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If you dig into the archives of organic chemistry, 1-chloro-2,4-dinitrobenzene (CDNB) comes up as a regular fixture—a chemical with a story stretching back into the heart of analytical chemistry’s formative years. It didn’t just appear in a catalog one day; researchers in the early-to-mid 20th century brought CDNB onto the stage because of its ability to play double duty in both industrial and medical research. CDNB has roots in classic substitution chemistry, spun out of efforts to advance synthetic routes for dyes, explosives, and pharmaceuticals. Its persistence in labs everywhere speaks to both its reliability and to the challenge chemists face in moving beyond legacy compounds once they find a place in protocols. Few compounds show this kind of staying power, so its ongoing use tells us something about path-dependency in chemistry and how new tools have to earn their place through serious proof, not just hype.
For most people, the string of numbers and syllables in “1-chloro-2,4-dinitrobenzene” blurs into the background. In the lab, it takes on a sharper edge—a yellow solid with a bitter almond smell, packing a punch far above its appearance. CDNB earns its keep as a powerful electrophile, snapping up nucleophiles in enzymatic assays and chemical reactions. It’s not just an obscure test compound; it pops up in research probing glutathione S-transferase (GST) activity, acts as a substrate for key detoxification studies, and finds a role in preparing calibration standards. In teaching labs, it’s a classic material for demonstrating substitution reactions, letting students see chemical theory in action. For those with an eye on process control or routine analytics, CDNB still ranks as a familiar standard thanks to its stability and consistent reaction profile.
Holding a bottle of CDNB reminds me how a few atoms in the right pattern can change everything. The molecule rides on a benzene ring—a classic aromatic core—decked out with two nitro groups and a chlorine atom. That particular mix transforms a stable ring into a reactive powerhouse. In daylight, CDNB shows off a striking yellow color, and it doesn’t evaporate easily. The nitro groups crank up the molecule’s reactivity, making the chlorine atom easier to swap in nucleophilic aromatic substitution. Most labs rely on its robust melting point, just shy of 54 degrees Celsius, and its predictable solubility in organic solvents. Mix that with a well-earned reputation for chemical aggression, and CDNB finds itself both respected and handled with steady caution.
Every chemist has been handed a bottle of CDNB with a red warning triangle somewhere in the labeling—a reminder of its dangers and the obligations that come with using it. Labels stress the need for gloves, goggles, and a fume hood, reflecting industry standards that demand clear communication about risks. The technical values printed alongside—purity, appearance, melting point, and batch number—bridge the gap between regulatory oversight and practical handling. These standards don’t just satisfy a rulebook; they reflect decades of trial, error, and hard-won lessons from mishaps and near-misses across generations of lab workers. Anyone who has spent time in a research lab can attest to the ways clear labeling saves more than paperwork—sometimes, it saves skin and eyesight.
The process of making CDNB follows a script many chemistry students first encounter in textbooks: take chlorobenzene, introduce it to a nitrating mix, and let the reaction unfold. The procedure lays out a pathway as direct as traffic on an empty road, though upscaling this process for industrial levels introduces some wrinkles—temperature control, mixing efficiency, and, always, waste management. The preparation spells out a larger challenge: every route to CDNB also yields waste acids and byproducts needing careful disposal. I remember grad students scrambling in hooded corners of labs, balancing yield with cleanup, and the experience drives home the push for cleaner, greener routes. Practical synthesis walks a tightrope between historical methods and new ambitions for sustainability.
CDNB proves itself not just as a curiosity but as a kind of chemical Swiss army knife, especially when it comes to nucleophilic aromatic substitution. The nitro groups draw electrons away, boosting reactivity—a fact exploited in enzymatic assays and organic transformation experiments. Whether reacting with thiols, amines, or other strong nucleophiles, CDNB serves up reliable, quantifiable conversions that form the backbone of GST research and wider biochemical screens. It’s not a molecule that sits quietly in a bottle, destined for one role and one role only; it flexes, shifting purpose as demands evolve. Small structural tweaks—swapping in a different halogen or modifying substituent positions—extend its scope, building a family of related compounds ready to meet new synthetic or analytic challenges.
