Back in the mid-twentieth century, scientists searching for reliable indicators in analytical chemistry started turning to a family of organic dyes. Catechol Violet grew out of this hunt, taking shape as researchers noticed how compounds blending catechol and sulfonphthalein backbones gave clear, sharp color changes. Laboratories across Europe and North America took their shot at refining this molecule, attracted by its clear shifts in color across pH levels. The name “Catechol Violet” popped up more and more in technical literature from the 1950s onward. Academic teams published protocols and spectral data, gradually building a reliable profile for this dye. Over decades, other dyes like Bromocresol Green and Methyl Orange came and went in certain applications, but Catechol Violet’s unique range and vibrant indicator transition kept it on the bench.
Catechol Violet appears as a solid, typically with a deep purple color when inspected in powder form. It dissolves in water to give a vivid violet solution, catching the eye before it even makes it to the test tube. With strong chromatic transitions, this dye earned its place as both an analytical indicator and a complexometric reagent. For buyers, suppliers usually offer it in bottles ranging from 10 grams up to a kilogram, labeled for laboratory research or industrial use. Some also provide ready-to-use indicator solutions for convenience. Labs value Catechol Violet’s clean response and long storage life when kept dry and away from sunlight.
Catechol Violet’s molecular formula is C19H14O7SNa, with a molar mass around 408 g/mol. Its melting point hovers near 300°C with decomposition, so no chance for sublimation or gentle heating. The compound is fairly stable under cool, dry storage. In solution, its purple hue speaks for itself, but add some acid or base and the color flips with authority. Ultraviolet-visible spectrophotometry shows strong absorption near 570 nm, marking a definitive place in colorimetric assays. The dye demonstrates moderate solubility in water and slightly less in organic solvents, reflecting its polar sulfonate group. As a sodium salt, it resists clumping and handles repeated dilution cycles without drama.
Quality specs matter. Laboratories expect Catechol Violet to hit a minimum purity of 95% for demanding work, with some reagent grades rated up to 99%. Colorimetric performance under defined pH changes stands among the chief test points, so every batch gets checked against a reference curve. Typical labeling lists CAS number 115-41-3, batch number, expiry date, and storage conditions. Suppliers add hazard pictograms for “Irritant” in compliance with GHS standards. Some bottles list the chemical’s empirical formula, certificate of analysis, and guidance for preparing standard solutions. Provided instructions flag proper disposal steps and PPE. With a clear hazard summary and tracking data, users avoid surprises and keep audits tidy.
Manufacturers synthesize Catechol Violet by condensing catechol with 4-sulfobenzenesulfonic acid under controlled heat, using sodium hydroxide as a base and sodium chloride as a stabilizer. The process cries out for tight temperature control—overheating ruins the product, sending unwanted side products across the flask. Once the reaction finishes, the dark mixture cools before filtration, and the solid gets washed, then recrystallized from water. This hands-on process, tweaked over decades, rewards patience and careful monitoring. Most labs prefer to buy the finished dye, since routine synthesis takes time and a well-ventilated fume hood.
Catechol Violet grabs attention for its willingness to chelate metal ions with a visible color shift. Mix it with calcium, magnesium, or even rare earth metals, and the solution’s color tells the story of the reaction. Chemists use this trait for endpoint detection in titrations, especially complexometric methods using EDTA. Outside the lab, researchers tweak the basic Catechol Violet structure by adding alkyl or halogen groups, shifting the absorption wavelength or adjusting solubility. Some teams couple it with polymer backbones to produce sensor films for metal detection. Oxidative degradation removes color, which serves forensic techs searching for environmental contaminants. The base molecule holds up to a surprising range of chemical games.
