BENZOTRIAZOLE

Benzotriazole (BTA) forms a durable protective film on copper and copper-alloy surfaces.
Cooling systems, metalworking fluids and industrial cleaners widely use Benzotriazole (BTA).
Effective metal passivation makes Benzotriazole (BTA) a reliable corrosion-control additive.

CAS Number: 95-14-7
EC Number: 202-394-1
Molecular Formula: C₆H₅N₃
Molecular Weight: 119.12 g/mol
MDL Number: MFCD00005699

Synonyms: BTA, BTAH, 1H-Benzotriazole, 1,2,3-Benzotriazole, 1H-1,2,3-Benzotriazole, 1,2,3-Triaza-1H-indene, 1,2,3-Triazaindene, Azimidobenzene, Aziminobenzene, Benzene azimide, Benzisotriazole, Benztriazole, 2,3-Diazaindole, 1,2-Aminoazophenylene, Cobratec 99, Cobratec 35G, Preventol BZT, NCI-C03521, NSC-3058, NSC 3058, U-6233, 1H-Benzo[d][1,2,3]triazole, 1,2,3-Benztriazole, T706, MFCD00005699, PubChem CID 7220, CAS 95-14-7, EC 202-394-1

Benzotriazole (BTA) has the molecular formula C₆H₅N₃ and a molar mass of approximately 119.12 g/mol.
The structure of Benzotriazole (BTA) combines a benzene ring with a nitrogen-rich triazole ring.

Benzotriazole (BTA) normally appears as a white to light-tan crystalline powder.
The physical appearance of Benzotriazole (BTA) can vary slightly according to purity and particle size.

Benzotriazole (BTA) provides limited to moderate solubility in water under ordinary conditions.
Alcohols and several polar organic solvents dissolve Benzotriazole (BTA) more readily.

Benzotriazole (BTA) can display weak acidic and basic behavior because of its nitrogen-containing ring.
The tautomeric structure of Benzotriazole (BTA) contributes to its distinctive coordination properties.

Benzotriazole (BTA) primarily functions as a corrosion inhibitor for copper and copper alloys.
Interaction with metal surfaces allows Benzotriazole (BTA) to form a thin and persistent protective film.

Copper, brass and bronze components benefit from the surface protection provided by Benzotriazole (BTA).
The protective layer formed by Benzotriazole (BTA) limits reactions between the metal and corrosive substances.

Cooling-water systems use Benzotriazole (BTA) to protect copper-containing pipes and heat exchangers.
Benzotriazole (BTA) can maintain metal protection in recirculating water-treatment formulations.

Antifreeze and engine-coolant products may contain Benzotriazole (BTA) as a copper corrosion inhibitor.
Benzotriazole (BTA) helps preserve radiators and other copper-containing cooling-system components.

Metalworking fluids use Benzotriazole (BTA) to reduce staining and corrosion of nonferrous metals.
The compatibility of Benzotriazole (BTA) with various additives supports its use in complex lubricant formulations.

Industrial cleaners can contain Benzotriazole (BTA) when copper or brass surfaces require protection.
Benzotriazole (BTA) helps cleaning formulations remove deposits without unnecessarily affecting protected metal surfaces.

Dishwashing and detergent formulations may employ Benzotriazole (BTA) to protect metallic decorative components.
Benzotriazole (BTA) can reduce tarnishing on copper-containing items during repeated cleaning cycles.

Coatings and protective finishes may incorporate Benzotriazole (BTA) as a metal-passivating additive.
Benzotriazole (BTA) can reinforce corrosion protection at the interface between a coating and a metal surface.

Electronics manufacturing uses Benzotriazole (BTA) during selected copper-cleaning and surface-treatment stages.
Benzotriazole (BTA) helps control the condition of copper surfaces used in electronic components and circuit boards.

Silver-protection formulations can also use Benzotriazole (BTA) to reduce surface discoloration.
The metal-binding ability of Benzotriazole (BTA) supports its use in anti-tarnish treatments.

Benzotriazole (BTA) can serve as an intermediate in the synthesis of specialty organic compounds.
Chemical modification of Benzotriazole (BTA) produces derivatives used in polymers, coatings and light-stabilizing systems.

