Section
| HS Code | 645896 |
| Productname | Malachite Green Crystals/Powder |
| Chemicalclass | Triarylmethane dye |
| Iupacname | 4-[(4-dimethylaminophenyl)-phenylmethyl]-N,N-dimethylaniline |
| Molecularformula | C23H25ClN2 |
| Molecularweight | 364.91 g/mol |
| Casnumber | 569-64-2 |
| Form | Crystals or powder |
| Appearance | Green crystalline solid or powder |
| Color | Green |
| Odor | Odorless |
| Solubility | Soluble in water and ethanol |
| Meltingpoint | 158-160 °C |
| Storageconditions | Store in a cool, dry, well-ventilated place protected from light |
| Stability | Stable under normal storage conditions |
As an accredited Malachite green Crystals/Powder factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Malachite green crystals/powder in 100 g amber glass bottles, securely sealed, hazard-labeled, and packed in protective outer cartons. |
| Container Loading (20′ FCL) | Malachite green crystals/powder is securely packed and loaded into a sealed 20′ FCL container for export shipment. |
| Shipping | Ship Malachite Green Crystals/Powder in tightly sealed, chemically resistant containers with clear hazard and product labels. Protect from moisture, avoid dust, and segregate from food, feed, and oxidizers. Follow the current SDS and carrier regulations; classify as environmentally hazardous/toxic for transport where required. |
| Storage | Store malachite green crystals/powder in a cool, dry, well-ventilated area away from direct sunlight and moisture. Keep containers tightly closed, clearly labeled, and in secondary containment. Segregate from oxidizing agents, acids, food, feed, and drinking water. Use a locked, dedicated chemical cabinet and avoid dust generation. Maintain SDS access and a suitable spill kit. |
| Shelf Life | Store tightly sealed, dry, and protected from light; malachite green crystals/powder typically remain stable for several years. |
Malachite green is exhausted as a cationic triphenylmethane dye onto polyacrylonitrile fibers containing sulfonate and carboxylate dye sites. The dye is predissolved in dilute acetic acid at 60°C and added to a package dyeing machine set at 70°C. For batch dyeing, the addition rate is 0.05–1.5% on weight of fiber (o.w.f.), with a cationic retarder at 0.5–2.0% o.w.f. and a liquor ratio of 1:10–1:20. The bath is buffered to pH 4.0–4.5 using acetic acid/sodium acetate; temperature is raised to 98–100°C at 1.0°C/min or less between 85°C and 100°C, held for 45–60 min, and cooled to 60°C before draining. On production-scale package dyeing machines with reversible circulation at 2–4 L/kg/s, differential pressure is maintained below 0.8 bar; rapid strike after 85°C without sufficient retarder produces outer-layer ring dyeing and batch-to-batch shade drift. Final exhaustion commonly exceeds 90%, but the process window narrows above 1.0% o.w.f. because the fiber's available anionic sites approach saturation, requiring longer levelling time and increased retarder.
Anionic wetting, dispersing, or levelling agents must not be introduced into the bath because they form insoluble complexes with the cationic dye and deposit on pump seals and yarn packages. Filtration of the dyebath through 10–25 µm stainless steel screens and use of nonionic or cationic auxiliaries are standard on package and hank dyeing lines. Dyehouse observation indicates that shade reproducibility degrades if the pH drifts above 5.0 during the holding phase, because partial deprotonation of carboxylate sites slows exhaustion and shifts the final tone. Compliance for EU supply falls under REACH Regulation (EC) No 1907/2006, with hazard communication under CLP Regulation (EC) No 1272/2008. Finished textile goods are typically assessed against Oeko-Tex Standard 100 (2025) and downstream brand restricted substance lists. Fastness is measured using ISO 105-B02:2014 for artificial light, ISO 105-C06:2010 for washing, ISO 105-E04:2013 for perspiration, and ISO 105-X12:2016 for rubbing. Terminal products include acrylic knit apparel, socks, blankets, faux fur, craft yarns, and indoor upholstery velvets. Because lightfastness on acrylic is typically not higher than grade 3–4 at 1.0% o.w.f., outdoor or automotive ultraviolet exposure is outside the recommended service window.
On silk and wool, malachite green behaves as a basic dye with high initial strike but lower wetfastness than acid dyeings. Textile processors apply a pre-mordant of tannic acid at 3–5% o.w.f. and tartar emetic at 1–2% o.w.f. to silk prior to dye addition; the malachite green addition is 0.1–1.0% o.w.f. The dye bath is set at 40°C, raised to 80–85°C for silk or 85–90°C for wool over 30–40 min, and held for 45 min. pH is controlled between 4.5 and 6.0 using acetic acid to reduce fiber swelling and preserve surface smoothness. The production process is usually carried out in overflow dyeing machines or side-paddle machines for narrow fabrics and yarn packages, with gentle mechanical action to limit fibrillation of wool. Terminal product types include bright silk ribbons, decorative embroidery yarns, costume fabrics, and low-washfastness wool craft textiles. Compliance follows the same REACH and Oeko-Tex framework as acrylic; wash fastness testing under ISO 105-C06:2010 is critical because malachite green on unmordanted wool produces severe staining of adjacent cotton and polyester multifiber. For applications requiring repeated aqueous cleaning, this dye is not equivalent to acid dyestuff and should be excluded.
