Registration Dossier
Registration Dossier
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EC number: 238-518-6 | CAS number: 14513-34-9
Water solubility
Administrative data
Link to relevant study record(s)
Description of key information
Water solubility [3-[dimethoxy(methyl)silyl]propyl methacrylate]: 240 mg/L at 20°C (QSAR)
Water Solubility [3-[dihydroxy(methyl)silyl]propyl methacrylate]: The concentration dissolved in water is limited to about 35 mg/l by condensation reactions. Calculated water solubility is 4.0E+04 mg/l at 20°C (QSAR)
Water solubility [methanol]: miscible at 20°C
Key value for chemical safety assessment
- Water solubility:
- 240 mg/L
- at the temperature of:
- 20 °C
Additional information
The requirement to conduct a water solubility study for the substance is waived on the basis that it hydrolyses rapidly to form 3-[dihydroxy(methyl)silyl]propyl methacrylate and methanol.
The water solubility of the parent substance 3-[dimethoxy(methyl)silyl]propyl methacrylate has been calculated using a validated QSAR method to be 240 mg/l.
The silanol hydrolysis product, 3-[dihydroxy(methyl)silyl]propyl methacrylate, may undergo condensation reactions in solution to give siloxane dimers, linear and cyclic oligomers. 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 silanediols 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. At loadings above about 35 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. In addition, the cyclic tetramer may have a high volatility from water and this may cause losses from water under some conditions. Further information is given in a supporting report (PFA 2016am) attached in Section 13.
The initial hydrolysis product, 3-[dihydroxy(methyl)silyl]propyl methacrylate, is very hydrophilic and hence the calculated solubility is 4.0E+04 mg/l using a QSAR method. However, the saturation concentration of 3-[dihydroxy(methyl)silyl]propyl methacrylate in water is limited by condensation reactions rather than lack of true solubility, as discussed above. The prediction is however considered valid for use in environmental exposure modelling because it is considered to adequately describe the hydrophilicity of the substance and hence the partitioning behaviour.
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.
PFA (2016am). Peter Fisk Associates, Silanols and aquatic systems, 404.105.003
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