Registration Dossier
Registration Dossier
Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.
The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.
Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.
EC number: 203-692-4 | CAS number: 109-66-0
Phototransformation in air
Administrative data
Link to relevant study record(s)
- Endpoint:
- phototransformation in air
- Type of information:
- read-across from supporting substance (structural analogue or surrogate)
- Remarks:
- Migrated phrase: estimated by calculation
- Adequacy of study:
- key study
- Study period:
- Up to 1985
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Non-GLP, non guideline study. Calculated data, published in peer review paper and was calculated in accordance with the TGD.
- Justification for type of information:
- A discussion and report on the read across strategy is given as an attachment in IUCLID Section 13.
- Reason / purpose for cross-reference:
- read-across: supporting information
- Principles of method if other than guideline:
- The author used data from other investigators. This data was generated using two methods: absolute and relative constant techniques. The author then applied a least squares analysis of degradation rate constants for organic chemicals by hydroxyl radicals developed by other investigators. This calculation was in accordance with the TGD
- GLP compliance:
- not specified
- Remarks:
- Not reported
- Specific details on test material used for the study:
- Details on properties of test surrogate or analogue material (migrated information):
No data reported - Estimation method (if used):
- Endpoint was calculated based on a rate constant of 3.5 E -12 and-OH radical concentration of 5 E5 molecules/cm3
- Details on light source:
- No data reported
- Details on test conditions:
- No data reported
- Preliminary study:
- No data reported
- Test performance:
- No data reported
- DT50:
- 2.3 d
- Results with reference substance:
- No data reported
- Conclusions:
- The dissipation half-life of 2-methylbutane was calculated as 2.3 days
- Executive summary:
Measured data from author and other investigators were quality assessed and then used to develop rate constants for different chemicals. Therefore, this value represents a valid rate constant for 2 -methylbutane based on all valid studies at the time of publication. The half life of 2 -methylbutane is 2.3 days.
- Endpoint:
- phototransformation in air
- Type of information:
- calculation (if not (Q)SAR)
- Remarks:
- Migrated phrase: estimated by calculation
- Adequacy of study:
- key study
- Study period:
- Up to 1985
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Non-GLP, non guideline study. Data calculated in accordance with TGD guideline. Study published in peer review literature.
- Principles of method if other than guideline:
- The author applied a least squares analysis of degradation rate constants for organic chemicals by hydroxyl radicals developed by other investigators.
- GLP compliance:
- not specified
- Remarks:
- No data reported
- Specific details on test material used for the study:
- Details on properties of test surrogate or analogue material (migrated information):
No data reported - Estimation method (if used):
- Calculated half life based on -OH radical concentration of 5 E5 molecules/cm3 as specified in the TGD
- Light source:
- not specified
- Details on light source:
- No data reported
- Details on test conditions:
- No data reported
- Preliminary study:
- No data reported
- Test performance:
- No data reported
- DT50:
- 3.95 d
- Test condition:
- No data reported
- Results with reference substance:
- No data reported
- Conclusions:
- The atmospheric half-life of n-pentane is estimated to be 3.95 days.
- Executive summary:
Measured data from author and other investigators were quality assessed and then used to develop rate constants for different chemicals. Therefore, this value represents a valid rate constant for n-pentane based on all valid studies at the time of publication. The half life of n-pentane is 3.95 days.
Referenceopen allclose all
Based on a calculated rate constant of 7.38E-12 cm3 molecule-1sec-1, and a hydroxyl radical concentration of 5E5 molecule.cm-3
The rate constant of the reaction between n-pentane and OH-radicals has been measured by several researchers. The result of the experiments have been reported and reviewed by Atkinson (1985). The reported values are between 3.5 and 5.3.10-12 cm3/(molecule.sec) at 300K (27C). On the basis of the review of available data Atkinson recommends a rate of 4.06.10-12 cm3/ (molecule.sec). The latter value has been used in the risk assessment. Taking into account the OH-radical concentration as given in the TGD of 5.105 molecules/cm3, atmospheric half-life of n-pentane is estimated to 3.95 days.
Description of key information
There is data available for this substance. Additionally, key data is available for the structural analogue 2 -methylbutane and is presented in the dossier. The data is read across to this substance based on analogue read across and a discussion and report on the read across strategy is provided as an attachment inIUCLID Section 13.
The dissipation half-life of 2-methylbutane was calculated as 2.3 days. Based on a calculated rate constant of 7.38E-12 cm3 molecule-1sec-1, and a hydroxyl radical concentration of 5E5 molecule.cm-3.
The atmospheric half-life of n-pentane is estimated to be 3.95 days. The rate constant of the reaction between n-pentane and OH-radicals has been measured by several researchers. The result of the experiments have been reported and reviewed by Atkinson (1985). The reported values are between 3.5 and 5.3.10-12 cm3/(molecule.sec) at 300K (27C). On the basis of the review of available data Atkinson recommends a rate of 4.06.10-12 cm3/ (molecule.sec). The latter value has been used in the risk assessment. Taking into account the OH-radical concentration as given in the TGD of 5.105 molecules/cm3
Key value for chemical safety assessment
- Half-life in air:
- 3.95 d
- Degradation rate constant with OH radicals:
- 0 cm³ molecule-1 s-1
Additional information
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
