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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:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
The study was conducted according to an appropriate EU test method but not compliant with GLP
Qualifier:
according to guideline
Guideline:
EU Method A.4 (Vapour Pressure)
GLP compliance:
no
Type of method:
static method
Key result
Test no.:
#1
Temp.:
20 °C
Vapour pressure:
9 Pa
Key result
Test no.:
#2
Temp.:
25 °C
Vapour pressure:
12 Pa

Table 1 below shows the data derived in the test.

Table 1. Temperature and pressure values derived in the study.

 Temperature

Pressure 

 °C

 Pa

 20.0

 10

 30.9

 20

 41.4

 31

 50.9

 41

 60.0

 92

 70.8

 174

 80.2

 245

Conclusions:
Vapour pressure values of 9 Pa at 20°C and 12 Pa at 25°C were obtained in a reliable study conducted in accordance with a standard guideline (static method). It was not conducted under GLP.

Description of key information

Vapour pressure (constituents of the substance): 9 Pa at 20°C (EU A4)

Vapour pressure (silanol hydrolysis products of the substance): 2.9E-05 Pa at 25°C (QSAR)

Vapour pressure (ethanol): 7910 Pa at 25°C

Key value for chemical safety assessment

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

Additional information

Vapour pressure values of 9 Pa at 20°C and 12 Pa at 25°C have been measured for 4,4,13,13-tetraethoxy-3,14-dioxa-8,9-dithia-4,13-disilahexadecane (S2, 56706-10-6), which is the major constituent of the multiconstituent submission substance. The data were obtained in a study conducted in accordance with a standard guideline (static method) but not conducted under GLP; they are considered reliable.

The vapour pressures of both the S2 and S3 constituents have been predicted using an appropriate method; each constituent is predicted to have similar vapour pressures, as may be expected from their very similar structures. The vapour pressure is predicted to be 0.46 Pa at 25°C for S2, which is in reasonable agreement with the measured value for the S2 component, and 0.44 Pa at 25°C for S3. Thus, the measured value of 9 Pa at 20°C for the S2 constituent is taken to also be similar to the vapour pressure of the other constituent.

The vapour pressure of the silanol hydrolysis product of each constituent of the substance has been predicted using the same method.

Ethanol has a reported vapour pressure of 7910 Pa at 25°C (Daubert, T E and Danner R P (1985).Physical and Thermodynamic properties of Pure Chemicals. Data Compilation).