Naphthenic Acid

Cas Number


Other Names


The formula



Naphthenic acid(NAs) is the name for an unspecific mixture of several cyclopentyl and cyclohexyl carboxylic acids with molecular weight of 120 to well over 700 atomic mass units. The main fraction are carboxylic acids with a carbon backbone of 9 to 20 carbons. McKee et al. claim that "naphthenic acids (NAs) are primarily cycloaliphatic carboxylic acids with 10 to 16 carbons."[1] Salts of naphthenic acids, which are naphthenates, are widely used as hydrophobic sources of metal ions in diverse applications.

Physical and Chemical Properties
Physical state and Appearance : Clear Colorless Liquid
Odor : Acetone-like Pleasant. Pungent. Sweetish. (Strong.)
Molecular Weight: 72.12g/mole
Boiling Point: 79.6 (175.3 °F)
Critical Temperature: 262.5°C (504.5 °F)
Flash point: -9 °C
Melting Point: -86°C (-122.8 °F)
Specific Gravity: 0.805 (Water = 1)
Vapor Pressure: 10.3 kPa (@ 20 °C)
Vapor Density: 2.41 (Air = 1)
Water/Oil Dist. Coeff: The product is more soluble in oil; log(oil/water) = 0.3
Dispersion Properties: See solubility in water, diethyl ether, acetone
Solubility: Soluble in cold water, diethyl ether, acetone
Content: 99.0% min
Acid value: 230 - 330 (mg KOH/g)

It has many industrial uses:-

Tire cord adhesion promoter


Fuel additive for corrosion inhibitors

Paint and ink drying promoters


Preservatives for wood and fabrics

Many other miscellaneous uses