Manufacturers commonly prepare Benzotriazole (BTA) from o-phenylenediamine and a nitrite source.
Cyclization creates the fused triazole ring that characterizes Benzotriazole (BTA).

Sodium and potassium salts prepared from Benzotriazole (BTA) offer improved compatibility with aqueous systems.
Formulators select the free form or salt form of Benzotriazole (BTA) according to the required solubility and pH.

The performance of Benzotriazole (BTA) depends on concentration, pH, temperature and metal composition.
Compatibility testing helps determine the appropriate amount of Benzotriazole (BTA) for each formulation.

Purity, moisture content, melting range and color represent important quality parameters for Benzotriazole (BTA).
Chromatographic and spectroscopic methods can confirm the identity and purity of Benzotriazole (BTA).

Among the most widely used heterocyclic corrosion inhibitors in industrial chemistry, benzotriazole owes its effectiveness to its unique ability to chemisorb onto copper and copper-alloy surfaces through its nitrogen atoms, forming a robust, multilayer, water-insoluble Cu–BTA coordination polymer film (copper benzotriazolate complex) that acts as a physical barrier against oxidative attack in aqueous, atmospheric, and sulfide-containing environments; this film is resistant to wiping, cleaning, and mechanical abrasion, and is effective across a wide pH range. Beyond corrosion inhibition, BTA is a versatile pharmaceutical and agrochemical scaffold — the benzotriazole nucleus is found in numerous bioactive compounds displaying antibacterial, antifungal, antiviral, anti-inflammatory, antihypertensive, and analgesic properties — and serves as a key intermediate in the Katritzky reaction and other synthetic transformations involving its activation of C–H and N–H bonds.

Uses of Benzotriazole:
Benzotriazole is used as the leading corrosion inhibitor for copper and copper alloys in industrial and commercial cooling water systems — cooling towers, heat exchangers, closed-loop chilled and hot-water circuits, and radiators — at typical treatment concentrations of 1–50 ppm; it reacts with copper ions at the metal surface to form an insoluble, multi-layer Cu(I)-BTA coordination polymer film (CuBTA) that passivates the surface against further oxidation, prevents galvanic corrosion between dissimilar metals, and inhibits pitting corrosion induced by soluble copper ions on stainless steel, aluminium, and solder; the film is effective in aqueous environments contaminated with sulfur dioxide, hydrogen sulfide, chloride, and salt mist.
Benzotriazole is used as an anti-corrosion and anti-wear additive in automotive and industrial lubricant formulations — engine motor oils, gear oils, hydraulic oils, brake fluids, transformer oils, and greases — at concentrations of 0.01–0.5%, where it protects copper alloy bearings, bushings, valve guides, and other yellow metal components from corrosive attack by sulphur-containing anti-wear additives (ZDDP decomposition products) and acidic oxidation by-products; it is often used alongside metal deactivator/passivator packages and complements zinc dithiophosphate (ZDDP) anti-wear chemistry without antagonism.
Benzotriazole and tolyltriazole (a mixture of 4-methyl- and 5-methyl-1H-benzotriazole) are the primary corrosion inhibitor agents in aircraft de-icing and anti-icing fluids (ADAF, Type I/II/III/IV) at concentrations up to 10%; it is estimated that approximately 3,785 litres of ADAF are consumed per de-icing of a large passenger jet, and approximately 8,000,000 litres are used annually in Canada alone; about 80% of ADAF is deposited on the ground due to spray drift, jet blast, and wind shear during taxiing and takeoff — the primary pathway for environmental contamination of airport groundwater and stormwater.
Benzotriazole is used in automotive antifreeze/coolant (ethylene glycol or propylene glycol based) at concentrations of 0.01–2.0%, where it protects the copper and brass components of radiators, water pumps, and heat exchangers against corrosive attack; it is also incorporated in vapour-phase corrosion inhibitor (VCI) formulations for the protection of copper surfaces during packaging and storage; in industrial circulating water treatment as a metal deactivator and scale inhibitor; and as an antioxidant additive in rust inhibitors.
Benzotriazole is used in household and commercial dishwasher detergent formulations as a silver protection agent, where it reacts with silver cutlery and tableware surfaces to form a silver-benzotriazole complex that prevents tarnishing and pitting during the dishwashing cycle; it is incorporated in both domestic (low concentration) and professional/institutional (higher dose) dishwasher products; this application is a significant pathway for benzotriazole entry into municipal wastewater streams.
Benzotriazole is used as a photographic restrainer, developer, and anti-fogging agent in silver halide photographic emulsions and film processing solutions, where it selectively inhibits the development of unexposed silver halide grains without significantly affecting exposed grains, thereby improving image contrast and reducing fog; it is also used as a reagent for the gravimetric and colorimetric determination of silver in analytical chemistry and as an anti-rust additive in photographic fixing baths.
Benzotriazole is used in the electronics and semiconductor industries to protect copper traces on printed circuit boards (PCBs), contact surfaces of connectors and cables, copper leadframes, and metal interconnects from atmospheric oxidation and tarnishing; it is incorporated in PCB surface finish processes (OSP — Organic Solderability Preservative), flux formulations, and cleaning solutions for electronic assemblies; it is also a key component of copper CMP (chemical mechanical planarisation) polishing slurries alongside EDTA and potassium iodide, where it acts as a controlled corrosion inhibitor to achieve selective material removal.
Benzotriazole is used as a UV stabiliser (ultraviolet light absorber) in polymers, plastics, paints, coatings, and films to prevent photodegradation; it is a scaffold for the synthesis of 2-(2-hydroxyphenyl)benzotriazole UV absorbers (Tinuvin series, e.g., Tinuvin P/328/329); as an antistatic agent in polymeric materials; as a plant growth regulator; in art restoration and copper/bronze conservation (Incralac coatings for outdoor sculptures and archaeological artefacts); and as a chemical intermediate for the synthesis of pharmaceuticals, dyes, fungicides, and specialty chemicals.

