| HS Code | 733621 |
| Productname | Cyanuric Chloride |
| Casnumber | 108-77-0 |
| Iupacname | 2,4,6-Trichloro-1,3,5-triazine |
| Molecularformula | C3Cl3N3 |
| Molecularweight | 184.41 g/mol |
| Appearance | White crystalline powder or granules |
| Odor | Pungent, irritating |
| Meltingpoint | 154 °C |
| Boilingpoint | 192 °C |
| Density | 1.32 g/cm³ at 20 °C |
| Vaporpressure | 0.2 mmHg at 20 °C |
| Watersolubility | Reacts with water; hydrolyzes |
| Organicsolventsolubility | Soluble in chloroform, benzene, ether, acetone |
| Stability | Stable under dry conditions; moisture sensitive |
| Purity | ≥99% |
As an accredited Cyanuric Chloride factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Cyanuric chloride is packaged as 25 kg net in UN-approved steel drums with polyethylene liners, moisture-tight seals, and corrosive labels. |
| Container Loading (20′ FCL) | 20′ FCL loading of Cyanuric Chloride: sealed, palletized drums; moisture-protected, securely braced; labeled corrosive UN 2670; shipped in dry container. |
| Shipping | Cyanuric chloride is shipped as UN 2670, Class 8 corrosive solid, Packing Group II. It is moisture-sensitive and must be transported in sealed, corrosion-resistant packaging. Packages require corrosive labels, proper shipping papers, and compliance with DOT, IMDG, or IATA regulations. |
| Storage | Store cyanuric chloride in a cool, dry, well-ventilated, locked area away from moisture, water, acids, bases, oxidizers, and food. Keep containers tightly closed, labeled, and upright. Use corrosion-resistant shelving and secondary containment. Protect from heat and direct sunlight. Store separately from incompatible materials. Handle in a fume hood; keep spill and emergency equipment available. Follow the SDS and local regulations. |
| Shelf Life | Cyanuric chloride has a shelf life of about two years when stored cool, dry, and tightly sealed away from moisture. |
In reactive dyestuff production, cyanuric chloride is not blended into a finished formulation as an additive but is condensed stepwise with chromophores, each stage governed by a temperature window that separates the reactivity of the first, second, and third chlorine atoms on the triazine ring. Production-scale equipment for this chemistry typically consists of glass-lined or stainless steel 10–20 m³ agitated reactors with jacket outlet temperature held between −5 °C and 0 °C during the first condensation, pH-stat dosing of 10% w/w sodium carbonate to maintain pH 6.0–7.0, and in-process HPLC monitoring to reject batches exceeding 1.5% hydrolyzed cyanuric acid content. The charge ratio for monofunctional monochlorotriazine reactive dye synthesis is 1.00–1.05 mol cyanuric chloride per mol of primary amino chromophore; for bifunctional triazinyl reactive dye structures, the stoichiometry increases to 2.02–2.08 mol cyanuric chloride per mol of bis-amino chromophore, with the excess compensating for competitive hydrolysis at the first substitution stage. The second chlorine is condensed at 35–45 °C and pH 6.5–7.5; the third chlorine, where required, is condensed at 80–95 °C and pH 7.0–9.0. Terminal product classes include cold-brand monochlorotriazine dyes, high-exhaustion dichlorotriazine dyes, and bifunctional reactive dyes for cotton, viscose, and nylon substrates. Compliance for European dye mills is anchored to REACH Regulation (EC) No 1907/2006 Annex VII substance registration and Oeko-Tex Standard 100 Annex 4 finished-textile residue limits; dye exporters additionally apply ZDHC MRSL V3.1 and ETAD Code of Ethics process safety requirements. The dominant operational boundary is hydrolysis: at pH above 7.5 during the first condensation, cyanuric chloride hydrolysis increases rapidly, reducing the yield of monochlorotriazine reactive dye and generating cyanuric acid impurities that pass through isolation and require reverse osmosis treatment of spent liquor.
