© 2026 Sinochem Nanjing Corporation,
All Right Reserved
Chemists first took interest in o-phenylenediamine in the late 19th century as part of a wider push to understand aromatic amines. This compound, a derivative of benzene, helped researchers unlock novel paths in synthetic chemistry, building a bridge between theoretical organic chemistry and applications in dyes and pharmaceuticals. Before the digital era, gaining pure samples came from meticulous distillation and crystallization, a process that demanded patience and a healthy respect for volatility. The journey from crude benzene to practical hydrochloride salt marked progress in purification and safe handling, a reflection of trial by fire in the early days of industrial chemistry. Through the decades, improvements in synthesis routes—such as nitrobenzene reduction—made lab work easier, and the growing body of scientific literature made it possible to share findings internationally without language or access barriers.
O-phenylenediamine hydrochloride, a white or light yellow crystalline powder, serves as a key intermediate for industries focused on creating colored products, drugs, and polymer science tools. Its formula, C6H8ClN2, hints at simple roots, but don’t let that fool you—this is a compound with wide reach. In veterinary and human pharmaceuticals, lab scientists have used it to synthesize antimicrobials, anti-tumor agents, and diagnostic color reagents, tools essential for modern medicine and biological research. Dyers and pigment manufacturers rely on it, too, especially in the creation of products like azo dyes and pigments found in textiles, paper, and inks. From a technical perspective, o-phenylenediamine hydrochloride balances reactivity with manageability, which means skilled professionals can work safely and effectively to meet both quantity and purity demands.
O-phenylenediamine hydrochloride presents as crystalline and highly soluble in water, with a melting point in the neighborhood of 255–257°C (with decomposition). The compound forms a hydrochloride salt, helping control volatility and making handling less hazardous compared to the parent aromatic diamine. Its reactivity comes from both amine groups placed ortho to each other, inviting a range of condensation and cyclization reactions. Under standard lab conditions, the hydrochloride exhibits stability, though prolonged exposure to air and moisture can result in gradual degradation and color change, underpinning the need for sealed storage under inert gas where possible. As a strong nucleophile with resonance stabilization, o-phenylenediamine hydrochloride acts as a springboard for syntheses that build up heterocyclic frameworks, essential for the modern chemical toolbox.
Manufacturers typically supply o-phenylenediamine hydrochloride with purity above 99%, which chemists check using melting point determination, spectroscopic methods like NMR and IR, and, when required, high-performance liquid chromatography. Packaging includes moisture-proof, air-tight containers labeled with hazard statements in line with GHS (Globally Harmonized System), structural formula, synonym list, batch number, and storage instructions. On the shelf, this compound calls for a cool, dry place out of the sun and away from oxidants and acids. Based on regulations in North America and Europe, the container also gives first-aid guidance, disposal recommendations, and emergency contact details. Compliance with these standards keeps lab work predictable and helps prevent dangerous accidents or environmental release.
O-phenylenediamine hydrochloride comes from reduction of orthonitroaniline or dinitrobenzene, a process chewy enough to satisfy chemical engineers and practical enough for industrial needs. Most plants deploy catalytic hydrogenation in the presence of hydrochloric acid, which streamlines both the reaction and isolation of the hydrochloride salt. Filtration removes insoluble material, and the concentrated solution cools to encourage crystallization. What once relied on iron filings and acid—the old-school method—now benefits from efficient, cleaner approaches involving palladium or Raney nickel catalysts, slashing waste and cutting processing time in half. Careful control of pH, temperature, and hydrogen pressure makes it feasible to turn out metric tons per year without shipping an environmental headache down the drain.
O-phenylenediamine hydrochloride stands tall as a versatile building block. Its ortho positioning means both amine groups can participate in cyclocondensation reactions to generate benzimidazoles, which feature in antifungal, antimicrobial, and anticancer compounds. Through diazotization, the diamine provides a launching pad for intricate dyes and intermediates. In large-scale colorant manufacturing, chemists couple this compound with various aromatic amines, sulfonates, or carboxylic acids to tailor hues and solubility for precise use cases. Reacting o-phenylenediamine with aldehydes or carboxylic acids creates a sturdy backbone for chelating ligands, essential in metal analysis and complexation chemistry. One cannot understate the ease with which synthetic chemists alter or append the framework, extending both research and industry’s reach across new frontiers.
