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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:
2014
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Justification for type of information:
QSAR prediction
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
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: Because an experimental melting point is available for 6.6`-Di-tert.-butyl-2.2`-methylenedi-p-cresol the applicablity domain is just described by the molecular weight range. With a molecular weight of 340.51 g/mole the substance is within the applicable range of 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 6,6'-di-tert-butyl-2,2'-methylenedi-p-cresol 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.

Conclusions:
The QSAR determination of the vapour pressure of 6,6'-di-tert-butyl-2,2'-methylenedi-p-cresol using the model MPBPWIN included in the Estimation Program Interface (EPI) Suite v4.11 revealed a value of 3.3E-007 Pa at 25 °C. The predicted value can be considered reliable yielding a useful result for further assessment.
Executive summary:

The vapour pressure of 6,6'-di-tert-butyl-2,2'-methylenedi-p-cresol was predicted using the QSAR calculation of the Estimation Programm Interface EPI-Suite v4.11. The experimental melting point of 123 °C was taken into account for estimation. Using the modified Grain method, the vapour pressure was estimated to be 3.3E-007 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 6,6'-di-tert-butyl-2,2'-methylenedi-p-cresol using the model MPBPWIN included in the Estimation Program Interface (EPI) Suite v4.11 revealed a value of 3.3E-007 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

Weight-of-evidence:

Five data sources (SFOS, SIDS, EPIWIN, ChemIDplus, PBT-report) were used for the weight-of-evidence approach. Since measured values are only available for elevated temperatures (SFOS: 0.2 mm Hg, corresponding to 26.6 Pa, at 150 °C, and 0.4 mm Hg, corresponding to 53.33 Pa, at 175 °C) or provide an imprecise result for a relevant temperature (SIDS: <10 Pa at 20 °C), the derivation of a vapour pressure value for the CSA was done on the basis of QSARs. The calculated values range from 4.7 x 10-11 Pa (SIDS) via 3.3 x 10-7 Pa (EPIWIN and ChemIDplus) to 4.6 x 10-7 Pa (PBT-report). The latter value was selected as worst case (highest calculated vapour pressure) for the CSA.