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Physical & Chemical properties

Water solubility

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Description of key information

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

Water solubility [tris(1-methylethyl)silanol]: Above approximately 10 mg/L condensation reactions can occur over time, limiting the concentration dissolved in water. The calculated solubility is 60 mg/L (QSAR)

Water solubility [acrylic acid]: Miscible at 25°C (secondary literature)

Key value for chemical safety assessment

Additional information

The requirement to conduct a water solubility study for the submission substance is waived on the basis that it hydrolyses very rapidly in contact with water to form tris(1-methylethyl)silanol and acrylic acid. Due to the hydrolytic instability of the substance, a water solubility value of 2.6 mg/l was obtained using a test protocol that is comparable to the preliminary test defined in the OECD test guideline. The value obtained was considered to be reliable as an estimate of the solubility of the parent substance.

The hydrolysis product, tris(1-methylethyl)silanol may undergo condensation reactions in water; these become important above approximately 10 mg/L and can limit the concentration dissolved in water. For details, see the overall physicochemical properties discussion.

The water solubility of the silanol hydrolysis product (tris(1-methylethyl)silanol has been calculated using a validated QSAR method to be 60 mg/L. However, the saturation concentration may in reality be limited by the formation of less soluble dimer rather than the solubility of the monomer itself.

Acrylic acid is reported to be miscible in water 25°C (ECB 2002).


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.