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Vapour pressure

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Reference
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Study period:
January 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Well conducted study under Internal management system , according to ASTM E1782-08, certificate of analysis included in the report.
Qualifier:
according to
Guideline:
other: ASTM E1782-08, Standard test method for determining vapour pressure by Thermal Analysis, 2008
Deviations:
no
Principles of method if other than guideline:
This test method is not included into EC Regulation 761/2009, Guideline A.4 Vapour pressure, nor into OECD Guideline 104 Vapour pressure. Nevertheless, this method was taken, because for substances which are thermally unstable it is a more suitable method than the other methods listed in the above-mentioned guidelines. Next to that this method is also more suitable for substances containing small amounts of volatile impurities, since with this method these volatiles are effectively removed during the measurements and they will not contribute to the measured vapour pressures. This was investigated for the test substance.
It is expected that this test method will be included into EC Guideline A.4 in the near future. In 2010 a request for inclusion was sent to the Dutch National Coordinator for EC Test Methods
GLP compliance:
no
Remarks:
Internal management system
Type of method:
other: Differential Scanning Calorimetry (DSC)
Key result
Temp.:
20 °C
Vapour pressure:
15 Pa

Test substance

Eight measurements at different pressures were carried out with the test substance. The intakes, the measuredboiling temperatures and their corresponding observed pressures are listed in the table below.

 

Measurement

Intake

[mg]

Observed pressure

[kPa]

Boiling temperature

[°C]

1

13.53

0.254

46.2

2

13.37

0.452

54.2

3

13.88

0.655

60.4

4

13.04

0.988

67.3

5

14.95

1.328

70.7

6

13.72

1.990

79.6

7

13.06

1.993

79.2

8

13.71

2.660

85.2

           

The vapour pressure plot of the individual measurements is shown in figure 1 in the attachment together with the Antoine fit (regression line) of the measured data.

The estimated vapour pressure of the test substance calculated from the equation in the attachment is 1.50∙10-2kPa at 20°C.

Discussion

The test substance contains several volatile impurities (see appendix 1), which have a significantly higher vapour pressure than1,1,3,3-tetramethylbutyl hydroperoxide. In order to get realistic vapour pressure data of 1,1,3,3-tetramethylbutyl hydroperoxide these volatiles should not be taken into account. With the test method used in this study these volatiles were removed during the measurements and did not contribute to the measured vapour pressures. This was investigated for the test substance and reported in a separate report .

So, the estimated vapour pressure of1.50∙10-2kPa at 20°C is the value of the test substance without the volatile impurities.

Conclusions:
The estimated vapour pressure of 1,1,3,3-tetramethylbutyl hydroperoxide (without volatile impurities) is 15 Pa at 20°C.
Executive summary:

The vapour pressure of 1,1,3,3-tetramethylbutyl hydroperoxidewas determined according toASTM E1782-08. This method is not includedintoEC Regulation No 761/2009, Guideline A.4, but it is expected that this will occur in the near future. In 2010 a request for inclusion was sent to the Dutch National Coordinator for EC Test Methods.

 

The test substance contains volatile impurities which will increase the vapour pressure of the test substance significantly. With the method applied for this study the volatile impurities were removed effectively and they did not contribute to the measured vapour pressures.So, the estimated vapour pressure determined in this way is the value for the test substance without volatiles, and this value is 15 Pa at 20°C.

Description of key information

The estimated vapour pressure of 1,1,3,3-tetramethylbutyl hydroperoxide (without volatile impurities) is 15 Pa at 20°C.

Key value for chemical safety assessment

Vapour pressure:
15 Pa
at the temperature of:
20 °C

Additional information