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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:
2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Detailed report, by using the ASTM E1782-03 method
Reason / purpose for cross-reference:
reference to same study
Qualifier:
according to guideline
Guideline:
EU Method A.4 (Vapour Pressure)
Deviations:
no
GLP compliance:
no
Type of method:
other: ASTM E1782-03, DSC (differential scanning calorimetry)
Key result
Temp.:
20 °C
Vapour pressure:
0.008 Pa
Key result
Temp.:
25 °C
Vapour pressure:
0.019 Pa

The experimental data obtained, with about 4 mg used in the SS test cell with a pierced lid, are listed below.

 

Measured Temperature °C

Pressure mbars

Pressure-corrected temperature °C

106.18

4

101.62

109.97

7

107.13

Starting of decomposition observed, with endotherm

10

Starting of decomposition observed, with endotherm

 

The Clausius-Clapeyron equation resulting is:

y = 14456x + 33.053 (correlation coefficient R2= 1)

Extrapolated data – with high uncertainty- at 20°C and 25°C are :

-Pressure vapour at 20°C is determined to 8.1 10 -5mbars ;

-Pressure vapour at 25°C is determined to 1.9 10 -4mbars.

Conclusions:
The vapour pressure of the substance is determined to be close to 0.019Pa at 25°C .
With DSC method, the impurities more volatile than the substance are evaporated, and thus, will not affect the vapour pressure determination.
Executive summary:

A detailed study report on the measurement of vapour pressures according to ASTM E-1782 -03 is available. The relationship between vapour pressure and temperature was established with the Clausius-Clapeyron equation.

With this method, the volatile impurities do not have an effect on the vapour pressure determination

The vapour pressure of the substance is determined to be close to 1.9 10-4mbars, or 0.019Pa, at 25°C .

Description of key information

The vapour pressure of tert-amyl peroxy-2-ethylhexanoate is determined to be 0.019 Pa at 25°C, determinded by DSC (in order to limit the effect of volatile impurities on the vapour pressure determination)

Key value for chemical safety assessment

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

Additional information

Well detailed studies are available.

The vapour pressure was firstly determined with static method. The vapour pressure was determined to be 10.5hPa at 25°C, but the presence of a volatile impurity (tert-amyl hydroperoxide, vapour pressure of 43.2hPa) may have affected the vapour pressure determination (small amounts of volatile impurities may increase the vapour pressure by several orders of magnitude).

The DSC method was then used, and the vapour pressure was determined to be 0.019 Pa (more representative of the substance as impurities more volatile than the substance are evaporated).

In both methods, the relationship between vapour pressure and temperature was fitted with the Clausius-Clapeyron equation.