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Adsorption / desorption

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Endpoint:
adsorption / desorption: screening
Type of information:
(Q)SAR
Adequacy of study:
supporting 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.
Sample No.:
#1
Type:
log Koc
Value:
-0.6 dimensionless
pH:
7
Temp.:
20 °C
Remarks on result:
other: Predicted for the silanol hydrolysis product 3 -aminopropylsilanetriol
Conclusions:
A predicted log Koc value of -0.6 at 20°C and pH 7 was determined for the silanol hydrolysis product of the submission substance using a relevant estimation method. The result is considered to be reliable.
Endpoint:
adsorption / desorption: screening
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
the study does not need to be conducted because the substance has a low octanol water partition coefficient and the adsorption potential of this substance is related to this parameter

Description of key information

Adsorption/desorption:

log Koc [3-(trimethoxysilyl)propyl isocyanate]: not relevant due to very rapid hydrolysis in contact with water

log Koc [3-(trimethoxysilyl)propylamine: not relevant due to rapid hydrolysis in contact with water

log Koc [3-aminopropylsilanetriol]: -0.6 at 20°C and pH 7 (QSAR)

Key value for chemical safety assessment

Additional information

3-(Trimethoxysilyl)propyl isocyanate hydrolyses very rapidly (half-life <5 min at pH 7 for the hydrolysis of the isocyanate group) to form 3-(trimethoxysilyl)propylamine (intermediate hydrolysis product) and carbon dioxide. The intermediate hydrolysis product is expected to hydrolyse rapidly (2.6 hours at pH 7) to the final hydrolysis product 3-aminopropylsilanetriol and methanol. In view of these hydrolysis rates, risk assessment for the submission substance is carried out for the silanol hydrolysis product 3-aminopropylsilanetriol and methanol.

The log Koc of the silanol hydrolysis product, 3-aminopropylsilanetriol has been predicted using a validated QSAR estimation method to be -0.6 at 20°C and pH 7.