Registration Dossier
Registration Dossier
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EC number: 221-660-8 | CAS number: 3179-76-8
Dissociation constant
Administrative data
Link to relevant study record(s)
Description of key information
Dissociation constant (amine group): pKa = ca. 10 (Estimation)
Dissociation constant 3-(dihydroxymethylsilyl)propylamine: pKa = ca. 12
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 rapidly. The hydrolysis products in this case are 3-(dihydroxymethylsilyl)propylamine and ethanol. There are no reliable measured data for the dissociation constant of 3-(dihydroxymethylsilyl)propylamine. The typical dissociation constants for the hydroxyl protons of silanediols are available from studies in other silanediols. It is appropriate to read-across dissociation constant data for 3-(dihdroxymethylsilyl)propylamine from dimethylsilanediol. This suggests that silanols are not expected to undergo significant dissociation within the range of pH relevant in the environment or in vivo. Dimethylsilanediol is reported in a secondary source to have a first dissociation constant of 11.9. Additional information is given in a supporting report (PFA 2013b) attached in Section 13 of the REACH technical dossier.
The acid dissociation constant of the amine group has been calculated using an appropriate predictive method to be ca. 10.
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