Benzotriazole

Benzotriazole (CAS 95-14-7), commonly abbreviated as BTA, is an organic heterocyclic compound used primarily as a corrosion inhibitor and metal deactivator.

Where is Benzotriazole used?

• Lubricants and metalworking fluids: copper passivator that prevents metal-catalyzed oil degradation and staining of non-ferrous components
• Water treatment: protects copper pipework and heat exchanger surfaces in recirculating cooling systems
• Automotive antifreeze and engine coolant: inhibits corrosion on brass and copper engine components throughout the coolant circuit
• Electronics manufacturing: surface treatment that prevents tarnishing of copper contacts and printed circuit board traces during storage and processing
• It forms stable complexes on copper and copper alloy surfaces, protecting them from oxidative degradation in both aqueous and non-aqueous systems.
• Hydraulic fluids: corrosion inhibitor.
• Aircraft de-icing fluids: component.
• Boiler descaling: acid inhibitor.
• Photographic emulsions: restrainer and anti-foggant.
• Chemical intermediate for dyes, pharmaceuticals, and fungicides.
• Main component for producing UV absorbers.

Formulation notes

• In Denmark, used in de-icing fluids such as propylene glycol at 0.1–0.2%.
• Decomposes on heating, producing toxic fumes including aniline and nitrobenzene.
• Tolyltriazole (TTA) is a closely related triazole used for copper corrosion inhibition when a methylated derivative is preferred.
• The choice between benzotriazole and tolyltriazole depends on the formulation and system requirements.

Typical specification

• Insoluble in water and soluble in ethanol.
• Sold in flake form.
• pKa of 8.2; acts as a weak acid.

Regulatory status

• Not subject to restriction under REACH.
• Not classified as a substance of very high concern (SVHC).
• Authorized as a corrosion inhibitor in cleaning products intended for industrial use, which must be rinsed with potable water or steam after use, or used for dish rinsing.

Storage, packaging and handling

• Has excellent thermal resistance and is stable at normal application temperatures; the pure substance decomposes exothermically above 160 °C when heated.
• Should be stored well closed.

Frequently asked questions about Benzotriazole

What is the maximum allowed concentration of benzotriazole in cleaning products?

The concentration in cleaning products must not exceed 0.5%.

Technical content is compiled and updated by the SoleChem product team from public technical sources; the certificate of analysis (COA) governs product-specific specifications.