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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:
0.011 Pa
A vapour pressure value of 0.011 Pa at 25°C has been determined for the substance using an appropriate estimation method. The result is considered to be reliable.

Description of key information

Vapour pressure [triethoxy(3-thiocyanatopropyl)silane]: 0.011 Pa at 25°C (QSAR)

Vapour pressure [(3-thiocyanatopropyl)silanetriol]: 2.0E-06 Pa at 25°C (QSAR)

Vapour pressure [ethanol]: 7910 Pa at 25°C

Key value for chemical safety assessment

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

Additional information

A predicted vapour pressure of 0.011 Pa at 25°C was determined for the registered substance using a validated QSAR estimation method; the result is considered to be reliable and is selected as key study. The QSAR value has been validated using reliable measurements for structural analogues reflecting the main constituent in the registered substance.


In the other available secondary source to which no reliability could be assigned, a vapour pressure of <1 hPa at 20°C was reported for the substance.

Triethoxy(3-thiocyanatopropyl)silane, CAS 34708-08-2; EC No. 252-161-3 hydrolyses moderately in contact with water to form (3-thiocyanatopropyl)silanetriol and ethanol, CAS 64-17-5; EC No. 200-578-6.


The vapour pressure of the silanol hydrolysis product, (3-thiocyanatopropyl)silanetriol was determined to be 2.0E-06 Pa at 25°C using a validated QSAR estimation method.


Ethanol has a reported vapour pressure of 7910 Pa at 25°C (Daubert, T E and Danner R P (1985))




Daubert, T E and Danner R P (1985).Physical and Thermodynamic properties of Pure Chemicals. Data Compilation)