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Vapour pressure

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Reference
Endpoint:
vapour pressure
Type of information:
(Q)SAR
Adequacy of study:
key study
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. The software used: see attached QMRF
2. The model(s) used: see attached QPRF

1. SOFTWARE
MPBPVPWIN v1.43 QSAR for vapour pressure in Pa at 25°C Dr. Robert
Boethling, U.S. Environmental Protection Agency, 1200 Pennsylvania Ave.,
N.W. (Mail Code 7406M) Washington, DC 20460, USA, Phone: # (202) 564-
8 5 3 3 , e - m a i l : b o e t h l i n g . b o b @ e p a . g o v
h t t p : / / w w w . e p a . g o v / o p p t i n t r / e x p o s u r e / p u b s / e p i s u i t e . h t m

2. MODEL (incl. version number)
Model or submodel name: MPBPVPWIN
Model version: Version 1.43
Reference to QMRF: QSAR for vapour pressure in Pa at 25ºC
Reason / purpose for cross-reference:
reference to same study
Qualifier:
according to guideline
Guideline:
other: REACH Guidance on QSARs R.6
Deviations:
not applicable
Principles of method if other than guideline:
Modified Grain method (Chapter 2, Lyman 1985) is one of the methods available in MPBPVPWIN’s methodology. According to this method, liquid VP is calculated based on normal boiling point (BP), temperature and structural factors (Chapter 14, Lyman et al., 1990) as inputs. For solids a second term is calculated and added to the liquid VP by using melting point (MP) to estimate solid VP. The input BP and MP can be both measured or estimated within MPBPVPWIN (based on atom/fragment contribution method). For more information and references mentioned we refer to the Help file of MPVPBPWIN.
GLP compliance:
no
Type of method:
other: Calculation by estimation / QSAR
Key result
Temp.:
25 °C
Vapour pressure:
0.015 Pa
Remarks on result:
other: Initial vapour pressure

MPBPVPWIN v1.43 model details

Reference to the type of model used

This program (MPBPVPWIN) estimates the boiling point (at 760 mm Hg), melting point and vapor pressure of organic compounds. MPBPVPWIN requires only a chemical structure to make these predictions. MPBPVPWIN estimates vapour pressure (VP) using the estimated boiling point.

 

Description of the applicability domain

Currently there is no universally accepted definition of model domain. However, users may wish to consider the possibility that property estimates are less accurate for compounds outside the

Molecular Weight range of the training set compounds, and/or that have more instances of a given fragment than the maximum for all training set compounds. It is also possible that a compound may have a functional group(s) or other structural features not represented in the training set, and for which no fragment coefficient was developed. These points should be taken into consideration when interpreting model results.

 

Training Set Molecular Weights:

Minimum MW: 16.04

Maximum MW: 943.17

Average MW: 194.22

Description and results of any possible structural analogues of the substance to assess reliability of the prediction

Internal validation with a dataset containing 3037 substances resulted in a correlation coefficient (r2) of 0.914, a standard deviation of 1.057 and an average deviation of 0.644.

Predictivity assessment of the internal validation set:

Validation Set Estimation Error:

within <= 0.10 - 34.1%

within <= 0.20 - 45.6%

within <= 0.40 - 60.0%

within <= 0.50 - 64.9%

within <= 0.60 - 69.0%

within <= 0.80 - 75.0%

within <= 1.00 - 80.0%

Uncertainty of the prediction

All constituents for which estimations were made fall within the applicability domain of the model.

Mechanistic domain

This program (MPBPVPWIN) estimates the boiling point (at 760 mm Hg), melting point and vapour pressure of organic compounds. MPBPVPWIN requires only a chemical structure to make these predictions. MPBPVPWIN estimates vapor pressure (VP) by three separate methods:

(1) the Antoine method,

(2) the modified Grain method, and

(3) the Mackay method.

 

All three use the normal boiling point to estimate VP. Unless the user enters a boiling point on the data entry screen, MPBPVPWIN uses the estimated boiling point from the adapted Stein and Brown method (For more information see: Stein, S.E. and Brown, R.L.   1994.   Estimation of normal boiling points from group contributions. J. Chem. Inf. Comput. Sci. 34: 581-7). MPBPVPWIN reports the VP estimate from all three methods. It then reports a "suggested" VP. For liquids and gases, the suggested VP is the average of the Antoine and the modified Grain estimates. The Mackay method is not used in the suggested VP because its application is currently limited to its derivation classes.

Conclusions:
The vapour pressure of Ketjenflex 8 (NETSA [N-ethyltoluene-(o/p)-sulphonamide]) is 0.015 Pa at 25°C.
Executive summary:

The vapour pressure of Ketjenflex 8 (NETSA [N-ethyltoluene-(o/p)-sulphonamide]) was estimated by calculation and found to be 0.015 Pa at 25ºC.

Description of key information

The vapour pressure of Ketjenflex 8 (NETSA [N-ethyltoluene-(o/p)-sulphonamide]) was estimated by calculation and found to be 0.015 Pa at 25ºC.

Key value for chemical safety assessment

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

Additional information