Registration Dossier
Registration Dossier
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EC number: 206-114-9 | CAS number: 302-01-2
Phototransformation in air
Administrative data
Link to relevant study record(s)
- Endpoint:
- phototransformation in air
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Basic data are given.
- Principles of method if other than guideline:
- The OH concentration was monitored as a function of time comparing the behaviour in the absence and presence of the test substance
- GLP compliance:
- not specified
- Details on test conditions:
- Sensitiser (for indirect photolysis): OH
Sensitiser concentration: smaller or equal than 1*E11 molecule/cm³ - DT50:
- 6.3 h
- Test condition:
- OH concentration of 500000 molecules/cm³; rate constant 6.1 E-11 cm³/(molecule * s) (T= 298 - 424 K)
- Executive summary:
Hydrazine is rapidly degraded under the presence of hydroxyl radicals yielding a temperature independent rate constante of 6.1 E-11 cm³/(molecule * s) (T= 298 - 424 K) (Pitts et al., 1980). Based on these results an atmospheric half life of 6.3 h can be calculated assuming an OH concentration of 500000 molecules/cm³.
Reference
- rate constants at different temperatures were reported as well:
298 K: 6.5*E11 cm³/(molecule * s)
355 K: 5.9*E11 cm³/(molecule * s)
424 K: 5.8*E11 cm³/(molecule * s)
Description of key information
Hydrazine is rapidly degraded under the presence of hydroxyl radicals yielding a temperature independent rate constant of 6.1 E-11 cm³/(molecule * s) (T= 298 - 424 K) (Pitts et al., 1980). An atmospheric half life of 6.3 h can be calculated based on the derived rate constant and an assumed OH concentration of 500000 molecules/cm³ indicating only a limited potential for a long range atmospheric transport.
Key value for chemical safety assessment
- Half-life in air:
- 6.3 h
- Degradation rate constant with OH radicals:
- 0 cm³ molecule-1 s-1
Additional information
According to the guidance document R.11 (ECHA, 2008, p19), substances with an atmospheric half-life < 2 days are not expected to stay in the atmosphere for long as they will degrade rapidly. Concludingly, there will be a limited potential for long range atmospheric transport when discussing the behaviour of hydrazine.
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