| Stage | Chlorine position | Reactant | Temperature range | pH window | Process signal |
|---|---|---|---|---|---|
| First condensation | C-6 | Chromophore amino group | 0–5 °C | 6.0–7.0 | pH-stat 10% Na₂CO₃ |
| Second condensation | C-4 | Substituted aniline or amine | 35–45 °C | 6.5–7.5 | Exotherm 8–12 °C |
| Third condensation | C-2 | Tertiary amine or ethanolamine | 80–95 °C | 7.0–9.0 | Reflux and colour shift |
Triazine herbicide active ingredient manufacture places cyanuric chloride under a narrow pH-temperature envelope because the first amine substitution is exothermic enough to raise batch temperature by 30–40 °C if the alkylamine is charged without jacket cooling and pH-stat-controlled acid acceptor. In a standard batch process for atrazine, simazine, terbuthylazine, or propazine, cyanuric chloride is dispersed in an aromatic solvent such as toluene or xylene at 0–5 °C, and the first primary alkylamine is added at 1.02–1.08 mol per mol cyanuric chloride while 30% w/w sodium hydroxide maintains pH 7.0–7.5. The second primary amine is then introduced at 40–50 °C at 1.05–1.12 mol per mol substituted intermediate. For methylthio-substituted triazines such as ametryn or prometryn, the third chlorine is replaced with sodium thiomethoxide at 70–80 °C under pH 7.5–8.5. Industrial reactors in this segment are typically 5–15 m³ glass-lined agitated vessels with reflux condensers and caustic scrubber vent systems because the reaction releases hydrogen chloride and amine vapours. Downstream isolation includes solvent extraction, vacuum distillation of recovered solvent, centrifugation, and fluid-bed drying to residual moisture below 0.5% w/w. Technical-grade actives are converted into formulation types including 500 g/L suspension concentrates, 80% w/w water-dispersible granules, and 50% w/w wettable powders. Regulatory anchor points include U.S. EPA 40 CFR Part 180 residue tolerance schedules where registered uses remain authorized, FAO/WHO Joint Meeting on Pesticide Specifications technical material requirements, and EU Regulation (EC) No 1107/2009 where national authorization exists. Atrazine itself faces specific geographic restrictions, so formulators must verify local registration before adding cyanuric chloride-derived actives to a portfolio. The main process failure mode is premature third-substitution hydrolysis when the second substitution is pushed above 55 °C without adequate pH control, generating hydroxy-triazine impurities that fail technical specifications and require rework.
| Substitution sequence | Cyanuric chloride basis | Reagent example | Temperature | Acid acceptor | Resulting product type |
|---|---|---|---|---|---|
| First chlorine replacement | 1.00 mol | Ethylamine | 0–5 °C | 30% w/w NaOH | Monoamino intermediate |
| Second chlorine replacement | After first substitution | Isopropylamine | 40–50 °C | 30% w/w NaOH | Atrazine, simazine, terbuthylazine |
| Optional third replacement | After second substitution | Sodium thiomethoxide | 70–80 °C | NaHCO₃ | Ametryn, prometryn |
Fluorescent whitening agent production based on 4,4′-diamino-2,2′-stilbenedisulfonic acid, commonly referred to as DSD acid, uses cyanuric chloride as the bridging triazine unit, with the first condensation executed in aqueous slurry at 0–5 °C and pH 4.0–5.0 to protect the first chlorine from hydrolysis. The molar addition ratio is 2.02–2.10 mol cyanuric chloride per mol DSD acid, a deliberate excess of 2–5% above the nominal 2:1 stoichiometry because hydrolysis at the slurry interface consumes a small fraction of the first acid chloride. The second chlorine is then substituted with aniline, sulfanilic acid, or a sulfonated amine at 40–45 °C and pH 7.0–7.5, and the third chlorine is capped with ethanolamine, diethanolamine, or morpholine at 80–90 °C to produce di/tetrasulfo or tetra/hexasulfo whitening agent structures. Production plants for this chemistry typically use glass-lined reactors of 8–20 m³ with external ice-brine cooling and automated pH-stat control; slurry viscosity can rise above 1000 mPa·s during the final capping step, so agitator torque rather than temperature is often the limiting parameter for batch size. Final formulations delivered to detergent and paper producers are added at 0.03–0.15% w/w of liquid laundry detergent or 0.05–0.30% w/w on dry coating solids in paper wet-end or coating formulations. Relevant compliance anchors are EU Regulation (EC) No 648/2004 on detergents and its Annex V biodegradability and labelling obligations, ISO 2470-1:2016 for optical brightness measurement, and U.S. FDA 21 CFR 176.170 and 21 CFR 176.180 for certain paper and paperboard food-contact uses where the specific whitening agent has a regulatory clearance. The primary processing limitation is salt load: the condensation generates sodium chloride as an acid-acceptor by-product, and downstream membrane desalination is required for high-purity liquid detergent grades.
