This Product Safety Summary is a high-level summary intended to provide the general public with an overview of product safety information on this chemical substance. It is not intended to provide emergency response, medical or treatment information, or to provide an overview of all safety and health information. This summary is not intended to replace the (Material) Safety Data Sheet. For detailed guidance on the use or regulatory status of this substance, please consult the (Material) Safety Data Sheet.

Chemical Identity

Naphthenic Acid

CAS #1338-24-5

EC # 215-662-8

Also commonly called

  • Carboxylic acid
  • Fatty acid

Product Overview

  • Naphthenic acid is a naturally occurring compound found in select crude oil deposits.  It is generated during treatment of crude oil prior to refining.   Merichem manufactures a wide range of naphthenic acids to meet our customer specifications.

  • Some applications for naphthenic acid are:The primary hazard for naphthenic acid is as an eye and skin irritant.  The material can be an inhalation irritant and is a low ingestion hazard.  There are no known chronic, mutagenic or teratogenic effects and no airborne exposure limits have been established.The material is stable at standard temperature and pressure and is not reactive.

    • Tire cord adhesion promoter

    • Lubricants

    • Fuel additive for corrosion inhibitors

    • Paint and ink drying promoters.

    • Surfactants

    • Preservatives for wood and fabrics

  • For further health and safety information, please consult the MSDS.

Physical/Chemical Properties

  • Naphthenic Acid is a clear, amber colored liquid with a hydrocarbon odor. 

  • pH = 5.2 – slightly acidic

  • Boiling point = 515 °F,  freeze point not established

  • Flash point = >300 °F

  • Not an oxidizer and not explosive

  • Vapor density = 6.5 (air =1), much more dense than air

  • Not water soluble

  • Stable (not reactive) at standard temperature and pressure

Health Information

Naphthenic acid is an eye and skin irritant.  It can also be a respiratory irritant if the material is swallowed or if there is exposure to very high vapor levels.  There are no known acute, mutagenic, or teratogenic hazards.

Skin contact

Wash affected areas with soap and water.


Do not induce vomiting.  Give 2-3 glasses of milk or water to dilute.  Contact physician or poison control center for further treatment.


Remove to fresh air.  Seek medical attention if irritation develops.

Eye Contact

Flush with water for 15 minutes.  Seek medical attention if irritation develops.

Environmental Information

  • Ecotoxicity – no data available

  • Persistence and degradability – no data available

  • Bioaccumulation potential – no data available

  • Mobility in soil – no data available

No formal ecological data is available.  As with any hydrocarbon liquid which is not soluble in water, care should be taken to prevent spilled material from reaching waterways, storm drains, sewers, or direct ground contact.

Additional Hazards

None known.

Exposure Potential

Naphthenic acid is intended as an industrial product only; no direct consumer contact is expected to occur.  Users should handle this material in strict accordance with MSDS guidelines and common industry practices.