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EC number: 220-941-2
CAS number: 2943-75-1
[triethoxy(octyl)silane]: 0.11 Pa at 25°C (QSAR)
[octylsilanetriol]: 2.7E-05 Pa at 25°C (QSAR)
Vapour pressure [ethanol]:
7910 Pa at 25°C
A measured vapour pressure of 170
Pa at 20°C was determined for the substance using the static method in
accordance with OECD Test Guideline 104 and in compliance with a known
quality system (ISO 9001:2008) (Haas 2012). This measured result is
considered too high for triethoxy(octyl)silane and is therefore
disregarded due to the following reasons:
- fewer temperature determinations
over a very narrow range was performed, three temperature points in
total were used
- the requirement to repeat the
vapour pressure determinations at low temperatures was not performed
- no evidence that the system is
completely degassed, since the method used (static method) is
susceptible to overestimate vapour pressure of a substance if volatile
impurities are not properly degassed before the measurements are taken.
Similarly, vapour pressure values
of <10 Pa at 20°C and 2900 Pa at 150°C were obtained for the substance
using a dynamic method (AQura 2010). However, the reliability of the
study is unassignable because (i) the purity of the test substance was
not reported (ii) vapour pressure was obtained at ambient temperature by
extrapolation from higher temperature of 128-259°C. Extrapolation from
such high temperature is prone to significant error.
The structural analogue of the
substance; trimethoxy(octyl)silane (CAS 3069-40-7) has a measured vapour
pressure of 2.1 Pa at 20°C using the dynamic method according to EU
Method A.4. Therefore, the measured results for triethoxy(octyl)silane
(CAS 2943-75-1) are not used for assessment purposes.
A predicted vapour pressure of
0.11 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
sources to which no reliability could be assigned, vapour pressure
values of <133 Pa and ca. 10 Pa at 20°C were reported for the substance.
Differences in vapour pressure determination could be as a result of
differences in the purity of the commercial samples tested and the test
In contact with water,
triethoxy(octyl)silane will hydrolyse at a moderate rate to form
octylsilanetriol and ethanol.
The vapour pressure of the silanol
hydrolysis product, octylsilanetriol was determined to be 2.7E-05 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
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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