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Partition coefficient

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Description of key information

log Kow [1-(tert-butyldimethylsilyl)piperazine]: not relevant due to very rapid hydrolysis

log Kow [tert-butyldimethylsilanol]: 2.5 at 20°C (QSAR)

log Kow [piperazine]: -1.5

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 tert-butyldimethylsilanol and piperazine.

The log Kow of the silanol hydrolysis product, has been predicted to be 2.5 using a validated QSAR estimation method. A measured log Kow value of 2.7 at 25°C was determined for the silanol hydrolysis product in a study conducted according to an appropriate guideline and in compliance with GLP. However, the selected mobile phase constituents were unsuitable for organosilicon substances. Furthermore, an important corrective adjustment that is necessary for interpretation of HPLC data for organosilicon substances was not performed. This study is therefore disregarded.

Piperazine has a reported log Kow value of -1.5 (Hansch 1995).


Hansch, C., Leo, A., D. Hoekman. Exploring QSAR - Hydrophobic, Electronic, and Steric Constants. Washington, DC: American Chemical Society., 1995., p. 10