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Chemistry rarely offers household names, but anyone spending years in a research lab picks up a few favorites. 4-Nitrophenyl butyrate grabbed my attention the first time I saw it used as a straightforward indicator for enzyme assays. Decades ago, folks hunting for a simple way to watch how enzymes chop up esters realized they needed a substrate that showed a color shift. Researchers found that coupling the nitrophenyl group to butyric acid gave them something both easy to measure and stable on the shelf. By solving a nagging problem—watching invisible enzyme action—chemists opened doors for a slew of research in biology and medicine.
In any well-stocked life sciences lab, you spot various flasks labelled with 4-nitrophenyl butyrate. While it's not the flashiest compound, this molecule stands as the go-to substrate for testing esterases or lipases. Its popularity grows out of practical needs: It dissolves cleanly in organic solvents like acetonitrile or ethanol, handles storage without fuss, and steps up to the plate every time a quick colorimetric readout needs to be run. The nitrophenyl group does the heavy lifting—when hydrolyzed, it releases a yellow product that’s easy to quantify with standard UV-vis spectrophotometry. This simple change helps busy labs keep costs low and data rolling in.
On paper, 4-nitrophenyl butyrate presents itself as a pale yellowish powder or crystals, with a molecular formula of C10H9NO4. It's got a melting point around 50-52°C, and it prefers organic solvents over plain water for dissolving. Many chemists, especially those new to benchwork, don't always see the wisdom behind these details until a botched experiment wastes a day’s work. Understanding those physical quirks keeps the science moving. The nitrophenyl group attached to the butyrate backbone not only provides the needed color change but also influences stability and reactivity, which in turn decides how experiments play out in real time.
Accurate technical specs on any chemical save time, money, and reputation. With 4-nitrophenyl butyrate, purity above 98 percent becomes essential for clean results—any extra moisture or breakdown product quickly interferes with color change assays. Good labeling goes beyond basic chemical name and structure; it should include warnings about light sensitivity and recommended storage. Careless handling or open vials left on the bench lead to hydrolysis or degradation, producing background noise and costing restless nights piecing together where the data veered off. For anyone teaching young researchers, proper labeling and a focus on specs aren’t bureaucratic hurdles—they train the next generation to take responsibility for their results.
Seasoned chemists favor a classic approach to making 4-nitrophenyl butyrate: React 4-nitrophenol with butyric anhydride under base-catalyzed, moisture-free conditions. The esterification step needs a gentle touch, controlled temperatures, and careful purification with chromatography. Any sloppiness leads to leftover starting material or mixed esters that mess with assay sensitivity. Purity here isn’t just about checkboxes—one off day in synthesis lands test runs in the trash. My respect for careful method grew watching mistakes unfold as cloudy solutions and unpredictable absorbance peaks. The prep process demonstrates how textbook methods meet real-world practice, where patience and precision earn their place at the bench.
In the hands of creative researchers, 4-nitrophenyl butyrate becomes more than a single-use tool. The molecule’s ester bond lends itself to various modifications; swap out the butyrate, and you tune the reactivity for different enzymes or temperatures. The nitrophenyl group, known for its chromogenic punch, can be exchanged for other functional groups enabling detection across different wavelengths or even coupling to more complex molecules for multi-analyte assays. Years spent watching teams tweak these structures taught me how small changes in a molecule redefine what’s possible, crafting tools tailored to emerging scientific questions.
While navigating catalogues, mistakes swirl unless chemists pay attention to synonyms and alternate names. 4-Nitrophenyl butyrate often appears as p-nitrophenyl butyrate or 4-NP butyrate. Any confusion here creates headaches, especially when other nitrophenyl esters exist for acetates, propionates, and palmitates. Misjudging product selection or misreading common abbreviations leads to wasted budget and backtracks in research milestones, reinforcing the value of thorough reading and double-checks in busy laboratory environments.
After seeing the aftermath of a few spills, I learned to take chemical safety seriously. 4-Nitrophenyl butyrate doesn’t demand hazmat suits, but skin and eye contact brings noticeable irritation. Gloves and goggles are minimum requirements—ventilated hoods further reduce inhalation risks. Waste disposal walks a fine line; organic solvents and by-products shouldn’t head down the drain, and keeping logs prevents mix-ups. Many mishaps in the lab come from people dismissing the basics, underestimating how easily spills or mislabeling escalate to bigger problems. Strict adherence to safety brings peace of mind and keeps everyone at the bench focused on the science, not the aftermath of mistakes.
