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EC number: 617-969-6 | CAS number: 87135-01-1
- 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
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Water solubility
Administrative data
Link to relevant study record(s)
Description of key information
Water solubility [1,6-Bis(trimethoxysilyl)hexane]: 0.526 g/l at 20°C (EU Method A.1)
Water Solubility [1,6-Bis(trihdroxysilyl)hexane]: 1E+06 mg/l at 20°C (QSAR); however, above approximately 100 mg/l condensation reactions can occur over time, limiting the concentration dissolved in water
Water solubility [methanol]: miscible with water at 20°C
Key value for chemical safety assessment
- Water solubility:
- 0.526 g/L
- at the temperature of:
- 20 °C
Additional information
The requirement to conduct a water solubility of the substance is waived because in contact with water the substance hydrolyses rapidly to form [1,6-Bis(trihydroxysilyl)hexane] and methanol. The hydrolysis half-lives of the substance are: 0.08 h at pH 5, 5.2 h at pH 7 and 0.15 h at pH 9 and 25.1°C.
However, the water solubility of the substance has been measured using a modified form of EU Test Method A.6. Mixtures of the test substance and distilled water were added to three separate flasks, flask 1, flask 2 and flask 3. The samples were shaken at 30°C for 1 hour, 3 hours and 24 hours respectively with all samples being equilibrated for 1 hour at 20°C. Following filtration of the samples, the concentration in water were measured using GC-FID. The mean water solubility result for samples/flasks 1 and 2 is 0.526 g/l at 20±0.05°C and pH 6.3-6.4. The result is considered to reflect that of the parent compound because of minimal hydrolysis that is considered to have occurred in flasks 1 and 2. The result for flask 3 was discounted as extensive hydrolysis was observed to have occurred.
The silanol hydrolysis product, 1,6-bis(trihydroxysilyl)hexane, 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.In the water solubility study, the formation of a white solid precipitate in the sample solution was observed following the equilibration period at 20°C.
The condensation reactions of silanetriol may be modelled as an equilibrium between monomer, dimer, trimer and tetramer cyclising to the thermodynamically stable cyclic tetramer. However, with silanetriol groups at both ends of the molecule cross linking reactions are highly probable creating insoluble particles. Condensation reactions are expected to become important at loadings above 100 mg/l causing the formation of insoluble polymeric particles (sols) and gels over time. Further information is given in a supporting report (PFA 2013am) attached in Section 13 of the IUCLID dataset.
The hydrolysis product, 1,6-bis(trihydroxysilyl)hexane, is 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. The prediction is however considered to be valid for use in calculation of the Henry's Law Constant and for environmental exposure modelling and toxicokinetics modelling because it is considered to adequately describe the hydrophilicity of the substance and hence the partitioning behaviour.
Methanol was reported to be miscible in water at 20°C (OECD 2004).
PFA, 2013am, Peter Fisk Associates, Silanols and aquatic systems, 350.001.003
OECD (2004): SIDS Initial Assessment Report for SIAM 19, Berlin, Germany, 18-20 October 2004, Methanol, CAS 67-56-1.
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