This compound answers to a surprising number of aliases—1,2-diaminobenzene hydrochloride, ortho-phenylenediamine hydrochloride, OPDA hydrochloride, and phenylene-1,2-diamine hydrochloride. Each name pops up in patent filings, scientific catalogs, or regulatory lists, and missing any one can cause confusion in procurement or safety auditing. Researchers and manufacturers need clarity, as cross-referencing product codes and synonyms prevents accidental substitutions or supply delays.
This is not a chemical to take lightly. Direct skin or eye contact can cause irritation, and inhaling dust challenges both lungs and immune system. International agencies, including OSHA and the European Chemicals Agency, tag o-phenylenediamine hydrochloride as a potential mutagen and skin sensitizer. Personal experience teaches that gloves, lab coats, face shields, and fume hoods serve as more than bureaucratic excess—they keep technicians out of the ER. Spill response protocols and proper labeling matter just as much as technical prowess, especially in school and industrial settings where turnover and inexperience heighten risk. Disposal must meet local hazardous waste laws; sending reactive amines down the drain means gambling with downstream pollution. Continuous safety training and responsible stewardship stand as the best prevention.
My time supporting chemical supply to the textile and diagnostics industry showed o-phenylenediamine hydrochloride popping up in surprising places. Dyes based on this amine anchor colorfast inks in security printing for currency and documents, where fade resistance carries legal consequences. Diagnostic kits bank on its reliable color change, lighting up enzyme-linked immunosorbent assays (ELISAs), especially for detecting low-level infections or chemical residues. Drug manufacturers incorporate benzimidazole derivatives in treatments for parasitic diseases, faithfully tracing the synthetic steps back to o-phenylenediamine hydrochloride. Environmental chemistry labs keep it handy for metal ion detection, leveraging its chelating power in water analysis. Year after year, established brands and upstart ventures alike bet on its pedigree and performance.
Continuous work targets safer, greener production routes, as the sector shifts from legacy methods to processes with a lower carbon footprint and fewer byproducts. Green chemistry teams explore solventless synthesis and recyclable catalysts, aiming to reduce operational costs and regulatory headaches. In academia, researchers push for better understanding of reactivity and selectivity, hoping to draw new heterocyclic architectures for antifungal or anti-inflammatory drugs. Materials science looks at polymer-bound derivatives, chasing after low-cost sensors and new generations of conducting polymers. In each case, cross-disciplinary partnerships open the door to creative solutions—a technician’s practical knack paired with a professor’s theoretical insight can break stale patterns and spur real progress on routes and applications.
Toxicologists have flagged concerns about the mutagenic and possible carcinogenic effects of o-phenylenediamine derivatives. Chronic contact or repeated exposure, especially among factory workers and lab staff, connects to skin allergies and rare but serious systemic effects. Animal studies spotlight DNA damage at high concentrations, stirring regulatory action and calling for low-exposure handling protocols. Newer studies map metabolic breakdown, searching for less harmful substitutes or detoxification strategies in living systems. Advances in personal monitoring and environmental sensors offer ways to reduce harm, but ongoing vigilance remains key. Corporate responsibility runs deeper than compliance—it relies on culture shifts and daily awareness at every production stage.
Shifting consumer preferences and tighter environment rules push companies and researchers to revisit their approach. Sustainable chemistry initiatives try to replace older, waste-heavy reduction methods with bio-catalytic or electrochemical strategies that cut both waste and exposure. Progress in life sciences could unlock new uses, such as probes for advanced diagnostics or as tethers for targeted therapeutics—if toxicity gets addressed by next-generation analogues. High-value markets, such as functional markers in biotechnology and advanced materials for electronics, give o-phenylenediamine hydrochloride a future beyond its 20th-century roots. A combination of responsible stewardship, bold science, and pragmatic engineering stands best poised to write the next chapter for this multifaceted chemical.
