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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:
01 November 2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method A.4 (Vapour Pressure)
Qualifier:
according to
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
GLP compliance:
yes (incl. certificate)
Type of method:
isoteniscope
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Supplied by Sponsor, Batch no 1909251800R
- Expiration date of the lot/batch: 25 September 2021
- Purity test date: 25 September 2019
- Purity: 99.945% w/w
- Physical state/appearance: Clear colorless liquid

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature in the dark
- Stability under test conditions: stable
Key result
Test no.:
#1
Temp.:
25 °C
Vapour pressure:
2.02 other: Log10 [Vp(25 ºC)]
Key result
Test no.:
#2
Temp.:
25 °C
Vapour pressure:
2.02 other: Log10 [Vp(25 ºC)]
Key result
Test no.:
#3
Temp.:
25 °C
Vapour pressure:
2.09 other: Log10 [Vp(25 ºC)]
Remarks on result:
not determinable because of methodological limitations
Remarks on result:
not determinable because of methodological limitations

Vapor pressure is related to temperature by the following equation:

Equation 1

Log10 [Vp (Pa)] =(slope/temperature (K))+intercept

A plot of Log10 Vp (Pa) versus reciprocal temperature (1/T(K)) therefore gives a straight line graph.

The vapor pressure of the sample was measured over a range of temperatures to enable extrapolation to 298.15 K.

Conclusions:
The vapor pressure of the test item has been determined to be 111 Pa at 25 ºC.
Executive summary:

The vapour pressure of butylal was determined using an isoteniscope system in which the sample's vapor pressure was measured using a mercury-in-glass manometer. The temperature of the sample was regulated by use of a silicone oil bath.

The isoteniscope method was chosen as a literature search, and information provided by the Sponsor, indicated the test item would have a vapor pressure outside the scope of the vapor balance method. The isoteniscope method requires the test item to be boiled under vacuum in order to “trap” the vapor in the isoteniscope tube. Due to the boiling point of the test item being approximately 179 °C, determinations below 50 °C were not possible as insufficient vapor would be present to allow readings to be taken.

A total of three runs were performed, the Vapour pressure was calculated as the mean of the three runs and was measured to be 111 Pa at 25 ºC.

Description of key information

The vapour pressure of Butylal has been measured according to OECD TG 104 and GLP, using the isoteniscope method. The vapour pressure was determined as a mean of three runs as 111 Pa at 25°C.

Key value for chemical safety assessment

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

Additional information

This key study is supported by non-GLP studies:

The vapour pressure of Butylal (purity of 99.8%) has been determined as 0.079 kPa at 20°C following an internal method that is in accordance with norm annex A.4 of the Directive 92/69/EEC. The method consist in the determination of a temperature-pressure curve in a pressure range of about 1 to 1000 hPa by the dynamic method. As 20 °C lies outside the temperature range belonging to this pressure range, the vapour pressure at 20 °C is calculated by extrapolation.

In published study (Palczewska, 2011), vapour pressure of dibutoxymethane (purity of 99.98%) was measured following comparative ebulliometric technique comprising a dynamic twin-ebulliometer assembly. Temperature measured with a platinum resistance thermometer operated in conjunction with a Mueller bridge and an electronic null detector. As 20 °C lies outside the temperature range belonging to this pressure range, the vapour pressure at 20 °C is calculated by extrapolation. The estimated vapour pressure of dibutoxymethane is 0.061 kPa at 20°C

Reid Vapour Pressure (RVP) of butylal was measured according ASTM D 323 modified at 20°C as <0.138kPa and as <0.25 kPa (Van Immerseel, 1995, 1998).