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EC number: 220-011-6 | CAS number: 2602-34-8
- 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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Dissociation constant
Administrative data
Link to relevant study record(s)
- Endpoint:
- dissociation constant
- Data waiving:
- study technically not feasible
- Justification for data waiving:
- the study does not need to be conducted because the substance has no ionic structure
- Endpoint:
- dissociation constant
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Principles of method if other than guideline:
- No determination of the dissociation constants in water was possible using OECD Method 112. The test material did not demonstrate pH sensitive spectral profiles in the ultraviolet region of the electromagnetic spectrum. In addition, the weakly acidic nature of the anticipated dissociating groups was not suitable for investigation by either the titration of conductometric methods. An estimation of the first dissociation constant was made using a procedure based on OECD Method 107 (partition coefficient by the shake flask method) and the relationship between partition coefficient, aqueous phase pH and dissociation constant.
- GLP compliance:
- yes (incl. QA statement)
- Dissociating properties:
- yes
- No.:
- #1
- pKa:
- 9.6
- Temp.:
- 22 °C
- Remarks on result:
- other: ±0.3
- No.:
- #2
- pKa:
- > 11
- Temp.:
- 22 °C
- Remarks on result:
- other: Estimate
- No.:
- #3
- pKa:
- > 11
- Temp.:
- 22 °C
- Remarks on result:
- other: Estimate
- Conclusions:
- A first dissociation constant of 9.6 for phenylsilanetriol was determined in a reliable study conducted in compliance with GLP.
Referenceopen allclose all
The results of each determination are shown in the following table:
Nominal test pH |
Sample Number |
Aqueous Phase pH |
Partition coefficient (P’ow) |
Dissociation constant (pKa) |
8.0 |
1 |
7.99 |
0.874 |
8.7* |
8.0 |
2 |
8.03 |
0.941 |
8.9* |
8.5 |
3 |
8.58 |
0.883 |
9.3 |
8.5 |
4 |
8.58 |
0.883 |
9.3 |
9.0 |
5 |
9.08 |
0.879 |
9.8 |
9.0 |
6 |
9.08 |
0.837 |
9.7 |
9.5 |
1 |
9.21 |
0.563 |
9.3 |
9.5 |
2 |
9.26 |
0.648 |
9.5 |
10.0 |
3 |
9.78 |
0.408 |
9.6 |
10.0 |
4 |
9.91 |
0.404 |
9.7 |
10.5 |
5 |
10.48 |
0.182 |
9.8 |
10.5 |
6 |
10.49 |
0.178 |
9.8 |
* The results at pH 8 were excluded from the determination of the final pKa mean and range on the basis that the accuracy of the estimation method decreased as the distance between the dissociation constant and the aqueous phase pH increased, pH 8.0 being >1.5 units from the final estimation value. This is consistent with the approach used in the titration method in OECD method 112.
Description of key information
Dissociation constant [3 -(2,3 -epoxypropoxy)propyl]triethoxysilane: No ionisable groups within relevant environmental pH
Dissociation constant 2,3-dihydroxypropoxypropylsilanetriol: 9.6
Key value for chemical safety assessment
Additional information
The requirement to test the substance for dissociation constant is waived because there are no groups present in the molecule that are expected to ionize within an environmentally relevant pH range. However, the substance will moderately hydrolyse in contact with water to form 2,3-dihydroxypropoxypropylsilanetriol and ethanol. There are no reliable measured data for the dissociation constant of 2,3-dihydroxypropoxypropylsilanetriol. The typical dissociation constants for the hydroxyl protons of silanetriols are available from studies in other silanetriols. It is appropriate to read-across dissociation constant data for 2,3-dihydroxypropoxypropylsilanetriol from phenylsilanetriol. This suggests that silanols are not expected to undergo significant dissociation within the range of pH relevant in the environment or in vivo. Phenylsilanetriol has a measured first dissociation constant ca.10 in a reliable study using a relevant test method, (reliability 1; read-across conclusion is given reliability 2). Additional information is given in a supporting report (PFA 2013b) attached in Section 13 of the REACH technical dossier.
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.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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