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CarCareTruth

Adipic Acid

  • Corrosion inhibitors
  • CAS 124-04-9
  • IUPAC: Hexanedioic acid

Adipic Acid (CAS 124-04-9) appears in 1 of the 2,168 car-care products CarCareTruth tracks (as of August 2026). It is readily biodegradable.

The organic-acid corrosion inhibitor in silicated organic acid technology (Si-OAT) coolant packages. The neat substance is severely irritating to eyes in animal testing (OECD 405), but at the low concentration used in a finished coolant (typically 1.5-5% by weight) it contributes to the mixture's own eye-irritation classification rather than carrying an independent hazard statement of its own.

Adipic acid is a dicarboxylic acid best known as a GRAS (Generally Recognized As Safe) food-grade acidulant used in baking powder and gelatin desserts, and as a monomer in nylon-6,6 production. In automotive coolant, it functions as one of the organic-acid corrosion inhibitors in Si-OAT (silicated organic acid technology) and OAT formulations, buffering pH and forming a protective film on aluminum and other cooling-system metals without the phosphates, nitrites, amines, or borates used in older inhibitor packages.

Adipic acid is readily biodegradable and carries no aquatic-toxicity classification in available testing. It is not listed on California's Proposition 65 list. As a neat substance it tests as severely irritating to eyes (OECD Test Guideline 405, rabbit), which is common for concentrated organic acids; at the low concentration disclosed in finished coolant products, this contributes to the mixture-level eye-irritation classification carried by the finished product rather than triggering a standalone hazard statement.

Health & environment profile

VOC
no
Prop 65 listed
no
Asthmagen
no
EPA Safer Choice
no
Aquatic toxicity
no
Biodegradable
yes
Bioaccumulative
no
Persistent
no
Ozone depleting
no
Microplastic
no
PFAS
no
Env. score
4/5
Purpose: Organic-acid corrosion inhibitor and pH buffer in Si-OAT/OAT coolant formulations

Common questions about Adipic Acid

What is Adipic Acid used for in car care?
Organic-acid corrosion inhibitor and pH buffer in Si-OAT/OAT coolant formulations
Is Adipic Acid a VOC?
No. Adipic Acid is not classified as a volatile organic compound (VOC).
Is Adipic Acid on California's Proposition 65 list?
No. Adipic Acid is not on California's Proposition 65 list.
Is Adipic Acid biodegradable?
Yes. Adipic Acid has a confirmed biodegradable profile.

1 product contain this

Related

Health and environment notes translate the manufacturer Safety Data Sheet, the GHS classification, and authoritative regulatory listings (California Prop 65, EPA). Not medical advice. They describe the ingredient itself; whether a hazard applies to a finished product depends on its concentration and how it's used.