On inventory sheets and publications, Catechol Violet masquerades under a string of names: o-Cresolphthalein Complexone, C.I. 42600, Acid Violet 4, and Pyrocatechol Violet. Chemical supply companies use wording like Sodium 4-(2,3-dihydroxybenzylidene)-2-hydroxy-5-sulfonaphthalene-1,3-disulfonate, but lab techs stick with Catechol Violet. In the textile world, Acid Violet 4 usually carries the conversation. The dye might show up as “pH Indicator Violet” in kits, confusing beginners before they settle on the most precise label for their work.
Catechol Violet doesn’t belong in the highest risk category, but its powder and dust can irritate eyes, skin, and breathing passages. Responsible labs store it in tightly sealed containers, away from acids, strong bases, and oxidizers. Standard practice keeps snacks and drinks away from benches, with gloves and goggles guarding against accidental contact. In a spill, cleaning crews use damp wipes to trap powder before mopping with water, then dispose of waste as non-halogenated organics. Wastewater—never down the drain before pH neutralization and evaluation. Most facilities require a chemical spill kit and eyewash station in sight. Staff and students get annual refresher training on handling, so a straightforward dye never becomes the source of a regrettable incident.
Catechol Violet plays the loyal partner in water hardness titrations, offering a clear signal as magnesium and calcium swap hands with EDTA. Environmental analysts reach for it when testing polluted water or soil for heavy metals. Biomedical researchers harness its pH-sensitive colors for rapid diagnostics and clinical chemistry, using it as a tracer in enzyme assays or colored tags in immunochemistry. Paint formulators add a pinch in corrosion indicators, while electronics manufacturers employ it as a trace component in certain sensor layers. Its chromatic sensitivity offers both beauty and brains—quick color reads cut down lab error without specialized machines. I’ve seen seasoned chemists and undergraduate trainees alike trust this dye for spot-checking and quantitative measurement.
Active R&D groups use Catechol Violet as a test case for new chemosensor technologies. Nanotech labs have built custom nanoparticles coated with Catechol Violet, which change color on contact with trace metals—turning old-school titration into next-generation field diagnostics. Spectroscopy teams keep using it in quantum yield studies, not just as a reference but as a platform for tweaking and modifying organic dyes. Green chemistry researchers try to extract similar chromophores from bio-based feedstocks mimicking its indicator qualities at lower environmental cost. Work continues on immobilizing Catechol Violet into hydrogels or membranes, stretching its use in point-of-care devices and continuous monitoring stations.
Toxicity studies on Catechol Violet generally point to low acute risks at common laboratory concentrations, but long-term effects remain under investigation. Some animal models show minor skin and eye irritation, so those working daily with large amounts wear protection and wash thoroughly. Oral toxicity in rodents sits well above practical exposure limits in labs or the field. Environmental monitoring groups test waste streams for any breakdown byproducts, since aromatic sulfonates have shown varied biological activity in aquatic systems. Regulatory agencies in Europe and Asia keep reviewing data, occasionally flagging Catechol Violet for closer waste tracking near sensitive watersheds.
Looking ahead, Catechol Violet won’t lose ground as an educational tool and mainstay of classic chemical analysis—it delivers instant feedback that digital sensors still find tough to replicate without electronics. Advances in miniaturization will keep bringing it into handheld testing kits and wearable sensors for rapid metal ion detection. Synthetic chemists keep exploring analogues and hybrids for tailored absorption spectra, improved water solubility, and smart response behavior. Environmental regulators motivate new studies on the dye’s fate in wastewater and soil, shaping more sustainable formulations. As industries and laboratories lean into colorimetric methods for greener operations and real-time analytics, Catechol Violet stands ready for another generation of practical, science-driven applications.
Catechol Violet doesn’t grab many headlines, but anyone stepping into a well-run chemistry lab probably comes across this striking purple dye at some point. Long before it brightened up test tubes, chemists were on the hunt for a reliable way to actually see what’s happening in reactions. That’s where Catechol Violet stakes its claim: as an indicator. This means scientists turn to it for a quick, vivid signal in their analytical work.
