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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
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.
GLP compliance:
20 °C
Vapour pressure:
91 Pa
A vapour pressure value of 91 Pa at 20°C was obtained using a validated QSAR method. The result is considered to be reliable.

Description of key information

QSAR: Vapour pressure: 91 Pa at 20°C (2,4,6,8,10-pentamethylcyclopentasiloxane)
Vapour pressure: 0.05 Pa at 20°C (methylsilanetriol)

Key value for chemical safety assessment

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

Additional information

One reliable value of 91 Pa at 20°C has been calculated using a validated QSAR model. This result is considered reliable and has been chosen as the key study.

The vapour pressure of the final hydrolysis product methylsilanetriol has been calculated using the same QSAR method.