Benefits and Advantages of Benzotriazole:
Benzotriazole is effective as a copper corrosion inhibitor at extremely low concentrations — typically 1–50 ppm in aqueous systems and 0.01–0.5% in oil-based lubricants — making it cost-effective relative to the extent of metal protection provided; this low effective dosage minimises the amount of chemical added to systems, reduces cost-in-use, and limits the quantity discharged to wastewater; no other class of corrosion inhibitor provides equivalent protection to copper and yellow metals at comparable concentrations under both aqueous and gaseous exposure conditions.
The Cu–BTA coordination polymer film formed on copper surfaces is strongly chemisorbed (not merely physisorbed) through N–Cu coordination bonds involving all three ring nitrogen atoms, producing a multilayer, three-dimensional polymer network that is resistant to mechanical removal, wipe tests, and chemical cleaning operations; this robustness, combined with effectiveness in both aqueous and gaseous environments contaminated with sulphur compounds (H₂S, SO₂), chlorides, and salt mist, makes BTA uniquely suitable for applications requiring long-term, durable protection under harsh service conditions that organic inhibitor coatings cannot withstand.
Benzotriazole is stable to dilute acids and alkalis across a broad pH range, compatible with a wide range of industrial formulation components (including glycols, alcohols, esters, mineral oils, synthetic base oils, scale inhibitors, biocides, and surfactants), and active as a corrosion inhibitor in both neutral and alkaline aqueous environments; this formulation versatility, combined with its commercial availability in multiple physical forms (granules, powder, needles, flakes, aqueous solution, glycol solution), makes it the universal choice for copper protection across the full spectrum of industrial water treatment, lubricant, and automotive fluid applications.
The benzotriazole ring system is an exceptionally versatile pharmacophore — its combination of hydrogen-bond donor (N-H), hydrogen-bond acceptors (two ring N atoms), aromatic pi system, and bioisosteric relationship with carboxylic acids and amides enables BTA-based molecules to bind to diverse biological targets; this has made benzotriazole-containing compounds important in pharmaceutical drug discovery, with representative bioactive derivatives including antihypertensives, antibacterials, antifungals, antivirals, anti-inflammatories, analgesics, and kinase inhibitors.