In research circles, CDNB is the go-to nickname, trimming the official moniker down to size. Paperwork might refer to it as chlorodinitrobenzene or 1-chloro-2,4-dinitro-1-benzene, and the registry number offers another shorthand for databases. These different labels might trip up newcomers, but in lab meetings and emails, “CDNB” signals instant recognition. Different suppliers and catalogs tack on variations, but across borders and research groups, the classic short form lends clarity in hurried conversations.
Every experienced chemist has a story about letting down their guard with something that seemed routine. CDNB commands respect; it stings skin, irritates eyes, and resists easy cleanup thanks to its persistent, oily nature. Regulations call for containment and ventilation because the risks aren’t just theoretical: prolonged exposure has concrete health consequences. Using CDNB in clinics or classrooms means real diligence—wearing gloves, keeping the fume hood sash low, logging each use. Most safety protocols took shape through accident and review, not wishful thinking, so the guidelines carry the weight of real-world experience. Regulatory bodies lay down limits and disposal mandates because CDNB’s toxicity isn’t a matter for debate. Training, oversight, and routine monitoring make the difference between a safe demonstration and a medical issue.
CDNB’s track record puts it near the top of the list for labs studying enzyme function, especially GSTs, which play pivotal roles in how bodies metabolize drugs and handle oxidative stress. In medical testing, this compound serves as a reference substrate, forming the backbone of diagnostics for genetic enzyme deficiencies and toxicological screens. Beyond medicine, CDNB lands in analytical chemistry, material science, and even industrial dye production. Its ability to react cleanly and give measurable, colorimetric responses makes it an anchor in standard methods—students and seasoned chemists alike rely on its reactions to teach, test, and troubleshoot. A walk through just about any academic chemistry building will turn up a bottle of CDNB on a shelf, silent proof of its ongoing relevance.
CDNB hasn’t faded into obscurity, despite new flashes in the pan appearing every year. Ongoing research looks at its use in developing enzyme inhibitors, studying detoxification pathways, or probing environmental stress responses. Each modification—whether to the core ring or through side-chain variation—prompts fresh rounds of evaluation for bioactivity, water solubility, and selective reactivity. Industrial labs and green chemistry advocates continually reassess old protocols, eyeing ways to reduce waste, substitute safer alternatives, or engineer milder conditions for existing transformations. The search for smarter, safer chemistry often starts with compounds as familiar as CDNB and builds outward, respecting the lessons of past decades while chasing future improvements.
Handling CDNB always raises questions of chronic effects, bioaccumulation, and idiosyncratic reactions—especially in sensitive individuals. Research reveals CDNB as an alkylating agent capable of modifying cellular proteins and DNA, leading to forms of toxicity more complicated than a skin rash. Medical case reports connect exposure to systemic symptoms and, in animal studies, to biochemical disruptions that map onto human vulnerabilities. Strict protocols for waste collection and environmental release aren’t just bureaucratic hurdles—they’re grounded in evidence of real harm from casual releases. Scientific inquiry keeps turning over stones, identifying new potential risks and refining safety measures as knowledge expands. This living body of research shapes everything from handling instructions to long-term storage strategies, bridging data gaps with purposeful caution.
Looking forward, the question isn’t whether CDNB will disappear but how its use will change. Its legacy in research and education won’t vanish overnight, but the rise in alternative substrates and test systems promises to shift the landscape. Emerging green chemistry pushes for both synthetic routes and new assay molecules that maintain reliability without the toxic baggage. Advances in computational modeling, miniaturized analytics, and biodegradable reagents all signal a path away from old standards—but the transition takes patience, robust demonstration, and economic incentive. In the meantime, CDNB remains both a benchmark and a challenge—a marker of chemistry’s past and a touchstone for rethinking risk, value, and scientific responsibility in the decades to come.
Familiarity with 1-chloro-2,4-dinitrobenzene doesn’t come easily unless you’ve worked in a lab or spent time in an industry focused on chemicals. Most people don’t realize how much science takes place behind the scenes, driving vital medical research and manufacturing. Years ago, during my university days in a research lab, little bottles with intimidating names arrived regularly. I remember our supervisor explaining the need for strong personal care when working with a yellow crystalline substance labeled 1-chloro-2,4-dinitrobenzene. The name says it all: this isn’t something you’d ever find on a drugstore shelf.
