Chlorotrifluoroethylene

Endpoint summary

Additional information

The EQC Fugacity III Model (EQC Fugacity III Model, v.2.02, May 2003)

was run assuming CTFE emissions only to air. The results obtained from this model confirm that all the CTFE released to air remains in this compartment. In the atmosphere the substance is rapidly degraded by reactions with photochemically produced hydroxyl radicals (OH).

With respect to reactions with hydroxyl radicals, a rate constant of 7.27 x 10^-12 cm cu/mol sec measured at 297 K (24°C) has been estimated for CTFE this corresponds to an atmospheric half-life of about 2.2 days at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm (Abbatt J.P.D. et al., 1991).

CTFE does not contain chromophores that absorb at wavelengths >290 nm and therefore is not expected to be susceptible to direct photolysis by sunlight ( Howard C.J. 1996).

In respect to the reaction with ozone a rate constant of 1.6X10^-20 cm cu/mol sec and a half-life for this of 715 days at an ozone concentration of 7X10+11 mol/cm cu has been estimated for CTFE ( Meylan W.M 1993).

CTFE is not listed in the Scientific Assessment of Ozone Depletion of the World Metereological Organization/United nations Environment Programme (WMO/UNEP) or the Montreal Protocol as it is not considered as a substance contributing to the Ozone depletion.

 

Due to the gaseous nature of the substance and its tendency to partition into the air, the hydrolytic degradation of CTFE is neither measurable nor expected.

Moreover, the Guidance on Information Requirements and Chemical Safety Assessment Chapter R.7a: Endpoint Specific Guidance, Appendix R.7.1-4 indicates that substances with a Henry's Law constant of around 1 hPa m3/mole rapidly volatilise from water.

According to section 2 of REACh Annex XI, testing hydrolysis is not technically feasible as CTFEis a volatile gas at ambient conditions.

Although no partition into water is expected, the tendency to hydrolyze has been however assessed basing on the chemical structure of CTFE molecule.

This does not contain any functional groups associated with hydrolysis properties at relevant environmental conditions.

Particularly, the carbon-fluorine bond is the strongest bond in organic chemistry (O'Hagan, 2008). Substitution of hydrogen atoms with fluorine results in increased bond strengths for both carbon-fluorine and adjacent carbon-carbon bonds over the corresponding hydrocarbon and would increase the resistance to hydrolysis (Lemal, 2003). Therefore, based on this qualitative structure-activity relationship, it can be concluded that hydrolysis is not a relevant degradation mechanism for CTFE.