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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Physical & Chemical properties

Partition coefficient

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Endpoint:
partition coefficient
Data waiving:
study technically not feasible
Justification for data waiving:
the study does not need to be conducted because the substance decomposes
Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model, but not (completely) 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.

The model is the publically available KOWWIN v1.68 program (USEPA 2011). KOWWIN is part of EPI Suite v4.1 and may be downloaded from http://www.epa.gov/oppt/exposure/pubs/episuite.htm. The model is based on fragment values. That is, the chemical structure is broken down into its constituent functional groups, and the contribution of each group toward the overall partition coefficient is calculated. The constants used within KOWWIN have been derived by SRC from a wide range of organic chemicals. The authors of this QMRF have carried out additional validation and found the method to be applicable organosilicon compounds, excluding di- and tri-alkoxysilanes.

USEPA 2011. KOWWIN v. 1.68, US EPA. 2011. Estimation Programs Interface Suite™ for Microsoft® Windows, v 4.10. United States Environmental Protection Agency, Washington, DC, USA. Available at http://www.epa.gov/oppt/exposure/pubs/episuite.htm.
Partition coefficient type:
octanol-water
Key result
Type:
log Pow
Partition coefficient:
-2.6
Temp.:
20 °C
pH:
7
Conclusions:
A partition coefficient value of -2.6 was obtained for the hydrolysis product of the registered substance, using an accepted calculation method. The result is considered to be reliable.
Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model, but not (completely) 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.

The model is the publically available KOWWIN v1.68 program (USEPA 2011). KOWWIN is part of EPI Suite v4.1 and may be downloaded from http://www.epa.gov/oppt/exposure/pubs/episuite.htm. The model is based on fragment values. That is, the chemical structure is broken down into its constituent functional groups, and the contribution of each group toward the overall partition coefficient is calculated. The constants used within KOWWIN have been derived by SRC from a wide range of organic chemicals. The authors of this QMRF have carried out additional validation and found the method to be applicable organosilicon compounds, excluding di- and tri-alkoxysilanes.

USEPA 2011. KOWWIN v. 1.68, US EPA. 2011. Estimation Programs Interface Suite™ for Microsoft® Windows, v 4.10. United States Environmental Protection Agency, Washington, DC, USA. Available at http://www.epa.gov/oppt/exposure/pubs/episuite.htm.
Partition coefficient type:
octanol-water
Key result
Type:
log Pow
Partition coefficient:
-2
Temp.:
20 °C
pH:
7
Conclusions:
A partition coefficient value of -2.0 was obtained for the hydrolysis product of the registered substance, using an accepted calculation method. The result is considered to be reliable.

Description of key information

Log Kow [Reaction mass of (3-(2,3-epoxypropoxy)propyl]trimethoxy)silane and triacetoxyvinylsilane]: waived due to rapid hydrolysis 

Log Kow [2-(3,4-epoxypropoxy)propylsilanetriol]: -2.6 at 20°C (QSAR)

Log Kow [vinylsilanetriol]: -2.0 at 20°C (QSAR)

Log Kow [acetic acid]: -0.17 at 20°C

Log Kow [methanol]: -0.82 to -0.64

Key value for chemical safety assessment

Additional information

The requirement to conduct an n-octanol/water partition coefficient study for the registration substance is waived because in contact with water the substance hydrolyses rapidly (all constituents have predicted half-lives of <12 hours at 20-25°C and pH 4, pH 7 and pH 9) to form [2-(3,4-epoxypropoxy)propyl]silanetriol, vinylsilanetriol, acetic acid and methanol.

 

The log Kow values of the silanol hydrolysis products, [3-(2,3-epoxypropoxy)propyl]silanetriol and vinylsilanetriol have been calculated to be -2.6 and -2.0 at 20°C respectively using a validated QSAR estimation method.

 

A partition coefficient value of -0.17 was reported for acetic acid (Hansch et al 1995).

Methanol has a reported log Kow of -0.82 to -0.64 (OECD 2004).

References:

Hansch. C., A. Leo and D. Hoekman (1995). Exploring QSAR. Hydrophobic, Electronic, and Steric Constants. ACS Professional Reference Book. Washington, DC: American Chemical Society.

OECD (2004). SIDS Initial Assessment Report for SIAM 19, Berlin, Germany, 18-20 October 2004, Methanol, CAS 67-56-1