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Vapour pressure

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Reference
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
GLP compliance:
not specified
Type of method:
other: modified Watson correlation
Key result
Temp.:
ca. 298 K
Vapour pressure:
< 2.35 other: x10E-24 Pa
Remarks on result:
other: Calculation based on a boiling point of 748°C of the component of the test substance with the smallest molecular weight, which has the highest vapour pressure.

Based on the calculated boiling points for the three representative compounds in the test item and using the modified Watson correlation, the vapour pressure of the compounds were calculated as follows: Table 1: Individual vapour pressures of the representative compounds of the test item

 Compound  Vapour pressure [Pa]
 Compound I  2.35 x 10EXP-24
 Compound II  5.20 x 10EXP-26
 Compound III  1.22 x 10EXP-27
Conclusions:
Based on the modified Watson Correlation in Annex of the OECD Guideline No. 104, the vapour pressures of the test substance is smaller than
2.35x10e-24.
Executive summary:

The estimation of the vapour pressure of the test item was based on the EEC directive 92/69, Part A, Methods for the determination of physico-chemical properties, A.4 "Vapour Pressure", EEC Publication No. L383, December 1992 and the OECD Guideline No. 104, ''Vapour Pressure", adopted July 27, 1995.

The boiling point of the component with the smallest molecular weight of the test substance was calculated to be approximately 478°C using Meissner's method. The vapour pressure was estimated for the three main components based on the boiling point calculated and using the Modified Watson Correlation. For the component with the smallest biling point the vapour pressure was calculated as 2.35x10e-24 Pa. Therefore, the vapour pressure of the test substance is smaller than 2.35x10e-24 Pa.

Description of key information

Vapour pressure: < 2.35 x 10EXP-24 Pa (calculated based on modified Watson Correlation in annex of the OECD 104)

Key value for chemical safety assessment

Additional information

Since the vapour pressure of the test item was expected to be so small that the value would be below the measurement limit of any experimental determination, e.g.the gas saturation method, the vapour pressure had to be calculated using the modified Watson correlation. This method is described by Lyman et al. (1990).

The boiling point of the component with the smallest molecular weight of the test substance was calculated to be approximately 478°C using Meissner's method. The vapour pressure was estimated for the three main components based on the boiling point calculated and using the Modified Watson Correlation. For the component with the smallest boiling point the vapour pressure was calculated to be 2.35x10EXP-24 Pa. For the components with higher molecular weights, the respective vapour pressure calculated were even smaller.