If you look back at the growth of organic chemistry, you’ll see that 5-Amino-O-Cresol didn’t just appear out of nowhere. Its origins come from the early days of coal tar chemistry, right when synthetic dyes and pharmaceuticals started changing manufacturing worldwide. Researchers at the end of the 19th century dug into the aromatic amine landscape, often up to their elbows in messy separations, sifting through samples to find something useful. Back then, the appeal was how these new amines and phenols brought new shades and molecule shapes to chemists’ benches, opening doors for further development in both pharmaceuticals and dyes. 5-Amino-O-Cresol’s discovery fit right into that story, first mentioned as part of ongoing investigations into aminophenol derivatives, and soon noticed for its unique behavior in both oxidative and reduction processes. Academic and industrial labs, from Germany’s BASF to England’s Imperial Chemical Industries, saw fit to catalog and test its properties, pushing our understanding of this tricky cresol further.
5-Amino-O-Cresol stacks up as a specialty intermediate. It’s not your everyday commodity chemical; lab catalogs and specialist suppliers highlight that they sell it to researchers working on specific syntheses. You don’t see truckloads of it shipped, but the demand runs steady within a few niches, such as hair dye formulation and certain fine chemical steps. In applications, the compound becomes valued for the way its amino and methyl groups change reaction pathways, affecting coloration, binding, and ease of further modification.
This compound’s physical makeup helps define its behavior. 5-Amino-O-Cresol comes as an off-white to grayish solid, packing a distinct chemical punch with both a hydroxyl and an amino group attached to a methylbenzene ring. Its melting point hovers close to 125–130°C. Solubility matters: it dissolves better in alcohol and ether than in water, making it friendlier in organic mixtures than in plain water systems. The presence of both amino and hydroxyl groups makes the molecule active in both acid–base and redox chemistry. The compound is not volatile and mostly stays put unless you hit it with enough heat or strong oxidizers.
Serious suppliers measure 5-Amino-O-Cresol’s assay above 98% for research grade, sometimes higher for highly sensitive synthesis. Impurities like other cresols or isomeric aminophenols remain tightly controlled, usually below 1%. Labeling typically lists batch number, date of manufacture, and storage instructions like “keep tightly sealed, protect from light, store in a cool, dry place.” Reputable shipments carry full hazard documentation. Labels also include chemical identifiers like the CAS number (2835-98-5) and details like GHS hazard statements—eye and skin irritation, for instance, plus handling advice.
Chemists most often prepare 5-Amino-O-Cresol by nitration of o-cresol to yield 5-nitro-o-cresol, followed by catalytic reduction to the amino compound. That reduction stage, often run over palladium on carbon or iron filings with acid, gives the desired amine with decent yield, so long as you keep close tabs on reaction temperature and avoid over-reduction or deamination. Purification typically involves recrystallization from ethanol or similar solvent, which dumps out any oily or tarry material left from side reactions. This kind of route gets repeated in many technical syntheses, both on the bench and at moderate production scale.
It’s hard to miss the versatility of this molecule. The amino group lets chemists make diazonium salts on demand, which paves the way for azo dye formation. Its phenolic hydroxyl group reacts in etherification, esterification, and coupling reactions, altering the backbone and functionality for downstream uses. N-alkylation or acylation of the amino group goes smoothly under mild conditions. Running oxidative or electrophilic substitutions on the aromatic ring, careful operators have found routes to interesting quinones and extended aromatic systems. In some cases, the molecule forms building blocks for pharmaceuticals and imaging dyes. This rich reactivity makes it a favorite for synthetic tinkering.
Anyone scanning catalogs should know that 5-Amino-O-Cresol appears under several aliases. “5-Amino-2-methylphenol” and “2-hydroxy-5-aminotoluene” both refer to the same structure, and these alternate names pop up in older literature as well as on current material safety data sheets. Trade names show up when this compound is blended into complex dye precursors—among German suppliers the term “Developer 21” has appeared in the context of hair color chemistry. The variety of synonyms reflects historical naming conventions in organic chemistry and helps tie together older research papers and modern product descriptions.
