Registration Dossier
Registration Dossier
Diss Factsheets
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EC number: 278-947-6 | CAS number: 78560-45-9
- 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

Endpoint summary
Administrative data
Description of key information
- pH; the condensation reaction may be either acid or base catalysed.
- Temperature.
- Other species present.
- The nature of the R group
- Timescale
- The number of Si-OH groups; silanetriols condense more rapidly than silanediols
The substance, [2-(perfluorohexyl)ethyl]trichlorosilane is not stable in water, which affects the approach to the determination of physicochemical properties. The significance of this for read-across is discussed in Section 1.4 of the CSR.
In accordance with ECHA decision number CCH-2120771164-56-01/F, a hydrolysis study is contracted with the registered substance. If the substance is demonstrated to decompose rapidly in contact with water, the water solubility and partition coefficient endpoints can be waived in accordance with Column 2 of REACH Annex VII. Should this not be the case, a water solubility study according to OECD TG 105 and a partition coefficient study using an HPLC method will be attempted, if the results of the hydrolysis study indicate that these may be technically feasible. The dossier will be further updated when the result of the hydrolysis study is available.
[2-(Perfluorohexyl)ethyl]trichlorosilane is a liquid at standard temperature and pressure, with a measured melting point of -21°C and a measured boiling point of 192.4°C. It has a predicted density of 1.6 g/cm3 at 20°C, a predicted log Kow of 7.0 and a predicted vapour pressure of 30 Pa at 25°C.
The substance is not classified for flammability according to Regulation (EC) No. 1272/2008. In a flash point study, decomposition was observed at 138°C without ignition. It has a measured auto-ignition temperature of 380°C at 1015 -1020 hPa, and is not oxidising on the basis of chemical structure.
[2-(Perfluorohexyl)ethyl]trichlorosilane was not explosive under the conditions of an explosivity study in accordance with EU Method A.14.
In contact with water under dilute conditions, [2-(perfluorohexyl)ethyl]trichlorosilane reacts very rapidly (estimated half-life by read-across of <1 minute pH 4, pH 7 and pH 9 and 25°C) to produce [2-(perfluorohexyl)ethyl]silanetriol and hydrochloric acid according to the following equation:
Cl3SiCH2CH2(CF2)5CF3+ 3H2O → CH2CH2(CF2)5CF3Si(OH)3 + 3HCl
Therefore, requirements for testing of water-based physicochemical properties for the substance are waived on the basis of instability in water. The properties of the silanol hydrolysis product, [2-(perfluorohexyl)ethyl]silanetriol are assessed instead of the parent.
The silanol hydrolysis product, [2-(perfluorohexyl)ethyl]silanetriol has a predicted water solubility of 0.58 mg/l at 20°C using a QSAR method and a predicted log Kow of 2.7.
The surface tension of[2-(perfluorohexyl)ethyl]trichlorosilane was waived because the substance hydrolyses very rapidly in contact with water to form [2-(perfluorohexyl)ethyl]silanetriol and hydrochloric acid. Instead, the surface tension of the silanol hydrolysis product, [2-(perfluorohexyl)ethyl]silanetriol, was determined from a study conducted in accordance with EU Method A.5 using [2-(perfluorohexyl)ethyl]trimethoxysilane (CAS No. 85857-16-5) as the test substance. In contact with water, [2-(perfluorohexyl)ethyl]trimethoxysilane reacts rapidly (half-lives of 0.4 h at pH 4, 0.4 h at pH 5, 8.8 h at pH 7, 0.1 h at pH 9 and 20-25°C) to form [2-(perfluorohexyl)ethyl]silanetriol and methanol. The silanol hydrolysis product, [2-(perfluorohexyl)ethyl]silanetriol is considered to be surface active based on a measured surface tension value of <22 mN/m at 20°C and 1 g/l.[2-(Perfluorohexyl)ethyl]silanetriol is much less volatile than the parent substance (vapour pressure = 6.9E-03 Pa at 25°C, predicted).The silanol hydrolysis product, [2-(perfluorohexyl)ethyl]silanetriol, 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.
Silanetriols may undergo condensation reactions to give siloxane dimers, oligomers and polymers, according to the scheme:
RSi(OH)3 ⇄ RSi(OH)2OSi(OH)2R ⇄ RSi(OH)2O[Si(R)(OH)O]nSi(OH)2R
(where R is an alkyl or aryl side-chain)
In an aqueous solution, a highly cross-linked gel may form. The degree of condensation that will occur may vary with:
In the case of this substance, the R group (C8H4F13) contains a perfluorohexyl chain; fluorocarbons have very low solubility in water, relative to hydrocarbons of equivalent chain length (e.g. Horvath 1982), so it would be expected that a substance with this R group would be of low solubility; the corresponding monomeric silanetriol is surface active based on measured and read-across data. The presence of fluorocarbon chains may mean that condensation products could have some surface activity. For these reasons, the effective limits of solubility of both the parent substance and monomeric silanol hydrolysis products are expected to be very low and all forms of the substance may have a tendency to enrich at surfaces rather than forming stable evenly dispersed solutions. These phenomena may limit the extent of hydrolysis under conditions at which the solubility of either parent or oligomer is exceeded. The predicted rates presented above relate to dilute conditions. These factors are important in any consideration of aqueous behaviour and properties.
Methanol is miscible with water, has low log Kow(-0.82 to -0.64) and high vapour pressure (12790 Pa at 20°C) (OECD, 2004a: SIDS Initial Assessment Report for SIAM 19, Berlin, Germany, 18 - 20 October 2004, Methanol, CAS 67-56-1).
Horvath A L (1982). Halogenated hydrocarbons: solubility-miscibility with water. CRC Press 26 February 1982.
Additional information
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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