In leather finishing departments, malachite green is not dosed as a primary drum dye for chrome-tanned wet blue because its cationic charge leads to shallow penetration and uneven uptake on the anionic collagen matrix. The realistic downstream use is surface coloration of vegetable-tanned or retanned leather and touch-up sprays, where malachite green is dissolved in an ethanol/water or ethanol/glycol ether carrier at 5–20 g/L. Application is performed with spray booths at 30–50°C and 2–3 bar atomizing air pressure, followed by forced-air drying at 40°C. The process does not require pH adjustment in the carrier, but film adhesion and rubfastness depend on the selected nitrocellulose or acrylic binder system. Anionic fatliquors high in sulfated fish or beef tallow are not mixed into the cationic dye spray because droplet sedimentation and filter blockage occur. Separate application and drying between coats is required when binder systems contain anionic emulsifiers. Terminal product types include decorative bookbinding leather, belts, equestrian accessories, costume accessories, and high-fashion trim where dry rubfastness requirements are moderate. Compliance evaluation uses ISO 11640:2018 for color fastness to rubbing and ISO 105-B02:2014 for light; solvent-borne spray formulations must also comply with local VOC regulations, including the EU Industrial Emissions Directive 2010/75/EU where applicable. Because lightfastness of basic triphenylmethane on leather is weak, outdoor leather goods are excluded from standard applications.
In microbiology quality control and teaching laboratories, malachite green functions as the primary stain in the Schaeffer-Fulton endospore staining technique. The working solution is prepared at 5% w/v in distilled water; the counterstain is 0.5% w/v safranin. A heat-fixed smear is flooded with the malachite green solution and steamed over boiling water for 5 min, rinsed, and counterstained for 30 s. Endospores retain malachite green after decolorization, while vegetative cells take up safranin. Vegetative cell counterstain immersion beyond 45 s can displace malachite green from spore-bearing sites; therefore timing is controlled with slide racks rather than manual flooding. Production of staining kits uses filtered dye powder with assay not less than 90% and controlled insoluble matter; manufacturers supplying analytical reagents apply ISO 6353-2:1983 or equivalent reagent specifications and ISO 17025:2017 laboratory quality management. Terminal product types include bottled spore staining kits, concentrated reagent sets for hospital microbiology laboratories, pharmaceutical environmental monitoring stains, and educational microbiology kits. This segment is governed more by reagent purity specifications than by textile ecotoxicity requirements, though Safety Data Sheet hazard communication under GHS remains mandatory.
Malachite green can serve as a low-pH acid-base indicator because its triphenylmethane chromophore shifts from yellow at pH 0.0 to blue-green at pH 2.0. The working indicator solution is prepared at 0.1% w/v in a 1:1 water/ethanol mixture; higher ethanol fractions above 70% cause dye aggregation and reduce transition sharpness. The addition rate in most titrimetric methods is 1–3 drops per 50 mL of analyte, though strongly colored matrices may require instrumental end-point detection. The downstream production process is standard laboratory reagent bottling: dry powder is dissolved, filtered through a 0.45 µm membrane, and packaged in amber glass ampoules to limit photodegradation. Terminal product types include ready-to-use pH indicator solutions, compound-indicator paper strips, and customized volumetric analysis reagent kits. Reagent-grade malachite green supplied to this segment is controlled under general reagent monographs, with common quality parameters including solubility in ethanol, residue after ignition below 0.1%, and loss on drying below 0.5%.
Paper stock coloration with malachite green is limited to non-food-contact grades because the colorant is not cleared under FDA 21 CFR 176.170 for food-contact paper and paperboard. In beater or stock pump addition, the cationic dye is introduced at 0.01–0.2% on oven-dry pulp. Retention is assisted by the anionic charge of unbleached or lightly bleached pulp and by alum addition at 1–3% on dry pulp; process pH is maintained between 4.5 and 5.5. The stock temperature during dye addition is held at 25–40°C to avoid premature dye aggregation. The downstream process may use a fan pump or mixing chest with 15–30 min residence time before sheet formation on a Fourdrinier or cylinder machine. Use of cationic malachite green in the presence of anionic optical brightening agents can produce fluorescent quenching and green undertone in white-lined chipboard. Terminal product types include colored tissue, cover paper, poster board, decorative napkin stock, and non-food packaging materials. Papermakers must verify dyed broke recycling behavior because malachite green may bleed from recycled fiber into process water.
