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 at 1013 hPa and a measured boiling point of 237.2°C at 1013 hPa. 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 Category 3 flammable liquid in accordance with Regulation (EC) No. 1272/2008 on the basis of a measured flash point of 42°C at 1013 hPa and a measured boiling point of 237.2°C at 1013 hPa. 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 a measured water solubility of <0.1 mg/L at 20°C.

Due to the moderate hydrolysis of the substance in contact with water, the key physicochemical properties of the hydrolysis products are presented below.

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 with a predicted vapour pressure of 1.2E-04 Pa at 25°C and a predicted log Kow of 0.9. The first dissociation constant of a structurally analogous silanetriol (phenylsilanetriol) has been reported to be around pKa = 10.

Additional information