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EC number: 227-575-2 | CAS number: 5894-60-0
- 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
Trichloro(hexadecyl)silane (CAS No. 5894-60-0) reacts violently with water and hydrolyses very rapidly (DT50 << 2 min at pH 7 and room temperature) to the silanol hydrolysis product hexadecylsilanetriol and hydrochloric acid. Furthermore, it is characterized by a low vapour pressure of 7.0E-05 Pa at 20°C, indicating a low potential for volatility. Trichloro(hexadecyl)silane and its silanol hydrolysis product do not contain chromophores that would absorb visible or UV radiation, so direct photolysis is not likely to be significant. Indirect photolysis resulting from gas-phase reaction with photochemically-produced hydroxyl radicals may occur. The calculated photodegradation half-life based on the reaction with hydroxyl radicals is 3.5 days. Therefore, photodegradation is not a relevant degradation pathway for the registered substance. However, for its silanol hydrolysis product a photodegradation half-life of 0.5 days was obtained. Based on the very low vapour pressure of hexadecylsilanetriol (< 1.0E-05 Pa at 25 °C) the evaporation into the air compartment is insignificant and therefore the photodegradation in air cannot be considered a relevant pathway for degradation of the silanol hydrolysis product.
The substance is expected to be inherently biodegradable based on evidence from the structurally analogue read-across substance cloro(dimethyl)octadecylsilane (CAS No. 18643-08-8). Thus, biodegradation contributes significantly to its degradation in the aquatic environment and the registered substance does not persist in the environment.
Silanol hydrolysis product hexadecylsilanetriol
The silanol hydrolysis product hexadecylsilanetriol is characterized by a moderate, estimated water solubility of 4.7 mg/L at 20 °C (QSAR). The silanol hydrolysis product is expected to be inherently biodegradable based on evidence from the structurally analogue read-across substance chloro(dimethyl)octadecylsilane (CAS No. 18643-08-8), which is the parent substance of a structurally very similar silanol hydrolysis product, octadecyldimethylsilanol. Thus, biodegradation contributes significantly to its degradation in the aquatic environment and hexadecylsilanetriol does not persist in the environment. Nevertheless, its potential for bioaccumulation and its affinity to soil and sediment might be high based on its estimated log Kow (5, QSAR) and its estimated log Koc value (5.6 (QSAR). Based on a low predicted vapour pressure of < 1.0E-05 Pa at 25 °C (QSAR) and a low calculated Henry’s Law constant of 5.9E-07 Pa m3mol-1, volatilization from the water phase into the atmosphere is negligible.
Second hydrolysis product hydrochloric acid (CAS No. 7647-01-0)
Hydrochloric acid is well characterized in the public domain. It has a high vapour pressure of 42200 hPa at 20 °C and a high solubility in water (823g/L at 0°C and 673 g/L at 30°C). In the environment, it is expected to distribute into the air and water. In water, it forms the aqueous solution hydrochloric acid.
In air, hydrogen chloride reacts with hydroxyl radicals into chloride free radicals and water (calculated half-life of 11 d). In water, hydrochloric acid readily dissociates into hydrated protons and chloride anions. Thus, it is ionised and neutralisation depends on the buffer capacity of the receiving water. Because hydrochloric acid is an inorganic substance, biodegradation is not a relevant degradation pathway. However, due to its high solubility and readily dissociation in water, it is not expected to accumulate in organisms. The aquatic hazard is mediated by the proton in a concentration-dependent manner (i.e. pH effect) and its potency strongly depends on the buffer capacity of the respective aquatic system. Toxicity only occurs when the buffering capacity of the receiving water is exceeded and pH values fall below pH 6. The pH in rivers and lakes fluctuates within a natural range. The natural pH range in aquatic systems is generally not expected to be perturbed to a relevant extent by anthropogenic emissions when appropriate risk control measures are in place. Variations in effect values of experimental studies can largely be explained by variations in the buffer capacity of the test media (OECD, 2002).
References:
OECD, 2002. Hydrogen Chloride - SIDS Initial Assessment Report for SIAM 15, Boston, USA: UNEP Publications.
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