Over the years, I watched countless projects start with this molecule as scientists ran quick screens for enzyme activity. Clinical laboratories rely on it for identifying lipase deficiencies and drug discovery teams use it for high-throughput screening of esterase inhibitors. Pharmaceutical companies measure enzyme kinetics across drug candidates, screening for off-target effects. Beyond the life sciences, the food industry checks enzyme quality in dairy and meat products, and environmental labs use these substrates to track microbial or chemical breakdown of fats in soil and water. Its versatility only grows as new industries borrow tools from biochemistry to answer their own pressing questions.
Continuous work sharpens and broadens the uses for 4-nitrophenyl butyrate. Scholars push for more sensitive chromogenic substrates for use in low-concentration enzymes or multiplexed assays. Others hunt for biodegradable versions to cut down on chemical waste, aiming for sustainability alongside scientific advancement. Industry partnerships between universities and biotech companies help shape how this molecule gets used outside academia, supporting large-scale manufacturing quality or clinical diagnostics. Every step forward makes the assays faster, the results more reliable, and the reach of this little molecule broader—all a testament to the enduring creativity of the research world.
Decades of handling 4-nitrophenyl butyrate taught me that every chemical—no matter how benign it appears—deserves careful assessment. Toxicity studies show the compound causes targeted irritation, and both the parent molecule and its hydrolysis product, 4-nitrophenol, raise red flags for aquatic toxicity and bioaccumulation. Large-scale manufacturing or disposal practices bring their own risks, especially as waste streams enter municipal waters. The regulatory environment keeps evolving to address concerns about chronic exposure and environmental impact. Ongoing research should keep asking hard questions about fate, transport, and long-term health effects, pushing for safer substitutes if needed, and ensuring lab safety measures actually limit exposure to meaningful thresholds.
The future of 4-nitrophenyl butyrate likely holds continued demand as biochemical testing grows in complexity. With machine learning and automation driving high-throughput screening, substrate molecules that provide crisp, rapid, and measurable outputs become even more valuable. Improvements around sensitivity, stability, and safety will shape new product generations, and the trend toward greener chemistry may prompt a shift to molecules with smaller environmental footprints. As a researcher who’s seen trends come and go, I find value in this molecule’s enduring presence: it signals a blend of utility and adaptability that new generations of scientists will continue to depend on as fresh questions about health, environment, and biology emerge. The road ahead will likely include more rigorous regulatory scrutiny, along with research to better understand environmental persistence and biodegradability. All of this underscores the need for smart, responsible stewardship in both academy and industry—lessons every scientist can take to heart, regardless of specialty.
4-Nitrophenyl butyrate isn’t famous outside of research circles, but the folks in white coats will know it as a trusty helper in enzyme work. Picture a colorless solution in a chemistry lab. A student adds a yellowish chemical, stirs for a few minutes, and watches the mixture go yellow. That change signals something important: enzymes breaking down the butyrate, causing the nitrophenol group to split off. The shift makes the liquid change color, and this simple reaction acts like a spotlight on enzyme activity.
Many experiments rely on tools that show clear, visible changes. 4-Nitrophenyl butyrate acts as a substrate for esterases and lipases, enzymes found everywhere in nature — in plants, animals, bacteria, and even fungi. Enzyme activity can be hard to measure, but with the right substrate, small changes appear clearly. The nitrophenol group released from the butyrate stands out by turning the solution yellow, allowing researchers to check enzyme strength, purity, or activity levels just by reading the color.
Universities and biotech companies keep this tool in their kits. It helps with screening for new antibiotics. When scientists want to see if a soil microbe produces enzymes that break down toxins or fats, this compound brings answers quickly. Screening isn’t just a one-off job—every batch of industrial enzyme, every new biotechnological process, calls for easy, repeatable checks. 4-Nitrophenyl butyrate saves time and keeps results honest by making mistakes easier to spot.
