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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 MPBPVPWIN 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:
710 Pa
A vapour pressure of 710 Pa at 25°C was determined for the substance using an appropriate estimation method. The result is considered to be reliable.

Description of key information

Vapour pressure [tert-butyl(chloro)dimethylsilane]: 710 Pa at 25°C (QSAR)

Vapour pressure [tert-butyl(dimethyl)silanol]: 60 Pa at 25°C (QSAR)

Key value for chemical safety assessment

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

Additional information

A predicted vapour pressure of 710 Pa at 25°C was determined for the submission substance using a validated QSAR estimation method. The result is considered to be reliable. In contact with water, the substance hydrolyses very rapidly to form tert-butyl(dimethyl)silanol and hydrochloric acid.

The vapour pressure of the silanol hydrolysis product was determined to be 60 Pa at 25°C using the same prediction method as the submission substance.