The real value of this compound sits with allergy and immunology experts. Physicians and researchers apply it to test skin sensitivity and diagnose certain kinds of dermatitis. The way it works isn’t complicated, but the science can get technical. Skin comes into contact with a tiny amount of this compound; specialists then watch for a reaction. If your immune system sends up red flags, that tells doctors something about what might be going wrong in the body’s defenses.
No test can capture every nuance about our immune system, but 1-chloro-2,4-dinitrobenzene remains one of the tools that doctors reach for when other, more common tests don’t offer clear answers. In my experience, physicians often put a lot more stock in the patterns they recognize from years of reading these reactions. This isn’t guesswork, either. In published medical studies, health professionals have found that this compound helps them identify deficiencies in cell-mediated immunity, giving them a clear path to pursue treatment.
Outside the hospital or lab, chemical manufacturers use this substance to produce dyes, pesticides, and some pharmaceuticals. It fits into the long tradition of using strong reagents to alter structures of other chemicals, creating building blocks for more useful molecules. Over the decades, teams trying to create better insecticides, or more stable dyes, have leaned on substances like this.
Safety can’t be ignored here, and the stakes are high for storage and transportation. Old stories from chemical plants show that, mishandled, these substances cause health problems or worse. That’s why international guidelines exist to make sure people know what they’re doing with them. My time working with these chemicals highlighted just how important gloves, goggles, and ventilation become. A hasty mistake leads to headaches, skin irritation, or more serious issues.
There’s pressure now to find less toxic alternatives, especially as more of the world gets serious about workplace safety and environmental health. Large companies have begun to swap out the older, riskier compounds with newer ones, but the process isn’t simple. Strict guidelines and careful disposal help, yet contamination worries and waste disposal costs keep piling up.
Regulation and oversight can only do so much. Change also comes from training workers and giving labs the budget to update procedures and invest in protective equipment. The more open we are about risks, the safer everyone becomes. Those lessons apply whether you’re designing a drug molecule, making an allergy test, or running a chemical plant.
Every tool in the lab or factory carries a story. 1-chloro-2,4-dinitrobenzene has spent decades at the edge of breakthrough science and tough safety conversations. The compound’s uses matter, not just for their technical impact, but as reminders that progress often demands a close look at the risks we accept—and the steps we take to protect each other.
Just looking at the bright yellow crystals of 1-Chloro-2,4-dinitrobenzene, most folks might not guess the risks. My time working with research chemists taught me a simple rule: treat every nitro compound with healthy suspicion. This one packs a triple punch—it's an irritant, a skin sensitzer, and its nitro groups set off alarm bells for toxicity.
No shortcuts mean suiting up before opening that bottle. Standard nitrile gloves just don’t cut it over a long shift. Thicker butyl rubber gloves offer better resistance, and after my first skin rash handling dinitrobenzenes years ago, I never skipped them again. Always check the gloves for pinholes or tears—once, a colleague discovered the hard way a miniscule tear means instant exposure.
Lab coats only go so far with splash risks. At my old bench, I often doubled up with a chemical apron and kept safety goggles on even during quick transfers. Splashing once is enough; I’ve seen a stray drop cause an ugly chemical burn.
Unlike some volatile solvents, 1-Chloro-2,4-dinitrobenzene doesn’t waft up into the air that quickly. Still, inhaling even tiny amounts irritates eyes and lungs. I’ve seen labs cut corners and skip fume hoods—big mistake. Always work under a certified fume hood, checking the airflow before starting. I once struggled through a splitting headache from poor ventilation, and those hours lost to poor air can seriously impact your day.
Spills do happen, even to the careful. I remember someone bumping a beaker and dousing a benchtop. We followed our plan: evacuate the area, suit up with supplied air respirators, use absorbent pads, and sweep with dedicated tools that stay in the ‘hazmat’ cabinet. Neutralizing agents like sodium carbonate help, but dry, careful cleaning works best. Never handle a spill solo; back-up is non-negotiable for anything this toxic.
Dumping leftover material down the drain looks tempting at the end of a long day, but everything about this compound says “handle as hazardous waste.” In our lab, strict double-bagging and sealed containers moved through the hazardous waste contractor—no exceptions, ever. Review your facility’s rules, since local restrictions often get stricter for anything nitro-based. One missed label, and a code violation lands on your desk, not just in your company’s records.