O-Phenylenediamine hydrochloride shows up in labs with a pretty straightforward formula: C6H8ClN2. Sometimes referred to by its full name, ortho-phenylenediamine hydrochloride, this compound brings together a benzene ring laced with two adjacent amino groups and paired with a chloride ion. Looking at it through a chemist’s eyes, the formula spells out a unique mix of carbon, hydrogen, nitrogen, and chlorine. Count out those atoms—six carbons, eight hydrogens, two nitrogens, and one chlorine. Simple on paper, but, in my experience, the impact of those elements stretches far beyond the surface.
In research, getting the chemical formula right isn’t just for paperwork. One missed atom spells disaster, especially with substances used for sensitive work. In dye manufacturing, lab technicians rely on materials like o-phenylenediamine hydrochloride to deliver the right hues safely. That hydrochloride arm attached to the formula doesn’t just sit there—it changes how the compound dissolves, stores, and reacts. Toss it into a synthesis reaction and you're not just making colors, you're handling compounds where purity means everything to the end result.
I’ve noticed in labs that folks treat o-phenylenediamine hydrochloride as a staple, especially in colorimetric assays. Medical diagnostic kits lean on its reliability for enzyme tests. Here’s where accurate formula knowledge comes in: one slip-up, and your test kit delivers false results. In small-scale industry, someone might cut corners by substituting the wrong salt form, thinking, “What’s the harm?” That attitude risks faulty goods or, worse, compromised safety standards.
Beyond the lab, educators use demonstrations with this compound to explain reduction reactions and basics of aromatic amine chemistry. Accuracy trickles down from textbooks to classroom glassware. Mixing up the hydrochloride salt with free-base o-phenylenediamine (C6H8N2) isn’t a trivial swap; each version interacts with other chemicals differently. I remember swapping stories with a teacher who ordered the base form and couldn’t get his demonstration to work until a colleague pointed out the mistake on the invoice.
Mistakes happen most when the line between similar-looking compounds blurs in catalogs or labels get smudged. In my lab time, I’ve seen researchers double-check every package before opening—no one likes surprises mid-experiment. Suppliers who clearly state both the chemical formula and the full name cut confusion right at the source.
Mislabeling wrecks more than one project. Clear standard operating procedures help. Some teams implement barcode systems tied to digital inventory records, where the formula pops up on screen every time someone scans a bottle. This extra step beats fishing through paperwork or hunting for a faded label under lab lights.
Science leans on details. The chemical formula C6H8ClN2 for o-phenylenediamine hydrochloride matters every time someone opens a bottle or fires up a reaction. Accurate chemical reporting, easy-to-spot labeling, and digital verification systems give more confidence to everyone—from fresh-faced undergrads to seasoned engineers. This careful attention to chemical identities lets research and industry grow responsibly, one properly labeled formula at a time.
O-Phenylenediamine Hydrochloride sounds like a tongue-twister for most folks, but it’s one of those under-the-radar ingredients quietly shaping a bunch of familiar items. It holds real value in not only science labs but also factories making everyday goods. Having spent years reporting on chemicals in consumer products, I’ve seen how this compound weaves through several practical areas—especially in colorants and diagnostics.
O-Phenylenediamine Hydrochloride shows up as a workhorse when companies need rich, lasting colors. It’s used to make dyes—especially those aimed at hair coloring or textiles. The compound steps up as a key ingredient in oxidative hair dyes, where it acts as a “developing agent.” This process relies on a reaction with hydrogen peroxide, which helps transform colorless ingredients into strong, stable pigments that grip hair fibers. Without it, many dyes would fade faster or struggle to deliver that deep, even color you see in salon results. That’s why hair color kits often mention “paraphenylenediamine” and its chemical cousin on the box—these chemicals can change brunettes to blondes or add pop to grays in minutes.
In the medical world, O-Phenylenediamine Hydrochloride makes a difference in diagnostic testing. Enzyme assays use it as a reagent—an ingredient that helps reveal tiny quirks about your blood or tissue samples. For example, glucose tests and assays for detecting certain diseases often rely on this compound. It helps medical staff identify enzyme activity, showing results as a visible color change. When doctors search for early signs of illness, these color shifts can mean the difference between catching something early or missing it altogether.
The rise of smartphones has shrunk the world of darkroom photography, but O-Phenylenediamine Hydrochloride had a hand in making pictures for over a century. Photographic developers once relied on similar aromatic amines because of their ability to reduce silver ions and build crisp, detailed negatives or prints. Even today, some niche photography processes or restoration work tap into this compound for reliable chemical reactions. Factories that make plastic resins or rubber products also pull this chemical in as a stabilizer or building block, aiming for longer-lasting and more flexible materials.