The medical world borrows this tool too. If someone has a suspected enzyme deficiency or metabolic disorder, labs use it as part of diagnostic panels to look for low enzyme activity. The quick yellow reaction gives doctors a lead in mere minutes instead of hours. Clinical research also uses these tests to explore new drug candidates that act by switching enzymes on or off. Data grows faster, and that speeds up the hunt for better treatments.
Chemical manufacturing depends on quality control. Each batch of an enzyme used in food processing, detergents, or biofuels must meet exact standards. 4-Nitrophenyl butyrate helps confirm this. If an enzyme works, the color changes fast and strong. If an impurity or contamination slows the process, the test exposes it. That means fewer defective products and more confidence in what reaches consumers.
Wastewater treatment plants and pollution monitoring labs use enzyme assays involving this chemical to map out harmful or beneficial bacteria. It’s easier to check if microbes can break down pesticides or fatty acids using a solution with 4-nitrophenyl butyrate. The tests inform strategies for cleanup or identify risks, shaping safer policies around environmental hazards.
4-Nitrophenyl butyrate isn’t perfect. It can be pricey and sometimes the waste needs special handling. Making this compound more sustainable, or finding ways to recycle byproducts, would cut costs for smaller labs and open doors for more widespread testing in low-resource settings. Companies also experiment with substitutes that reduce waste but keep simplicity and accuracy.
Better regulations, clear labeling, and safer handling instructions mean fewer accidents and less environmental impact. Investing in greener chemistry — something the scientific community wants — lines up with responsible development. Scientists rely on these tests. Reliable, accessible tools benefit everyone, from researchers searching for medicine to everyday workers checking water quality.
A clear answer matters in the lab. Every scientist, from grad student to seasoned researcher, will run across bottles and labels that shout out a string of numbers. Pick up a vial of 4-Nitrophenyl Butyrate, the molecular weight stares right back: 209.19 g/mol. A label isn’t just a convenience. That number shapes every single calculation behind reactions, assays, or enzyme kinetics. Get it wrong, and time, samples, and money go right down the drain.
Let’s see what makes up that 209.19 g/mol. A single molecule of 4-Nitrophenyl Butyrate has the formula C10H9NO4. For anyone crunching numbers, each atom brings its own weight—carbon at 12.01, hydrogen at 1.01, nitrogen as 14.01, and oxygen coming in at 16.00. Put it all together:
Add these, the total lands at 209.20, which lines up with what most vendors and databases list (209.19 or 209.20, depending on decimal choices). Anyone planning to prep a buffer, dose a reaction, or measure product knows these numbers from muscle memory.
Molecular weight kicks off everything from dilutions to enzyme kinetics. Enzyme assays love 4-Nitrophenyl Butyrate since it turns a distinct yellow after being broken down, making it easy to track with a spectrophotometer. I remember running my own undergraduate project where being off by just 0.1 grams in a solution led to scrambling and wasted afternoons. This taught me respect for numbers and the habits labs depend on.
Most reputable sources like Sigma-Aldrich or PubChem confirm that 209.19 g/mol is the go-to value. Even small changes in calculation tweak assay outcomes, so it’s not just chemical trivia—accuracy keeps research reproducible and honest.
Seeing “molecular weight” on a spec sheet, many early researchers focus on bigger ideas, but the devil always sits in the details. If the value changes—maybe a typo slides into lab notes or a supplier changes production routes—results get skewed. Labs avoid this mess by double-checking identifiers like CAS numbers (2635-84-9 for this reagent), cross-referencing values before ordering, and sticking to current reagent certificates.
Every school and commercial lab aims for quality. Taking an extra five minutes to check the math or vet supplier data can save hours later. Training early on this, sharing bookmarks for reliable databases, and double-confirming formula weights plug the leaks in sloppy technique.
So the molecular weight of 4-Nitrophenyl Butyrate, at 209.19 g/mol, covers more ground than a line on a label. It shows a commitment to precision, the muscle memory of careful science, and respect for all those who come after, building on reliable data.
Most experienced lab workers know: chemicals like 4-Nitrophenyl Butyrate give you clues about their temperament. A pale yellow color, fine crystalline texture—simple at first glance. But all sorts of trouble can pop up if you don’t pay close attention to storage. Direct sun, drifting humidity, or careless handling can prompt breakdown or even dangerous reactions. People deserve to work without unnecessary risk, and keeping this compound stable goes a long way toward safety and reliability in the lab.
