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EC number: 241-816-9 | CAS number: 17865-07-5
- 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
Additional information
It is well known that triacetoxisilane undergoes rapid hydrolysis in aqueous or moist environments to acetic acid and trisilanol.
The confirm that hydrolysis of acetoxysilanes is fast, the test of hydrolysis of propyl triacetoxysilane in water was performed. It was measured, that the process was very fast. The half-life at different pH of propyltriacetoxysilane was determined to be < 37.5 seconds since the test item was completely hydrolysed at 150 seconds after the initial contact with water.
As it is stated in different publications, silanols hydrolyse well in water and the carbon- bounded substituents can have profound effects on the rate of hydrolysis. (Arkles B., Chemtech 1977; Pluddemann E.P., Plenum Press NY, 1982; Kay, B.D. and Assink R.A, J. Non-Cryst. Solids, 1988).
The rates of hydrolysis of the alkoxy groups are generally related to their steric bulk: CH3O>C2H5O> t-C4H9O and a methoxysilane hydrolyzes at 6-10 times rate of an ethoxysilane. Smith (Smith K. J. Org. Chem 1986) proved that increased organic substitution enhances the hydrolysis rate Me3SiOMe> Me2Si(OMe)2> MeSi(OMe)3.
During the performed hydrolysis test, the condensation and polimerysation of the molecules formed in hydrolysis were observed too. It was observed as the phase separation. Unfortunately, this phase separation caused the technical difficulties of the determination of the molecular weight of larger condensation products. It was possible to determined MW of smaller condensates which still are in solutions. Their average MW were between 604-695.
This phase separation as a result of condensation was described by Arkles. The hydrolysis of propyltrimetoxysilane showed that oligomers are formed and branched structures presages phase separation (Arkles B. et al, Silanes and Coupling Agents, 1992).
Taking in account both, the hydrolysis and condensation, it is expected that the observed in the hydrolysis test phase changed product contains large chain polymers with MW>1000.
Authors showed that molecules of MW>1000 cannot be biologically available (Van Gestel et a, Reg. Toxicol. and Pharmacol., 1985, 5, 422-31 and Zitko V, Handbook of Environmental Chemistry, v. 2 221-29).
A stated before, triacetoxysilane is not stable when exposed to water or moisture and undergo rapid hydrolysis. The hydrolysis produces 3 moles of acetic acid and the silanetriol which condensate to higher weight siloxanes. The polymerization products are considered biologically unavailable and the toxicity is driven by acetate anion.
The toxicity of propyltriacetoxysilane should be evaluated as the toxicity of acetic acid.
The results from aquatic toxicity studies for propyltriacetoxysilane are as follow:
- Short-term toxicity to fish. Weight of evidence: LC50 (96h) = 108.89 mg/L (based on mortality) (read-across from supporting substance acetic acid).
- Short-term toxicity to aquatic invertebrates: Weight of evidence: EC50 (48h) = 89.59 mg/L (based on mobility and without pH adjustment) (read-across from supporting substance acetic acid).
- Toxicity to aquatic algae: Key study: EC50 (72h) = 24.41 mg/L and NOEC (72h) = 18 mg/L (based on growth rate and without pH adjustment)
- Toxicity to microorganisms: Key study: NOEC (28 days) = 105.45 mg/L (based on biodegradation) (read-across from analogue substance methyltriacetoxysilane).
Based on the results from the aquatic toxicity (at least one value between 10 and 100 mg/L) but since the substance is readily biodegradable and according to CLP Regulation 1272/2008, the substance propyltriacetoxysilane is not classified for aquatic toxicity.
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