Registration Dossier

Physical & Chemical properties

Dissociation constant

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

Dissociation constant [chloro(dimethyl)vinylsilane]: Not relevant
Dissociation constant [dimethyl(vinyl)silanol]: pKa approximately 11

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 hydrolyses very rapidly. The hydrolysis products in this case are dimethyl(vinyl)silanol and hydrochloric acid. There are no reliable measured data for the dissociation constant of dimethyl(vinyl)silanol. The typical dissociation constants for the hydroxyl protons of silanols are available from studies in other silanols. It is appropriate to read-across dissociation constant data for dimethyl(vinyl)silanol from trimethylsilanol. This suggests that silanols are not expected to undergo significant dissociation within the range of pH relevant in the environment or in vivo. Trimethylsilanol is reported in a secondary source to have a first dissociation constant of ca. 11. Additional information is given in a supporting report (PFA 2013b) attached in Section 13 of the REACH technical dossier.