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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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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Endpoint:
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
the study does not need to be conducted because the substance is insoluble
Justification for type of information:
JUSTIFICATION FOR DATA WAIVING
Based on its chemical structure, no ionisation is anticipated for the parent substance, in particular under environmentally relevant pH range.
Moreover, as presented under IU section 4.8, the solubility in water is expected to be very low.
Endpoint:
dissociation constant
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Study period:
run on 2013-02-26
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
results derived from a (Q)SAR model, with limited documentation / justification
Remarks:
The value is not an experimental result, however the QSAR model is recommended by the ECHA guidance document on information requirements, but no documentation is available in the on-line calculator with regard to the applicability domain and validation parameters according to OECD principles.
Principles of method if other than guideline:
QSAR calculation
Dissociating properties:
yes
pKa:
3.56
Temp.:
20 °C

The above value is for the reaction R-C(=O)OH <---> R-C(=O)O-

Conclusions:
The pKa for the test substance is below the environmentally relevant pH range of 5-9.
The substance will be mainly under its ionised form in this range.
Executive summary:

The dissociation constant of the test substance was estimated using the recommended QSAR model SPARC v4.6. No data is available with regard to validation parameters according to OECD principles.

The calculated result is pKa = 3.56 at 20°C.

Endpoint:
dissociation constant
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Study period:
run on 2013-02-26
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
results derived from a (Q)SAR model, with limited documentation / justification
Remarks:
The value is not an experimental result, however the QSAR model is recommended by the ECHA guidance document on information requirements, but no documentation is available in the on-line calculator with regard to the applicability domain and validation parameters according to OECD principles.
Principles of method if other than guideline:
QSAR calculation
Dissociating properties:
yes
pKa:
4.33
Temp.:
20 °C

The above value is for the reaction R-C(=O)OH <---> R-C(=O)O-

Conclusions:
The pKa for the test substance is below the environmentally relevant pH range of 5-9.
The substance will be mainly under its ionised form in this range.
Executive summary:

The dissociation constant of the test substance was estimated using the recommended QSAR model SPARC v4.6. No data is available with regard to validation parameters according to OECD principles.

The calculated result is pKa = 4.33 at 20°C.

Endpoint:
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
Justification for type of information:
JUSTIFICATION FOR DATA WAIVING
Based on its chemical structure, no ionisation is anticipated for the metabolite DD, in particular under environmentally relevant pH range.

Description of key information

pKa = 3.56 and 4.33 respectively for degradation products DD-ma and DD-mp.

Both substances will be mainly under their ionised form at environmental pH (5-9), and totally ionised in alkaline media (pH>7).

The third metabolite DD is not anticipated to dissociate.

Key value for chemical safety assessment

Additional information

As the parent substance is likely to degrade into DD-ma, DD-mp and DD, information is provided on the pKa of the metabolites, which are the relevant species for the environmental risk assessment, and have both a carboxylic acid function.

The pKa was estimated using the QSAR model SPARC.