100-year GWP of 1430.{{cite book|author1=P. Forster|author2=V. Ramaswamy|author3=P. Artaxo|author4=T. Berntsen|author5=R. Betts|author6=D.W. Fahey|author7=J. Haywood|author8=J. Lean|author9=D.C. Lowe|author10=G. Myhre|author11=J. Nganga|author12=R. Prinn|author13=G. Raga|author14=M. Schulz|author15=R. Van Dorland|editor1-last=Solomon|editor1-first=S.|editor2-last=Miller|editor2-first=H.L.|editor3-last=Tignor|editor3-first=M.|editor4-last=Averyt|editor4-first=K.B.|editor-link4=Kristen Averyt|editor5-last=Marquis|editor5-first=M.|editor6-last=Chen|editor6-first=Z.|editor7-last=Manning|editor7-first=M.|editor8-last=Qin|editor8-first=D.|title=Climate Change 2007: the physical science basis. Contribution of Working Group I to the fourth assessment report of the Intergovernmental Panel on Climate Change|date=2007|publisher=Cambridge University Press|location=Cambridge, United Kingdom and New York, NY, USA|language=en|chapter=Chapter 2: Changes in atmospheric constituents and in radiative forcing|chapter-url=https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch2.html|access-date=9 October 2016|archive-date=1 December 2016|archive-url=https://web.archive.org/web/20161201152606/http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch2.html|url-status=dead}}{{cite web |title=Air conditioning in new vehicle models requires a greener gas |url=https://www.autodata-group.com/ie/news/industry/air-conditioning-new-vehicle-models-requires-greener-gas/ |access-date=26 July 2018 |website=Autodata |date=2017}} HFO-1234yf can be handled very similarly to R-134a in repair shops, although it requires some different, specialized equipment due to its flammability.{{cite news |last1=Gordon |first1=Jacques |date=April 12, 2017 |title=Real world experience with R1234yf: The new refrigerant is finally here; are you ready? |url=https://www.autoserviceprofessional.com/article/97838/real-world-experience-with-r1234yf-the-new-refrigerant-is-finally-here-are-you |access-date=26 July 2018 |work=Auto Service Professional}} Another issue affecting the compatibility between HFO-1234yf and R-134a-based systems is the choice of lubricating oil.{{cite news |last1=Johnson |first1=Alec |title=Understanding refrigerant oils |url=https://refrigeranthq.com/understanding-refrigerant-oils/ |access-date=26 July 2018 |work=Refrigerant HQ |date=October 13, 2017}}

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.{{cite press release |title=GM first to market greenhouse gas-friendly air conditioning refrigerant in U.S. |url=https://media.gm.com/media/us/en/gm/home.detail.html/content/Pages/news/us/en/2010/July/0723_refrigerant.html |access-date=26 July 2018 |work=GM Corporate Newsroom |date=2010-07-23}} Shortly thereafter, Honeywell and DuPont announced that they would jointly build a manufacturing facility in Changshu, Jiangsu Province, China to produce HFO-1234yf."Automakers Go HFO", Chemical & Engineering News, July 26, 2010 In 2012, Cadillac produced the first American car using R-1234yf.{{cite news |last1=Schaeber |first1=Steve |date=February 27, 2017 |title=R-1234yf at the 2017 PHL Auto Show |url=https://macsworldwide.wordpress.com/2017/02/27/r-1234yf-at-the-2017-phl-auto-show/ |access-date=26 July 2018 |work=MACS Worldwide}} Since then, Chrysler,{{Cite press release |first=David |last=Zatz |url=http://www.allpar.com/news/index.php/2013/10/chrysler-adopting-r1234yf |title=Chrysler adopting R1234YF |date=October 1, 2013 |work=Allpar News |access-date=2018-06-16 |language=en-US}}GMC,{{cite news |date=September 22, 2016 |title=GMC hits the road with R-1234yf |url=https://macsworldwide.wordpress.com/2016/09/22/gmc-hits-the-road-with-r-1234yf/ |access-date=26 July 2018 |work=MACS Worldwide}} and Ford{{cite news |last1=Schaeber |first1=Steve |date=August 17, 2016 |title=Ford dealers selling their first MPVs with R-1234yf |url=https://macsworldwide.wordpress.com/2016/08/17/ford-dealers-selling-their-first-mpvs-with-r-1234yf/ |access-date=26 July 2018 |work=MACS Worldwide}} have all begun transitioning vehicles to R1234yf.

