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Physical & Chemical properties

Dissociation constant

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Description of key information

substance: not relevant
Dissociation constant (silanetriol hydrolysis product): approximately 10, based on read-across from phenylsilanetriol

Key value for chemical safety assessment

Additional information

The requirement to test the substance for dissociation constant is waived because in contact with water the substance rapidly hydrolyses to form propylsilanetriol and methanol. There are no reliable measured data for the dissociation constant of propylsilanetriol. 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 propylsilanetriol 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 9.6 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.