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EC number: 210-519-6 | CAS number: 617-52-7
Phototransformation in air
Administrative data
Link to relevant study record(s)
Description of key information
Rapid atmospheric depletion (QSPR estimation)
Key value for chemical safety assessment
- Half-life in air:
- 6.858 h
- Degradation rate constant with OH radicals:
- 1.617 m³ molecule-1 d-1
Additional information
Experimental data on phototransformation in air are not available for the submission item. As this endpoint is not a standard information requirement in REACH and there is no indication from the Chemical Safety Assessment on the need to investigate further the fate and behaviour of the substance (Annex X, 9.3.4. requirement), no testing is considered necessary.
Direct photolysis
Due to the spectral properties of the submission item, i.e. the absorption at 210 nm within the spectral range of natural daylight (ca. 200 to 2500 mn), direct photodegradation is assumed a relevant degradation pathway in the stratosphere at about 10 to 50 km altitude.
Indirect photolysis
The Atmospheric Oxidation Program for Microsoft Windows (AOPWIN) estimates the rate constant for the atmospheric, gas-phase reaction between photochemically produced hydroxyl radicals and organic chemicals. It also estimates the rate constant for the gas-phase reaction between ozone and olefinic/acetylenic compounds. The rate constants estimated by the program are then used to calculate atmospheric half-lifes for organic compounds based upon average atmospheric concentrations of hydroxyl radicals and ozone.
Hydroxyl radicals
Using AOPWIN v1.92 from the U.S. EPI-Suite (version 4.10) software, input: SMILES O=C(OC)CC(=C)C(=O)OC, the 25 °C overall OH∙ Rate constant was estimated to be 18.7147 E-12 cm³/(molecule · s) = 1.61695 m³/(molecule · d) and the half-life t½ to be 0.572 days (12-h day; 1.5 E6 OH∙/cm³) or 6.858 h. The submission item is therefore expected to undergo hydroxylation by OH∙ radicals in the troposphere up ca. 17 km altitude.
Ozonisation
The Ozone Rate constant was with the same tool estimated to be 1.137500 E-17 cm³/(molecule · s) = 0.0000009828 m³/(molecule · d) and the half-life to be 1.007 days or 24.2 hours (ozone concentration 7 E11 mol/cm³). In the ozonosphere, a layer in the stratosphere at approximately 20 to 30 km altitude, the submission item will be subject to relevant ozonisation.
Overall conclusion
In result rapid depletion of any atmospheric submission item is expected.
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