Registration Dossier
Registration Dossier
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EC number: 445-890-5 | CAS number: 201290-01-9
Partition coefficient
Administrative data
Link to relevant study record(s)
Description of key information
log Kow [N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane]: not determinable due to very rapid hydrolysis in water
log Kow [3-(diethoxymethylsilyl)propylamine]: -0..5 at pH 7 and 20°C (QSAR)
log Kow [3-(dihydroxymethylsilyl)propylamine]: -4 at pH 7 and 20°C (QSAR)
log Kow [trimethylsilanol]: 1.1 at 20°C (QSAR)
log Kow [ethanol]: -0.3
Key value for chemical safety assessment
Additional information
The requirement to conduct an n-octanol/water partition coefficient for the substance is waived because in contact with water, the substance hydrolyses very rapidly to form 3-(diethoxymethylsilyl)propylamine as an intermediate hydrolysis product and trimethylsilanol. The intermediate hydrolysis product, 3-(diethoxymethylsilyl)propylamine undergoes further hydrolysis to form 3-(dihydroxymethylsilyl)propylamine and ethanol.
A predicted log Kow value of 2.5 was determined for 3-(diethoxymethylsilyl)propylamine using a validated QSAR estimation method. This prediction refers to the unionised form of the substance. The amine group in the substance will protonate in solution; therefore the estimated log Kow for the unionised form was corrected for ionisation using the equation provided in the ECHA Guidance R.7a (2008). The corrected log Kow values at pH 2, pH 4, pH 7 and pH 9 were -4, -3.5, -0.5 and 1.4 respectively.
Similarly, the unionised form of the silanol hydrolysis product; 3–(dihydroxymethylsilyl)propylamine has a predicted log Kow value of -0.9 using a validated QSAR estimation method. The corrected value at pH 2, pH 4 and pH 7 is -4, at pH 9, the log Kow is -1.9.
Trimethylsilanol also has a predicted log Kow value of 1.1 at 20°C using a validated QSAR estimation method.
Ethanol has a reported log Kow of -0.3 (Hansch et al 1995).
Reference:
Hansch. C., A. Leo and D. Hoekman (1995). Exploring QSAR. Hydrophobic, Electronic, and Steric Constants. ACS Professional Reference Book.,: American Chemical Society
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