(1E)-1-chloro-3,3,3-trifluoroprop-1-ene

Phototransformation in air

Link to relevant study record(s)

Reference

Endpoint:

phototransformation in air

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Acceptable, well documented publication which meets basic scientific principles.

Qualifier:

no guideline required

GLP compliance:

no

Details on test conditions:

FTIR–smog chamber system at Ford:
Experiments were performed in a 140-l Pyrex reactor interfaced to a Mattson Sirus 100 FTIR spectrometer. The reactor was surrounded by 22 fluorescent blacklamps (GE F15T8-BL) which were used to photochemically initiate the experiments. CH3ONO was synthesized by the drop wise addition of concentrated sulfuric acid to a saturated solution of NaNO2 in methanol. O3 was produced from O2 via silent electrical discharge using a commercial O3 ozonizer. Samples of t-CF3CH=CHCl were supplied by Honeywell International Inc. at purities > 99.9 %. All other reagents were obtained from commercial sources at purities > 99 %.
Relative rate and absolute rate experimental methods were used as described above. Experiments were conducted in 700 Torr total pressure of air/N2 diluent at 295 ± 2 K. The loss of t-CF3CH=CHCl and reference compounds was monitored by FTIR spectroscopy using a calibrated analytical path length of 27.1 m and a spectral resolution of 0.25 cm−1. A liquid nitrogen cooled midband MCT detector was used in this study. Infrared spectra were derived from 32 coadded interferograms. Reactant and reference compounds were monitored using absorption features over the following wavenumber ranges (cm−1): C2H2, 650–800; C2H4, 900–1000; O3, 980–1070; t-CF3CH=CHCl, 669, 847, 935, 1311, and 1648.

FTIR–smog chamber system at University of Copenhagen:
The Copenhagen experiments were performed in a 100-l quartz reactor equipped with a Bruker IFS 66V FTIR spectrometer. The experimental setup was equipped with a temperature control system that kept the temperature steady at 293 ± 0.5 K. An InSb detector was chosen for this study. Chlorine atoms were produced by photolysis of Cl2 according to reaction (Cl2 + hv → Cl + Cl), using UVA lamps (Osram Eversun L100/79) with the main emissions peak at 368 nm. Ozone was produced using a commercially available ozone generator from O3-Technology. The ozone was preconcentrated using a silica gel trap, reducing the amount of O2 introduced into the chamber. Samples of t-CF3CH=CHCl were supplied by Honeywell International Inc. at purities > 99.9 %. All other reagents were obtained from commercial sources at purities > 99 %.
Relative rate and absolute rate experimental methods were used as described above. The Cl atom relative rate experiments were conducted in 700 Torr total pressure of N2 diluent. Ozone kinetics experiments were conducted in 700 Torr total pressure of air diluent. The White-type optical system propagating the IR beam through the reaction chamber had a path length of 86 m. Spectra were obtained at a resolution of 0.115 cm−1 and were derived from 64 coadded interferograms. Reactant and reference compounds were monitored using absorption over the following wavenumber ranges (cm−1): C2H2, 3175–3375; C2H4, 2940–3040; O3, 2950–3065; t-CF3CH=CHCl, 3060–3130. FTIR spectra were analyzed using a linear least squares fitting procedure developed by Griffith. Reference spectra of O3 and HCl were taken from the HITRAN database, and used to improve the spectral fitting for the larger molecules. For the other components, reference spectra were recorded using the same conditions (700 Torr, 293 ± 0.5 K) employed in the kinetics experiments.

DT50:

26 d

Reaction with:

OH radicals

Remarks on result:

other: 4.4E-13 cm3/molecule/s

Reaction with:

ozone

Remarks on result:

other: 1.46E-21 cm3/molecule/s

Validity criteria fulfilled:

not applicable

Conclusions:

The atmospheric lifetime of t-CF3CH CHCl is determined by reaction with OH radicals and is approximately 26 days.

Executive summary:

Long path length Fourier transform infrared (FTIR)–smog chamber techniques were used to study the kinetics of the gas-phase reactions of Cl atoms, OH radicals and O₃ with trans-3,3,3-trifluoro-1-chloropropene, t-CF₃CH=CHCl, in 700 Torr total pressure at 295 ± 2 K. Values of k(Cl + t-CF₃CH=CHCl) = (5.22 ± 0.72)E-11 cm³/molecule/s, k(OH + t-CF₃CH=CHCl) = (4.40 ± 0.38)×10E-13 cm³/molecule/s and k(O3 + t-CF₃CH CHCl) = (1.46 ± 0.12)E-21 cm³/molecule/s, were established (quoted uncertainties are 2σ). The IR spectrum of t-CF₃CH=CHCl is reported. The atmospheric lifetime of t-CF₃CH=CHCl is determined by reaction with OH radicals and is approximately 26 days. The global warming potential of t-CF₃CH=CHCl is approximately 7 for a 100-year time horizon.

Description of key information

Based on estimation with the QSAR model AOPWIN (v1.93), the substance using its SMILES notation FC(F)(F)C=CCl undergoes in air rapid degradation after reaction with hydroxyl radicals (ozone could not be estimated). The DT50 values after reaction with hydroxyl radicals are 1.782 days for the cis-isomer and 1.571 days for the trans-isomer (based on a 24-hour time frame and 0.5E+06 OH radicals/cm3, default settings in AOPWIN). The DT50 values after reaction with ozone are 91.6 days for the cis-isomer and 45.8 days for the trans-isomer (at 7E+11 mol/cm3). The half-lives in the air are not used in the risk characterisation because it is not an experimental value.

A publication from Andersen et al., (2008) supports the rapid phototransformation in the air. The study shows that the atmospheric lifetime of t-CF3CH CHCl is approximately 26 days. The degradation rate constant with OH-radicals is 4.4E-13 cm3/molecule/s.

Additional information

Publication results (Andersen et al. 2008)

Long path length Fourier transform infrared (FTIR)–smog chamber techniques were used to study the kinetics of the gas-phase reactions of Cl atoms, OH radicals and O₃ with trans-3,3,3-trifluoro-1-chloropropene, t-CF₃CH=CHCl, in 700 Torr total pressure at 295 ± 2 K. Values of k(Cl + t-CF₃CH=CHCl) = (5.22 ± 0.72)E-11 cm³/molecule/s, k(OH + t-CF₃CH=CHCl) = (4.40 ± 0.38)E-13 cm³/molecule/s and k(O3 + t-CF₃CH CHCl) = (1.46 ± 0.12)E-21 cm³/molecule/s, were established (quoted uncertainties are 2σ). The IR spectrum of t-CF₃CH=CHCl is reported. The atmospheric lifetime of t-CF₃CH=CHCl is determined by reaction with OH radicals and is approximately 26 days. The global warming potential of t-CF₃CH=CHCl is approximately 7 for a 100-year time horizon.