No chemical is without worries, and O-Phenylenediamine Hydrochloride brings its own health questions. Research shows high exposures may irritate skin or, if handled carelessly, introduce health hazards. The European Chemicals Agency and U.S. FDA both monitor its use and recommend limits—especially in products meant for personal care. Manufacturers follow guidelines and label products carefully, but the average consumer can help by checking for ingredient lists and using gloves or other protection during home hair dyeing.
Demand for safer colorants continues to push researchers to try new formulas. Green chemistry efforts push for molecules that do the same work without the drawbacks—less skin irritation, fewer allergies. Some companies now explore plant-based or less sensitizing substitutes in cosmetics and textiles, but matching that deep, bold color profile isn’t easy. Until science cracks the code, O-Phenylenediamine Hydrochloride will likely keep serving as a quiet force behind the scenes, especially where vibrant color and reliable chemical reactions matter most.
O-Phenylenediamine Hydrochloride finds use in laboratories, especially in chemical synthesis and analytical testing. Its reputation for toxicity is well earned, and not only on paper—skin exposure can trigger irritation, and inhaling its dust can lead to respiratory discomfort. Longer-term or repeat contact may even affect organs. I’ve seen new lab techs underestimate how quickly a small spill can become a big problem, as the powdered form spreads easily into the air.
Personal experience reminds me that gloves alone won’t prevent problems. Choose chemical-resistant gloves; cheap disposable ones may break down or soak through. Eye protection is non-negotiable: goggles beat standard safety glasses since powder and splashes can come from unexpected angles. Some colleagues use face shields for extra defense, especially during weighing or pouring. Long sleeves, lab coats, and closed shoes stop powder from making contact with skin—or worse, getting tracked outside the workspace.
No matter how careful you feel, airborne dust is the weakest link. A chemical fume hood or even a local exhaust system makes a big difference. Not using ventilation leads to headaches or coughing. I met one researcher who relied on just a window; eventually low-level exposure gave him sensitivity in his hands and eyes. These stories stick with you.
This chemical likes darkness and dry air, so tight sealing and labeling stops confusion and accidental mixing. Keep incompatible substances like oxidizers away; mixing these by mistake invites dangerous reactions. I always double-check shelf labels. If you spill any amount, treat it like an emergency: ventilate, scoop the powder gently—never sweep, as that spreads it—and dump contaminated items in a secure chemical waste container. Not all labs train properly on this, and I’ve witnessed near-misses due to shortcuts taken in cleanup.
O-Phenylenediamine Hydrochloride can’t just go down the drain. Pouring it out without neutralization not only breaks the law, it can hurt someone later. I’ve noticed more labs embracing closed waste containers and clear documentation on disposal logs. Check with licensed disposal firms or your institution’s guidelines—playing it safe prevents both fines and long-run contamination.
Having clear procedures and hands-on training makes all the difference. I’ve watched teams where someone skipped reading the MSDS suffer from confusion during critical moments. Teams that practice emergency drills respond faster, fix issues before they escalate, and protect each other more effectively.
Manufacturers issue clear warnings for a reason. Taking O-Phenylenediamine Hydrochloride seriously—gloves, goggles, ventilation, spill prep, and waste management—means fewer accidents and better health. Every bit of extra care now prevents regret later, for the handler and for everyone sharing the same workspace.
I’ve spent time in the lab, double-checking shelf labels and watching for crystalline leaks, especially with tricky compounds. O-Phenylenediamine Hydrochloride comes up more than you'd think. This substance delivers value in many dye and pharmaceutical processes, but safety will always outweigh convenience. My approach keeps both real-world experience and science in play—protect the team, the environment, and the research investment.
O-Phenylenediamine Hydrochloride doesn’t like moisture or fluctuating temperatures. Leave the jar in a muggy, warm room and you raise the risk of clumping, decomposition, or worse, dangerous vapors. The bottle belongs in a dry, cool cabinet—controlled environments limit breakdown, which usually means a dedicated chemical storage refrigerator, away from food or drink. Reliable climate management makes a huge difference here. Trust me, nobody enjoys tossing out expensive material because of humidity-induced spoiling.
