Registration Dossier
Registration Dossier
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EC number: 213-934-0 | CAS number: 1067-53-4
Dissociation constant
Administrative data
Link to relevant study record(s)
- Endpoint:
- dissociation constant
- Data waiving:
- study scientifically not necessary / other information available
- Justification for data waiving:
- the study does not need to be conducted because the substance is hydrolytically unstable (half-life less than 12 hours)
Reference
Description of key information
Dissociation constant [tris(2-methoxyethoxy)(vinyl)silane]: Not relevant due to rapid hydrolysis in contact with water
Dissociation constant [vinylsilanetriol]: pKa approximately 10
Key value for chemical safety assessment
Additional information
The requirement to conduct a dissociation constant study for the substance is waived because in contact with water, the substance hydrolyses rapidly. The hydrolysis products in this case are vinylsilanetriol and 2-methoxyethanol.
There are no reliable measured data for the dissociation constant of vinylsilanetriol. 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 vinylsilanetriol 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. Additional information is given in a supporting report (PFA 2013b) attached in Section 13 of the REACH technical dossier.
2 -Methoxyethanol has a first dissociation constant of 14.8 at 25°C, reported in a secondary source (Serjeant 1979).
References:
PFA (2013b). Peter Fisk Associates, Dissociation constant Analogue report, PFA.300.001.001
Serjeant, E.P., Dempsey B (1979). Ionisation Constants of Organic Acids in Aqueous Solution. International Union of Pure and Applied Chemistry (IUPAC). IUPAC Chemical Data Series No. 23, 1979. New York, New York: Pergamon Press, Inc., p. 46
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