Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

HFP kinetic dimer is a volatile liquid with low water solubility. It is expected to distribute into the atmospheric compartment after emission. Phototransformation reactions with hydroxyl radical will remove HFP kinetic dimer with an atmospheric lifetime of 0.82 years. The pathway for decay is expected to be analogous to that for perfluorobutene (1), i.e., addition of hydroxyl radical to the unsaturated group followed by scission to form a carboxylate moiety from each of the two unsaturated carbons. The ultimate degradation products are expected to be perfluoroisobutyric acid (i-PFBA, CAS# 335-10-4), trifluoroacetic acid (TFA, CAS# 76-05-1) and hydrofluoric acid (HF, CAS# 7664-39-3).

We have proposed waiving hydrolysis testing based on limited water solubility and volatility. Hydrolysis is not expected to be important to the fate of HFP kinetic dimer. Also, no unexpected components were observed by GC-MS during the water solubility and partition coefficient studies, or by NMR after extended contact with moderately hard reconstituted water (daphnia medium), further supporting the lack of importance of hydrolysis to fate.

1) C.J. Young, M.D. Hurley, T.J. Wallington, S.A. Maybury. 2009. Atmospheric chemistry of perfluorobutenes (CF3CF=CFCF3 and CF3CF2CF=CF2); kinetics and mechanisms of reactions with OH radicals and chlorine atoms, IR spectra, global warming potentials, and oxidation to perfluorocarboxylic acids. Atmospheric Environment: Vol. 43, pp. 3717-3724.