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EC number: 201-201-8
CAS number: 79-38-9
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) and a vapour pressure of
612 kPa at 25 °C (ISCS No. 0685, NIOSH).
A value of water solubility of 380 mg/l was
experimentally determined in a completely sealed system with an
atmosphere saturated with CTFE (Oriani R., 2001). The experimental test
conditions did not represent the natural condition in the environment
and therefore, although the
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.
On the basis of the above quoted
physico-chemicals properties, CTFE is expected to partition into
Even the Henry’s Law constant of 31,500 Pa
m3/mol (HENRYWIN v.3.0, EPI Suite v.4.0) suggest that the substance is
expected to rapidly volatise from water and soil to the air.
In order to evaluate the environmental fate
of CTFE, a Level III fugacity model was conducted (EQC Fugacity III
Model, v.2.02, May 2003), assuming steady-state but not equilibrium
The Level III Fugacity Model predicts
partitioning between four environmental compartments (air, soil,
sediment and water) using a combination of default parameters and
various input physico-chemical parameters. The model was run assuming
emissions only to air. In fact, in case of an accidental emission, CTFE
is uniquely released to air, because of its volatility at ambient
conditions and boiling point ranging from -26.2°C to -26.8°C. °C.
The environmental fate of the substance,
assessed through the model, confirmed that, following emissions in air,
CTFE remains in this compartment. The rates of transfer to soil and
water are very low and only negligible amounts of the total emission
remain in these media and in sediment.
As far as the CTFE stability is concerned, in
the atmosphere the substance 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). A
model prediction for evaluating the environmental fate of CTFE (EQC
Fugacity III Model, v.2.02, May 2003) confirms that the whole amount of
CTFE released to air remains in this compartment.
Hydrolysis studies cannot be conducted with
volatile substances (section 2 of REACH Annex XI). However, although no
partition into water is expected, the tendency to be hydrolyzed has been
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 this substance.
Although no release to the aquatic
environment is expected on the basis of CTFE profile and on its
environmental fate, a further assessment based on Quantitative Structure
Activity Relationships (QSARs) has been however applied.
In particular, the ready biodegradability of
CTFE has been estimated with a model prediction BIOWIN v4.10, EPI Suite
v.4.0 which result reports that the substance is not readily
No experimental bioaccumulation data are
available for the substance; however, in order to evaluate the
bioaccumulation hazard of profile of CTFE, the BCFBAF model v.3.0, EPI
Suite v 4.0 has been applied.
The model prediction for CTFE yielded a BCF
of 5.7, indicating that CTFE has a very low potential to bioaccumulate
in aquatic organisms.
No releases to the soil are expected on the
basis of CTFE profile and environmental fate, however the KOCWIN model v
2.0, EPI Suite v 4.0 has been applied in order to evaluate the soil
adsorption hazard profile of CTFE.
On the basis of the model results, estimated
both with the Molecular Connectivity Index (MCI) and with the log Kow
(KOCWIN model v 2.0, EPI Suite v 4.0), it is deemed unlikely that CTFE
can adsorb to sediment and particulates matter.
On the basis of the above reported
evaluations, the substance is not expected to persist in the
environment. In fact, the whole amount of CTFE released to air
partitions in this compartment where it is readily photochemically
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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