Digging deeper, Catechol Violet helps pinpoint the presence or absence of particular metals—especially rare earth metals and transition metals. When I was still running trial titrations in the lab, watching those color changes with Catechol Violet made the invisible world of ions feel a little more personal and immediate. Instead of staring at mystery solutions, the answer pops right out with a color shift. That speed and clarity matter, especially in labs where time and precision go hand in hand.
Industrial labs love Catechol Violet for a reason. Take water quality checks: detecting tiny amounts of copper, magnesium, or calcium saves a city headaches down the line. Add just a drop of this dye, and contamination shows up in seconds. Pharmaceutical companies lean on this trick to test drug purity. In education, students new to chemistry usually experiment with Catechol Violet to learn about complexation—when ions form a chemical embrace with another molecule. Watching the change from yellowish to purple or blue feels almost magical, but it really delivers measurable confidence in their results.
People often overlook just how much trust analytical chemists put in their tools. If Catechol Violet didn’t hold up to tough standards, entire batches of medicines or consumer goods could slip below safe thresholds. One small misread, and water supplies might get tainted. The science community has studied how factors like pH and impurities can mess with the indicator’s reliability. Careless handling turns experiments into guessing games. That’s why good lab practices and product quality make such a difference.
Discussions about chemicals in the world of industry or education don’t always land with everyone. People ask why it even matters. From experience, cutting corners—whether it’s mixing up the pH or skipping a calibration—means the end result gets fuzzy, and people could get hurt. That’s a lesson worth repeating. Offering steady training and reviewing techniques reduces mistakes, and sourcing Catechol Violet from reputable suppliers stops confusion before it starts.
Efficient science, whether in the classroom or a multimillion-dollar lab, owes plenty to little indicators like this. Relying on trusted dyes like Catechol Violet means safer products, cleaner water, and sharper lessons for tomorrow’s scientists. Not every hero in the lab wears a lab coat. Sometimes, it just shows up as a splash of purple in a tiny vial.
Catechol Violet stands out in the chemical world as more than a simple dye. Pull apart its structure, and you'll see the molecule features a benzene ring with two hydroxyl groups sitting at the 1 and 2 positions, much like classic catechol. On top of that, the backbone extends to include a sulfonic acid group and additional aromatic rings. This network of rings and substituents gives Catechol Violet its unmistakable purple-blue hue and its versatility in lab work.
Easy to overlook in a bottle, chemicals like Catechol Violet carry stories and surprises locked in their structures. The two hydroxyl groups attached to the aromatic ring come from the original catechol scaffold and are central to how this dye binds with various ions in solutions. One glance at the molecule, chemists recognize the importance of those groups for chelation—the process where the dye grabs hold of metal ions. This makes Catechol Violet very useful in chemical titrations.
The sulfonic acid part gives the molecule a solubility edge in water. A molecule needs to dissolve well for most lab applications, and the presence of sulfonic acid means Catechol Violet plays well in water-based experiments. It also supports environmental safety efforts because water solubility can influence the dye's breakdown and impact after use.
Ask anyone who worked in an analytical laboratory—they’ll probably recall using Catechol Violet in complexometric titrations, especially in detecting trace amounts of metals like calcium or magnesium. The color changes, driven directly by the molecule’s structure, make the readings for these tests clear and straightforward. This isn’t just a trick of light; it comes from real, measurable interactions between functional groups on the molecule and ions in solution. You can trust the results because the structure does the talking, not just the color.
In water testing, Catechol Violet offers a quick signal for the presence of certain contaminant metals. A shift from green to blue or from yellow to violet in a small vial can steer decisions for public health and industry, without the need for expensive machinery. The reliability of such indicators relies on the unique structure responsible for stable color shifts—something that doesn’t get the attention it deserves outside chemistry circles.
