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Physical & Chemical properties

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Description of key information

Tri(isopropoxy)(vinyl)silane is a liquid at standard temperature and pressure, with a measured melting point of <-65°C and a measured boiling point of 176°C. It has a predicted density of 0.9 g/cm3 at 20°C and a predicted vapour pressure of 64 Pa at 25°C.

The substance is classified for flammability according to Regulation (EC) No 1272/2008 on the basis of a measured flash point of 43.5°C and a measured boiling point of 176°C. It has a measured auto-ignition temperature of 246°C, and it is not explosive and not oxidising on the basis of chemical structure.

In contact with water, the submission substance reacts rapidly (predicted half-life of 0.3 hours at pH 4, 7 hours at pH 7 and 0.1 hours at pH 9 and 20-25°C) to produce vinylsilanetriol and isopropanol according to the following equation:

C11H24SiO3+ 3H2O → C2H6SiO+ 3C3H8O

 

Therefore, requirements for testing of water-based physicochemical properties for the substance are waived on the basis of instability in water. The properties of the hydrolysis products vinylsilanetriol and isopropanol are assessed instead.

However, the key physicochemical properties of the submission substance have been predicted using validated QSAR estimation methods. The substance has a predicted water solubility value of 130 mg/l at 20°C and a predicted log Kow value of 3.8 at 20°C.

The hydrolysis of the submission substance produces vinylsilanetriol and 3 molecules of isopropanol.

Isopropanol has a reported water solubility of 1.0E+06 mg/L (Riddick et al 1986), low log Kow value of 0.05 (Hansch et al (1995)) and a vapour pressure of 6053 Pa at Pa at 25°C (Daubert and Danner (1985).

 

The saturation concentration in water of the silanol hydrolysis product, vinylsilanetriol is limited by condensation reactions that can occur over time at loadings above approximately 1000 mg/L. However, it is very hydrophilic (calculated solubility is 1.0E+06 mg/l at 20°C using a QSAR method) and has a low log Kow (-2.0, predicted).

The silanol hydrolysis product is not expected to be surface active and it is much less volatile than the parent substance (vapour pressure = 0.017 Pa at 25°C, predicted).

References:

Daubert and Danner (1985). Daubert, T.E., R.P. Danner. Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, D.C.: Taylor and Francis, 1989.

Hansch et al., (1995). Hansch C, Leo A and Hoekman D. Exploring QSAR. Hydrophobic, Electronic, and Steric Constants. ACS Professional Reference Book. Washington, DC: American Chemical Society.

Riddick, J., Bunger, W.B., Sakano, T.K. (1986). Organic Solvents: Physical Properties and Method of Purification. 4th Edition, John Wiley & Sons, New York

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