Registration Dossier

Physical & Chemical properties

Endpoint summary

Administrative data

Description of key information

Triethoxy(2,4,4-trimethylpentyl)silane is a liquid at standard temperature and pressure, with a measured melting point of <-20°C, and a measured boiling point of 237.2°C. It has a measured relative density of 0.876 at 20°C, a measured kinematic viscosity of 1.98 mm2/s at 20°C and measured vapour pressure values of 0.14 Pa and 0.22 Pa at 20°C and 25°C respectively.

The substance is classified as flammable liquid category 3 in accordance with Regulation (EC) No. 1272/2008 on the basis of a measured flash point of 42°C and a measured boiling point of 237.2°C. It has a measured auto-ignition temperature of 251°C at 964 -967 hPa, and is not explosive and not oxidising on the basis of chemical structure.

In contact with water, the substance hydrolyses at a moderate rate (half-lives of 0.9 h at pH 4, 43 h at pH 7 and 0.5 h at pH 9 and 20-25°C) resulting in the formation of (2,4,4-trimethylpentyl)silanetriol and ethanol according to the following equation:

(CH3)3CCH2CH(CH3)CH2Si(OCH3CH2)3+ 3H2O → (CH3)3CCH2CH(CH3)CH2Si(OH)+ 3CH3CH2OH


The substance has an estimated log Kow value of >6.5 and measured water solubility of <0.1 mgl at 20°C.

Ethanol is miscible with water, has low log Kow (-0.3) and high vapour pressure (7910 Pa at 25°C).


The saturation concentration in water of the silanol hydrolysis product, (2,4,4-trimethylpentyl)silanetriol, is limited by condensation reactions to approximately 200 mg/l. However, it is very hydrophilic (calculated solubility is 2.4E+05 mg/l using a QSAR method). (2,4,4 -Trimethylpentyl)silanetriol is not surface active and is much less volatile than the parent substance (vapour pressure = 1.2E-04 Pa at 25°C predicted). The first dissociation constant of a structurally analogous silanetriol (phenylsilanetriol) has been reported to be around pKa= 10.

Additional information