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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:
2011
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a (Q)SAR model, with limited documentation / justification, but validity of model and reliability of prediction considered adequate based on a generally acknowledged source
Justification for type of information:
US EPA. [2011]. Estimation Programs Interface Suite™ for Microsoft® Windows, v 4.11 or insert version used]. United States Environmental Protection Agency, Washington, DC, USA. From
MPBPVP (v1.43)
Calculations done with structures having different branching (number of terminal CH3), possible constituents of the substance.
See report.
Qualifier:
according to
Guideline:
other: QSAR calculation
Principles of method if other than guideline:
Vapor Pressure is estimated by three methods; all three methods use the boiling point.  The first is the Antoine method (see Chapter 14 of W.J. Lyman's book "Handbook of Chemical Property Estimation Methods", Washington, DC: American Chemical Society, 1990).  The second is the modified Grain method (see page 31 of Neely and Blau's Environmental Exposure from Chemicals, Volume I, CRC Press, 1985).  The third is the Mackay method (see page 31-2 of Neely and Blau's Environmental Exposure from Chemicals, Volume I, CRC Press, 1985).
GLP compliance:
not specified
Type of method:
other: QSAR
Temp.:
25 °C
Vapour pressure:
0.021 Pa
Remarks on result:
other: C12 (main fraction)
Temp.:
25 °C
Vapour pressure:
>= 0.041 - <= 0.066 Pa
Remarks on result:
other: all components BAB

Vp estimation of C12 constituents of BAB: 0.21-1.1 RANGE FROM ESTIMATES in C12

Measured values of linear alkylbenzenes vs estimated values

C9: 0.761 VS estimé 0.65-1.34

C10: 0.171 VS estimé 0.23-0.55

C11: 0.0323 VS estimé 0.075-0.21

C12: 0.00681 VS estimé 0.035-0.113

C13: 0.00169 vs estimé 0.011-0.043

Therefore in C12 the mean VP (from minimal and maximal estimates) is overestimated 11-fold

Corrected range: 0.041-0.066 Pa

Conclusions:
Modeling data indicate that the vapor pressure of the main constituents C12 branched is in the range of 0.041-0.066 Pa.
The value range of 0.041-0.066 Pa determines that the substance is of low volatility.
Executive summary:

The vapour pressure of C12 components of branched alkylbenzenes (BAB) was estimated with EPIWIN. The estimated values of vapour pressure for components of linear alkylbenzenes were also estimated with EPIWIN and compared to available experimental values. Based on the results it was concluded that for C12 of branched alkylbenzene the mean VP (from minimal and maximal estimates) is overestimated 11-fold and it was corrected from calculated range 0.21 -1.1 Pa to 0.041 -0.066 Pa.

Description of key information

The value of vapour pressure has been obtained using US EPA’s EPIsuite v4.10 QSAR estimates, corrected by QSAR/experimental bias based on LAB data. To have a better approach of the product structure a group of structures has been introduced and the estimate range of vapour pressure 0.041 to 0.066 Pa at 25°C is the value used for CSR/CSA.

Key value for chemical safety assessment

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

Additional information