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EC number: 241-931-4 | CAS number: 18023-33-1
- 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
Ecotoxicological Summary
Administrative data
Hazard for aquatic organisms
Hazard for air
Hazard for terrestrial organisms
Hazard for predators
Additional information
- Read-across from trimethoxy(vinyl)silane (CAS 2768-02-7) to tri(isopropoxy)(vinyl)silane (CAS 18023-33-1)
The hydrolysis half-life of tri(isopropoxy)(vinyl)silane is 7 h at pH 7, 20-25⁰C. The registered substance will hydrolyse in contact with water and atmospheric moisture to vinylsilanetriol and isopropanol.
REACH guidance (ECHA 2016b, R.16) states that “for substances where hydrolytic DT50 is less than 12 hours, environmental effects are likely to be attributed to the hydrolysis product rather than to the parent substance itself”. TGD and REACH guidance (EC 2003, ECHA 2016c, R.7b) also suggest that when the hydrolysis half-life is less than 12 hours, the breakdown products, rather than the parent substance, should be evaluated for aquatic toxicity.Therefore, the environmental chemical safety assessment (aquatic, sediment and soil) is based on the properties of the silanol hydrolysis product, vinylsilanetriol, in accordance with REACH guidance. Condensation reactions of the silanetriol are possible, as described in Section 4.
READ-ACROSS JUSTIFICATION
In order to reduce animal testing, read-across is proposed to fulfil up to REACH Annex X requirements for the registration substance, from substances that have similar structure and physicochemical properties. Ecotoxicological studies are conducted in aquatic medium or in moist environments; therefore the hydrolysis rate of the substance is particularly important since after hydrolysis occurs the resulting product has different physicochemical properties and structure.
The registration substance, its silanol hydrolysis productand the substance used as a surrogate for read-across (see detailed discussion below) are part of a class of non-functional compounds which act via a non-polar narcosis mechanism of toxicity. The group of organosilicon substances in this group contain alkyl, aryl, alkoxy or hydroxy groups attached to the Si atom when present in aqueous solution. Secondary features may be present in the alkyl chain (e.g. halogen, nitrile, unsaturated bonds) that do not affect the toxicity of the substances. The silanol hydrolysis products may be susceptible to condensation reactions, see Section 1.3 of the CSR. The registered substance hydrolyses rapidly in water and therefore the selection of surrogate substance is based on log Kowof the resulting silanols and the chemical groups present in them.
Additional information is given in a supporting report (PFA 2016y), attached in Section 13.
In the following paragraphs the read-across approach for tri(isopropoxy)(vinyl)silane is assessed for each surrogate substance taking into account structure, hydrolysis rate and physico-chemical properties. The table below presents the properties of the registered and surrogate substances (and their respective hydrolysis products) alongside for comparison.
Tri(isopropoxy)(vinyl)silane (CAS 18023-33-1) and trimethoxy(vinyl)silane (CAS 2768-02-7) both hydrolyse rapidly in contact with water (6.6 h at pH 7, 20-25°C, and 0.2 h at pH 7, 20°C respectively). The organosilicon hydrolysis product is vinylsilanetriol in both cases, with isopropanol and methanol respectively being released as a by-product.
Trimethoxy(vinyl)silane (CAS 2768-02-7) is used to read across to short-term aquatic toxicity to invertebrates and algal growth endpoints. E(L)C50 values of 120 mg/l and >64 mg/l (expressed in terms of concentration of the hydrolysis product, vinylsilanetriol) have been determined.
· Considerations on the non-silanol hydrolysis products:
Methanol and isopropoanol are both well-characterised in the public domain literature and are not hazardous at the concentrations relevant to the studies; the short-term EC50 and LC50 values are in excess of 1000 mg/l (OECD 2004a - SIDS for methanol; OECD 1997 - SIDS for isopropanol) and do not require quantitative consideration.
Table: The key physicochemical parameters and ecotoxicological data for the registered and surrogate substances.
CAS Number |
2768-02-7 |
18023-33-1 |
Chemical Name |
trimethoxyvinylsilane |
tri(isopropoxy)(vinyl)silane |
Si hydrolysis product |
Vinylsilanetriol |
Vinylsilanetriol |
Molecular weight (parent) |
148.2 |
232.4 |
Molecular weight (hydrolysis product) |
106.2 |
See left |
log Kow(parent) |
1.1 |
|
log Kow(silanol hydrolysis product) |
-2 |
See left |
Water sol (parent) |
1.9E+04 mg/l |
|
Water sol (silanol hydrolysis product)) |
1.0E+06 mg/l |
See left |
Vapour pressure (parent) |
1190 Pa |
|
Vapour pressure (hydrolysis product) |
0.02 Pa |
See left |
Hydrolysis t1/2at pH 7 and 25°C |
0.2 h (at 20⁰C) |
6.6 h (QSAR) |
Hydrolysis t1/2at pH 4 and 25°C |
0.04 h |
0.3 h (QSAR) |
Hydrolysis t1/2at pH 9 and 25°C |
0.004 h |
0.1 h (QSAR) |
Short-term toxicity to fish (LC50) |
191 mg/l |
Not available |
Short-term toxicity to aquatic invertebrates (EC50) |
169 mg/l |
Not available |
Algal inhibition (ErC50and NOEC) |
72-h ErC50: >89 mg/l and NOErC >=89 mg/l (7-d) EyC50: 210 mg/l and EyC10 32 mg/l |
Not available |
Long-term toxicity to fish (NOEC) |
Not available |
Not available |
Long-term toxicity to aquatic invertebrates (NOEC) |
Not available |
Not available |
Long-term sediment toxicity (NOEC) |
Not available |
Not available |
Short-term terrestrial toxicity (L(E)C50) |
Not available |
Not available |
Long-term terrestrial toxicity (NOEC) |
Not available |
Not available |
Toxicity to microorganisms (EC50, EC10, NOEC) |
oxygen consumption (P. putida) 5hr EC10 1.1 ml/l |
Not available |
Conclusion on classification
The substance has reliable short-term E(L)C50 values of 263 mg/l in invertebrates and >140 mg/l in algae based on read-across from the hydrolysis product of an analogous alkoxysilane (expressed as concentration of the registration substance to release the same concentration of vinylsilanetriol). It has reliable ErC10 >=140 mg/l in algae, EyC10(7d) = 50 mg/l (recalculated on the same basis).
The substance hydrolyses at a moderate rate in water. It is expected to be readily biodegradable (based on read across from a structural analogue, attributed to degradability of the alkoxy groups; vinylsilanetriol is not expected to be significantly biodegradable).
These data are consistent with the following classification under Regulation (EC) No 1272/2008 (as amended) (CLP):
Acute toxicity: Not classified.
Chronic toxicity: Not classified.
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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