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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Physical & Chemical properties

Endpoint summary

Administrative data

Description of key information

[3-(2,3-Epoxypropoxy)propyl]trimethoxysilane is a liquid at standard temperature and pressure, with a melting point of -20°C, and a measured boiling point of 260.4°C. It has a measured relative density of 1.071 at 20°C, a measured kinematic viscosity of 3.43 mm²/s at 20°C and a predicted vapour pressure of 1.1 Pa at 25°C.

The substance is not classified for flammability according to Regulation (EC) No. 1272/2008 on the basis of a measured flash point of 136°C and a measured boiling point of 260.4°C. It has a measured auto-ignition temperature of 236°C at 97.7 to 98.4 kPa and is not oxidising on the basis of chemical structure. [3-(2,3-Epoxypropoxy)propyl]trimethoxysilane was obtained not to exhibit explosivity hazard under the conditions of an EU Method A.14 test method.

In contact with water [3-(2,3-epoxypropoxy)propyl]trimethoxysilane reacts rapidly (half-life of 6.5 hours at pH 7, 0.15 hours at pH 5, 0.13 hours at pH 9 and 24.5°C) to produce [3-(2,3-epoxypropxy)propyl]silanetriol and methanol according to the following equation:

(OCH3)3Si(C3H6OC3H5O) + 3H2O ¿ Si(OH)3(C3H6OC3H5O) + 3CH3OH


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, [3-(2,3-epoxypropoxy)propyl]silanetriol and methanol are assessed instead. However, the log Kow and water solubility of the submission substance was predicted to be 0.5 at 20°C and 1.1E+05 mg/l at 20°C respectively.

Methanol is miscible with water, has low log Kow (-0.82 to -0.64) and high vapour pressure (12790 Pa at 20°C) (OECD, 2004a: SIDS Initial Assessment Report for SIAM 19, Berlin, Germany, 18 - 20 October 2004, Methanol, CAS 67-56-1).


The saturation concentration in water of the hydrolysis product, [3-(2,3-epoxypropoxy)propyl]silanetriol is limited by condensation reactions to approximately 1000 mg/l. However, it is very hydrophilic (calculated solubility is 1.0E+06 mg/l using a QSAR method) and has a low log Kow (-2.6, predicted).

It is not expected to be surface active and is not expected to undergo significant dissociation within the environmentally-relevant range. The first dissociation constant of a structurally analogous silanetriol (phenylsilanetriol) has been reported to be around pKa of 10. It is much less volatile than the parent substance (vapour pressure = 1.7E-05 Pa at 25°C, predicted).


Additional information