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Physical & Chemical properties

Dissociation constant

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Reference
Endpoint:
dissociation constant
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
1. SOFTWARE
Marvin Suite (can be downloaded at www.chemaxon.com)
2. MODEL (incl. version number)
Version 17.4.3.0
3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL:
OC(=O)C1=CC=C(C=C1C(O)=O)S(O)(=O)=O

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
The dissociation constant method using microconstants is based mainly on empirically calculated partial charges. Hydrogen bonds are also parameterized and taken into account within the calculation. Predicted and experimental values are in good correlation (r2 =0.95, s=0.72, n=1670; y=0.98pKa,exp+0.12). For additional details see https://www.chemaxon.com/library/prediction-of-dissociation-constant-using-microconstants.

5. APPLICABILITY DOMAIN
For common organic compounds and pharmaceutical molecules

6. ADEQUACY OF THE RESULT
The dissociation constants derived from the microconstant method are scientifically reliable as it falls into its applicability organic substance domain. The derived value will not be used for hazard classification purposes however, it will allow us to predict fate, transport, and toxicokinetic properties.
Qualifier:
according to
Guideline:
other: The method empirically calculates partial charges and hydrogen bonds are also parameterized and taken into account within the calculation.
Principles of method if other than guideline:
The method is based mainly on empirically calculated partial charges. Hydrogen bonds are also parameterized and taken into account within the calculation. Predicted and experimental values are in good correlation (r =0.95, s=0.72, n=1670) for common organic compounds and pharmaceutical molecules.
GLP compliance:
no
Remarks:
not applicable
Dissociating properties:
yes
No.:
#1
pKa:
ca. -2.85
Temp.:
25 °C
Remarks on result:
other: red hydrogen (see picture)
No.:
#2
pKa:
ca. 2.78
Temp.:
25 °C
Remarks on result:
other: blue hydrogen (see picture)
No.:
#3
pKa:
ca. 5.34
Temp.:
25 °C
Remarks on result:
other: green hydrogen (see picture)
Conclusions:
The value of ithe calculated dissociation constants (pKa) for the reaction mass of 3-sulphophthalic acid and 3-sulphophthalic acid falls into the range -2.85 to 5.34.

Description of key information

The Marvin Suite (Version 17.4.3.0) value of the calculated dissociation constants (pKa) for the reaction mass of 3-sulphophthalic acid and 3-sulphophthalic acid falls into the range -2.85 to 5.34.

Key value for chemical safety assessment

pKa at 20°C:
-2.85

Additional information