This compound tends to break down under light. If you leave it sitting out in a clear jar, the shelf life shrinks and potential hazards increase. Opaque or amber-glass containers handle exposure best. An airtight seal delivers confidence, not only keeping air out but also minimizing exposure to lab fumes or splash accidents. Double-seal containers—one lid, one sealable zip-bag—and store them in a labeled, UV-resistant bin.
Never pile a bunch of mismatched chemicals in one spot. Strong oxidizers or acids react badly with diamines like this one. In practice, a little organization pays off—you avoid dangerous mishaps and headaches for the next shift. Labs that keep a separate area just for organics or amines manage issues faster. Clear signs and inventory checklists cut down on mix-ups.
The best storage strategy doesn’t end at the cabinet. Handling matters, too. Gloves, goggles, and a lab coat come out every single time the bottle does. This stuff stains skin in seconds, and breathing dust brings on coughing or allergic reactions. Emergency eyewash stations and spill kits should always be stocked and accessible. I’ve watched an intern clean up a spill with a napkin once—training and reminders go a long way.
Expired or contaminated O-Phenylenediamine Hydrochloride goes straight into a designated hazardous-waste bin. No regular trash. Proper disposal keeps people and groundwater safe—environmental rules label this compound as a threat to both. I always keep the waste log updated and push for regular removal pickups instead of waiting for a bin to fill up.
Mistakes with chemical storage don’t just threaten data; they risk real injuries and lost resources. Nobody wants to call the fire department because a neglected jar turned into a potential bomb. Training, documentation, and the right storage materials set a foundation for real safety. Small habits—like writing the date you opened a container—add up to big gains in reliability and peace of mind.
Investing in modern chemical cabinets, humidity alarms, and routine safety checks pays off. Labs that build habits around careful storage see fewer accidents, more consistent results, and stronger trust from collaborators. The simple moves—separation, labeling, airtight containers—make every researcher’s job easier and safer, and protect the progress of the whole team.
Working in laboratories and production-scale facilities, I’ve seen plenty of well-intentioned plans go sideways over something as basic as raw material purity. O-Phenylenediamine Hydrochloride (OPDA.HCl) sits in this zone, used by chemists, pharmacologists, and materials science experts for organic synthesis, dye manufacture, and biochemical diagnostics.
Most suppliers put their names behind a purity level of 98% for O-Phenylenediamine Hydrochloride. Independent testing from research institutes backs up those claims. Spectroscopic analysis (NMR, HPLC, GC-MS) confirms that what comes in those brown bottles meets expectations. If you’re running a pharmaceutical assay or prepping a diagnostic kit, purity above 98% helps reduce complications. Impurities aren’t just wasted material—they spark side reactions, degrade results, or prompt safety concerns.
No one wants to boil away time on failed reactions. That’s where transparency in batch analysis steps in. Suppliers who publish batch-specific Certificates of Analysis (COAs) give you more than a printed promise. You see how much of the sample is OPDA.HCl, what trace metals pop up, and the amounts of moisture or unreacted starting material lurking inside. Some heavyweights in chemical supply back their claims by providing third-party test results on request.
Experience has shown that trace iron salts and organic by-products tag along during manufacture. Even a tenth of a percent of these can cause problems. In analytical chemistry, that contamination introduces background noise or shifts results. In colorant or polymer manufacture, those traces alter color shade, performance, or shelf stability.
Trusted chemical suppliers invite scrutiny. They embrace traceability—recording not just the batch purity, but the test methods (HPLC for purity, ICP-OES for metals, Karl Fischer for water content). I once caught a major supplier off guard by requesting homogeneity verification and documentation for several lots. They delivered within a week, earning my team’s trust for future procurements.
Tougher regulatory environments force users to document every ingredient. Agencies like the FDA or EMA won’t take your word for it. Batches of O-Phenylenediamine Hydrochloride listed as “98% minimum” need paperwork showing compliance with pharmacopoeial or in-house specifications. That creates a stronger audit trail, protecting both the end-product and the reputation of your laboratory or brand.