Working with 5-Amino-O-Cresol requires the usual respect for aromatic amines and phenols. Direct contact can cause irritation, especially to the eyes and skin, so gloves and goggles should always come out for weighing and handling. Inhalation of dust ought to be avoided—the usual fume hood applies when preparing quantities or scaling up reactions. Waste from reactions involving cresol derivatives can’t just go down the drain; specialized disposal is standard in labs. Larger facilities should monitor air quality for amine concentrations and keep appropriate spill remediation equipment close by. Companies supplying this chemical provide robust safety sheets, recommending storage below 25°C, out of strong sunlight, and away from oxidizers or acids to prevent degradation.
Most people outside chemistry don’t realize this compound finds its primary work in hair dye formulations and in certain specialty dye systems for fibers. The compound helps bring brown shades to hair colors, adjusting hue by working as a coupler or oxidative dye precursor. Its union of amino and phenol groups provides color stability and helps modulate final tone during the development stage. Some fine chemical syntheses use it as an intermediate for more elaborate pharmaceuticals, especially ones needing an aminophenol backbone. Researchers creating sensitive analytical reagents have also based colorimetric sensors on its derivatives, proving useful in water quality labs and chemical testing kits.
R&D teams in chemical companies sometimes see 5-Amino-O-Cresol as a steppingstone for new products. Ongoing work explores how it interacts with metals and other organics, searching for smarter catalyst supports or more effective dye molecules. Innovation in green chemistry looks at using less hazardous reduction agents, trimming down toxic waste in its preparation. Universities routinely report new routes for its safe modification, chasing after low-impact derivatives that work as antioxidants, potential drug leads, or imaging markers. Each year brings fresh conference papers discussing not just the molecule but also unexpected products that come from reimagining its core structure.
Aromatic amines have earned a reputation for health risks—think aniline and its cancer links. Studies of 5-Amino-O-Cresol haven’t shown the dramatic carcinogenicity of some other amines, but animal studies do reveal moderate toxicity at higher exposures, with effects on liver and kidney tissue when administered in high doses. In hair dye use, finished formulations keep the concentration tightly controlled, and European regulations set maximum allowed levels, mandating clear labeling on products. In environmental studies, this compound shows potential for slow breakdown in soil and water, encouraging ongoing work to develop biodegradable alternatives or better waste treatment. The demand for strong safety data keeps academic toxicologists busy, hunting for long-term effects and metabolic byproducts.
The future for 5-Amino-O-Cresol ties closely to changing trends in personal care, environmental stewardship, and specialty synthesis. As hair dye regulations tighten and customers demand lower-toxicity and more eco-friendly products, researchers push for new derivatives that offer similar function but less environmental baggage. In specialty chemistry, interest stays firm as long as new uses for arylic amines and phenols keep surfacing. Advances in process engineering and catalytic chemistry could reshape its production, lowering waste and hazard profiles. In research circles, a fresher look at its core chemistry may yet spark a breakthrough—another innovative dye or a clever pharmaceutical scaffold. Researchers, industry watchdogs, and application chemists will continue tracking its developments, weighing benefits against risks at each step ahead.
5-Amino-o-cresol rarely lands in headline news, but it matters for more than meets the eye. This small, aromatic chemical, known to chemists for its amine and methyl groups, stands out in a world of dyes and personal care products. I remember walking through chemistry labs in university, passing by small vials labeled with strange names. Sometimes you stop to ask, “What does this stuff even do?” That’s where stories like this begin.
Hair dyes make up a market fueled as much by fashion as by science. Many folks want a new look or simply to cover gray. Behind those transformations sits a set of coloring agents, with 5-amino-o-cresol as a familiar ingredient for dark, permanent shades. This compound reacts easily with others, locking color into hair fibers, which stops it from washing out with the next rainstorm or swim at the pool.
Market studies suggest that most permanent hair dyes mix together several small aromatic molecules like 5-amino-o-cresol. These join up under the action of peroxide, fixing pigment deep in the hair shaft. Think about that next time you see a friend with a rich mahogany shade—there’s real chemistry giving them that glow.