Polycarbonate glazing compounds that require extended outdoor weathering performance often use hydroxyphenyl-s-triazine UV absorbers synthesized from cyanuric chloride because the triazine chromophore provides lower migration than benzotriazoles at equivalent loading. The synthetic route first replaces two chlorine atoms with phenyl groups via aryl Grignard addition at 0–10 °C in a mixed tetrahydrofuran/toluene system, then attaches resorcinol or a resorcinol derivative through a Friedel-Crafts step at 60–80 °C under anhydrous aluminium chloride. The molar ratio of phenyl magnesium bromide to cyanuric chloride is held at 2.02–2.10 mol, and the resorcinol derivative is charged at 1.02–1.08 mol per mol disubstituted intermediate. After quench, the absorber is crystallized from methanol/toluene, and residual hydrolyzable chlorine is reduced to <50 ppm to avoid visible polymer haze. In polycarbonate sheet extrusion, the absorber is pre-dried with resin at 120 °C for 4 h and compounded at 280–300 °C on a twin-screw extruder with L/D 44:1, with vacuum venting below 200 mbar; use levels run 0.3–1.5 phr in polycarbonate and 0.2–0.8 wt% in polyester, while masterbatch concentrates are typically let down at 2–10% w/w. Weatherability is verified by ISO 4892-2:2013 accelerated xenon-arc exposure and ASTM D1003-21 haze/transmission testing, with an acceptance target of ΔYI < 2 after 3000 h for pigmented opaque grades. Terminal products include multiwall polycarbonate architectural sheet, automotive headlamp lenses, PET packaging, and weatherable powder coatings. Regulatory anchors include EU No 10/2011 for plastic food-contact materials and U.S. FDA 21 CFR 178.2010 where the specific substance is listed; formulators must additionally screen for compatibility with metal-ion scavengers and should avoid combining these absorbers with free primary amine additives because residual acid or hydrolyzable chlorine can form amine hydrochloride haze.
Cyanuric chloride loaded into an API intermediate train for triazine-containing pharmaceuticals is normally limited to batches where the third chlorine replacement is driven to completion under closed pressure-rated equipment, because any residual first- or second-substitution impurity changes the impurity profile against ICH Q3A reporting thresholds. In the synthesis of altretamine, cyanuric chloride is suspended in dry toluene or tetrahydrofuran and reacted with dimethylamine at a molar ratio of 1.0:3.1–3.3, the excess amine serving both as nucleophile and acid scavenger. The first nitrogen substitution proceeds at 0–20 °C; the batch is then heated to 60–80 °C and held until in-process HPLC shows total mono- and bis-substituted impurities below 0.10 area%. The terminal triazine crystal is isolated by aqueous quench, phase separation, solvent distillation, and recrystallization from toluene/heptane, with residual solvent controlled to ICH Q3C(R9) option 2 limits. API synthesis trains for this conversion use GMP stainless steel or glass-lined reactors rated to 4–6 bar, with scrubber systems for dimethylamine and off-gas HCl. The resulting active pharmaceutical ingredient is formulated into 50 mg hard gelatin capsules for use in specific oncology treatment protocols, though clinical use is determined by regional regulatory dossiers and not by the intermediate supplier. Compliance is governed by 21 CFR Part 210 and Part 211 for GMP manufacturing, ICH Q3D for elemental impurities, U.S. Pharmacopeia general chapters <232> and <233> for metal testing, and REACH for the cyanuric chloride feed material. The dominant processing boundary is moisture: cyanuric chloride hydrolyzes to cyanuric acid and hydrogen chloride, so transfer lines, solvent dryers, and reactor jacketing must be managed with automatic interlocks that stop dimethylamine dosing if headspace relative humidity exceeds 35%.