Features of Benzotriazole:
Benzotriazole is a white to light yellow-brown crystalline solid at room temperature, available as needles, flakes, granules, or fine powder with a slight characteristic odour; it exists as tautomers in solution but X-ray crystallography establishes the 1H (hydrogen at N-1 position) tautomer as the dominant form in the solid state; melting point 98.5°C (lit.); boiling point 204°C at 2 kPa (15 mmHg) / 350°C at atmospheric pressure; decomposition at approximately 260°C; sublimation at 200°C; density 1.36 g/cm³ (20°C); vapour pressure 5 Pa (0.04 mmHg) at 20°C; vapour density 4.1 (vs air); refractive index 1.5589 (estimated); flash point 170–195°C (open cup); autoignition temperature 210°C.
Water solubility 2 g/100 mL (20 g/L) at room temperature (moderate — slightly soluble in cold water); soluble in ethanol, methanol, benzene, toluene, chloroform, DMF, DMSO, glycols, alcohols, and esters; pH 5 at 2.5% aqueous solution; pKa 8.37 (acid-base equilibrium of the N-H form); it is a weak acid in aqueous solution; the fused bicyclic ring system consists of N=N bond length 1.306 Å and HN–N bond length 1.340 Å (from X-ray crystallography).
IMPORTANT SAFETY NOTE: benzotriazole may explode during vacuum distillation (documented hazard at 220°C or under reduced pressure — necessary precautions must be taken; recrystallisation from toluene, chloroform, or DMF is the preferred purification method); it is a combustible solid; dust-air mixtures may form explosive mixtures in air; the substance is absorbed through inhalation and ingestion; repeated/prolonged contact may cause skin sensitisation; the substance is harmful to aquatic organisms; it is highly resistant to biodegradation and is a recognised persistent environmental contaminant in groundwater, rivers, and lakes; UV irradiation at pH below 7 can degrade BTA and reduce toxicity by approximately 65%.
Benzotriazole is not readily biodegradable and is only partially removed in conventional wastewater treatment plants (WWTP), meaning a substantial fraction enters surface water and groundwater; it has been detected in groundwater, river water, tap water, and drinking water in numerous countries; the EU benzotriazole round table (concluded June 2023) issued a final report on reducing benzotriazole discharge from cooling water, de-icing fluid, and dishwasher detergent applications; for environmental reasons, its use is subject to increasing regulatory scrutiny in Europe and North America.

Chemical Properties of Benzotriazole:
Benzotriazole has IUPAC name 1H-benzotriazole (preferred: 1H-benzo[d][1,2,3]triazole), CAS 95-14-7, molecular formula C₆H₅N₃, molecular weight 119.12 g/mol, InChI=1S/C6H5N3/c1-2-4-6-5(3-1)7-9-8-6/h1-4H,(H,7,8,9), InChIKey QRUDEWIWKLJBPS-UHFFFAOYSA-N; EC 202-394-1; MDL MFCD00005699; PubChem CID 7220; ChEBI (1H-benzotriazole is the simplest member of the class of benzotriazoles, consisting of a benzene nucleus fused to a 1H-1,2,3-triazole ring; it has a role as an environmental contaminant and a xenobiotic).
Key chemical reactions of benzotriazole: (1) complexation with Cu(I) → Cu(I)-BTA coordination polymer film (CuBTA) on copper surfaces — the primary mechanism of corrosion inhibition (chemisorption via N → Cu coordination); (2) chelation with Ag(I) → silver-BTA complex (application in photographic emulsions and dishwasher silver protection); (3) complexation with other metal ions (Al, Co, Zn) — BTA is a versatile metal chelating agent; (4) synthesis of amines from glyoxal (synthetic utility); (5) N-alkylation to form N1- or N2-substituted benzotriazole derivatives (Katritzky reaction); (6) Mannich-type and acylation reactions at C-1 nitrogen for pharmaceutical synthesis; (7) thermal decomposition above 260°C → aniline, nitrobenzene, and other toxic nitrogen-containing fumes; (8) diazotisation of o-phenylenediamine with NaNO₂/AcOH → BTA (production route).
Benzotriazole is produced industrially by diazotisation of o-phenylenediamine (1,2-diaminobenzene) with sodium nitrite in the presence of acetic acid under controlled temperature conditions: o-phenylenediamine is dissolved in water at 50°C, glacial acetic acid is added, the mixture is cooled to 5°C, sodium nitrite is added with stirring; the reaction mixture turns dark green, temperature rises to 70–80°C, solution turns orange-red; after 2 hours at room temperature, crystals are filtered, washed with ice water, and dried; the crude product is vacuum-distilled and collected at 201–204°C (2.0 kPa), then recrystallised from benzene; yield approximately 80% with melting point 96–97°C; CAUTION: vacuum distillation may cause explosion — necessary precautions must be taken.
The benzotriazole family includes three principal compounds: (1) 1H-benzotriazole (CAS 95-14-7, MW 119.12) — the parent compound; (2) 4-methyl-1H-benzotriazole (CAS 29878-31-7) and (3) 5-methyl-1H-benzotriazole (CAS 136-85-6) — a mixture of (2) and (3) is called tolyltriazole; all three are used as corrosion inhibitors and are collectively referred to as "benzotriazoles" in environmental monitoring; benzotriazole is a persistent environmental contaminant particularly problematic in groundwater monitoring near airports (ADAF source) and urban areas (cooling water and dishwasher detergent sources).

