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Physical & Chemical properties

Dissociation constant

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Study is scientifically unjustified

Key value for chemical safety assessment

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In accordance with column 2 of REACH Annex VII, the Dissociation constant study does not need to be conducted as the substance is hydrolytically unstable (half-life less than 12 hours at pH 4, 7 and 9).

There are no reliable measured data for the dissociation constant of methylsilanetriol. 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 methylsilanetriol from phenylsilanetriol. This suggests that silanols are not expected to undergo significant dissociation within the range of pH relevant in the environment orin vivo.

Phenylsilanetriol has a measured first dissociation constant approximately 10 in a reliable study using a relevant test method. Additional information is given in a supporting report (PFA 2013b) attached in Section 13.