Registration Dossier
Registration Dossier
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EC number: - | CAS number: -
Water solubility
Administrative data
Link to relevant study record(s)
- Endpoint:
- water solubility
- Data waiving:
- study scientifically not necessary / other information available
- Justification for data waiving:
- the study does not need to be conducted because the substance is hydrolytically unstable at pH 4, 7 and 9 (half-life less than 12 hours)
- Endpoint:
- water solubility
- Type of information:
- (Q)SAR
- Adequacy of study:
- supporting study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification
- Principles of method if other than guideline:
- The result was obtained using an appropriate QSAR method.
The model is an adaptation of the existing SRC model WaterNT v 1.01, aka WaterFrag, which is a component of the EPI Suite. This model is based on fragment values, i.e. the chemical structure is broken down into its constituent functional groups and the contribution of each group toward the overall solubility is calculated. Certain correction factors may also apply. Whilst this method is good in principle, it suffers from not having reliable fragment values for substances containing Si-O bonds. Therefore, multiple linear regression on a set of organosilicon compounds has been used to generate new fragment values for silicon and oxygen bound to silicon (with separate values for –OH and other oxygen). The adapted model applies to substances containing Si-O bonds. - Water solubility:
- 1 000 000 mg/L
- Temp.:
- 20 °C
- Conclusions:
- A water solubility of 1.0E+06 mg/l at 20°C was obtained for the hydrolysis product of the registered substance using an appropriate calculation method.
- Endpoint:
- water solubility
- Type of information:
- (Q)SAR
- Adequacy of study:
- supporting study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification
- Principles of method if other than guideline:
- The result was obtained using an appropriate QSAR method.
The model is an adaptation of the existing SRC model WaterNT v 1.01, aka WaterFrag, which is a component of the EPI Suite. This model is based on fragment values, i.e. the chemical structure is broken down into its constituent functional groups and the contribution of each group toward the overall solubility is calculated. Certain correction factors may also apply. Whilst this method is good in principle, it suffers from not having reliable fragment values for substances containing Si-O bonds. Therefore, multiple linear regression on a set of organosilicon compounds has been used to generate new fragment values for silicon and oxygen bound to silicon (with separate values for –OH and other oxygen). The adapted model applies to substances containing Si-O bonds. - Water solubility:
- 1 000 000 mg/L
- Temp.:
- 20 °C
- Conclusions:
- A water solubility of 1.0E+06 mg/L at 20°C was obtained for the hydrolysis product of the registered substance using an appropriate calculation method.
Referenceopen allclose all
Description of key information
Water Solubility [Reaction mass of 3-(2,3-epoxypropoxy)propyltrimethoxysilane and triacetoxyvinylsilane]: waived due to rapid hydrolysis
Water Solubility [3-(2,3-epoxypropoxy)propyl]silanetriol]: above approximately 1000 mg/l condensation reactions can occur over time, limiting the concentration dissolved in water. The calculated solubility (indicative of the hydrophilicity of the substance) is 1.0E+06 mg/l (QSAR).
Water Solubility [vinylsilanetriol]: above approximately 1000 mg/l condensation reactions can occur over time, limiting the concentration dissolved in water. The calculated solubility is (indicative of the hydrophilicity of the substance) 1.0E+06 mg/l (QSAR).
Water Solubility [acetic acid]: miscible with water
Water Solubility [methanol]: miscible with water
Key value for chemical safety assessment
Additional information
The requirement to conduct a water solubility study for the submission substance is waived because in contact with water; the registration substance hydrolyses rapidly (all constituents have predicted half-lives of <12 hours at 20-25°C and pH 4, pH 7 and pH 9) to [3-(2,3-epoxypropoxy)propyl]silanetriol, vinylsilanetriol, acetic acid and methanol.
The silanol hydrolysis products, [3-(2,3-epoxypropoxy)propyl]silanetriol and vinylsilanetriol, 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 a silanetriol may considered as an equilibrium between monomer, dimer, oligomers and cross-linked polymeric particles. At low loadings of silanol, the soluble monomer is expected to predominate in solution (>99%) with small amounts of dimer and oligomers. At concentrations above about 200 mg/l, significant condensation reactions may occur over time causing the formation of insoluble polymeric particles (sols) and gels. Further information is given in a supporting report (PFA 2016am) attached in Section 13.
The silanol hydrolysis products, [3-(2,3-epoxypropoxy)propyl]silanetriol and vinylsilanetriol, are very hydrophilic and hence the calculated solubility is 1E+06 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. A prediction of 1E+06 mg/l is indicative but has no practical meaning. However, the prediction is considered valid for use in environmental exposure modelling and toxicokinetics modelling because it is considered to adequately describe the hydrophilicity of the substance and hence the partitioning behaviour.
Acetic acid was reported to be miscible with water in a secondary source which has been subject to peer review (O'Neil 2013).
Methanol is miscible in water at 20°C based on experimental data (OECD 2004).
References:
OECD (2004). SIDS Initial Assessment Report for SIAM 19, Berlin, Germany, 18-20 October 2004, Methanol, CAS 67-56-1
O’Neil M.J (2013). O’Neil M.J. (Editor-in-Chief). The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals, Fifteenth Edition, The Royal Society of Chemistry, UK, 2013.
PFA (2016am). Peter Fisk Associates, Silanols and aquatic systems, 404.105.003
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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