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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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.

Diss Factsheets

Environmental fate & pathways

Phototransformation in air

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Administrative data

Link to relevant study record(s)

Reference
Endpoint:
phototransformation in air
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
up to 2010
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: QSAR calculations, acceptable with restrictions
Justification for type of information:
QSAR prediction
Qualifier:
no guideline required
Guideline:
other: QSAR
Principles of method if other than guideline:
The estimation methods used by AOPWIN are based upon the structure-activity relationship (SAR) methods developed by Dr. Roger Atkinson and co-workers. AOPWIN incorporates updated fragment and reaction values as cited in Kwok and Atkinson (1995).
The AOPWIN version used in this study is v.193.
GLP compliance:
no
Remarks:
QSAR
Specific details on test material used for the study:
SMILES: C(C(C=CC12)C1)(C2C=C3)C3
CAS number: 77-73-6
Estimation method (if used):
Measured data from author and other investigators were quality assessed and then used to develop rate constants for different chemicals. The author applied a least squares analysis of degradation rate constants to calculate a preferred value.
Light source:
not specified
Details on light source:
Not reported
Details on test conditions:
Not reported
Reference substance:
no
Remarks:
QSAR
Preliminary study:
Not reported
Test performance:
Not reported
Key result
% Degr.:
50
Sampling time:
1.077 h
Test condition:
OH Rate Constant = 119 E-12 cm^3/molecule-sec. Half-life = 0.090 Days (12 hour day; 1.5E6 OH/cm^3)
Remarks on result:
other: Result from QSAR
Key result
% Degr.:
50
Sampling time:
41.26 min
Test condition:
Ozone Rate Constant = 40.0 E-17 cm^3/molecule-sec. Half-life = 0.029 Days (at 7E11 mol/cm^3)
Remarks on result:
other: Result from QSAR
Transformation products:
not specified
Results with reference substance:
Not reported

Author reports a recommended rate constant of 119 E-12 cm3 molecule-1sec-1. Half life is calculated based on this rate constant and a hydroxyl radical concentration of 1.5 E+6 molecule.cm-3

Overall OH rate constant = 119.1993 E-12 cm3/molecule-sec

Half-life = 0.090 days (12-h day; 1.5E6 OH/cm3)

Half-life = 1.077 h

Overall ozone rate constant = 40.000000 E-17 cm3/molecule-sec

Half-life = 0.029 days (at 7 E+11 mol/cm3)

Half-life = 41.256 min

Validity criteria fulfilled:
not applicable
Remarks:
QSAR
Conclusions:
The overall OH rate constant was calculated to be 119.1993E-12 cm^3 molecule^-1 s^-1
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 based on all valid studies at the time of publication.

The prediction is considered to fall within the model domain.

Description of key information

Atmospheric photooxidation half-life of 1.077 hours (hydroxyl radicals) has been reported.

Key value for chemical safety assessment

Half-life in air:
1.077 h

Additional information

In Atkinson (1985), 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 based on all valid studies at the time of publication. The estimated half life is 1.077 hours based on an overall OH rate constant of 119.1993 E-12 cm³ molecule-1 s-1.