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Dissociation constant

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Reference
Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Principles of method if other than guideline:
Data was taken from a peer-reviewed article or handbook
Dissociating properties:
yes
No.:
#1
pKa:
>= 5 - <= 6
Temp.:
25 °C

Chemically, naphthenic acids behave like typical carboxylic acids with similar acid strengths as the higher fatty acids. Dissociation constants are in the order of 10-5 to 10-6. They are slightly weaker acids than low molecular weight carboxylic acids such as acetic acid, but are stronger acids than phenol and cresylic acid.

Conclusions:
Dissociation constants of naphthenic acids are in the order of 10^(-5) to 10^(-6).

Description of key information

Dissociation constants are in the order of 10-5 to 10-6 based on literature data considered reliable with restrictions (K2) and assigned as key study.

Key value for chemical safety assessment

pKa at 20°C:
5

Additional information

Chemically, naphthenic acids behave like typical carboxylic acids with similar acid strengths as the higher fatty acids. Dissociation constants are in the order of 10-5to 10-6. They are slightly weaker acids than low molecular weight carboxylic acids such as acetic acid, but are stronger acids than phenol and cresylic acid.