2,3,3,3-Tetrafluoropropene, HFO-1234yf, is a

hydrofluoroolefin Hydrofluoroolefins (HFOs) are unsaturated organic compounds composed of hydrogen, fluorine and carbon. These organofluorine compound are of interest as refrigerants. Unlike traditional hydrofluorocarbons (HFCs) and chlorofluorocarbons (CFCs), whic ...

(HFO) with the formula CH₂=CFCF₃. It is also designated R-1234yf as the first of a new class of

refrigerants A refrigerant is a working fluid used in the refrigeration cycle of air conditioning systems and heat pumps where in most cases they undergo a repeated phase transition from a liquid to a gas and back again. Refrigerants are heavily regulate ...

: it is marketed under the name Opteon YF by

Chemours Chemours (, ) is an American chemical company that was founded in July 2015 as a spin-off from DuPont. It has its corporate headquarters in Wilmington, Delaware, United States. History In October 2013, DuPont announced that it was planning to ...

and as Solstice YF by

Honeywell Honeywell International Inc. is an American publicly traded, multinational conglomerate corporation headquartered in Charlotte, North Carolina. It primarily operates in four areas of business: aerospace, building technologies, performance ma ...

. HFO-1234yf has a

global warming potential Global warming potential (GWP) is the heat absorbed by any greenhouse gas in the atmosphere, as a multiple of the heat that would be absorbed by the same mass of carbon dioxide (). GWP is 1 for . For other gases it depends on the gas and the time ...

(GWP) of less than 1, compared to 1,430 for

R-134a 1,1,1,2-Tetrafluoroethane (also known as norflurane (INN), R-134a, Freon 134a, Forane 134a, Genetron 134a, Green Gas, Florasol 134a, Suva 134a, or HFC-134a) is a hydrofluorocarbon (HFC) and haloalkane refrigerant with thermodynamic properties ...

and 1 for

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...

. This colorless gas is being used as a replacement for

as a refrigerant in automobile air conditioners. As of 2022, 90% of new U.S. vehicles from "original equipment manufacturers" (OEMs) are estimated to use HFO-1234yf. One drawback is it breaks down into

persistent organic pollutant Persistent organic pollutants (POPs), sometimes known as "forever chemicals", are organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes. They are toxic chemicals that adversel ...

short chain perfluorinated carboxylic acids (PFCAs).

Adoption by automotive industry

HFO-1234yf was developed by a team at

DuPont DuPont de Nemours, Inc., commonly shortened to DuPont, is an American multinational chemical company first formed in 1802 by French-American chemist and industrialist Éleuthère Irénée du Pont de Nemours. The company played a major role in ...

, led by

Barbara Haviland Minor Barbara Haviland Minor is an American chemical engineer who has worked at DuPont (between 1981 and 2015) and Chemours (since 2015). She develops new refrigerants to be used in air conditioning and refrigeration systems, in Europe, North Americ ...

, which worked jointly with researchers at Honeywell. 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 GWP below 150. 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. It can be used as a "near drop-in replacement" for R-134a, the product previously used in automobile AC systems, which has a 100-year GWP of 1430. This meant that automakers would not have to make significant modifications in assembly lines or in vehicle system designs to accommodate the product. HFO-1234yf had the lowest switching cost for automakers among the proposed alternatives. The product 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 mild flammability of HFO-1234yf. Another issue affecting the compatibility between HFO-1234yf and R-134a-based systems is the choice of lubricating oil. Shortly after confirmation from automakers that HFO-1234yf would be adopted as a replacement of R-134a automotive air-conditioning refrigerant, in 2010,

and DuPont announced that they would jointly build a manufacturing facility in

Changshu Changshu (; Suzhounese: /d͡ʐan¹³ ʐoʔ²³/) is a county-level city under the jurisdiction of Suzhou, Jiangsu province, and is part of the Yangtze River Delta. It borders the prefecture-level city of Nantong to the northeast across the Yan ...

, Jiangsu Province, China to produce HFO-1234yf."Automakers Go HFO", ''

Chemical & Engineering News ''Chemical & Engineering News'' (''C&EN'') is a weekly news magazine published by the American Chemical Society, providing professional and technical news and analysis in the fields of chemistry and chemical engineering.Geismar, Louisiana, USA to produce the new refrigerant as well. Although others claim to be able to make and sell HFO-1234yf, Honeywell and DuPont hold most or all of the patents issued for HFO-1234yf and are considered the leading players in this area as of 2018.

Flammability

Although the product is classified slightly flammable by

ASHRAE The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE ) is an American professional association seeking to advance heating, ventilation, air conditioning and refrigeration (HVAC&R) systems design and constructi ...

, several years of testing by

SAE International SAE International, formerly named the Society of Automotive Engineers, is a United States-based, globally active professional association and standards developing organization for engineering professionals in various industries. SAE Internatio ...

proved that the product could not be ignited under conditions normally experienced by a vehicle. In addition several independent authorities evaluated the safety of the product in vehicles and some of them concluded that it was as safe to use as R-134a, the product then in use in cars. In the atmosphere, HFO-1234yf degrades to

trifluoroacetic acid Trifluoroacetic acid (TFA) is an organofluorine compound with the chemical formula CF3CO2H. It is a structural analogue of acetic acid with all three of the acetyl group's hydrogen atoms replaced by fluorine atoms and is a colorless liquid with ...

, which is a mildly phytotoxic strong organic acid with no known biodegradation mechanism in water. In case of fire it releases highly corrosive and toxic

hydrogen fluoride Hydrogen fluoride (fluorane) is an inorganic compound with the chemical formula . This colorless gas or liquid is the principal industrial source of fluorine, often as an aqueous solution called hydrofluoric acid. It is an important feedstock ...

and the highly toxic gas

carbonyl fluoride Carbonyl fluoride is a chemical compound with the formula COF2. It is a carbon oxohalide. This gas, like its analog phosgene, is colourless and highly toxic. The molecule is planar with ''C''2v symmetry, bond lengths of 1.174 Å (C=O) and 1.312 ...

