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Physical & Chemical properties

Partition coefficient

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Description of key information

log Kow [ tri(isopropyl)silyl acrylate]: Not relevant due to very rapid hydrolysis in contact with water

log Kow [tris(1-methylethyl)silanol]: 3.9 at 20°C (QSAR)

log Kow [acrylic acid]: 0.46 at 25°C (non-ionised form)

Key value for chemical safety assessment

Additional information

The requirement to conduct an n-octanol/water partition coefficient for the submission substance is waived because in contact with water, the substance hydrolyses very rapidly to form tris(1-methylethyl)silanol and acrylic acid.

An estimated log Kow of 5.2 was obtained for the parent substance based on estimation of the solubility of the substance in octanol and in water.

The silanol hydrolysis product has a predicted log Kow of 3.9 at 20°C using a validated QSAR estimation method.

Acrylic acid has a log Kow value of 0.46 at 25°C (ECB 2002). Log Kow of value of -2.3 for the ionised form of acrylic acid at pH 7 and 25°C was obtained from the log Kow value of the un-ionised form using the standard equation as stated in R7a (ECHA 2008).


ECB (2002). European Union Risk Assessment Report acrylic acid CAS No: 79-10-7 EINECS No: 201-177-9 Risk Assessment, PL-1 Vol 28, 2002.

ECHA (2008) Guidance on information requirements and chemical safety assessment. Chapter R.7a: Endpoint specific guidance.