Production of Benzotriazole:
Benzotriazole is produced commercially by diazotisation of o-phenylenediamine with sodium nitrite and acetic acid: o-phenylenediamine is dissolved in water (with heating to approximately 50°C), glacial acetic acid is added, and the solution is cooled to 5°C; sodium nitrite is then added slowly with stirring to effect diazotisation; the reaction mixture undergoes colour changes from dark green to orange-red as benzotriazole crystallises; after standing at room temperature for 2 hours, crystals are collected by filtration, washed with ice water, and dried; the crude product is purified by vacuum distillation (collecting the 201–204°C / 2.0 kPa fraction) and/or recrystallisation from benzene, toluene, chloroform, or DMF; yield approximately 80%; melting point 96–97°C for the purified product.
PURIFICATION CAUTION: vacuum distillation of benzotriazole may cause explosion — recrystallisation from toluene, CHCl₃, or DMF is preferred; if vacuum distillation is used, all necessary explosion precautions must be taken; losses during recrystallisation are minimised compared with distillation; after recrystallisation the product may be dried at room temperature or in a vacuum oven at 65°C.
Commercial benzotriazole is available in: granular (preferred for handling and formulation ease — reduces dust exposure risk); fine powder (for analytical and specialty applications); needle crystals (recrystallised product); flakes; liquid forms including sodium benzotriazole in water and BTA dissolved in glycols, alcohols, or esters (preferred for user safety and ease of dosing); typical grades: technical (≥98%, ≥99%), high-purity (≥99.8%); packaging: bags (25 kg, 50 kg), 55-gallon drums, supersack quantities; storage: cool, dry place, well-closed, away from high temperatures and ignition sources; recommended storage in a refrigerator for long-term archival storage of research-grade material.

Benzotriazole Material Safety Data Sheet (MSDS):

Handling of Benzotriazole:
Benzotriazole is a combustible solid and moderate inhalation/ingestion hazard; key handling precautions: prevent dust dispersion (finely dispersed particles form explosive mixtures in air); use closed systems and dust-explosion-proof electrical equipment; no open flames; maintain strict hygiene; do not eat, drink, or smoke in work areas; use local exhaust ventilation; wear appropriate PPE; avoid repeated skin contact (skin sensitisation risk — H317).
CRITICAL SAFETY WARNING: benzotriazole may explode during vacuum distillation at 220°C or under reduced pressure — recrystallisation from toluene, chloroform, or DMF is the recommended purification method; if vacuum distillation is absolutely required, all documented explosion precautions must be implemented; the substance can be absorbed into the body by inhalation of aerosol and by ingestion; evaporation at 20°C is negligible, but dust concentrations can build up quickly; keep away from heat, ignition sources, and open flames.

Benzotriazole SDS:

Stability and Reactivity of Benzotriazole:

Chemical stability:
Benzotriazole is stable under normal ambient storage conditions; it is stable in dilute acids and alkalis.
It decomposes on heating above 260°C to produce toxic fumes including aniline and nitrobenzene; it may explode at 220°C or during vacuum distillation — appropriate precautions are essential.

