Registration Dossier
Registration Dossier
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EC number: 203-571-6 | CAS number: 108-31-6
Phototransformation in air
Administrative data
Link to relevant study record(s)
- Endpoint:
- phototransformation in air
- Type of information:
- calculation (if not (Q)SAR)
- Remarks:
- Estimated by calculation
- Adequacy of study:
- key study
- Study period:
- no data
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- accepted calculation method
- Qualifier:
- no guideline available
- Principles of method if other than guideline:
- Calculated using structure-reactivity relationships and linear free-energy relationships.
- GLP compliance:
- no
- Estimation method (if used):
- PHOTOCHEMICAL REACTION WITH OH RADICALS
- Concentration of OH radicals: 1,000,000 molecule/cm³
- Degradation rate constant: 4.6E-11 cm³/(molecule*sec) - DT50:
- 8.5 h
- Test condition:
- OH concentration = 500000 molecules/cm³, rate constant = 4.6E-11 cm³/molecule*s
- Validity criteria fulfilled:
- not applicable
- Conclusions:
- Half life: 8.5 hours
- Executive summary:
A calculation assuming a sensitizer-concentration (OH-radical) of 1,000,000 molecules/cm³ and a rate constant of 4.3E-11 cm³/molecule*sec predicted a half-life in the atmosphere of 4.5 hours (Grosjean and Williams, 1991, cited in OECD SIDS 2004). Taking into account a regular OH concentration of 500,000 molecules/cm³ the half-life increases to 8.5 hours.
Reference
Developed structure-reactivity relationships between reaction rate constant and ionization potential for classes of compounds.
Reaction products expected were CO, CO2,and dicarbonyls, which undergo further rapid reaction.
Description of key information
After evaporation or exposure to the air, the substance will be rapidly degraded by photochemical processes.
Key value for chemical safety assessment
Additional information
A calculation assuming a sensitizer-concentration (OH-radical) of 1,000,000 molecules/cm³ and a rate constant of 4.3E-11 cm³/molecule*sec predicted a half-life in the atmosphere of 4.5 hours (Grosjean and Williams, 1991, cited in OECD SIDS 2004). Taking into account a regular OH concentration of 500,000 molecules/cm³ the half-life increases to 8.5 hours. Nevertheless, photodegradation is not supposed to be an important fate path in the atmosphere as the substance would hydrolyse rapidly with the atmospheric water forming maleic acid.
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