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Physical & Chemical properties

Dissociation constant

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Description of key information

Dissociation constant [trimethoxy(vinyl)silane]: Not relevant due to very rapid hydrolysis in contact with water

Dissociation constant [vinylsilanetriol]: ca. 10

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 hydrolyse very rapidly. The hydrolysis products in this case are vinylsilanetriol and methanol. 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.