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Environmental fate & pathways

Hydrolysis

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Evidence from TFE manufacture and polymerisation in aqueous media above ambient temperature show that TFE does not readily undergo hydrolysis. Furthermore, the hydrolysis of TFE in the environment is of little relevance, since its high volatility and low water solubility will cause it to volatilise rapidly from water bodies.

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Additional information

A priori, it cannot be concluded that TFE is unlikely to undergo hydrolysis, since:

  • The four electron withdrawing fluorine atoms in TFE render the double bond susceptible to attack by nucleophiles. Indeed such reactions with alcohols, amines, etc are well known (Coffman et al, 1949).
  • The addition of water, followed by the hydrolysis of the difluoroacetyl fluoride initially formed, would lead to difluoroacetic acid:

H2O + CF2=CF2HCF2CF2OH→ HCF2COF + HF

HCF2COF + H2O → HCF2COOH + HF

  • Difluoroacetate has been observed as a by-product of the addition of sulphite to TFE in the presence of water at 120°C (Harmer et al, 2007).

Nevertheless, evidence from PTFE manufacturing indicates TFE clearly does not readily undergo hydrolysis. In the pyrolysis reaction to make TFE from chlorodifluoromethane TFE is in contact with hot steam. No reaction with water is known. If there was a reaction it would not be possible to make TFE by this route. In the autoclaves, TFE is polymerised at elevated temperature and pressure in the presence of water in the pH range of 4 to 10. There is no evidence of the presence of the potential hydrolysis product 1,1,2,2-tetrafluoroethanol at the end of these polymerisation reactions. Furthermore, the hydrolysis of TFE in the environment is of little relevance, since its high volatility and low water solubility will cause it to volatilise rapidly from water bodies. Therefore, in accordance with section 1, subsection 1.2 of REACH Annex XI, Weight of Evidence, the study does not need to be conducted.

Coffman DD, Raasch MS, Rigby GW, Barrick PL, Hanford WE, 1949. Addition reactions of tetrafluoroethylene. Journal of Organinc Chemistry 14, 747 -753

Harmer MA, Junk C, Rostovtsev V, Carcani LG, Vickery J, Schnepp Z, 2007. Synthesis and applications of superacids. 1,1,2,2 -tetrafluorosulphonic acid, supported on silica. Green Chemistry 9(1), 30 -37.