Chemicals like Catechol Violet make life easier and safer, but their reactivity also means they need careful handling. Overuse or careless disposal can introduce unnecessary dye into waterways. This kind of pollution brings its own risks. The very structure that makes Catechol Violet powerful can also help it persist in the environment, and that tracks back to the sulfonic acid group, which hinders breakdown. Anyone working with these types of chemicals needs training and a clear view of the chain of responsibility, from storage to eventual disposal.
Learning about Catechol Violet's structure encourages better design for future dyes and indicators. Scientists can use this knowledge to build molecules that give clear reactions but break down faster after use, reducing environmental side effects. By refining functional groups or modifying side chains, chemists can keep the benefits—strong color changes, reliable sensitivity—while easing the burden on natural water systems. For schools and smaller labs, education around responsible disposal and safer alternatives also makes a difference.
Structure shapes performance, and Catechol Violet proves that complexity in design often points the way toward useful, reliable chemistry.
People who work with chemicals know the story: ignore storage, and projects flop or, worse, accidents happen. Catechol Violet isn’t the most dangerous stuff in a lab, but careless handling can wreck data, create risks, and make ordering new supplies a regular headache. Labs rely on their chemicals holding up, especially for sensitive work like colorimetric analysis and calcium titration, where any slight contamination or degradation wipes out accuracy and trust in results.
Catechol Violet is pretty sensitive. Leave a bottle sitting out in sunlight, you’ll see its signature purple color fade over a handful of weeks or months. Heat speeds up this process. Many dyes, especially organic compounds like this one, are prone to breaking down with warmth and light. This affects the dye's performance in every application, from simple classroom demos to research that goes into published papers.
Oxygen is another problem nobody should ignore. Catechol Violet reacts with air and moisture, changing its chemical makeup. Over time, this can cause clumping, reduced solubility, or uneven color response. If the container isn’t sealed tight, the powder just won’t behave the way the data sheet says it should.
Glass or high-density polyethylene containers with airtight lids work best. There’s a reason most suppliers ship the powder in these. Polyethylene resists most acids and solvents, and doesn’t leach weird stuff into the dye.
I always label the container with the date received and keep it in a dry cabinet away from direct sunlight. Some chemists like to split a new batch into smaller vials so only the working vial gets opened regularly. That keeps the rest safe from continual air and moisture exposure, especially in busy labs where people don’t always check the cap after use.
Room temperature doesn’t mean next to the window. Standard lab advice sets storage at 15-25°C, out of sunlight, and definitely not above any heat source like radiators. Lower temperatures shield the powder from fast chemical breakdown, but freezing isn’t a good idea. Ice crystals can pull moisture into the container, and tiny bits of water can start unwanted reactions or clumping. Dessicant packs inside the storage container take care of any stray humidity.
Spills and contamination crop up in cluttered storage spaces. Regularly check the Catechol Violet supply and throw out any clumped or faded batches. Record shelf life and color changes, keeping everyone in the loop. Some labs ignore these steps, but an organized setup saves money, prevents waste, and sets a standard the whole team follows.
Good storage habits avoid dangerous reactions and ruined experiments. Following published guidelines from chemical suppliers and safety agencies is basic, but it pays off. Well-stored Catechol Violet keeps its sharp color change, gives reliable results, and limits risks to lab staff. For anyone serious about their chemistry, those aren’t just guidelines—they’re habits that make or break the work.
Catechol Violet pops up in labs all over the world, mostly in classrooms and research centers. This dye works as an indicator in experiments. Toss it into a solution, and it changes color based on the acidity or metal ion concentration—handy for anyone learning chemistry. Most people grab a small vial from a shelf and think of it as just another colorful powder. But the safety data sheet for this chemical paints a more complicated picture.
This isn’t kitchen-table science. Catechol Violet—also called Acid Violet 4—is no cupcake ingredient. Direct skin or eye exposure can irritate and burn, and that purple dust shouldn’t be floating in the air near your face. Swallowing or even inhaling it by accident may upset the stomach, cause coughing, or trigger headaches. If you spill some and don’t clean it up, it can linger in the environment far longer than most realize.