Reactivity:
Benzotriazole is a weak acid in aqueous solution (pKa 8.37); it forms coordination complexes with copper(I), silver, and other metal ions.
Dust-air mixtures may form explosive mixtures in air; violent reaction may occur during vacuum distillation.

Conditions to avoid:
Temperatures above 220°C — risk of explosion.
Vacuum distillation — documented explosion hazard; use recrystallisation instead.
Dust generation near ignition sources — explosive dust-air mixtures.
Open flames.

Incompatible materials:
Strong oxidising agents at elevated temperature.
No specific incompatibilities under normal ambient conditions.

Hazardous decomposition products:
Aniline and nitrobenzene (toxic) upon heating above 260°C.
Nitrogen oxides (NOₓ) and other toxic nitrogen-containing fumes upon combustion or thermal decomposition.

Handling and Storage of Benzotriazole:

Handling:
Prevent dust dispersion; use local exhaust ventilation; employ closed systems and dust-explosion-proof equipment.
Wear particulate filter respirator, safety spectacles, protective gloves, and protective clothing.
No open flames; strict hygiene; do not eat, drink, or smoke during handling.
Do NOT attempt vacuum distillation without documented explosion precautions.

Storage:
Store in a well-closed container in a cool, dry, well-ventilated place away from heat, ignition sources, and oxidising agents.
Recommended storage temperature: cool, dry place (<25°C); refrigerator for research-grade material.
Keep away from high temperatures.
Shelf life: stable for extended periods under recommended conditions.
Packaging: bags (25 kg, 50 kg), drums, supersack quantities.

First Aid Measures for Benzotriazole:

Inhalation: Move to fresh air; rest; if symptoms persist, seek medical attention; under normal conditions, vapour exposure is negligible, but dust inhalation may cause irritation.
Skin contact: Remove contaminated clothing; rinse with water, then wash with water and soap; if allergic skin reaction develops (sensitisation), seek medical attention.
Eye contact: Rinse with plenty of water for several minutes (remove contact lenses if easily possible); if redness or pain persists, seek medical attention — the substance causes eye irritation/damage.
Ingestion: Rinse mouth; give one or two glasses of water to drink; seek medical attention — the substance is harmful if swallowed (H302).

Firefighting Measures for Benzotriazole:

Suitable extinguishing media: Water spray; do not use dry chemical near dust (risk of dust explosion).
Specific hazards: Combustible solid; finely dispersed dust forms explosive mixtures in air; combustion and thermal decomposition produce toxic fumes (aniline, nitrobenzene, NOₓ); may explode under vacuum distillation conditions.
Protective equipment for firefighters: SCBA and full protective clothing; prevent dust dispersion during firefighting; prevent contaminated runoff from entering waterways.

Accidental Release Measures for Benzotriazole:

Personal precautions: Prevent dust dispersion; wear particulate filter respirator, protective gloves, and protective clothing; moisten spill first if appropriate to prevent dust formation; do NOT let the chemical enter the environment.
Environmental precautions: Benzotriazole is a persistent environmental contaminant harmful to aquatic organisms; do not allow entry into sewers, waterways, or soil; notify environmental authorities for significant releases.
Clean-up methods: Sweep or vacuum (wet method preferred to prevent dust) into covered, labelled containers; dispose per local/national regulations for hazardous chemical waste.

Exposure Controls / Personal Protective Equipment for Benzotriazole:

Engineering controls: Closed system; local exhaust ventilation; dust-explosion-proof electrical equipment; prevent dust generation and deposition.
Eye protection: Safety spectacles / chemical splash goggles.
Hand protection: Protective gloves (nitrile recommended); note skin sensitisation risk.
Body protection: Protective clothing; chemical-resistant safety shoes.
Respiratory protection: Particulate filter respirator (P2/P3) adapted to airborne dust concentration; SCBA for fire or high-concentration scenarios.