5-Amino-o-cresol doesn’t stay in the salon. It plays a part in the textile world, helping bind certain colors to fibers in fabrics. Mills looking to get solid, heat-stable, and fade-resistant color need something to react quickly without messing up delicate yarns. Industry data points out its reliability in dye houses, where manufacturers choose specific aromatic amines like this one for their repeat performance.
Skin creams, shampoos, and even some medicated ointments have shown traces of 5-amino-o-cresol. It acts mostly as a coloring agent or an intermediate, helping other ingredients form active compounds. Regulations get strict here—too much residue, or bad breakdown products, trigger recalls and consumer pushback. Real-world monitoring by agencies in Europe and North America puts 5-amino-o-cresol through regular reviews to check for long-term effects. In my view, that is a responsible approach, especially since personal health is on the line.
No chemical rides free of scrutiny, especially those with applications close to the body. Some early research pointed to skin irritation potential and rare cases of allergic reaction. Occupational exposure studies keep an eye out for more serious risks, such as links to certain cancers. Dermatologists and toxicologists look for better ways to protect everyone, especially salon staff exposed for long hours.
Stronger labeling rules, proper training, and robust research into alternatives could keep people safer down the road. Many manufacturers already look for less reactive, more biodegradable colorants; innovation here could ease some of the worries. Sharper health monitoring and stricter ingredient disclosure would help consumers and workers make more informed choices.
5-Amino-o-cresol doesn’t grab the spotlight. Even so, it sits quietly in our daily routines—coloring a favorite sweater, gilding hair in a new tone, or working as a chemical assistant behind the scenes. As science and regulations move forward, so does the promise of safer, smarter use of chemical tools. With more transparency and innovation, we keep what works and improve on what doesn’t.
Most folks hear “5-Amino-O-Cresol” and picture a complicated lab, but this compound pops up in industries from dyes to cosmetics. Working around chemicals like this means real risks, not just for experts in white coats. Years in a lab taught me plenty about safety, not from reading manuals, but by watching what actually works when people get busy.
Inhalation or skin contact with 5-Amino-O-Cresol can cause irritation and allergic reactions. Swallowing it can be far worse—central nervous system symptoms, damage to organs over repeated exposure, and the genuine risk of burns if it splashes. People often underestimate how quickly a situation changes after a single mistake with such chemicals.
Gloves, goggles, lab coats—these sound basic, but they make a huge difference. Polyvinyl or nitrile gloves work better than latex with aromatic compounds. Ordinary clothes offer almost no protection if a spill hits your lap. I’ve seen colleagues who took off their safety glasses “just for a quick look” and wound up at the doctor. Companies encourage goggles, face shields, and chemical-resistant aprons for a reason.
Nobody should count on just a window fan. Fume hoods or localized extraction keep vapors or powders out of the air and off your skin. I watched supervisors switch from open-bench work to properly vented hoods and cut accidents in half. Proper ventilation lowers the chance of inhalation symptoms and keeps the workplace healthier for everyone.
Improper storage invites trouble: 5-Amino-O-Cresol should stay in tightly sealed, labeled containers, away from sunlight and anything reactive. Storing it with acids or oxidizers is a disaster waiting to happen. A clear, uncluttered workspace makes all the difference if a spill occurs. I keep spill kits within arm’s reach—absorbent pads, neutralizing agents, and plenty of wipes. If a spill happens, containing it quickly, airing out the area, and reporting it saves headaches and prevents harm.
Dumping leftovers in the sink isn’t just illegal; it’s reckless. Hazardous waste bins, clearly marked, keep harmful chemicals out of the water system. Companies face fines and workers face exposure when waste isn’t handled right. In places I’ve worked, regular audits and training helped everyone take disposal seriously, from interns to senior chemists.
Safety meetings can sound boring, but real-world stories from coworkers about near-misses and accidents stick. Training isn’t just about ticking boxes—it's about getting everyone to care. Clear up-to-date procedures, regular refreshers, and posted emergency contacts—all help prevent accidents. My confidence with 5-Amino-O-Cresol comes from years of shared experience and learning from each other’s slip-ups.