OPDA.HCl isn’t just another white powder. It triggers skin and eye irritation. Smart labs store it in tightly sealed, low-humidity containers and use gloves, goggles, and fume hoods during transfers. Good labeling and waste disposal habits prevent mix-ups and environmental concerns down the line.
Laboratories and commercial buyers push for even higher purity—sometimes up to 99.5%—for sensitive syntheses. While this adds cost, it pays off in reliability and cleaner results. The most reliable partners don’t just chase high numbers; they prepare for lot-to-lot consistency and strong, ongoing quality controls. Open back-and-forth between buyers and suppliers helps keep both sides honest and focused on the details that matter.
| Names | |
| Preferred IUPAC name | 2,3-Diaminobenzenium chloride |
| Other names |
o-Phenylenediamine dihydrochloride 1,2-Phenylenediamine dihydrochloride OPDA dihydrochloride |
| Pronunciation | /ˌoʊ fəˈnɪlɪnˌdaɪ.əˈmiːn haɪˌdrɒxɪˈklaɪd/ |
| Identifiers | |
| CAS Number | 637-27-0 |
| 3D model (JSmol) | Here is the **JSmol 3D model string** for **O-Phenylenediamine Hydrochloride**: ``` CNc1ccccc1N.Cl ``` This is the **SMILES** string, which can be used as input in JSmol or other 3D visualization tools. |
| Beilstein Reference | 82252 |
| ChEBI | CHEBI:85144 |
| ChEMBL | CHEMBL3037077 |
| ChemSpider | 83645 |
| DrugBank | DB01886 |
| ECHA InfoCard | 100.028.752 |
| EC Number | 200-431-6 |
| Gmelin Reference | 122071 |
| KEGG | C06157 |
| MeSH | D010713 |
| PubChem CID | 61083 |
| RTECS number | SS9625000 |
| UNII | K6FNS2R10U |
| UN number | UN1673 |
| CompTox Dashboard (EPA) | DTXSID9020607 |
| Properties | |
| Chemical formula | C6H8ClN2 |
| Molar mass | 144.59 g/mol |
| Appearance | Yellow to brown solid |
| Odor | Odorless |
| Density | 1.36 g/cm³ |
| Solubility in water | soluble |
| log P | -2.18 |
| Acidity (pKa) | 6.0 |
| Basicity (pKb) | -4.7 |
| Magnetic susceptibility (χ) | -49.5×10⁻⁶ cm³/mol |
| Refractive index (nD) | 1.642 |
| Dipole moment | 3.2 D |
| Thermochemistry | |
| Std molar entropy (S⦵298) | 104 J·mol⁻¹·K⁻¹ |
| Std enthalpy of formation (ΔfH⦵298) | -83.9 kJ/mol |
| Std enthalpy of combustion (ΔcH⦵298) | -509.6 kJ/mol |
| Hazards | |
| Main hazards | Toxic if swallowed, in contact with skin or if inhaled; causes skin irritation; causes serious eye irritation; may cause allergy or asthma symptoms or breathing difficulties if inhaled; may cause an allergic skin reaction; may cause cancer. |
| GHS labelling | GHS02, GHS06, GHS08 |
| Pictograms | GHS05,GHS07 |
| Signal word | Danger |
| Hazard statements | H301 + H311 + H331: Toxic if swallowed, in contact with skin or if inhaled. H317: May cause an allergic skin reaction. H319: Causes serious eye irritation. H373: May cause damage to organs through prolonged or repeated exposure. |
| Precautionary statements | Precautionary statements: P261, P280, P301+P312, P304+P340, P305+P351+P338, P309+P311 |
| NFPA 704 (fire diamond) | 2-3-0-** |
| Flash point | 158 °C |
| Autoignition temperature | 293 °C (559 °F; 566 K) |
| Lethal dose or concentration | LD50 oral rat 670 mg/kg |
| LD50 (median dose) | LD50 (median dose): 44 mg/kg (oral, rat) |
| NIOSH | SS8050000 |
| PEL (Permissible) | Not established |
| REL (Recommended) | 0.1 mg/m³ |
| IDLH (Immediate danger) | Unknown |
| Related compounds | |
| Related compounds |
Phenylenediamine o-Phenylenediamine m-Phenylenediamine p-Phenylenediamine Aniline Benzidine |