Benzotriazole Identifiers:
CAS Number: 95-14-7
EC Number: 202-394-1
EINECS: 202-394-1
MDL Number: MFCD00005699
PubChem CID: 7220
ICSC: 1091
IUPAC Name: 1H-Benzotriazole (preferred: 1H-benzo[d][1,2,3]triazole)
Molecular Formula: C₆H₅N₃
Molecular Weight: 119.12 g/mol
InChI: InChI=1S/C6H5N3/c1-2-4-6-5(3-1)7-9-8-6/h1-4H,(H,7,8,9)
InChIKey: QRUDEWIWKLJBPS-UHFFFAOYSA-N
pKa: 8.37 (aqueous acid dissociation)
Melting point: 98.5°C (lit.)
Boiling point: 204°C (2 kPa / 15 mmHg); 350°C (atmospheric)
Decomposition: ~260°C
Flash point: 170–195°C (open cup)
Autoignition temperature: 210°C
Density: 1.36 g/cm³ (20°C)
Vapour pressure: 5 Pa / 0.04 mmHg (20°C)
Water solubility: 20 g/L (2 g/100 mL, moderate)
GHS Classification: H302 (harmful if swallowed), H318/H319 (serious eye damage/irritation), H317 (may cause allergic skin reaction)
Carcinogen classification: Category 3 (MAK, Germany — inconclusive); not listed IARC/NTP
MAK: Not established; skin notation (H)
Biodegradability: Not readily biodegradable; persistent environmental contaminant
Environmental: Harmful to aquatic organisms; persistent in groundwater and surface water

Properties of Benzotriazole:
Physical state: Solid (crystalline)
Appearance: White to light yellow/brown crystalline powder, needles, flakes, or granules
Odour: Slight, characteristic
Molecular formula: C₆H₅N₃
Molecular weight: 119.12 g/mol
Melting point: 98.5°C (lit.; range 94–100°C depending on purity)
Boiling point: 204°C (2 kPa); 350°C (atmospheric)
Decomposition temperature: ~260°C
Sublimation point: 200°C
Flash point: 170–195°C (open cup)
Autoignition temperature: 210°C
Density: 1.36 g/cm³ (20°C)
Vapour pressure: 5 Pa (0.04 mmHg) at 20°C
Vapour density: 4.1 (vs air)
Water solubility: 20 g/L (2 g/100 mL)
pKa: 8.37 (aqueous)
pH: 5 at 2.5% solution
Refractive index: 1.5589 (estimated)
Solubility: Water, ethanol, methanol, benzene, toluene, chloroform, DMF, DMSO, glycols, alcohols, esters
GHS: H302, H318/H319, H317
Biodegradability: Not readily biodegradable
Storage: Cool, dry, well-closed; away from heat and ignition sources

Benzotriazole Properties — Specifications:
Product name: Benzotriazole (1H-Benzotriazole, BTA)
CAS Number: 95-14-7
EC Number: 202-394-1
Molecular Formula: C₆H₅N₃
Molecular Weight: 119.12 g/mol
Purity: ≥98% (technical); ≥99% (standard); ≥99.8% (high purity)
Appearance: White to light yellow/brown crystalline powder, needles, granules, or flakes
Melting point: 96–100°C (grade-dependent)
Density: 1.36 g/cm³ (20°C)
Water solubility: 20 g/L (moderate)
pH (2.5% solution): 5
Flash point: 170–195°C
GHS: H302, H318/H319, H317
Storage: Cool, dry place; well-closed; refrigerator recommended for long-term storage
Packaging: 25 kg, 50 kg bags; 55-gallon drums; supersack quantities; liquid forms in drums/IBCs
Documents: CoA, SDS/MSDS, ICSC 1091, EU Round Table report on benzotriazole in water

Names of Benzotriazole:
Benzotriazole
BTA
BTAH
1H-Benzotriazole
1,2,3-Benzotriazole
1H-1,2,3-Benzotriazole
1H-Benzo[d][1,2,3]triazole
1,2,3-Triaza-1H-indene
1,2,3-Triazaindene
1,2,3-Benztriazole
Azimidobenzene
Aziminobenzene
Benzene azimide
Benzisotriazole
Benztriazole
2,3-Diazaindole
1,2-Aminoazophenylene
Cobratec 99
Cobratec 35G
Preventol BZT
NCI-C03521
NSC-3058
NSC 3058
U-6233
T706
MFCD00005699
PubChem CID 7220
CAS 95-14-7
EC 202-394-1
ICSC 1091A).