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Physical & Chemical properties

Vapour pressure

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Reference
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Study period:
14 JAN 2002 - 21 MAR 2002
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose:
reference to same study
Reason / purpose:
reference to same study
Qualifier:
according to
Guideline:
EU Method A.4 (Vapour Pressure)
Version / remarks:
Guideline 92/69/EEC, 1992
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
other: dynamic mehtod and effusion method (vapour pressure balance)
Temp.:
25 °C
Vapour pressure:
0.24 hPa

Dynamic method

The vapour pressure was measured in the temperature range of 91 °C to 210 °C.

 Temperature [°C]  Vapour pressure [hPa]

90.9

15.0
106.0 29.9
119.0 49.8

129.6

74.8
137.4 100.1 
163.9 250.5
185.6 500.2
201.0 750.2
209.5 899.7
170.3 300.2
 149.6 150.4 

The attached background material give the logarithm of vapour pressure of the dynamic method as a function of the inverse temperature (1/T, T in Kelvin). Only for better readability the temperature is reported in a centigrade scale.

Vapour pressure balance (effusion method)

To check the vapour pressure in the temperature range 20 - 50 °C an additional measurement with the vapour pressure balance was carried out.

Due to the relatively high vapour pressure for this method it was only possible to measure a few data points. At lower temperature the shutter and the orifice was blocked by stiffed test substance (freezing point: 268.5 K) due to the high vapour pressure. At higher temperature the test substance evaporated to quickly, so that the test substance was nearly totally evaporated. When the apparatus was opened at the end of the measurement the test substance totally disappeared. Due to this only two reliable measurement had been possible. The following table shows the measured pressure data at the corresponding temperatures:

 Temperature [°C]  Vapour pressure [hPa]

17.5

1.6 x 10 -1
19.5 1.3 x 10 -1

The attached background material give the logarithm of vapour pressure of the dynamic method and the vapour pressure balance as a function of the inverse temperature (1/T, T in Kelvin). Only for better readability the temperature is reported in a centigrade scale. The values for 20, 25 and 50 °C are calculated, using the Antoine constants A, B and C as shown.

A comparison of the results of the dynamic method with those of the combination of dynamic method and vapour pressure balance shows a good coincidence for the temperature range

20 - 50 °C. The vapour pressure values for 20, 25 and 50 °C calculated from the dynamic method are slightly higher compared to those calculated from the combination of dynamic method and vapour pressure balance. This means, the dynamic method would have been a conservative calculation.

In this case the vapour pressure values for 20, 25 and 50 °C calculated from the combination of dynamic method and vapour pressure balance are used as final results.

Conclusions:
The calculated vapour pressure of the test substance was 0.24 hPa at 25°C.
Executive summary:

The vapour pressure of the sample was tested according to EU Method A.4 and OECD Guideline 104 in a GLP study with the dynamic method and the effusion method.

The calculated vapour pressure values are extrapolated:

p (20 °C) = 1.6 x 10 -1 hPa

p (25 °C) = 2.4 x 10 -1 hPa

p (50 °C) = 1.5 x 100 hPa

Description of key information

The vapour pressure of the sample was tested according to EU Method A.4 and OECD Guideline 104 in a GLP study with the dynamic method and the effusion method.

The calculated vapour pressure values are extrapolated:

p (20 °C) = 1.6 x 10-1hPa

p (25 °C) = 2.4 x 10-1hPa

p (50 °C) = 1.5 x 100hPa

Key value for chemical safety assessment

Vapour pressure:
0.24 hPa
at the temperature of:
25 °C

Additional information

The values for 20, 25 and 50 °C are calculated, using the Antoine constants.