In ornamental freshwater fish and egg disinfection, malachite green is applied as a bath treatment for fungal and protozoal infections, but it is not approved for food-producing aquatic animals in the United States, the European Union, or Canada. The historically cited bath concentration for ornamental fish is 0.05–0.10 mg/L for 24 h, while egg disinfection may use short dips up to 2.0 mg/L for 5–10 min; published data for warm-water ornamental species is limited due to regulatory restrictions. The production process involves preparing a stock solution in warm water, then distributing it through aeration or mixing pumps in quarantine holding tanks; water temperature is normally maintained at 22–26°C and hardness above 80 mg/L CaCO₃ to reduce acute toxicity. Water changes after treatment at 48 h intervals are required to reduce residual accumulation; activated carbon filtration removes residual dye but spent carbon requires disposal as chemical waste. Terminal product applications include not-for-food ornamental fish quarantine, koi pond disease management in jurisdictions where authorized, and ornamental fish egg antifungal treatments. Compliance is dominated by veterinary drug residue regulations: the U.S. FDA prohibits use in food-producing aquatic animals, and EU reference laboratories enforce minimum required performance limits in edible fish tissue. Because malachite green residues can enter food chains, this application should only be considered for strictly non-food ornamental use and only where national law permits.
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Malachite green Crystals/Powder is a triarylmethane dye marketed as either the chloride salt or the oxalate salt of Basic Green 4, Colour Index CI 42000. The chloride salt, CAS 569-64-2, has the molecular formula C23H25ClN2 and a formula weight of 364.92 g/mol; the oxalate salt, CAS 2437-29-8, contains the malachite green cation paired with oxalate counterion and therefore differs in formula weight and chromophore mass fraction. The technical material appears as dark green crystals or a fine green powder with a metallic lustre, while purified biological stain grades are supplied as finely divided powders. In dilute aqueous solution, the dye shows maximum absorbance near 617 nm; the exact band position depends on counterion, pH, and solvent polarity. Supplier-specific model codes, such as chloride or oxalate suffixes and technical versus stain grade designations, are not ISO-harmonized and should be interpreted only against the corresponding certificate of analysis.
Commercial CoA documents typically report dye content, water content, loss on drying, residue on ignition, residual solvents, and selected heavy metals. Dye content is commonly not less than 85% for technical grades and not less than 90% for stain grade material when assayed by spectrophotometric area normalization at λmax against a reference lot; because the method is relative, absolute identity should be confirmed by thin-layer chromatography or retention time matching against a certified reference standard. Water content by Karl Fischer titration under ISO 760 is often specified below 10% for powder grades, while loss on drying at 105 °C may be reported as not more than 1.0% for crystalline chloride lots. Residue on ignition values vary with counterion; sulfated ash testing should use a temperature ramp to 650 °C and the result should be read against the CoA rather than a generic limit. Heavy metals are typically controlled by ICP-OES after microwave digestion following US EPA Method 3052; reporting limits are supplier-specific and should be confirmed for each lot. Residual solvent profiles depend on the final crystallization solvent; methanol, ethanol, and isopropanol are common, and a gas chromatographic headspace method with flame ionization detection is used to confirm that volatile organic levels are below the supplier’s release limits. Particle size is not standardized, but powder grades may be milled or sieved to pass a nominal 100 µm or 200 µm screen; crystalline grades are coarser and generate less dust. The chloride salt has a higher chromophore mass fraction than the oxalate salt because the oxalate counterion contributes additional mass without absorbing in the visible band; this requires molar correction when replacing one salt with the other in quantitative work. Purchasing specifications should therefore state CAS number, salt form, dye content, water content, and particle size rather than relying on model names alone.
For reproducible aqueous staining or dyeing, the dry powder is first wetted into a small volume of warm deionized water to break aggregates before dilution to the final volume; direct dumping into cold hard water can produce colloidal aggregates that pass through filters and reduce effective dye concentration. The pH of the make-up water strongly influences colour intensity. Under acidic conditions below pH 2.0, the dye is yellow; the blue-green chromophore develops as pH rises. In alkaline solutions above pH 11.6, conversion to the colourless carbinol base reduces absorbance and staining performance. For this reason, aqueous stock solutions are typically maintained at pH 3.0–4.5 with dilute acetic acid or citrate buffer when long-term stability is required. Elevated temperatures accelerate dissolution, but prolonged boiling of open solutions can drive off volatile acid and shift pH upward; covered vessels and controlled cooling are recommended. Solubility is counterion-dependent: the oxalate salt tends to dissolve more slowly than the chloride in cold deionized water, though particle size reduction improves dissolution at the cost of increased dust. Published exact solubility limits vary with pH and temperature; users should standardize a filtration step and verify absorbance at 617 nm against a dilution series rather than relying on nominal solubility alone. When preparing a 1% w/v working solution, the analytical aim is not solely complete dissolution but also reproducible absorbance; visible absorbance or tristimulus value should be checked after 24 h storage to confirm that no pH drift or precipitation has occurred.