Intumescent flame-retardant packages for polypropylene and polyethylene use nitrogen-rich triazine-ethanolamine charring agents prepared by exhaustive substitution of cyanuric chloride with ethanolamine or diethanolamine. The first hydroxylamine substitution is carried out at 0–5 °C in water or acetone with a molar ratio of cyanuric chloride to ethanolamine of 1.0:1.02–1.08; subsequent substitutions require 1.02–1.08 mol ethanolamine per chlorine site and are driven at 80–90 °C, yielding a triazine-triol charring agent after neutralization and vacuum drying. In polypropylene compounding, the charring agent is combined with ammonium polyphosphate at a weight ratio of 3:1 to 4:1 and a total additive loading of 20–30 wt%; compounding is performed on a twin-screw extruder with L/D 36:1 to 44:1, barrel temperature profile 170–200 °C, and side-feeding of the flame-retardant package to limit thermal history. Fire performance is evaluated by UL 94 at 1.6 mm specimen thickness and by limiting oxygen index using ASTM D2863-23; typical V-0 formulations reach LOI values in the 28–34% range depending on resin grade and loading. Terminal product types include flame-retardant polypropylene wire and cable insulation, halogen-free building membranes, and water-based intumescent coatings for steel substrates, where the triazine charring agent contributes to cellular char formation but does not substitute for the full coating formulation. Regulatory anchors for the final products are REACH Regulation (EC) No 1907/2006, RoHS 2011/65/EU for bromine-free formulations, and EN 13501-1 construction product fire classification where applicable. Because the charring agent is hygroscopic after exhaustive hydroxyl substitution, compounders must pre-dry the additive at 80 °C for 2 h and maintain sealed feeder hoppers during humid weather; published data for specific resin grades is limited, so end-users verify performance through their own UL 94 test panels rather than relying solely on supplier-formulated values.
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Cyanuric chloride (2,4,6-trichloro-1,3,5-triazine; CAS 108-77-0; EINECS 203-614-9; UN 2670) is supplied as a white to off-white crystalline solid with molecular formula C3Cl3N3 and molecular weight 184.41 g/mol. The compound melts over a narrow range of 145–148 °C and has a density of approximately 1.32 g/cm³ at 20 °C; it sublimes without boiling at atmospheric pressure, a property that complicates open handling near melt-processing temperatures. Technical material is produced by catalytic trimerization of cyanogen chloride or by chlorination of cyanuric acid, and is usually offered as granular or milled product with purity from 98.5 wt% to above 99.0 wt%. Its primary industrial role is as a three-site electrophilic triazine intermediate rather than as a direct chlorinating agent. Each of the three chlorine substituents can be displaced by amines, alcohols, thiols, or phenols under successively higher thermal input.
Unlike trichloroisocyanuric acid (CAS 87-90-1), which contains N–Cl bonds and functions primarily as a hypochlorous acid donor in disinfection and bleaching, cyanuric chloride contains covalent C–Cl bonds on an aromatic triazine ring. Hydrolysis of cyanuric chloride releases cyanuric acid and hydrogen chloride; hydrolysis of trichloroisocyanuric acid releases cyanuric acid and hypochlorous acid. This difference determines incompatibility profiles: cyanuric chloride does not provide available chlorine in the same manner and is not used as a swimming pool sanitizer.
