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Dissociation constant

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Endpoint:
dissociation constant
Type of information:
calculation (if not (Q)SAR)
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Principles of method if other than guideline:
The pKa of the amine group was obtained using the SPARC on-line property calculator.
GLP compliance:
no
Dissociating properties:
yes
No.:
#1
pKa:
8.5
No.:
#2
pKa:
9.8
Conclusions:
pKa1 of 8.5 and pKa2 of 9.8 were determined for the amine groups using an appropriate predictive method.
Endpoint:
dissociation constant
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
the study does not need to be conducted because the substance is hydrolytically unstable (half-life less than 12 hours)

Description of key information

Dissociation constant [Constituent 1]: pKa1 = 8.5, pKa2 = 9.8

Dissociation constant [N-[3-(trihydroxysilyl)propyl]-1,3-benzenedimethanamine]: pKa1 = 8.8, pKa2 = 10.4, pKa3 = 12.1

Key value for chemical safety assessment

Additional information

The requirement to conduct a dissociation constant study for the substance is waived because in contact with water, the constituents of the substance hydrolyses rapidly or very rapidly. The final hydrolysis products in this case are N-[3-(trihydroxysilyl)propyl]-1,3-benzenedimethanamine and methanol.

Dissociation constants for the amino groups present in Constituent 1 and the final silanol hydrolysis product have been predicted using a relevant calculation method. The results indicate that both amine nitrogens will be protonated at neutral and acid pH.