Historically, malachite green was used in freshwater aquaculture as a topical immersion treatment for ectoparasites and fungal infections; the reduced metabolite leucomalachite green is the principal residue, and its persistence in muscle and skin is a regulatory marker. This use is now prohibited in food-producing aquatic species in the European Union because no maximum residue limit can be established for a substance with genotoxic and carcinogenic potential. In bacterial endospore staining, an aqueous malachite green solution, typically prepared in the range 1–5% w/v, is applied with steam heat for 3–5 min to force the dye into the endospore; after cooling and washing, safranin or another red counterstain is applied for 30–60 s. Endospores retain malachite green and appear green, while vegetative cells stain pink or red. The success of this procedure depends on the age of the culture, heat control, and the use of low-porosity spore-formers; older cultures may require longer steaming. In mycobacterial media, malachite green acts as a selective inhibitor at concentrations that suppress contaminating flora without fully inhibiting mycobacteria; medium batches should be standardized by inoculation with reference strains because the inhibitory limit is lot-dependent. As a pH indicator, transition intervals at pH 0.0–2.0 and 11.6–13.2 allow use in strong-acid and strong-alkali titrimetry; however, the dye decomposes slowly in strong mineral acids and should not be used where prolonged contact is expected. In textile dyeing, the chloride form is used as a basic dye for silk, leather, and acrylics; cellulosic substrates generally require pre-mordanting with tannic acid or a synthetic mordant to achieve acceptable washfastness. In polymer-film marking and holographic recording media, malachite green has been used as a photochromic dopant, but published migration and thermal stability data for industrial polymer matrices are limited and must be generated for each resin system.
Substitution among malachite green, crystal violet, and brilliant green requires attention to spectral shift, counterion, and selectivity. Malachite green chloride has λmax near 617 nm, while crystal violet chloride shows λmax near 590 nm; brilliant green absorbs at longer wavelengths near 625 nm. Crystal violet carries three dimethylamino-substituted phenyl groups, giving higher molar mass and greater affinity in Gram staining protocols; malachite green has two dimethylamino groups and one unsubstituted phenyl group, which alters its lipid solubility and retention in endospores. Brilliant green contains diethylamino substituents and is commonly used as a selective agent in enteric media, whereas malachite green is used in mycobacterial media. Differences in counterion also affect formulation: the chloride form has a higher chromophore mass fraction than the oxalate form, so equal-mass substitution of one for the other without molar correction produces different staining intensities. Products sold as malachite green carbinol or leuco base are not equivalent to the chloride or oxalate salts; they are uncharged or reduced species with different solubility and absorbance, and they should not be used as direct substitutes in aqueous staining protocols without revalidation.
| Parameter | Malachite green chloride | Crystal violet chloride | Brilliant green sulfate |
|---|---|---|---|
| Colour Index | CI 42000 | CI 42555 | CI 42040 |
| CAS number | 569-64-2 | 548-62-9 | 633-03-4 |
| λmax in water | 617 nm | 590 nm | 625 nm |
| Approximate cationic substitution | two dimethylamino, one phenyl | three dimethylamino | two diethylamino, one phenyl |
During weighing and transfer, the powder should be handled under a local exhaust hood or in a weigh-downflow booth because fine dye particles can become airborne and present an inhalation exposure risk. Nitrile gloves and a fitted particulate respirator with a P2 or N95 cartridge are appropriate for operations generating dust. The material is toxic by ingestion and has been reported to have mutagenic and carcinogenic potential in screening assays; therefore, open bench handling without engineering controls is not appropriate. Malachite green is very toxic to aquatic organisms and must not enter drains or surface water; spent dye baths and first rinse waters should be collected and disposed through a licensed waste handler in accordance with national and local hazardous waste regulations. Strong oxidizing agents, strong reducing agents, and highly alkaline solutions should be kept away from storage areas because they can degrade the dye or convert it to reduced forms. Store the container tightly closed in a cool, ventilated area; crystalline material tends to cake if exposed to humidity above 60% RH, so desiccated storage or controlled low-humidity rooms are recommended for powder grades. In the European Union, malachite green is not authorized for use in food-producing animals; Commission Regulation (EU) No 37/2010 lists it among prohibited pharmacologically active substances. Analytical detection of malachite green and leucomalachite green residues in fish and water samples is typically performed by LC-MS/MS after extraction and cleanup; method detection limits in the sub-µg/kg range are common in regulatory monitoring.