Compared with phosphorus oxychloride and thionyl chloride, cyanuric chloride is a solid at ambient temperature with three reactive sites, allowing controlled construction of trisubstituted triazine architectures rather than simple replacement of a hydroxyl group by chlorine. Phosphorus oxychloride produces phosphoric acid-derived byproducts; thionyl chloride generates sulfur dioxide and hydrogen chloride and leaves no scaffold in the target molecule. Cyanuric chloride therefore occupies an intermediate position: it is less volatile than thionyl chloride, more structure-forming than phosphorus oxychloride, and more water-sensitive than trichloroisocyanuric acid under basic pH.
A representative technical-grade release specification for granular material is shown below. Because cyanuric chloride hydrolyzes in the presence of atmospheric moisture, packaging is typically 25 kg or 50 kg high-density polyethylene drum with an inner polyethylene liner, or 500 kg fiber drum with a sealed liner. Model nomenclature is supplier-specific rather than standardized; typical descriptors are “granular,” “milled,” “micronized,” and “technical,” with purity and particle size distinguishing the grades.
| Parameter | Typical range or limit | Method |
|---|---|---|
| Appearance | White crystalline solid | Visual |
| Purity | ≥99.0 wt% | GC-FID |
| Melting point | 145–148 °C | Capillary melting point |
| Moisture | ≤0.1 wt% | ASTM E203 |
| Ash | ≤0.05 wt% | Gravimetric |
| Iron | ≤10 mg/kg | ICP-OES |
| Particle size D50, milled | 25–75 µm | ISO 13320 |
| Particle size D50, granular | 150–400 µm | ISO 13320 |
Routine release testing is challenging because the product hydrolyzes on contact with moisture. Sampling must be performed under dry nitrogen, and glassware for Karl Fischer titration must be pre-dried. GC-FID methods require exclusion of moisture to avoid on-column hydrolysis. Melting point is a useful purity index, but impurities such as cyanuric acid, sodium chloride, and heavy metals may not depress the melting point sufficiently. Therefore purity is confirmed by GC-FID or by titration of chloride after controlled hydrolysis. Supplier certificates of analysis typically report purity, melting point, moisture, ash, and iron; particle size and bulk density are supplied on request.
Reaction temperature, not stoichiometry alone, controls the selectivity of cyanuric chloride. The first chlorine atom is displaced rapidly at 0–5 °C in aqueous acetone or ice-water slurries by primary amines, alcohols, phenols, and mercaptans. The second substitution becomes practical at 20–40 °C, and the third generally requires 60–100 °C in polar solvents, often with acid scavengers such as sodium carbonate or sodium bicarbonate. This stepwise activation allows the synthesis of unsymmetrical 2,4,6-trisubstituted triazines without protecting-group chemistry.
| Substitution step | Typical temperature window | Typical medium | Examples |
|---|---|---|---|
| First chlorine | 0–5 °C | Water/acetone slurry | Primary amines, phenols, alcohols, thiols |
| Second chlorine | 20–40 °C | Aqueous suspension | Second amine or alcohol |
| Third chlorine | 60–100 °C | Polar solvent | Third nucleophile or controlled hydrolysis |
The first substitution proceeds with sufficient rate at 0–5 °C only if the pH is kept near 6.5–7.5. Below pH 5 the amine is protonated and unreactive; above pH 8 hydrolysis of unreacted cyanuric chloride becomes significant. Production-scale batch reactors for first-stage amination are commonly fitted with jackets capable of holding 0–5 °C, and cooling capacity must account for reaction exotherm. Excessive local pH rise precipitates cyanuric acid and lowers yield. In atrazine production, cyanuric chloride is reacted sequentially with ethylamine and isopropylamine in a stirred slurry reactor; the first amination is maintained below 5 °C to avoid dichloro intermediate formation, and the second is conducted at 30–40 °C with pH control. The third chlorine is replaced under alkaline conditions at 60–80 °C.
