Registration Dossier
Registration Dossier
Data platform availability banner - registered substances factsheets
Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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
Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.
EC number: 253-973-0 | CAS number: 38495-30-6
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Water solubility
Administrative data
Link to relevant study record(s)
Description of key information
Water solubility [12,12-dimethyl-2,5,8,11,13,16,19,22-octaoxa-12-silatricosane]: 4.7E+05 mg/l at 20°C (QSAR)
Water solubility [dimethylsilanediol]: Above approximately 1000 mg/l condensation reactions can occur over time, limiting the concentration dissolved in water. The calculated solubility is 1E+06 mg/l at 20°C (QSAR)
Water solubility [2-[2-(2-methoxyethoxy)ethoxy]ethan-1-ol]: 1.05E+06 mg/l at 20°C
Key value for chemical safety assessment
- Water solubility:
- 470 000 mg/L
- at the temperature of:
- 20 °C
Additional information
The water solubility of the substance has been calculated using a validated QSAR method to be 4.7E+05 mg/l at 20°C.
In contact with water, the substance hydrolyses moderately rapidly to form dimethylsilanediol and 2-[2-(2-methoxyethoxy)ethoxy]ethan-1-ol (triethylene glycol, CAS 112-35-6).
The silanol hydrolysis product, dimethylsilanediol, may undergo condensation reactions in solution to give siloxane dimers, and linear and cyclic oligomers 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 silanediols may be modelled as an equilibrium between monomer, dimer, trimer and tetramer, with the linear tetramer cyclising to the thermodynamically stable cyclic tetramer. At higher loadings, cross-linking reactions between the cyclic tetramers may occur. 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 dimethylsilanediol, a solution at 100 mg/l (often the top loading used in ecotox tests) is predicted to contain >99% monomer, with small amounts of dimer, trimer, and cyclic tetramer. At loadings above 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. In addition, the cyclic tetramer is expected to 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, 2014am) attached in Section 13 of the IUCLID dataset.
The initial hydrolysis product, dimethylsilanediol, is very hydrophilic and hence the calculated solubility is 1E+06 mg/l using a QSAR method. However, the saturation concentration of dimethylsilanediol 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. The prediction is however considered valid for use in calculation of the Henry’s Law Constant and for environmental exposure modelling because it is considered to adequately describe the hydrophilicity of the substance and hence the partitioning behaviour.
On the ECHA disseminated dossier webpage, the non-silanol hydrolysis product, 2-[2-(2-methoxyethoxy)ethoxy]ethan-1-ol has a reported water solubility value of 1.05E+06 mg/l (1049 g/l) at 20°C at pH 7.
Reference:
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.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.