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Environmental fate & pathways

Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
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 method has been developed specifically for organosilicon compounds. It is a linear regression based model. The descriptors are the log Kow and an indicator variable for the presence of an amine. See QMRF and QPRF for further details.
Key result
Sample No.:
#1
Type:
log Koc
Value:
1.4 dimensionless
pH:
7
Temp.:
20 °C
Remarks on result:
other: Predicted for triethoxy(3-thiocyanatopropyl)silane
Conclusions:
A predicted log Koc value of 1.4 at 20°C and pH 7 was determined for the submission substance using a relevant estimation method. The result is considered to be reliable.

Description of key information

Adsorption/desorption:

log Koc [triethoxy(3-thiocyanatopropyl)silane]: 1.4 at 20°C and pH 7 (QSAR)

log Koc [(3-thiocyanatopropyl)silanetriol]: 0.24 at 20°C and pH 7 (QSAR)

Key value for chemical safety assessment

Koc at 20 °C:
25.1

Additional information

A predicted log Koc value of 1.4 was obtained for triethoxy(3-thiocyanatopropyl)silane using a validated QSAR estimation method. The result is considered to be reliable and used for assessment purposes.

The substance hydrolyses moderately to form (3-thiocyanatopropyl)silanetriol and ethanol which have low log Kow values (<3) and thus have low potential for adsorption.

Where the log Kow is >3 as is the case for the parent substance, a validated QSAR estimation method is used for calculating the log Koc. However, for environmental exposure assessment, adsorption is predicted for the silanol hydrolysis product using the ‘non-hydrophobics’ log Kow-based prediction method for log Koc developed by Sabljić and Güsten (1995) for the European Commission, and recommended in EU Guidance.

The relevant equation is:

Log Koc = 0.52 log Kow + 1.02

Therefore, log Koc for silanol hydrolysis product, (3-thiocyanatopropyl)silanetriol = 0.24

Reference:

Sabljić A and Güsten H (1995). QSARs for soil sorption. in: overview of structure-activity relationships for environmental endpoints. Hermens JLM (ed), report prepared within the framework of the project "QSAR for prediction of fate and effects of chemicals in the environment", an international project of the Environmental Technologies RTD programme (DG XII/D-1) of the European Commission under contract number EV5V-CT92-0211.