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Administrative data

Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2003
Report date:
2003

Materials and methods

Principles of method if other than guideline:
Information on acid base properties of ZK 232105 was to be obtained as a contribution to the Schering project “Ecotoxicological Evaluation of Starting Materials, Intermediates and Drug Substances”. The project is part of the “Freiwillige Selbstverpflichtung der deutschen chemischen Industrie für die Erfassung und Bewertung von Stoffen” (voluntary self commitment of the German chemical industry to catalogue and evaluate chemicals) as promoted by the VCI (Verband der Chemischen Industrie). Since the dissociation properties of the free Jotroxinoic acid ZK 24524 and their disodium salt ZK 232105 are totally equal in aqueous solution, the free acid was used for determination of the acid dissociation constants. Measurements were carried out at 25 °C with a photometric titration method giving the following dissociation constants: pKa1 = 1.2 and pKa2 = 11.8.

Test material

Constituent 1
Chemical structure
Reference substance name:
Disodium-3,3´-{Oxybis[2,1-ethanediyloxy(1-oxo-2,1-ethanediyl)imino]}bis(2,4,6-triiodobenzoate)
EC Number:
942-225-5
Molecular formula:
C22H16I6N2O9
IUPAC Name:
Disodium-3,3´-{Oxybis[2,1-ethanediyloxy(1-oxo-2,1-ethanediyl)imino]}bis(2,4,6-triiodobenzoate)
Test material form:
solid: bulk
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: WBF, Schering AG; Batch number 61704006

Results and discussion

Dissociating properties:
yes
Dissociation constantopen allclose all
No.:
#1
pKa:
1.2
Temp.:
25 °C
Remarks on result:
other: calculated
No.:
#2
pKa:
11.8
Temp.:
25 °C
Remarks on result:
other: calculated

Any other information on results incl. tables

Table 1: pKa values obtained at different wavelength
Wavelength (nm)   pKa1 Wavelength (nm)  pKa2
237 1.27 230 11.72
240 1.22 235 11.8
---- ---- 300 11.86

Applicant's summary and conclusion

Conclusions:
acid base properties of the test substance were to be obtained with a photometric titration method. Since the dissociation properties of the free Jotroxinoic acid ZK 24524 and their disodium salt ZK 232105 are totally equal in aqueous solution, the free acid was used for determination of the acid dissociation constants. Measurements were carried out at 25 °C giving the following dissociation constants: pKa1 = 1.2 and pKa2 = 11.8.
Executive summary:

acid base properties of the test substance were to be obtained with a photometric titration method. Since the dissociation properties of the free Jotroxinoic acid ZK 24524 and their disodium salt ZK 232105 are totally equal in aqueous solution, the free acid was used for determination of the acid dissociation constants. Measurements were carried out at 25 °C giving the following dissociation constants: pKa1 = 1.2 and pKa2 = 11.8.

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