Manufacturers and employers who provide good training, suitable gear, and enforce standards provide a safer place to work. Every individual’s responsibility shapes how safe a team works. Respecting the risks, using the protective tools, and staying alert create a workplace where nobody pays the price for shortcuts.
5-Amino-O-cresol takes me back to chemistry classes where curiosity felt like the main ingredient in the lab. The name itself tells a story: you get a cresol backbone, an amino group, and a methyl group, all fitting together in a specific way. Chemists pay attention to this arrangement because the way atoms connect makes or breaks a molecule’s impact.
5-Amino-O-cresol features a benzene ring holding three key guests: an amino group (–NH2), a hydroxyl group (–OH), and a methyl group (–CH3). The names “O-cresol” and “5-amino” tell you where to look. “O” gives you the ortho position—a couple of atoms sitting next to each other on the ring—while the “5-amino” points out the location of the amino group relative to the hydroxyl.
The molecular formula for 5-Amino-O-cresol is C7H9NO. You find seven carbon atoms forming the skeleton, nine hydrogens, one nitrogen, and one oxygen. On paper, that’s all someone might see. Step into the world of hair dyes or organic synthesis and that extra nitrogen atom becomes a secret door. It’s no surprise that compounds like this one end up as core ingredients in hair colorants, toners, and sometimes in the synthesis of pharmaceuticals.
In drawing its structure, each corner of the benzene ring delivers function. The hydroxyl group helps the molecule dissolve a bit better in water, and the amino group interacts differently with oxidizing agents compared to simple cresol. When manufacturers create hair dyes, the role of 5-Amino-O-cresol stands out. Its structure means it can react with other dye intermediates to form specific colors, especially brown and black tones. This isn’t just chemical cleverness—it helps millions of people cover grays, switch up styles, or recover confidence.
Safety sits tightly with function here. Every year, regulatory agencies like the European Chemicals Agency (ECHA) and U.S. Food and Drug Administration (FDA) keep tabs on aromatic amines. 5-Amino-O-cresol lands under the spotlight, thanks to both its usefulness and potential hazards. Not all amino phenols are equal—some raise toxicity flags, and misuse can lead to allergic reactions or harmful exposure. The position of each functional group alters not only how the chemical works, but also how it impacts skin, hair, and health.
Regulations demand clear labeling, patch testing, and strict control of concentrations in retail products. Facts matter here: data from ECHA shows that concentrations above 2% in hair dyes can increase the chance of adverse reactions. Companies focus research on finding balanced formulas and educating consumers about safe use. Speaking honestly, ignoring the details in chemical structures costs more than just a bad batch—it can threaten public health and consumer trust.
Learning about chemicals such as 5-Amino-O-cresol reminds me that science opens the door, but ethics guide the way. Better personal protective equipment in labs reduces the risk of exposure. For home or salon use, clearer product information and accessible safety tips eliminate guesswork. Regulatory bodies, research labs, and industry move forward faster when safety and transparency stay central.
With rising demand for safer ingredients, chemists are examining analogues and alternatives to aromatic amines. They experiment with plant-based precursors or tweak functional groups to lower toxicity without losing performance. Open data sharing among scientists means safer hair colorants will continue to make it to shelves, giving people more choices and peace of mind.
One thing stays clear: the details in molecular structure guide safety, function, and innovation for everybody, from the lab bench to the store shelf.
Anyone who has spent time around chemicals—whether in the classroom, a lab, or the back room of a salon—knows that some things demand more attention than others. 5-Amino-O-Cresol falls in that category. This isn’t something to keep out in the open or tuck onto an unlabeled shelf. Think of it more like the bleach under your kitchen sink: you know the harm it can cause, so you don’t leave it where little hands or careless minds might grab it.
This compound can irritate skin and eyes, and inhaling dust won’t do lungs any favors. That’s not just a possibility; it has happened to plenty of experienced professionals who lost track of labels or lids. Nobody wants to deal with itchy eyes or worse during a busy day, so controlling spills and minimizing dust in the air becomes part of the routine.