It’s easy to let habits slip, especially during busy stretches. Annual safety refreshers keep everyone in the loop on specific risks, plus updated protocols. I saw real improvement after one lab made 'mock drills' part of the quarterly routine—a surprise scenario forces everyone to prove their know-how, rather than just signing a safety sheet. Chemical labels fade, exhaust fans break, and supplies run out; regular checks prevent small issues from spiraling into emergencies.
1-Chloro-2,4-dinitrobenzene doesn’t forgive carelessness. Following best practices protects not just your own skin and lungs, but everyone working nearby. Seeing a coworker rushed off for emergency decontamination leaves an impression. Safety steps seem tedious until you add up the risks of skipping them.
1-Chloro-2,4-dinitrobenzene, often shortened to CDNB, brings a punchy mix of atoms to the table. The core structure gets its name from the standard rules of organic chemistry, where the benzene ring forms the backbone, and positions two, four, and one tell you exactly where things sit. There’s a chlorine attached at position one. Step over to positions two and four, and you’ll spot nitro groups (-NO2), those classic electron grabbers. Put together, the molecular formula reads C6H3ClN2O4.
I’ve seen laboratories lean on CDNB when teaching enzyme mechanics. It’s often used to measure glutathione S-transferase activity: you add CDNB, toss in an enzyme sample, and watch the reaction take place. There’s something real and concrete about seeing color changes in a test tube with your own eyes. It’s these everyday applications that remind people chemistry doesn’t just live on paper.
On a bigger scale, CDNB links to both industrial and academic research. Its structure—rigid and loaded with electron-withdrawing groups—makes it reactive. People use it to track how chemicals behave when they meet an aromatic compound decorated with strong groups like nitro and chlorine. If you get your hands on CDNB, respect its power: both nitro and chloro groups bring health and environmental hazards. I’ve gone through the process of carefully weighing and pipetting it, always aware that its chemical power brings risks, especially for respiratory health and skin contact. The presence of nitro groups rings alarm bells because they’re connected with mutagenicity, carcinogenic effects, and persistent pollution.
Each lab or facility looking to use CDNB can take steps to balance discovery with responsibility. Standard operating procedures start with fundamental protective measures—good gloves, reliable goggles, real ventilation. Training new scientists goes a long way: I’ve seen even seasoned techs underestimate compounds that seem simple but carry hidden dangers tied to their electron-thirsty groups.
On the regulatory side, supply and distribution stick to guidelines born from hard lessons. Labeling stays clear so no one mistakes what they’re handling. Waste disposal gets serious focus here too; nitroaromatics don’t break down easily, so finding safe ways to neutralize or dispose of them—incineration, chemical reduction—prevents environmental headaches down the road.
Textbooks and scientific databases both cite C6H3ClN2O4 as a benchmark substrate in enzyme assays, and reports from the U.S. Environmental Protection Agency (EPA) highlight just how persistent nitroaromatic waste can become. Studies show the nitro groups account for much of the high reactivity but also raise serious toxicological concerns. A literature review published in the “Journal of Hazardous Materials” reports acute toxicity data and discusses the compound’s reactivity toward nucleophiles—another reminder of the weight it carries in chemistry and in environmental science.
Making chemistry safer doesn’t mean skipping powerful compounds like 1-chloro-2,4-dinitrobenzene. Substitution provides one solution, encouraging the use of less hazardous compounds when possible. But as long as CDNB serves as a standard in laboratories, informed handling, strict safety protocols, and investment in green chemistry alternatives work together to keep progress moving without sacrificing wellbeing or the world outside the lab.
1-Chloro-2,4-dinitrobenzene isn’t something most folks use at home. It has a spot in labs and manufacturing, mostly because of its role in chemical reactions and testing. From years in a university lab, I learned that specialty chemicals like this can do a lot of good work in controlled hands. Still, they come with a punch if mishandled. Storage plays a huge part in keeping both buildings and people safe.
Even a quick online search pulls up warnings: 1-Chloro-2,4-dinitrobenzene can irritate the skin, and the eyes, and affect the airways if sniffed. What worried me most is the potential for explosion or fire, especially if people treat it like something as harmless as table salt. Mishaps do happen. I once saw a minor chemical spill make a whole lab evacuate. All over a single unlabelled bottle. It confirms the obvious: proper storage isn’t optional.