. In July 2008,

/ Du-Pont published a report claiming "HFO-1234yf is very difficult to ignite with electric spark" detailing the tests they did passing the gas over a hot plate heated to various temperatures in the range of 500–900 °C. Ignition was only seen when HFO-1234yf was mixed with PAG oil and passed over a plate that was >900 °C. In August 2012,

Mercedes-Benz Mercedes-Benz (), commonly referred to as Mercedes and sometimes as Benz, is a German luxury and commercial vehicle automotive brand established in 1926. Mercedes-Benz AG (a Mercedes-Benz Group subsidiary established in 2019) is headquarte ...

showed that the substance ignited when researchers sprayed it and A/C compressor oil onto a car's hot engine. 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." Combustion occurred in more than two thirds of their simulated head-on collisions. The engineers also noticed etching on the windshield caused by the corrosive gases. On September 25, 2012, Daimler issued a press release and proposed a recall of cars using the refrigerant. 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, which included members of 13 automotive companies, to extend its previous testing and investigate Daimler's claims. A preliminary update as of December 2012 and a final report publicly released on July 24, 2013 agreed that R-1234yf was safe to use in automotive direct-expansion air conditioning systems. R-1234yf was believed not to increase the estimated risk of vehicle fire exposure. The report further stated that "the refrigerant release testing completed by Daimler was unrealistic" and "created extreme conditions that favored ignition". The final report was supported by Chrysler/Fiat, Ford, General Motors, Honda, Hyundai, Jaguar Land Rover, Mazda, PSA, Renault and Toyota. Daimler, BMW and Audi chose to withdraw from the SAE R-1234yf CRP Team. Following Mercedes' claims that the new refrigerant could be ignited, Germany's Kraftfahrt-Bundesamt (KBA, Federal Motor Transport Authority) conducted its own tests. They submitted a report to the

European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are located primarily in Europe, Europe. The union has a total area of ...

in August 2013. The Authority concluded that while R-1234yf was potentially more hazardous than previously used R-134a, it did not comprise a serious danger. Daimler disagreed with this conclusion and argued that the report supported their decision to continue to use older refrigerants. On July 23, 2010,

General Motors The General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. It is the largest automaker in the United States and ...

announced that it would introduce HFO-1234yf in 2013 Chevrolet, Buick, GMC, and Cadillac models in the U.S.

Cadillac The Cadillac Motor Car Division () is a division of the American automobile manufacturer General Motors (GM) that designs and builds luxury vehicles. Its major markets are the United States, Canada, and China. Cadillac models are distributed ...

became the first American car to use R-1234yf in 2012. Since then,

Chrysler Stellantis North America (officially FCA US and formerly Chrysler ()) is one of the " Big Three" automobile manufacturers in the United States, headquartered in Auburn Hills, Michigan. It is the American subsidiary of the multinational automotiv ...

, GMC and Ford have all begun transitioning vehicles to R1234yf. Japanese automakers are also making the transition to R1234yf.

Honda is a Japanese public multinational conglomerate manufacturer of automobiles, motorcycles, and power equipment, headquartered in Minato, Tokyo, Japan. Honda has been the world's largest motorcycle manufacturer since 1959, reaching a producti ...

and

Subaru ( or ; ) is the automobile manufacturing division of Japanese transportation conglomerate Subaru Corporation (formerly known as Fuji Heavy Industries), the twenty-first largest automaker by production worldwide in 2017. Subaru cars are ...

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. Mixing HFO-1234yf with 10–11%

R-134A 1,1,1,2-Tetrafluoroethane (also known as norflurane (INN), R-134a, Freon 134a, Forane 134a, Genetron 134a, Green Gas, Florasol 134a, Suva 134a, or HFC-134a) is a hydrofluorocarbon (HFC) and haloalkane refrigerant with thermodynamic properties ...

is in development to produce a hybrid gas under review by

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. 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

mutagen In genetics, a mutagen is a physical or chemical agent that permanently changes genetic material, usually DNA, in an organism and thus increases the frequency of mutations above the natural background level. As many mutations can cause cancer i ...

ic.

Production

Typical methods for producing HFO-1234yf start with

1,2,3,3,3-pentafluoropropene 1,2,3,3,3-Pentafluoropropene is the unsaturated fluorocarbon with the formula HFC=C(F)CF. This colorless gas is of interest as a precursor to hydrofluoroolefins (HFOs), which are used as refrigerant A refrigerant is a working fluid used in the ...

. Hydrogenation of this alkene gives 1,2,3,3,3-pentafluoropropane, which upon heating with an Al-based catalyst undergoes

dehydrofluorination In chemistry, dehydrohalogenation is an elimination reaction which removes a hydrogen halide from a substrate. The reaction is usually associated with the synthesis of alkenes, but it has wider applications. Dehydrohalogenation from alkyl hali ...

:Rao, Velliyur Nott Mallikarjuna; Sievert, Allen Capron; Nappa, Mario Joseph "Process to manufacture 2,3,3,3-tetrafluoropropene" PCT Int. Appl. 2008, WO 2008030440 A2 20080313 (to duPont). :CF₃CFHCFH₂ → CF₃CF=CH₂ + HF

References

{{DEFAULTSORT:Tetrafluoropropene, 2, 3, 3, 3- Haloalkenes Organofluorides Refrigerants Automotive chemicals Trifluoromethyl compounds

Adoption by automotive industry

Flammability

Production

See also

References