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Vapour pressure

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Reference
Endpoint:
vapour pressure
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
2013
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
1. SOFTWARE
Individual model MPBPWIN included in the Estimation Programs Interface (EPI) Suite.

2. MODEL (incl. version number)
MPBPWIN v1.43 included in EPISuite v 4.11, 2000 - 2012
The modified Grain method/ Mackay method

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
a. Input for prediction: A SMILES notation was entered in the initial data entry screen. In the structure window, the molecular weight, structural formula and the structure of the input SMILES notation is shown. If available, experimental determined values of melting point and boiling point are taken for input.
b. Descriptor values: As the substance is a liquid, the model uses only the boiling point for estimation:
The following parameters were applied:
The boiling point was experimentally determined to be > 300°C at 1013 hPa (BTS, 2012). This value was not used for the calculation of the vapour pressure as this would lead to an unrealistic result and the vapour pressure would be overestimated to a large extent. As a conclusion the boiling point was calculated instead.
- Boiling point: 539.75 °C at 1013 hPa (calculated by MPBPWIN)

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
a. Defined endpoint: Vapour pressure
b. Unambigous algorithm: The modified Grain method equation was used for calculation.
c. Applicability domain: With a molecular weight of 706.15 g/mol the substance is within the applicable range of 16 - 943 g/mol. Regarding the structure, the fragment descriptors used by the program for the estimation of the boiling point are complete and listed in Appendix F of the MPBPWIN help file.
d. Statistical characteristics : Correlation coefficient of the total test set is r2= 0.949.
e. Mechanistic interpretation : The vapour pressure is related to fugacity models describing the distribution of the substance in the environment.
f. The uncertainty of the prediction (OECD principle 4):
Bis(2-ethylhexyl) tetrabromophthalate is not highly complex and the rules applied for the substance appear appropriate. An individual uncertainty for the investigated substance is not available.

5. APPLICABILITY DOMAIN
a.Domains:
i. Molecular weight: With a molecular weight of 706.15 g/mol the Bis(2-ethylhexyl) tetrabromophthalate is within the range of the training set (16 -– 943 g/mol).
ii. Structural fragment domain: Regarding the structure, the fragment descriptors used by the program for the estimation of the boiling point are complete and listed in Appendix F of the MPBPWIN help file.
iii. Mechanism domain: No information available
iv. Metabolic domain, if relevant: not relevant
b. Structural analogues: No information available
c. Considerations on structural analogues: No information available

6. ADEQUACY OF THE RESULT
a. Regulatory purpose: The data may be used under any regulatory purpose.
b. Approach for regulatory interpretation of the model result: If no experimental data are available the estimated value may be used to fill data gaps needed for hazard and risk assessment. Further the value is used for other calculations.
c. Outcome: The prediction of vapour pressure yields a useful result for further evaluation.
d. Adequacy of prediction: The result for Bis(2-ethylhexyl) tetrabromophthalate falls within the applicability domain described above and the estimation rules applied for the substance appears appropriate. Therefore the predicted value can be considered reliable yielding a useful result for further assessment.
e. Conclusion: The result is considered as useful for regulatory purposes.
Guideline:
other: REACH guidance on QSARs R.6, May 2008
Principles of method if other than guideline:
The Estimation Program Interface (EPI) Suite v4.11 includes the model MPBPWIN for estimating the vapour pressure of organic compounds. The Estimation Programs Interface was developed by the US Environmental Agency's Office of Pollution Prevention and Toxics and Syracuse Research Corporation (SRC). © 2000 - 2012 U.S. Environmental Protection Agency for EPI SuiteTM. Published online in November 2012.
GLP compliance:
no
Type of method:
other: QSAR
Specific details on test material used for the study:
related to the pure substance
SMILES: O=C(OCC(CCCC)CC)c(c(c(c(c1Br)Br)Br)C(=O)OCC(CCCC)CC)c1Br
use descriptors applied in the model:
melting point: (not used for liquids)
boiling point: 539.75°C at 1013 hPa (calculated by EPI-Suite)
Temp.:
25 °C
Vapour pressure:
0 Pa
Remarks on result:
other: modified Grain method

Validity of the model:

1. Defined Endpoint: Vapour pressure

2. Unambigous algorithm: The modified Grain method equation was used for calculation.

3. Applicability domain: For the substance the applicablity domain is just described by the molecular weight range. With a molecular weight of 706.15 g/mole the substance is within the range of the training set (16 - 943 g/mole).

4. Statistical characteristics: Correlation coefficient of the total test set is r2= 0.949.

5. Mechanistic interpretation: The vapour pressure is related to fugacity models describing the distribution of the substance in the environment.

Adequacy of prediction: The result for bis(2-ethylhexyl) tetrabromophthalate falls within the applicability domain described above and the estimation rules applied for the substance appear appropriate. There is no individual uncertainty of the prediction available. Therefore the predicted value can be considered reliable yielding a useful result for further assessment.

Descriptor value:

As bis(2-ethylhexyl) tetrabromophthalate is a liquid, the model uses only the boiling point for estimation.

The boiling point was experimentally determined to be > 300°C at 1013 hPa (BTS, 2012). This value was not used for the calculation of the vapour pressure as this would lead to an unrealistic result and the vapour pressure would be overestimated to a large extent. As a conclusion the boiling point was calculated instead.

The following parameters were applied:

Boiling point: 539.75°C at 1013 hPa (calculated by MPBPWIN v1.43)

Structural fragment domain:

Regarding the structure, the fragment descriptors used by the program for the estimation of the boiling point are complete and listed in Appendix F of the MPBPWIN help file.

Conclusions:
The QSAR determination of the vapour pressure of the substance using the model MPBPWIN included in the Estimation Program Interface (EPI) Suite v4.11 revealed a value of 3.56E-7 Pa at 25°C. The predicted value can be considered reliable yielding a useful result for further assessment.
Executive summary:

The vapour pressure of the substance was predicted using the QSAR calculation of the Estimation Program Interface EPI-Suite v4.11. The calculated boiling point of 539.75°C (at 1013 hPa) was taken into account for estimation. Using the modified Grain method , the vapour pressure was estimated to be 3.56E-7 Pa at 25°C. The predicted value can be considered reliable yielding a useful result for further assessment.

Description of key information

The QSAR determination of the vapour pressure of the substance using the model MPBPWIN included in the Estimation Program Interface (EPI) Suite v4.11 revealed a value of 3.56E-7 Pa at 25°C. The predicted value can be considered reliable yielding a useful result for further assessment.

Key value for chemical safety assessment

Vapour pressure:
0 Pa
at the temperature of:
25 °C

Additional information

The vapour pressure of the substance was predicted using the QSAR calculation of the Estimation Program Interface EPI-Suite v4.11. The calculated boiling point of 539.75°C (at 1013 hPa) was taken into account for estimation using the modified Grain method.