Registration Dossier
Registration Dossier
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EC number: 201-143-3 | CAS number: 78-79-5
Phototransformation in air
Administrative data
Link to relevant study record(s)
Description of key information
The atmospheric photo-oxidation half-life of 3.8 hours by reaction with hydroxyl radicals has been reported.
Key value for chemical safety assessment
- Half-life in air:
- 3.8 h
- Degradation rate constant with OH radicals:
- 0 cm³ molecule-1 s-1
Additional information
Isoprene is volatile and, if released to the environment, has the potential to partition to the atmosphere to a significant extent. In the air, the dominant degradation process would be photo-oxidation with hydroxyl radicals. Isoprene has been shown to react with hydroxyl radicals in the vapour phase and can be rapidly degraded in the air by this process.
The estimated half-life of isoprene in air is based on a recommended reaction rate with hydroxyl radicals (Atkinson 1989) and the concentration of hydroxyl radicals recommended in the Technical Guidance Document (2003). Measured data from the author and other investigators were quality assessed and then used to develop rate constants for different chemicals. The result therefore represents a valid rate constant for isoprene based on all the valid studies at the time of publication.
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