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EC number: 239-311-3
CAS number: 15267-95-5
(Chloromethyl)triethoxysilane is a
liquid at standard temperature and pressure. It is predicted to have a
melting point of <-20°C, a predicted boiling point of 200°C
and a predicted density of 1.04 g/cm3at 25°C. The
static viscosity of the substance is predicted to be 1.2 mm2/s
at 20°C and the vapour pressure of the substance is predicted to be 6.5
Pa at 25°C. The substance is classified as a flammable liquid on
the basis of the boiling point and a measured flash point of 49°C. It is
not pyrophoric or flammable in contact with water. It has a measured
self-ignition temperature of 225°C, and is not explosive and not
oxidising on the basis of chemical structure. It is not surface active.
In contact with water
(chloromethyl)triethoxysilane reacts rapidly (half-life 2.5 hours at pH
7 and 20 - 25°C) to produce chloromethylsilanetriol and ethanol
according to the following equation:
(CH3CH2O)3SiCH2Cl + 3H2O → ClCH2Si(OH)3 + 3CH3CH2OH
Therefore, requirements for
testing of the water-based physicochemical properties for the substance
and measurement of the surface tension are waived on the basis of
instability in water. The properties of the hydrolysis products are
assessed in instead.
The silanol hydrolysis product,
chloromethylsilanetriol, is predicted to be very soluble in water 20oC
(1E+06 mg/l) and has a log Kowof -2.1 (predicted). It
is less volatile than the parent substance with a vapour pressure of
2.1E-03 at 25°C (predicted). The first dissociation constant (hydroxyl
groups) of a structurally analogous silanetriol (phenylsilanetriol) has
been reported to be around pKa10.
Methanol is miscible with water,
has low log Kowof -0.3 and high vapour pressure of 7910 Pa at
20°C) (OECD, 2004).
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
A highly cross-linked gel
may form. The degree of condensation that will occur may vary with:
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