Chlorotrifluoroethylene

Endpoint summary

Additional information

Chlorotrifluoroethylene (CTFE) is a volatile gas at ambient conditions with a boiling point in the range of -26.2°C (The Beilstein database. Reference: Miller - 1951 ) to -26.8°C (The Beilstein database. Reference: Henne - 1948) a vapour pressure of 612 kPa at 25°C (ISCS No. 0685, NIOSH) . CTFE is also characterized by a moderate water solubility of 380 mg/L.

The value of water solubility of 380 mg/l was experimentally determined in a completely sealed system with an atmosphere saturated with CTFE. Althoughthe value of 380 mg/l itself reveals a moderate water solubility, it represents an overestimation of the actual water solubility of CTFE in the natural system since the experimental conditions did not represent the natural conditions.

The Henry’s Law constant of CTFE was calculated to be 31.500 Pa m3/mol (HENRYWIN v3.20, EPI Suite v4.0), suggesting that the substance is expected to rapidly volatilise from water to the air

in fact:

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

Basing on its physico-chemical properties it is expected that CTFE primarily and rapidly partitions to the atmosphere. In addition the EQC Fugacity III Model (Version 2.02, The Canadian Centre for Environmental Modelling and Chemistry, May 2003)

confirms that the whole amount of CTFE released to atmosphere remains in this compartment. The model was run assuming emission only to air. In case of an accidental emission, CTFE is only released to atmosphere, because CTFE is a volatile gas at ambient conditions with a boiling point ranging from -26.2°C to -26.8°C.

Due to the gaseous nature of the substance and its partition to the atmosphere, as well as the consequent difficulty to appropriately test CTFE and provide meaningful results, no experimental data are reported for the adsorption/desorption endpoint. However, in order to evaluate the soil adsorption hazard profile of CTFE despite the fact that it is expected to rapidly partition to the atmosphere compartment, the results of the KOCWIN model ( v.2.0, EPI Suite v 4.0) are attached.

As indicated in the Guidance on Information Requirements and Chemical Safety Assessment Chapter R.7a: Endpoint Specific Guidance, Appendix R.7.1.15 (Adsorption/Desorption), substances with a Koc below 500 -1,000 L/Kg are generally unlikely to adsorb to sediment. The estimated soil adsorption coefficient of CTFE ( Koc = 94.94 L/Kg from MCI and Koc = 27.02 L/Kg from log Kow) indicates that the potential adsorption of CTFE to soil and sediment is expected to be low.

In the atmosphere CTFE is rapidly degraded by reaction with photochemically produced hydroxyl radicals with half-lives, determined from experimentally derived rate constants. A rate constant for the chlorine-atom initiated oxidation of chlorotrifluoroethylene in the atmosphere gives CClF2CF(O) as the major product; the quantum yield of oxidation for this reaction is >1000 relative to the quantum yield for olefin (Sanhueza E et al.1956), Reaction with ozone gives an estimated half-life of 715 days (Meylan W.M, 1993). The primary product of this reaction is the corresponding carbonyl product (Heicklen J.P.,1975). A rate constant of 2.7X10-11 cm cu/mol sec is reported for the reaction of chlorotrifluoroethylene with atomic oxygen (Heicklen J.P.,1975). C2F3Cl 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 (Laube J.C., 2008).