- HFO -1234yf
- 2,3,3,3 - tetrafluoropropylene
1.1 g · cm -3 at 25 ° C (liquid)
-152.2 ° C
-30 ° C
- 6067 hPa ( 21.1 ° C)
- 14203 hPa ( 54.4 ° C)
Very poor in water ( 198.2 mg · l-1 at 24 ° C)
Template: Infobox chemical / molecular formula search available
2,3,3,3 - Tetrafluoropropene or HFO -1234yf (trade name: R1234yf ) is a chemical compound from the group of substances of alkenes and organic fluorine compounds.
Production and representation
A representation of the compound in a plurality of stages, starting with 1,2,3- trichloropropane, possible. However, the average fluorine atom is first introduced through elimination and subsequent addition. After formation of a tetrachloro -fluoro propane by chlorination in sunlight, the connection is partially fluorinated. In the final steps, first by dehydrohalogenation of 3-chloro -2 ,3,3- trifluoropropene and 3.3 -dichloro-2 ,3- difluorpropen shown, which are reacted with antimony pentafluoride to 2,3,3,3 - tetrafluoropropene.
Is produced R1234yf exclusively by Dupont and Honeywell that hold a patent.
2,3,3,3 - Tetrafluoropropene is a flammable, colorless gas with a faint odor. In contrast to chlorinated hydrocarbons, it is not ozone depleting and therefore does not harm the ozone layer. Also its global warming potential is low and amounts to 4.4 (based on 100 years of carbon dioxide = 1). It is therefore in contrast to other fluorocarbons such as 1,1,1,2 -tetrafluoroethane with a global warming potential of 1430. The reason for this is the rapid degradation of 2,3,3,3 - Tetrafluoropropene, its average lifetime in the atmosphere is only about 12 days. It reacts primarily with the reactive hydroxyl radicals in the atmosphere, where it eventually degrades first to trifluoroacetylfluoride and by hydrolysis to the stable trifluoroacetic acid.
The vapor pressure function is given by Antoine corresponding log10 (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.
In addition to carbon dioxide, 2,3,3,3 - Tetrafluoropropene comes as a substitute for 1,1,1,2 -tetrafluoroethane as a refrigerant in the air conditioning of future vehicles in question, but because of its flammability and the risk of rich combustion product of hydrogen fluoride controversial.
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 explosive limit ( LEL) and 12.3 vol% as the upper explosive limit ( UEL). A second source is at a range of 6.7 vol% to 11.7 vol%. Self-ignition temperature is between 400 ° C and 405 ° C. When combustion is toxic and corrosive hydrogen fluoride, and carbonyl fluoride ( COF2 ) free.
Both for the Association for the Promotion of the German Fire Protection, as well as for the German Association of Fire Fighters changes in the risk situation by the new refrigerant in the vehicle nothing. On the other hand calls for the Professional Association Fire Department was founded only a few years because of the dangers associated with this substance a prohibition on use. In Switzerland, the Federal Council rejected a ban on the use, on the ground, other similar substances are similar risky, but would have used for decades safely thanks to technical Schutzvorkehren; which also applies to Tetrafluoropropene. A single nation can in the international automotive industry impose no change in technology, and the high price and the risks of Tetrafluoropropene would ensure that it only gets used where no alternative exists.
Daimler announced in September of 2012, the new refrigerant R1234yf not want to use more, because that would be too dangerous. In our own studies using internal standards have been found that the funds in the hot engine compartment ignited. This could be any time demonstrated reproducible. In early October 2012, Daimler stressed the importance of these results by the fact that for all filled with R1234yf vehicles was a recall in the workshops. It was a back filling with R134a made , for which the EU had granted an exemption due to drug shortages to 31st December 2012.
Also, the Volkswagen Group announced in an industry conference in Berlin that he favored carbon dioxide and in a transition period, the old refrigerant would use R134a. In tests of a compact car Opel contrast, R1234yf did not inflamed despite leaks to the cooling system in the vicinity of the hot exhaust manifold. The Federal Motor Transport Authority can be determined in tests with different types of cars, whether escaping R1234yf ignites from defective air conditioning on hot parts.
The by Daimler - tests newly kindled debate about the safety of Tetrafluoropropene did not result in Daimler's his opinion alone and isolated stands as the most important association of automotive engineers SAE end of 2012 turned out. A team of experts employed within the SAE (CRP-1234 - 4 Team ) to investigate the new reservations and report the end of February 2013 preliminary and final in the summer to do so. Because apparently insurmountable contrarian views gave both Daimler and BMW and Audi beginning in February 2013 announced to leave the SAE expert group prematurely.
In April 2013, the SAE announced as a result of investigations carried out that R1234yf is safe for use in vehicles. The test used by Daimler would be unrealistic, since some factors of a real accident were not complied with. The final report was published in June 2013. Thus is the risk that an occupant is exposed to a fire due to inflammation of R -1234yf, almost six orders of magnitude lower than the risk of a vehicle brands at all.
The resulting after the tests of Daimler new situation for Flammability of R1234yf in an accident sat by the subsequent refusal to fill this refrigerant, the federal government under pressure. The EU commission called for evidence supporting this claim. Safety Guidelines for the registration of motor vehicles are regulated by a product safety Code of KBA. It was necessary to make a decision after weighing the two legal goods product safety and conformity with EU standards. For this, the KBA has commissioned the TÜV Rheinland with the participation of BAM, the Federal Highway Research Institute and the Federal Environment Agency to carry out further tests.
The report presented to the advisory opinion in August 2013, preliminary interim report confirmed after two R1234yf the test procedures no increased risk, which would have to consider measures according to viewpoints of product safety. However, were shown after carrying out an extended scenario both inflammation in the engine compartment, as well as formation of hydrogen fluoride in significant concentrations. Since endangering rescuers and occupants can not be excluded in both cases, the KBA strongly recommends to carry out further investigations. Likewise, a regulated future safety evaluation of vehicle climate control is possible. Overall, the safety of vehicles with R1234yf as refrigerant filling 'll deteriorated compared with R134a.
On March 7, 2013, the Joint Research Centre (JRC) has announced the results of their scientific study on the use of the refrigerant HFO-1234yf R1234yf or the European Commission announced. The review of the Federal Motor Transport Authority (KBA ) tests carried out showed that there is no danger for use in motor vehicles.