Trifluoroacetic acid

Trifluoroacetic acid


Trifluoroacetic acid Unlike CFCs, the alternative fluorocarbons (HCFCs and HFCs) will break down readily in the lower atmosphere1 to form simple inorganic species already present in the environment. However, a few of the HCFCs 1, HFCs and HFOs can be expected to form trifluoroacetic acid, a substance apparently resistant to further degradation.In 1991, the fluorocarbon industry instigated a research programme to ascertain basic environmental and toxicological data. The risk from the future environmental levels of trifluoroacetic acid from future emissions of HCFCs and HFCs has now been assessed, with the conclusion that “they do not pose a threat to the environment”2. In the same assessment, the toxicity of trifluoroacetic acid to algae, higher plants, fish, animals and humans was evaluated. It was found to be of very low toxicity to all of these organisms.There is a very large quantity of trifluoroacetic acid in the sea 3 4 5 6 significant concentrations have been found in both coastal and deep-ocean seawater. The amount implied from these measurements (approximately 100 to 200 million tonnes) suggests a long term source that has continued for at least 100 years (probably several thousand). Thus, trifluoroacetate is a natural component of seawater 5 6 . Speculatively, it is formed in and around hydrothermal vents in the oceans 6.Trifluoroacetic acid is also found in rain, river and lake water  7 8. The rainwater concentration has been sampled most frequently in Germany and western USA and the concentrations measured are far in excess of those that could occur as a result of atmospheric oxidation of man-made fluorocarbons. Although the source of trifuoroacetate deposited over land has not been confirmed, the concentrations and locations are consistent with transport of oceanic material in much the same way as sea salt aerosol. This is released from the sea surface and transported in the atmosphere to be deposited several hundred kilometres inland  9 10.More recently, further studies were undertaken to investigate the burden that can be reasonable expected to be caused by the degradation of HFO-1234yf as a result of its wide-spread use in automobile air-conditioning, replacing HFC-134a (which also has TFA as a degradation product). Since HFO-1234yf has a much shorter atmospheric lifetime (10 days vs 14 years for HFC-134a) 11, the distribution of TFA could change as a result.12, 13, 14 These studies concluded that the estimated maximum concentration of TFA in surface water was approximately 60 to 80 times smaller than that of the NOAEL (No Observed Adverse Effect Level) for aquatic ecotoxicity.

1. Proceedings of the workshop on the atmospheric degradation of HCFCs and HFCs, Nov 17-19, 1993, Boulder, CO; published by AFEAS, Washington, USA.2. Boutonnet et al., Environmental Risk Assessment of Trifluoroacetic Acid, Human and Ecological Risk Assessment, 5(1), 59-124, 1999.3. Scott B.F., et al., Haloacetic Acids in the Freshwater and Marine Environment, First International Symposium on Atmospheric Reactive Substances, 14-16 April 1999, Bayreuth, Germany.4. Von Sydow L., A. Grimvall, H. Boren, K. Laniewski, A. Nielsen, Natural background levels of trifluoroacetate in rain and snow, Environ. Sci. Technol., 34, 3115-3118, 2000.5. Frank H., E.H. Christoph, O. Holm-Hansen and J.L. Bullister, Trifluoroacetate in Ocean Waters, Environ. Sci. Technol., 36, 12-15, 2002.6. Scott B. F., R.W. Macdonald, K. Kannan, A. Fisk, A. Witter, N. Yamashita, L. Durham, C. Spencer and D.C.G. Muir, Trifluoroacetate (TFA) Profiles in the Arctic, Atlantic and Pacific Oceans, Environ. Sci. Technol., 39, 6555-6560, 2005.7. Wujcik C.E., D. Zehavi and J.N. Seiber, Trifluoroacetic acid levels in 1994-1996 fog, rain, snow and surface waters from California and Nevada, Chemosphere, 36(6), 1233-1245, 1998.8. Jordan A. and H. Frank, Trifluoroacetate in the Environment. Evidence for sources other than HFC/HCFCs, Environ. Sci. Technol., 33, 522-527, 1999.9. Manders A.M.M., M. Schaap, X. Querol, M.F.M.A. Albert, J. Vercauteren, T.A.J. Kuhlbusch and R. Hoogerbrugge, Sea salt concentrations across the European continent, Atmos. Environ., 44, 2434-2442, 2010. 10. Sofiev M., J. Soares, M. Prank, G. de Leeuw and J. Kukkonen, A regional-to-global model of emission and transport of sea salt particles in the atmosphere, J. Geophys. Res., 116, D21302, doi:10.1029/2010JD014713, 2011.11. M.D. Hurley, T.J. Wallington, M.S. Javadi , O.J. Nielsen, Atmospheric chemistry of CF3CF=CH2: Products and mechanisms of Cl atom and OH radical initiated oxidation, Chemical Physics Letters 450 (2008) 263–26712. D . J . Luecken, R.L Waterland, S. Papasavva, K.N. Taddonio, W.T Hutzell, J.P. Rugh and S.O Andersen, Ozone and TFA Impacts in North America from Degradation of 2,3,3,3-Tetrafluoropropene (HFO-1234yf), A Potential Greenhouse Gas Replacement, Environ. Sci. Technol. 2010, 44, 343–34813. Hideo Kajihara, Kazuya Inoue, Kikuo Yoshida, Ryuichi Nagaosa, Estimation of environmental concentrations and deposition fluxes of R-1234-YF and its decomposition products emitted from air conditioning equipment to atmosphere, proccedings  2010 International Symposium on Next-generation Air Conditioning and Refrigeration Technology, 17 .– 19 February 2010, Tokyo, Japan14. Stephan Henne, Dudley E. Shallcross, Stefan Reimann, Ping Xiao, Dominik Brunner, Simon O’Doherty, and Brigitte Buchmann, Future Emissions and Atmospheric Fate of HFC-1234yf from Mobile Air Conditioners in Europe, Environ. Sci. Technol., 2012 Feb 7; 46(3):1650-8 Last upadate: June 2013 PDF