Reactive dye manufacture uses cyanuric chloride to attach chromophores to cellulose fibers through monochlorotriazine or dichlorotriazine reactive groups. A typical monochlorotriazine dye is prepared by reacting a water-soluble chromophore bearing an amino group with cyanuric chloride at 0–5 °C, then condensing the remaining chlorine with an aniline or sulfanilic acid derivative at 30–40 °C. Dichlorotriazine dyes retain two labile chlorine atoms and are applied at lower fixation temperatures, while monochlorotriazine dyes require higher fixation temperatures but offer better storage stability. Optical brighteners of the 4,4′-bis(triazinylamino)stilbene-2,2′-disulfonic acid class are similarly built by sequential substitution on cyanuric chloride. In these applications, residual chloride content and pH control are critical because premature hydrolysis of the second chlorine creates a non-reactive monohydroxy intermediate that cannot covalently bond to cellulose.
Replacement of thionyl chloride with cyanuric chloride is considered only when the target molecule must retain a triazine core or when a solid reagent is preferred for dosing. Thionyl chloride is a liquid at 20 °C with a boiling point of 79 °C and produces sulfur dioxide and hydrogen chloride; cyanuric chloride is a solid with a melting point of 145–148 °C and produces cyanuric acid and hydrogen chloride upon complete hydrolysis. Process differences include gas evolution profile and reactor metallurgy. Thionyl chloride off-gas requires scrubbers for sulfur dioxide and hydrogen chloride; cyanuric chloride hydrolysis generates only hydrogen chloride and cyanuric acid, but unreacted cyanuric chloride can sublime into vent lines if local hot spots exceed 145 °C. Stainless steel 316L or glass-lined equipment is generally suitable for cyanuric chloride; carbon steel is not recommended because hydrogen chloride corrosion rates increase above 60 °C. In API and fine-chemical chlorinations, published data for direct replacement of thionyl chloride with cyanuric chloride is limited because the reactivity and selectivity profile is not equivalent.
Continuous dosing of milled cyanuric chloride through loss-in-weight feeders and pneumatic conveying lines is influenced by particle size distribution, moisture, and surface charge. Granular material with a D50 in the 150–400 µm range flows reliably in screw feeders but dissolves more slowly in aqueous reactors; milled material with a D50 below 75 µm disperses quickly in slurry tanks but tends to bridge in hoppers if moisture exceeds 0.1 wt%. Batch-to-batch particle size drift in milled product can shift feed rate at constant screw speed when the span exceeds 2.0, a behavior observed in agitated filter-dryer discharge operations. To reduce dust and hydrolysis, closed transfer systems with nitrogen purging are used. Rotary valves and flexible screw conveyors are constructed from stainless steel 316L with polytetrafluoroethylene seals because of corrosive hydrogen chloride contact. Dust explosion testing under EN 14034-1 is sometimes required for micronized grades; published data for this specific configuration is limited, but the dust is not expected to be combustible after wetting.
Storage conditions require dry, cool warehouses below 30 °C and relative humidity below 60% because the product reacts with water to form cyanuric acid and hydrogen chloride. Containers must be kept closed and inerted; nitrogen blanketing is applied where repeated partial-drum withdrawal exposes material to humid air. Cyanuric chloride is classified under CLP Regulation (EC) No 1272/2008 with Acute Tox. 2 H330, Acute Tox. 4 H302, Skin Corr. 1A H314, Eye Dam. 1 H318, Skin Sens. 1 H317, and EUH014/EUH029 water-reaction hazard statements. Transport classification is UN 2670, Class 8, Packing Group II. Incompatibilities include primary and secondary amines, alcohols, aqueous alkalis, strong oxidizers, and water; combination with aqueous ammonia may cause violent exotherm and release of toxic fumes. Workplace exposure controls use continuous local exhaust ventilation at bag-dump stations and enclosed transfer lines. Under REACH Regulation (EC) No 1907/2006, the registered dossier includes the harmonised classification and is maintained by the lead registrant. Applications in cosmetic and food-contact materials are not supported; the substance is intended for industrial use only.
