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Dissociation constant

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Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP guideline study, solvent used, therefore results are not so accurate
Qualifier:
according to guideline
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
GLP compliance:
yes
Specific details on test material used for the study:
The test was performed with 2-phenylphenol, the conjugate acid of sodium 2-biphenylate.
99.9 % 2-phenylphenol
No.:
#1
pKa:
11.4
Remarks on result:
other: No temperature control. As about 30 % acetone was added to increase the solubility of the test substance, the received pKa value was higher than the one determined in demineralized water in study no.: A 89/0062/06 LEV
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
Qualifier:
according to guideline
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
GLP compliance:
yes
Specific details on test material used for the study:
The test was performed with 2-phenylphenol, the conjugate acid of sodium 2-biphenylate.
99.89 % 2-phenylphenol
Dissociating properties:
yes
pKa:
9.5
Temp.:
20 °C
Remarks on result:
other: Acid-base constant: pKa = 9.5 ± 0.1

Description of key information

pKa (2-phenylphenol) = 9.5 at 20 °C

(OECD 112)

Key value for chemical safety assessment

pKa at 20°C:
9.5

Additional information

A pKa value of 9.5 at 20 °C was determined for 2-phenylphenol (conjugate acid of sodium 2-biphenylate) during tests according to OECD Guideline 112. A pKa value of 11.4 was determined in a different study during tests according to OECD Guideline 112. The difference between the two measured values could be attributed to the use of solvent in the second study.