The best spot for this chemical: a cool, dry, well-ventilated room, away from sunlight and direct heat. Bright light doesn’t just make the container look dingy faster—over time, UV rays can break down some chemicals, and 5-Amino-O-Cresol is no exception. A few red blotches or unexpected odors are a warning sign. Once, after a sunny window warmed our storage rack for a few days in July, I caught one container with a warped lid and odd discoloration. A simple oversight nearly ruined an entire batch, and no insurance policy covers carelessness.
Keep the chemical in its original, tightly closed container with the label in plain sight—not scribbled shorthand or sticky notes. Good labeling keeps everyone honest and avoids mistakes. The International Agency for Research on Cancer and the U.S. National Library of Medicine both say that improper storage leads to avoidable health risks. Secure shelving, out of reach from children or pets, protects more than just the workers. On a personal note, watching a coworker cough up a storm after a careless spill leaves a lasting memory; since then, segregation from acids, oxidizing agents, and food storage has been a non-negotiable rule in every workplace I’ve managed or visited.
Gloves, goggles, and strengthened ventilation matter here. Ventilation isn’t just a box ticked for health inspectors; it actually helps clear any lingering fumes and keeps accidental dust at bay. Wherever I’ve worked, running a small fan near the chemical shelf or placing storage cabinets under exhaust hoods has helped keep spaces safer. If a spill does happen—because they do, even for the careful—sweeping up with a damp cloth and immediately sealing any waste in a marked, leak-proof bag keeps situations from escalating. Just dumping the waste with other trash only invites problems with both regulations and safety.
Every responsible facility has written protocols that actually get followed, not just filed away. Chemical storage logs and regular checks catch problems before they grow. I’ve seen the difference between places with tight routines and those that treat storage like an afterthought—and the former rarely need emergency calls. If there's good collaboration between teams, spills taper off, and everyone goes home healthy. Resources like the NIOSH Pocket Guide and official Safety Data Sheets (SDS) help reinforce these habits and answer any lingering questions.
It comes down to this: respect the material, pay attention to details, and trust good habits built by experience and evidence. That’s what keeps the day running smoothly and everyone around safe.
If you’ve ever looked closely at a hair dye box in the store, you may have noticed a string of chemical names on the label — 5-Amino-O-Cresol is sometimes among them. This compound turns up in dye formulations for both cosmetic and industrial applications. Its use raises questions about health, safety, and oversight.
For years, safety data around chemicals like 5-Amino-O-Cresol have often been scattered, but certain threads stand out. Research from toxicology databases indicates that it can be irritating to the eyes and skin, and inhalation of its dust or fumes may cause respiratory discomfort. Some animal studies suggest repeated, direct contact can damage organs such as the liver or kidneys. Applying hair dye or similar products once in a while may not put you at immediate risk, but exposure in labs or manufacturing plants presents a different story — where repeated or high doses are possible, the margin of safety tightens.
I worked in a college chemistry lab, where we handled many amines in small batches. Even with gloves and goggles, I remember the smell and quickness with which discomfort set in if a compound spilled. Information from safety data sheets (SDS) is crucial in environments like these. For 5-Amino-O-Cresol, the SDS typically signals hazard in direct contact situations, lists precautionary measures, and refers to its potential for harm if handled carelessly.
In the United States, the Environmental Protection Agency (EPA) and the Occupational Safety and Health Administration (OSHA) keep lists of regulated chemicals. At this time, 5-Amino-O-Cresol does not appear as a standalone chemical under federal restrictions such as those found in the Toxic Substances Control Act (TSCA). The Food and Drug Administration (FDA) keeps tabs on colorants and ingredients in cosmetics — 5-Amino-O-Cresol appears on the list of permitted substances, but with notes about concentration limits and intended use.
Europe tends to bring stricter oversight. Under the European Union’s Cosmetics Regulation, 5-Amino-O-Cresol falls under Annex III, which means its use in hair dyes is allowed but only below specified concentrations and with warnings on packages. The EU European Chemicals Agency also flags possible long-term effects, requiring manufacturers to report how much is being handled and to take steps to limit human exposure.
