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Environmental fate & pathways

Additional information on environmental fate and behaviour

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Endpoint:
additional information on environmental fate and behaviour
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Data taken from accepted publication with limited details on methods and results. This study was selected as the key study because the information provided for the hazard endpoint is sufficient for the purpose of classification and labelling and/or risk assessment.

Data source

Reference
Reference Type:
publication
Title:
Atmospheric Chemistry of (Z)-CF3CH=CHCF3: OH Radical Reaction Rate Coefficient and Global Warming Potential
Author:
Baasandorj M, Ravishankara AR, Burkholder JB
Year:
2011
Bibliographic source:
J. Phys. Chem. A, 115:10539–10549

Materials and methods

Principles of method if other than guideline:
No guideline available. Rate coefficients and atmospheric lifetime determined
GLP compliance:
not specified
Type of study / information:
In this study, rate coefficients for reaction 1, k1(T), were measured as a function of temperature (212-374 K) and pressure (20-200 Torr, He, N2) using a pulsed laser photolysis -laser induced fluorescence (PLP-LIF) technique and at 296, 345, and 375 K using a relative rate (RR) technique at pressures between 100 and 300 Torr (He). Rate coefficients for the OD reaction
OD + test item > Products
were also measured as part of this study to gain additional insight into the mechanism of reaction. A comparison of the (Z)- CF3CH = CHCF3 reactivity with that of other unsaturated fluorinated compounds is presented. The reaction of (Z)- CF3CH = CHCF3 with O3 was briefly examined and shown to represent only a minor atmospheric loss process. The radiative efficiency and global warming potential of (Z)- CF3CH = CHCF3 were calculated using its infrared absorption spectrum measured as part of this work.

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
-Purity: not reported

Results and discussion

Any other information on results incl. tables

Rate coefficients for the analogous OD radical reaction were determined over a range of temperatures (262-374 K) at 100 Torr (He) to be k2(T) = (4.81 ± 0.20) x 10-19 x T2 x exp[(776 ± 15)/T], with k2(296 K) = (5.73 ± 0.50) x 10-13 cm3molecule-1s-1. The rate coefficient has a non-Arrhenius behaviour that is well-described by the expression k1(T) = (5.73 ± 0.60) x 10-19 x T2 exp[(678 ± 10) / T] cm3molecule-1s-1where k1(296 K) was measured to be (4.91 ± 0.50) x 10-13 cm3molecule-1s-1and the uncertainties are at the 2σ level and include estimated systematic errors. A room-temperature rate coefficient for the O3+ test item reaction was measured using an absolute method with O3 in excess to be <6 x 10-21 cm3molecule-1s-1. The atmospheric lifetime of the test item due to loss by OH reaction was estimated to be20 days. Infrared absorption spectra of test item measured in this work were used to determine a test item global warming potential (GWP) of9 for the 100 year time horizon.

Applicant's summary and conclusion

Conclusions:
This study and the conclusions which are drawn from it fulfil the quality criteria (validity, reliability, repeatability).
Atmospheric lifetime of the test item due to loss by OH reaction was estimated to be∼20 days.
Global warming potential (GWP) of aprox. 9 for the 100 year time horizon.

Executive summary:

Rate coefficients, k, for the gas-phase reaction of the OH radical with the test item were measured under pseudo-first-order conditions in OH using pulsed laser photolysis (PLP) to produce OH and laser-induced fluorescence (LIF) to detect it.

Rate coefficients for the analogous OD radical reaction were determined over a range of temperatures (262-374 K) at 100 Torr (He) to be k2(T) = (4.81 ± 0.20) x 10-19 x T2 x exp[(776 ± 15)/T], with k2(296 K) = (5.73 ± 0.50) x 10-13cm3molecule-1s-1. 

The rate coefficient has a non-Arrhenius behaviour that is well-described by the expression k1(T) = (5.73 ± 0.60) x 10-19x T2 exp[(678 ± 10) / T] cm3molecule-1s-1where k1(296 K) was measured to be (4.91 ± 0.50) x 10-13cm3molecule-1s-1and the uncertainties are at the 2σ level and include estimated systematic errors.

 A room-temperature rate coefficient for the O3+ test item reaction was measured using an absolute method with O3in excess to be <6 x 10-21cm3molecule-1s-1. The atmospheric lifetime of the test item due to loss by OH reaction was estimated to be20 days. Infrared absorption spectra of test item measured in this work were used to determine a test item global warming potential (GWP) of9 for the 100 year time horizon.