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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Physical & Chemical properties

Dissociation constant

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Link to relevant study record(s)

Description of key information

Dissociation constant [1-(tert-butyldimethylsilyl)piperazine]: Not relevant due to very rapid hydrolysis


Dissociation constant [piperazine]: pKa1 = 9.73 and pKa2 = 5.33

Key value for chemical safety assessment

Additional information

The requirement to conduct a dissociation constant study for the submission substance is waived because in contact with water, it hydrolyses very rapidly to form tert-butyldimethylsilanol and piperazine.

The silanol hydrolysis product is not expected to dissociate within relevant pH associated with environmental assessment.

Piperazine has reported pKa1 = 9.73 and pKa2 = 5.33 (Perrin DD 1972).


Perrin DD (1972). Dissociation Constants of Organic Bases in Aqueous Solution. IUPAC Chemical Data Series: Supplement. Buttersworth, London