When I ran a safety training for new lab techs, I used to tell a story about how a single oversight — a glove with a tiny rip — turned a routine day into a scramble for eye wash and medical assessment. People who formulate, package, or use products containing 5-Amino-O-Cresol on a daily basis should not have to pay the price for lack of information or sloppy regulation. Using only what’s needed, following strict labeling, and offering proper training protect both workers and consumers.
Substituting less hazardous chemicals works in some cases, but for dyes and colorants, suitable alternatives with the same performance aren’t always available. A practical step is strict storage, clear labeling, protective equipment, and straightforward information at the point of sale. Transparency from manufacturers about the risks of their ingredients also helps people make choices. Regulatory agencies and industry watchdogs can increase their focus on how such chemicals move from factory to salon to bathroom shelf, and encourage practices that cut down on unnecessary exposure.
Anyone who wants a safer workspace or product shelf needs more than hope — regular review of chemical safety data, clear labeling rules, and up-to-date exposure guidelines make a real difference. Advocacy from users and workers can drive regulatory attention where it’s missing. For 5-Amino-O-Cresol, that means pushing for as much knowledge and caution as possible, before a minor hazard becomes something worse.
| Names | |
| Preferred IUPAC name | 5-Amino-2-methylphenol |
| Other names |
3-Amino-5-methylphenol 5-Hydroxy-2-methylaniline |
| Pronunciation | /faɪ-əˈmiːnoʊ-oʊ-ˈkrɛsoʊl/ |
| Identifiers | |
| CAS Number | 2835-97-4 |
| Beilstein Reference | 1577653 |
| ChEBI | CHEBI:38470 |
| ChEMBL | CHEMBL64829 |
| ChemSpider | 126706 |
| DrugBank | DB14296 |
| ECHA InfoCard | 100.011.083 |
| EC Number | 200-432-1 |
| Gmelin Reference | 733259 |
| KEGG | C14381 |
| MeSH | D04.552.943.169.150 |
| PubChem CID | 17555 |
| RTECS number | DH8225000 |
| UNII | 9LTW5M52VQ |
| UN number | UN2811 |
| CompTox Dashboard (EPA) | 5AminoOCresol |
| Properties | |
| Chemical formula | C7H9NO |
| Molar mass | 137.17 g/mol |
| Appearance | Light yellow to brown solid |
| Odor | Odorless |
| Density | 1.181 g/cm3 |
| Solubility in water | Soluble |
| log P | 0.36 |
| Vapor pressure | 0.000183 hPa (25 °C) |
| Acidity (pKa) | 10.21 |
| Basicity (pKb) | 7.84 |
| Magnetic susceptibility (χ) | -6.9e-6 cm³/mol |
| Refractive index (nD) | 1.649 |
| Viscosity | Viscous liquid |
| Dipole moment | 1.41 D |
| Thermochemistry | |
| Std molar entropy (S⦵298) | 234.7 J·mol⁻¹·K⁻¹ |
| Std enthalpy of formation (ΔfH⦵298) | -62.6 kJ/mol |
| Std enthalpy of combustion (ΔcH⦵298) | -3584.6 kJ/mol |
| Pharmacology | |
| ATC code | D03AX03 |
| Hazards | |
| Main hazards | Harmful if swallowed, causes skin and eye irritation. |
| GHS labelling | GHS05, GHS07 |
| Pictograms | GHS07 |
| Signal word | Danger |
| Hazard statements | H302, H315, H319, H317 |
| Precautionary statements | Precautionary statements: P280, P305+P351+P338, P337+P313 |
| NFPA 704 (fire diamond) | 3-2-1 |
| Flash point | 146°C |
| Autoignition temperature | 540°C |
| Lethal dose or concentration | LD50 (rat, oral): 1750 mg/kg |
| LD50 (median dose) | LD50 (median dose): Oral rat LD50 = 375 mg/kg |
| NIOSH | B131 |
| PEL (Permissible) | Not established |
| REL (Recommended) | 0.1 mg/L |
| IDLH (Immediate danger) | Not established |
| Related compounds | |
| Related compounds |
4-Amino-2-methylphenol 5-Amino-2-methylphenol 5-Amino-m-cresol o-Cresol 5-Nitro-o-cresol 5-Chloro-o-cresol |
