Registration Dossier
Registration Dossier
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EC number: 201-081-7 | CAS number: 78-08-0
Endpoint summary
Administrative data
Description of key information
Additional information
- Concentration of the silanol; the greater the initial concentration, the greater the degree of condensation. Significant condensation is not expected at concentrations less than approximately 100 mg/l, but is dependent on specific conditions.
- pH; the condensation reaction may be either acid or base catalysed.
- Temperature.
- Other species present.
- The nature of the R group
Physicochemical properties
Triethoxy(vinyl)silane is a liquid at standard temperature and pressure, with a measured melting point of -92°C and a predicted boiling point of 169°C at 1013hPa. It has a predicted density of 0.92 g/cm3 at 25°C, a predicted viscosity of 0.9 mm²/s at 20°C and a measured vapour pressure of 304 Pa at 25°C.
The substance is classified as a flammable liquid on the basis of a measured flash point of 42.5°C. Triethoxy(vinyl)silanehas a measured auto-ignition temperature of 250°C, and is not explosive and not oxidising on the basis of chemical structure.
In contact with water,triethoxy(vinyl)silanereacts rapidly to produce vinylsilanetriol and ethanol according to the following equation:
(CH3CH2O)3SiCH=CH2 + 3 H2O → CH2=CHSi(OH)3 + 3 CH3CH2OH
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 silanol hydrolysis product, vinylsilanetriol, are assessed instead.
Vinylsilanetriol is predicted to be very soluble in water (1E+06 mg/l) with a predicted low log Kow value of -2.0. It is not surface active and does not undergo significant dissociation within the environmentally-relevant range. It is much less volatile than the parent substance (vapour pressure = 0.017 Pa at 25°C, predicted).
Silanetriols may undergo condensation reactions to give siloxane dimers, oligomers and polymers, according to the scheme:
RSi(OH)3 ⇄ RSi(OH)2OSi(OH)2R ⇄ RSi(OH)2O[Si(R)(OH)O]nSi(OH)2R
(where R is an alkyl or aryl side-chain)
A highly cross-linked gel may form. The degree of condensation that will occur may vary with:
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