The Joint FAO/WHO Expert Committee on Food Additives, the CDC, and the European Chemicals Agency have all pointed out that chronic exposure to certain synthetic dyes adds unnecessary stress to the liver and kidneys in mammals. There’s not much specific long-term toxicity data for Catechol Violet, but it shares a structure with compounds flagged for mutagenicity or cancer links. That sets off enough alarm bells for medical professionals and researchers.
During graduate school, we used this dye for quick titrations. Cleanup required gloves and goggles every time. Once, a classmate ignored warnings, skipped gloves for “just a quick test,” and ended up with stained, irritated hands that burned for hours. Afterward, our professor reminded us that, just because a powder looks harmless on the outside, that doesn’t give anyone a free pass to skip precautions.
Most folks don’t keep vials of Catechol Violet under the kitchen sink, but the bigger picture matters. Schools and companies, often strapped for resources, sometimes relax chemical hygiene if nobody gets visibly hurt. This sends a dangerous message down the line to students and workers: take shortcuts, and you might pay for it later. Safe handling practices for every chemical—no matter how common—should be expected.
Archival research from the United States National Library of Medicine shows that industrial dyes in waterways can disrupt aquatic life. Fish and invertebrates exposed to low concentrations sometimes stop growing and reproducing normally. Many dyes also resist breaking down in sunlight, sticking around in the ecosystem much longer than anticipated. Pollution from a single bottle, poured down a drain, can snowball into bigger problems.
Order only as much as you need and label all containers clearly. Wear gloves and goggles, even for small quantities. Ventilated hoods keep airborne particles in check. Liquid waste needs a separate container, and leftover powder shouldn't go into a regular trash bin or sink. Keep a well-stocked spill kit nearby—a few absorbent pads have saved more than one morning in my own lab.
Teachers and supervisors need to speak up about risks and not rely on “common sense.” Training students and staff about hazards isn’t bureaucracy—it’s a basic responsibility to protect people and the environment from needless chemical exposure.
Working with dyes brings color to the lab, but it also brings certain risks. Catechol Violet, popular for its use as a pH indicator and in analytical chemistry, carries hazards that some might overlook. Anyone who’s ever spilled even a small amount knows it stains more than just glassware—sometimes your hands, sometimes your sense of safety. Taking shortcuts on safety can mean trading your well-being for a few minutes of convenience.
Catechol Violet doesn’t mess around. Skin can become irritated, and eyes are extra sensitive to splashes. Breathing in dust or vapors may cause headaches or respiratory discomfort. I’ve seen more than one seasoned chemist surprised by how quickly the powder can spread. The bottom line—if you wouldn’t want it on your sandwich, you shouldn’t have it on your skin.
The Safety Data Sheet lists risks: irritation from contact, problems if inhaled, and potential harm to aquatic life. It’s not meant for careless handling or poor clean-up.
No one wants a trip to the emergency room because of a routine experiment. Keeping hands and faces safe starts with wearing gloves—those nitrile ones work best. Throwing on safety glasses might seem like overkill, but it keeps your eyes out of harm’s way. Lab coats or long sleeves save your skin from accidental splashes and drips.
Labs have seen their share of powder clouds forming with a little too much enthusiasm opening bottles. Scooping gently, moving slow, and avoiding open containers keeps things under control. Some will tell you to measure over a tray—less mess, easier to clean up if things go sideways.
Breathing in the stuff isn’t a fun time. Work with Catechol Violet inside a fume hood. Not every workstation has one, but those who don’t regret the investment after a mishap. I remember an intern who skipped the hood for a “quick” weigh-out; the cough stuck around for days.
After the experiment wraps up, cleaning comes next. Don’t leave powder or stained containers sitting out. Spills need prompt attention with damp cloths or paper; dry sweeping only stirs up dust. Any contaminated gloves or towels should go straight into designated waste containers—no shortcuts.
