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Vapour pressure

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vapour pressure
Type of information:
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
See attached QMRF/QPRF
Principles of method if other than guideline:
The result was obtained using an appropriate QSAR method (see attached QMRF and QPRF for details).

The model is an adaptation of the existing SRC model MPBPVPWIN v 1.43, which is a component of the EPI Suite. This existing model uses the normal boiling point as input. Whilst this method is good in principle, the model was developed using a wide range of organic chemicals and only a few organosilicon compounds. Therefore, a validation procedure was undertaken to assess the applicability of the model to organosilicon compounds. It was noted that the MBBPVPWIN model gave a systematic error; therefore, the current model was developed to correct this. The current model is a linear regression based QSAR, with the vapour pressure prediction from MPBPVPWIN as the descriptor. The adapted model applies to organosilicon substances.
Key result
Test no.:
25 °C
Vapour pressure:
32 Pa
A vapour pressure value of 32.0 Pa at 25°C has been obtained for the substance using an appropriate estimation method. The result is considered reliable.

Description of key information

Vapour pressure [dichloro(methyl)(phenyl)silane]: 32 Pa at 25°C (QSAR)

Vapour pressure [methylphenylsilanediol]: 0.0036 Pa at 25°C (QSAR)

Key value for chemical safety assessment

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

Additional information

There is no reliable measured vapour pressure study for the registered substance. Therefore, the vapour pressure of the registered substance has been predicted to be 32 Pa at 25°C using a validated QSAR estimation method. The result is considered to be reliable and is used as key study.

In a handbook or collection of reliable data, vapour pressure value of 47 Pa at 20°C was reported for the substance.

In a secondary source to which reliability could not be assigned, vapour pressure value of <200 Pa at 20°C was reported for the substance.

In contact with water, dichloro(methyl)(phenyl)silane hydrolyses very rapidly to form methylphenylsilanediol and hydrochloric acid.

The vapour pressure of the silanol hydrolysis product, methylphenylsilanediol was determined to be 0.0036 Pa at 25°C using a validated QSAR estimation method.