Glass jars with tight caps stood the test of time in my experience. Polyethylene bottles work too, but only if the lid screws on snug and the material can handle strong chemicals. I saw a coworker try reusing a flimsy food container—terrible call. That sort of shortcut risks dangerous leaks over time. Always pick containers that don’t let in moisture. This keeps the chemical stable and avoids reactions that can make things go sideways.
Back during a heatwave, I watched the temperature in a storage room climb fast. That’s all it takes to ruin not just the chemicals, but your entire schedule. For 1-Chloro-2,4-dinitrobenzene, you want a cool, dry spot, far from radiators or windows. A steady temperature prevents breakdowns and unwanted reactions—both costly and dangerous to clean up.
A missing or faded label leads to panic when you don’t know what’s inside. Sharpies fade, so always use durable chemical-resistant labels. I slipped a name, date, and hazard notes on every bottle during chemical inventories. Cross-checking labels saved our lab from some close calls. If you need a quick refresher, the label should include full chemical names and safety warnings. Skipping this step is never worth the shortcut.
I’ve walked into chemical storerooms where everything was locked tight, even for basic solvents. For 1-Chloro-2,4-dinitrobenzene, a locked cabinet—ideally flameproof—fits best. Keep the key away from curious hands. Separate it from food, and keep acids and bases far away to dodge nasty surprises. Ventilation makes a difference, especially for anything that might evaporate or spill.
Spill kits were my silent reassurance in the lab. Even with the best storage plans, accidents show up uninvited. Equip your storage space with absorbent materials, gloves, goggles, and instructions on dealing with spills. Post emergency contact numbers and have clear evacuation routes. These aren’t overreactions. They’re real steps that protect both people and property if something goes wrong.
Take storage as seriously as handling. Look up local hazardous material laws, and don’t cut corners. With the right habits, what’s risky becomes routine—and you sleep a lot better at night knowing the workspace is safe.
1-Chloro-2,4-dinitrobenzene, often used in laboratories and industries, doesn't make headlines unless a disaster or health scare crops up. Many folks in chemistry labs have run into it during experiments, especially those related to immunology — it's a classic tool for testing allergic skin responses. But outside of scientific circles, few know its darker side.
Skin comes into immediate risk from this chemical. Touching even a small amount can cause itchy, red rashes. These reactions aren't just fleeting; people with repeated exposure sometimes develop dangerous allergic dermatitis. On a personal note, I still remember a friend’s experience in grad school — a drop landed on his wrist, and within an hour, his skin lit up like a warning sign. Washing with soap and water offered no relief, and he had to get help at the health center. Stories like his aren't rare, especially among professionals in research labs or factories where this compound pops up.
Breathing in dust or vapor isn't harmless. Many toxicology reports show respiratory irritation, headaches, and nausea. The chemical can enter the bloodstream faster than you'd expect, leading to longer-term risks, such as damage to blood cells. In one study, researchers noticed changes in blood counts after rats breathed in low doses. For humans, there’s a risk of anemia if contact happens often, and with enough exposure, some cases link it to hemolytic anemia, where the body destroys its own red blood cells.
Organs like the liver and kidneys take a hit as they filter out toxins. Toxicology journals detail how repeated low-level exposure stresses these organs. Signs like jaundice, back pain, and fatigue sometimes point back to a heavy chemical load, especially among those working without modern protective equipment. Occupational safety data shows workers in older production facilities reporting more cases of “unexplained” fatigue and stomach trouble than in populations with less exposure.
This chemical stands out for its potential to trigger immune reactions. Sometimes, sensitivity lingers for years. Individuals once affected often react to even trace amounts, which means returning to a job with even a hint of this compound turns risky. Studies out of Europe highlighted an increase in chronic skin problems among chemical plant workers, with higher rates for those exposed before protective policies caught up.
Jobs handling this compound benefit from more than just gloves and lab coats. Proper training and routine monitoring go a long way. Research conducted on safety improvements shows declines in rashes and respiratory issues after improved ventilation and stricter handling protocols. People working from home or in small labs, sometimes with fewer resources, face higher risks if they don’t keep up with best practices. Checking safety data sheets, investing in exhaust fans, and avoiding shortcuts makes a difference.