Storage gets overlooked far too often. Catechol Violet belongs in sealed, clearly labeled containers, away from food or common spaces. Moisture or high temperatures mess with stability and can change the dye, so a dry, controlled spot is best.
A safe lab grows from regular reminders and training, not just signs on the wall. Everyone, from the veteran chemist to the undergrad, learns the value of double-checking their protective gear. Sharing stories—spills, close calls, stubborn stains—teaches newcomers that caution is earned by those who take it seriously.
Keeping things safe with Catechol Violet boils down to respect for the chemicals and your own health. Good habits—gear up, slow down, clean thoroughly—make chemistry more enjoyable and productive. Safety isn’t a box to tick. It’s a practice built from experience, stories, and a real concern for health, both yours and the planet’s.
| Names | |
| Preferred IUPAC name | 3,3'-[(3,3'-Dimethoxy-1,1'-biphenyl-4,4'-diyl)bis(azanediyl)]bis(2-hydroxyprop-2-en-1-one) |
| Other names |
4-(2,4,6-Trihydroxyphenylazo)benzene-1,2,3-triol o-Cresol Violet Pyrocatechol Violet Catechol Purple Pyrocatechol Violet sodium salt |
| Pronunciation | /ˈkæt.ɪ.kɒl ˈvaɪ.ə.lət/ |
| Identifiers | |
| CAS Number | 115-41-3 |
| Beilstein Reference | 1360475 |
| ChEBI | CHEBI:86023 |
| ChEMBL | CHEMBL2105931 |
| ChemSpider | 55054 |
| DrugBank | DB14015 |
| ECHA InfoCard | 100.019.427 |
| EC Number | 232-602-0 |
| Gmelin Reference | 16559 |
| KEGG | C11641 |
| MeSH | D017987 |
| PubChem CID | 73434 |
| RTECS number | GG3150000 |
| UNII | OO4V52AWFG |
| UN number | UN2811 |
| CompTox Dashboard (EPA) | DTXSID7032372 |
| Properties | |
| Chemical formula | C18H16N2O6S |
| Molar mass | MW: 358.32 g/mol |
| Appearance | Dark violet powder |
| Odor | Odorless |
| Density | 1.6 g/cm³ |
| Solubility in water | soluble |
| log P | 1.17 |
| Acidity (pKa) | 7.5 |
| Basicity (pKb) | 6.5 |
| Magnetic susceptibility (χ) | -68.0·10⁻⁶ cm³/mol |
| Refractive index (nD) | 1.675 |
| Viscosity | Viscous liquid |
| Dipole moment | 3.8895 D |
| Thermochemistry | |
| Std molar entropy (S⦵298) | 282 J·mol⁻¹·K⁻¹ |
| Hazards | |
| Main hazards | Harmful if swallowed, causes serious eye irritation, may cause respiratory irritation. |
| GHS labelling | GHS02, GHS07 |
| Pictograms | GHS06,GHS08 |
| Signal word | Warning |
| Hazard statements | H302 + H312 + H332: Harmful if swallowed, in contact with skin or if inhaled. |
| Precautionary statements | P264, P280, P305+P351+P338, P337+P313 |
| NFPA 704 (fire diamond) | 2-1-2 |
| Flash point | Flash point: 246°C |
| Lethal dose or concentration | LD50 (oral, rat): 4200 mg/kg |
| LD50 (median dose) | LD50 (median dose): Oral rat 1100 mg/kg |
| NIOSH | SN1750000 |
| PEL (Permissible) | Not established |
| REL (Recommended) | 10 mg/L |
| IDLH (Immediate danger) | No IDLH established |
| Related compounds | |
| Related compounds |
Bromocresol green Bromothymol blue Chlorophenol red Cresol red Methyl orange Methyl red Phenol red Thymol blue |