Japanese automakers are also transitioning to R1234yf. Honda and Subaru began to introduce the new refrigerant with the 2017 models. 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.{{cite news |date=May 15, 2018 |title=Ask the expert: How many light duty OEs use HFO-1234yf refrigerant? |url=https://www.vehicleservicepros.com/in-the-bay/tools-equipment/air-conditioning-a-c-repair-service/r-1234yf-tools-and-equipment/article/21005163/tech-tip-current-list-of-oes-that-use-hfo1234yf-refrigerant |access-date=26 July 2018 |work=Vehicle Service Pros}}

In 2017, Honeywell opened a new plant in Geismar, Louisiana, to handle increased demand for the compound.{{cite press release |title=Honeywell announces major investments to increase HFO-1234yf production in the United States |url=https://www.honeywell.com/newsroom/pressreleases/2013/12/honeywell-announces-major-investments-to-increase-hfo-1234yf-production-in-the-united-states |access-date=26 July 2018 |work=Honeywell |date=December 10, 2013 |archive-date=26 July 2018 |archive-url=https://web.archive.org/web/20180726235518/https://www.honeywell.com/newsroom/pressreleases/2013/12/honeywell-announces-major-investments-to-increase-hfo-1234yf-production-in-the-united-states |url-status=dead }}{{cite press release |title=Honeywell starts up $300 million automotive refrigerant production facility in Louisiana |url=https://www.honeywell.com/newsroom/pressreleases/2017/05/honeywell-starts-up-300-million-automotive-refrigerant-production-facility-in-louisiana |access-date=26 July 2018 |work=Honeywell |date=May 16, 2017}} Honeywell and DuPont hold most patents issued for HFO-1234yf and remained the pre-eminent manufacturers in 2018.{{cite news |last1=Marwa |first1=Stefen |title=HFO-1234yf market 2018 global share and projections: Honeywell and Chemours |url=https://theaerospacenews.com/hfo-1234yf-market-2018-global-share-and-projections-honeywell-and-chemours/204170/ |access-date=26 July 2018 |work=The Aerospace News |date=July 26, 2018 |archive-url=https://web.archive.org/web/20180726235811/https://theaerospacenews.com/hfo-1234yf-market-2018-global-share-and-projections-honeywell-and-chemours/204170/ |archive-date=26 July 2018 |url-status=dead }}

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.{{cite web |last1= Lewandowski |first1=Thomas A. |title=Additional risk assessment of alternative refrigerant R-1234yf prepared for SAE International cooperative research program CRP1234-4 |url=https://www.sae.org/standardsdev/tsb/cooperative/crp_1234-4_report.pdf |website=SAE International |access-date=26 July 2018|date=July 24, 2013}} Tests conducted in 2008 indicated that ignition requires temperatures exceeding {{Convert|900|C|F|abbr=on}} and mixture with PAG oil.{{Cite web|url=http://www.aa1car.com/library/hfo-1234yf_info_honeywell.pdf|title=HFO-1234yf Low GWP Refrigerant Update|last1=Spatz|first1=Mark|last2=Minor|first2=Barbara|date=July 2008}} Once in flame, 2,2,3,3{{Nbh}}tetrafluoropropene releases highly corrosive and toxic gaseous hydrogen fluoride and carbonyl fluoride.{{Cite journal |last=Feller |first=Michael |last2=Lux |first2=Karin |last3=Hohenstein |first3=Christian |last4=Kornath |first4=Andreas |date=2014-04-01 |title=Structure and Properties of 2,3,3,3-Tetrafluoropropene (HFO-1234yf) |url=https://www.degruyter.com/document/doi/10.5560/znb.2014-4017/html?lang=en |journal=Zeitschrift für Naturforschung B |language=en |volume=69 |issue=4 |pages=379–387 |doi=10.5560/znb.2014-4017 |issn=1865-7117}}

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{{Nbh}}tetrafluoropropene and A/C compressor oil onto a car's hot engine, the mixture burned in two out of three times.{{cite news |last1=Hetzner |first1=Christiaan |title=Coolant safety row puts the heat on Europe's carmakers |url=https://uk.reuters.com/article/uk-europe-cars-refrigerant/coolant-safety-row-puts-the-heat-on-europes-carmakers-idUKBRE8BB0HE20121212 |archive-url=https://web.archive.org/web/20180726233831/https://uk.reuters.com/article/uk-europe-cars-refrigerant/coolant-safety-row-puts-the-heat-on-europes-carmakers-idUKBRE8BB0HE20121212 |url-status=dead |archive-date=July 26, 2018 |access-date=26 July 2018 |work=Reuters |date=December 12, 2012}} In September, Daimler issued a press release, proposed a recall of cars using the refrigerant, and continued to use older refrigerants in its own designs.{{cite news |last1=Bolduc |first1=Douglas A. |date=August 8, 2013 |title=German officials provide mixed ruling on Honeywell refrigerant Despite fire risk, agency does not seek recall of cars using HFO-1234yf |url=http://europe.autonews.com/article/20130808/ANE/130809861/german-officials-provide-mixed-ruling-on-honeywell-refrigerant |access-date=26 July 2018 |work=Automotive News Europe|url-access = subscription}} The German automakers argued for development of carbon dioxide refrigerants, which they argued would be safer.