The march toward safer handling of harsh chemicals relies on more than rulebooks. Real change comes from open conversations between workers and managers, training tailored to specific risks, and investing in high-quality safety gear. Regulatory agencies regularly update exposure limits, and folks on the ground must stay sharp, reading bulletins and taking refreshers. Mistakes from the past, widely documented in medical case studies and factory audits, remind us that paying attention now prevents harm later.
No one expects to get sick at work, but it only takes a single slip-up to change everything. Maintaining labeled containers, avoiding skin contact, and running regular hazard reviews help keep exposure to a minimum. If symptoms show up, early medical attention often makes a big difference. As new research surfaces, updating workplace protocols should come before problems, not after. In environments with known risk, awareness and action mean better days for everyone involved.
| Names | |
| Preferred IUPAC name | 1-chloro-2,4-dinitrobenzene |
| Other names |
1-Chloro-2,4-dinitrobenzol 2,4-Dinitrochlorobenzene CDNB Chlorodinitrobenzene DNCB |
| Pronunciation | /waɪnˈklɔːrəʊ tuː fɔː ˈdaɪnaɪtrəʊ ˈbɛnziːn/ |
| Identifiers | |
| CAS Number | 97-00-7 |
| Beilstein Reference | 87837 |
| ChEBI | CHEBI:35008 |
| ChEMBL | CHEMBL1569 |
| ChemSpider | 2021 |
| DrugBank | DB06733 |
| ECHA InfoCard | 100.004.511 |
| EC Number | 204-400-1 |
| Gmelin Reference | 74221 |
| KEGG | C13530 |
| MeSH | D003564 |
| PubChem CID | 8453 |
| RTECS number | CZ9800000 |
| UNII | PA7VDM9F74 |
| UN number | UN1570 |
| Properties | |
| Chemical formula | C6H3ClN2O4 |
| Molar mass | 202.55 g/mol |
| Appearance | Yellow crystalline solid |
| Odor | Odorless |
| Density | 1.50 g/mL |
| Solubility in water | slightly soluble |
| log P | 1.93 |
| Vapor pressure | 0.001 mmHg (25 °C) |
| Acidity (pKa) | 13.74 |
| Basicity (pKb) | 13.2 |
| Magnetic susceptibility (χ) | −46.0·10⁻⁶ cm³/mol |
| Refractive index (nD) | 1.669 |
| Viscosity | 3.2 cP (20°C) |
| Dipole moment | 3.97 D |
| Thermochemistry | |
| Std molar entropy (S⦵298) | 202.3 J·mol⁻¹·K⁻¹ |
| Std enthalpy of formation (ΔfH⦵298) | −83.6 kJ/mol |
| Std enthalpy of combustion (ΔcH⦵298) | -811.6 kJ/mol |
| Pharmacology | |
| ATC code | D08AX01 |
| Hazards | |
| Main hazards | Toxic if swallowed, in contact with skin or if inhaled; causes severe skin burns and eye damage; may cause an allergic skin reaction; very toxic to aquatic life |
| GHS labelling | GHS02, GHS05, GHS06, GHS08 |
| Pictograms | GHS06, GHS08, GHS09 |
| Signal word | Danger |
| Hazard statements | H302, H315, H317, H319, H331, H334, H335, H341, H351, H410 |
| Precautionary statements | P261, P264, P270, P271, P272, P273, P280, P301+P310, P302+P352, P304+P340, P305+P351+P338, P308+P311, P370+P378, P363, P403+P233, P405, P501 |
| NFPA 704 (fire diamond) | Health: 3, Flammability: 1, Instability: 1, Special: -- |
| Flash point | 78 °C (closed cup) |
| Autoignition temperature | > 553 °C |
| Lethal dose or concentration | LD50 oral rat 276 mg/kg |
| LD50 (median dose) | LD50 (median dose): 283 mg/kg (oral, rat) |
| NIOSH | CN9625000 |
| PEL (Permissible) | PEL (Permissible Exposure Limit) of 1-Chloro-2,4-dinitrobenzene is 0.1 mg/m³ |
| REL (Recommended) | 0.01 mg/m³ |
| IDLH (Immediate danger) | IDLH: 5 mg/m3 |
| Related compounds | |
| Related compounds |
1-Fluoro-2,4-dinitrobenzene 2,4-Dinitrochlorobenzene 1-Bromo-2,4-dinitrobenzene 1-Iodo-2,4-dinitrobenzene |
