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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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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dissociation constant
Data waiving:
study technically not feasible
Justification for data waiving:
the study does not need to be conducted because the substance has no ionic structure

Description of key information

Dissociation constant: not relevant

Key value for chemical safety assessment

Additional information

The requirement to test the substance for dissociation constant is waived because there are no ionisable groups present in the molecule.

In contact with water, the ketone group of Cyrene™ ((1S,5R)-6,8 -dioxabicyclo[3.2.1]octan-4-one) hydrates to form the Gem Diol form. The hydration is fully reversible and a dynamic equilibrium is established (see attached document in Section13 for further details).

The hydroxy (-OH) group in Gem Diol is expected to dissociate under strong basic conditions, it has a calculated pKa value of 14.5 using the SPARC estimation method. Therefore, in the range of pH usually considered relevant to the human body and environment, i.e. pH 2-9, Gem Diol is expected to be non-ionised.