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Physical & Chemical properties

Water solubility

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water solubility
Type of information:
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The result was obtained by an appropriate predictive method.
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6
Principles of method if other than guideline:
The result was obtained using an appropriate QSAR method (see QMRF and QPRF for details).
GLP compliance:
Water solubility:
3 300 mg/L
20 °C
A water solubility of 3300 mg/l was obtained for the test substance using an appropriate calculation method. The result is considered reliable.

Description of key information

Water solubility [3-(2,3-epoxypropoxy)propyl]triethoxysilane: 3300 mg/L at 20°C (QSAR)

Water solubility [2,3-dihydroxypropoxypropylsilanetriol]: At concentrations above 1000 mg/L condensation reactions can occur over time, limiting the concentration dissolved in water. The calculated water solubility is 1.0E+6 mg/L at 20°C (QSAR)

water solubility [ethanol]: miscible with water

Key value for chemical safety assessment

Water solubility:
3 300 mg/L
at the temperature of:
20 °C

Additional information

A predicted water solubility value of 3300 mg/L at 20°C was determined for the substance using a validated QSAR estimation method. The result is considered to be reliable.


In contact with water, [3-(2,3-epoxypropoxy)propyl]triethoxysilane will hydrolyse moderately rapidly (half-life 12-36 hours at pH 7 and 25°C) to form 2,3-dihydroxypropoxypropylsilanetriol and ethanol.


The water solubility of the silanol hydrolysis product, 2,3-dihydroxypropoxypropylsilanetriol was predicted to be 1.0E+6 mg/L at 20°C using a relevant estimation method.


The silanol hydrolysis product, 2,3-dihydroxypropoxypropylsilanetriol may undergo condensation reactions in solution to give siloxane dimers, linear and cyclic oligomers and highly cross-linked polymeric particles (sol) that may over time form an insoluble gel and a dynamic equilibrium is established. The overall rate and extent of condensation is dependent on nominal loading, temperature and pH of the system, as well as what else is present in the solution.


The condensation reactions of silanetriols may be modelled as an equilibrium between monomer, dimer, trimer and tetramer, with the linear tetramer cyclising to the thermodynamically stable cyclic tetramer. The reactions are reversible unless the cyclic tetramer concentration exceeds its solubility; in this case, the cyclic tetramer forms a separate phase, driving the equilibrium towards the tetramer. For 2,3-dihydroxypropoxypropylsilanetriol, at loadings about 1000 mg/L the concentration of the cyclic tetramer of the silanol hydrolysis product is predicted to exceed its solubility, resulting in formation of a separate phase. Further information is given in a supporting report (PFA 2016am) attached in Section 13.


The hydrolysis product, 2,3-dihydroxypropoxypropylsilanetriol, is very hydrophilic and hence the calculated solubility is 1.0E+6 mg/L using a QSAR method. This QSAR method for water solubility cannot be validated for silanetriols because the saturation concentration of silanetriols in water is limited by condensation reactions rather than lack of true solubility as discussed above. The prediction is considered to be valid for use in calculation of environmental exposure modelling and toxicokinetics modelling because it is considered to adequately describe the hydrophilicity of the substance and hence the partitioning behaviour.


Ethanol is miscible with water (Riddick J.A 1986).



PFA (2016am). Peter Fisk Associates, Silanols and aquatic systems, 404.105.003


Riddick J.A (1986). Riddick,J.A.; Bunger,W.B.; Sakano,T.K.; Organic Solvents: Physical Properties and Methods of Purification. Techniques of Chemistry. 4th ED. New York,NY: Wiley-Interscience. 2:PP.1325 1986.