In October 2012, SAE International established a new Cooperative Research Project, CRP1234-4, to extend its previous testing and investigate Daimler's claims. 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".{{cite news |title=A heated row over coolants |url=https://www.economist.com/business/2013/08/31/a-heated-row-over-coolants |access-date=26 July 2018 |newspaper=The Economist |date=August 31, 2013}} Germany's {{Ill|Kraftfahrt-Bundesamt|lt=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 constitute a serious danger.

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

{{quote|"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."}}

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.{{Cite web|url=https://www.coolingpost.com/world-news/r134a-alternative-is-virtually-non-flammable/|title=R134a alternative is "virtually non-flammable"|website= Cooling Post| date= 30 November 2014 |language=en-GB|access-date=2017-06-09}}

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.{{cite web |title=US6969701B2 Azeotrope-like compositions of tetrafluoropropene and trifluoroiodomethane |url=https://patents.google.com/patent/US6969701B2/en |website=Google patents |access-date=26 July 2018}}

In open atmosphere, HFO refrigerants including R-1234yf actually forms HFC-23 as one of its secondary atmospheric breakdown products. HFC-23 is a very potent greenhouse gas with a GWP100 of 14,800. This makes the secondary GWP of R-1234yf in the range of 1,400±700 considering the amount of HFC-23 which may form from HFO-1234yf in the atmosphere. Besides the global warming potential, when HFOs decompose in the atmosphere, trifluoroacetic acid (TFA(A)) is formed, which also remains in the atmosphere for several days. The trifluoroacetic acid then forms trifluoroacetate (TFA), a salt of trifluoroacetic acid, in water and on the ground. Due to its high polarity and low degradability, it is difficult to remove TFA from drinking water (ICPR 2019).{{cite web |last1=Kauffeld |first1=Michael |date=June 11, 2021 |title=Environmental impact of HFO refrigerants & alternatives for the future |url=https://www.openaccessgovernment.org/hfo-refrigerants/112698/ |website=Global Access Government}} {{cite web |last1=McGillen |first1=Max |date=December 11, 2023 |title=Ozonolysis can produce long-lived greenhouse gases from commercial refrigerants |url=https://www.pnas.org/doi/abs/10.1073/pnas.2312714120}} {{cite web |last1=Hansen |first1=Christopher |date=February 5, 2023 |title=Photodissociation of CF3CHO provides a new source of CHF3 (HFC-23) in the atmosphere: implications for new refrigerants. |url=https://www.researchsquare.com/article/rs-199769/v1}} {{cite web |last1=van der Hoff |first1=Menno |date=October 3, 2022 |title=Onderzoek toont zorgwekkende toename van TFA als afbraakproduct van HFK's en HFO's |url=https://www.koudeenluchtbehandeling.nl/101296/onderzoek-toont-zorgwekkende-toename-van-tfa-als-afbraakproduct-van-hfks-en-hfos}} {{cite journal | doi = 10.1021/es902481f | title = Ozone and TFA Impacts in North America from Degradation of 2,3,3,3-Tetrafluoropropene (HFO-1234yf), A Potential Greenhouse Gas Replacement | date = 2010 | last1 = Luecken | first1 = Deborah J. | last2 = Waterland | first2 = Robert L. | last3 = Papasavva | first3 = Stella | last4 = Taddonio | first4 = Kristen N. | last5 = Hutzell | first5 = William T. | last6 = Rugh | first6 = John P. | last7 = Andersen | first7 = Stephen O. | journal = Environmental Science & Technology | volume = 44 | issue = 1 | pages = 343–348 | pmid = 19994849 | bibcode = 2010EnST...44..343L }} {{cite journal |last1=Hurley |first1=M.D |last2=Wallington |first2=T.J |last3=Javadi |first3=M.S |last4=Nielsen |first4=O.J |year=2008 |title=Atmospheric chemistry of CF₃CF=CH₂: Products and mechanisms of Cl atom and OH radical initiated oxidation |journal=Chemical Physics Letters |volume=450 |issue=4–6 |pages=263–267 |doi=10.1016/j.cplett.2007.11.051}}

• 1,3,3,3-Tetrafluoropropene (HFO-1234ze)

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Category:Fluoroalkenes

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Category:Trifluoromethyl compounds

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