Naphthenic acids

Dissociation constant

Link to relevant study record(s)

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.