Leaving 4-Nitrophenyl Butyrate out in the open on a bench invites unwanted surprises. It reacts quickly to moisture, losing its edge and giving off some unpleasant byproducts. I learned early on to check desiccators and dry cabinets before taking stock of sensitive chemicals. A cool, dry spot slows down decay and preserves quality. Temperature swings in older storage spaces can shorten shelf life, and humidity creeps in wherever it finds a gap. High-quality, airtight bottles with secure caps hold up best—ideally glass bottles or HDPE containers with tight seals.
Sun and even fluorescent bulbs encourage decomposition in 4-Nitrophenyl Butyrate, making storage in amber vials more than just a routine habit. Some chemicals seem robust but lose effectiveness from a single afternoon’s exposure. I’ve seen stable-looking powders fade or clump just from being left near a south-facing window. Brown glass containers block out enough light to slow those changes to a crawl. Even with the lights on all day, you want to shield the contents from preventable breakdown.
Routine can lead to trouble when labels wear off or fade. I once worked with someone who left several powders unmarked, only to lose track of which batch came from which shipment. With compounds like 4-Nitrophenyl Butyrate, traceability links directly to safety. Any chemical—especially those with the risk of degradation products—should show date received, lot number, original concentration, and hazard warnings. Invest in chemical-resistant marker pens and backup online inventories so nothing slips through the cracks.
Lab culture either supports safety or erodes it. Workers ought to know why tight storage routines matter, not just how to follow them. Gloves, goggles, and sturdy lab coats prevent direct contact. As experience grows, the sense of what's reasonable and what’s reckless sharpens. Regular reviews of storage protocols, along with reminders about risks of breakdown, inspire better habits. Even on busy days, a strict rule against leaving containers uncapped makes a difference.
Chemical hoarding always carries a cost. I’ve seen well-meaning researchers keep expired 4-Nitrophenyl Butyrate, hoping the next experiment will use up the dregs. Testing for activity or physical changes helps, but if a batch appears cloudy or the color shifts, it should head for proper disposal. Waste storage should be just as disciplined; never mix with incompatible compounds, and always follow local environmental guidelines.
Digital inventory systems alert me now when a bottle is nearing its end or outstaying its welcome. Modern labs justify investments in better storage rooms—cool, filtered, climate-controlled spaces. Written SOPs, posted right by the chemical storage room, make expectations clear. Even in older buildings, smart routines and vigilance cut down on lost product, wasted time, and health hazards.
Keep 4-Nitrophenyl Butyrate cool and dry, far from light and moisture. Never store it in direct sunlight or in spaces prone to temperature jumps. Prioritize sealed containers and reliable labeling. Regular training, digital tracking, and prompt disposal routines create a safer and more effective workplace for everyone.
People working in chemistry labs see all kinds of chemicals. Some are easy to handle, some demand heavy gloves and smelly fume hoods. 4-Nitrophenyl butyrate, a yellowish powder, gets used a lot for enzyme activity tests. Anyone grabbing a bottle of this stuff for the first time wonders: just how dangerous is it? Most information sitting in lab safety binders says “Harmful if swallowed, may cause irritation.” That doesn’t feel super reassuring, but it also doesn’t sound like a death sentence.
In college, I spent my fair share prepping test tubes with 4-nitrophenyl butyrate. One practical lesson: getting it on your hands causes mild tingling, a little like using an old cleaning product. I always washed right away and never saw burns, but I knew a friend who got a light rash after spilling a concentrated solution. That stuff absorbs. The chemical breaks down in water to produce butyric acid and the notorious 4-nitrophenol; both play their own roles in creating risk. A graduate supervisor liked to repeat, “Wear gloves, and if you smell anything odd, leave the bench.” Sensible words, especially if you remember how fast skin can pick up dissolved organics.
No one wants powder flying into the air, since breathing 4-nitrophenyl butyrate dust feels like a throat scratcher. Most safety data sheets warn against inhalation and recommend using a fume hood. Even tiny bits floating around can dry out eyeballs or set off sneezing. Honestly, curiosity sometimes tempts folks to skip protective glasses, but one accidental splash gets trust back into goggles real quick. That’s the thing — a chemical might seem mild until it’s in your eye.
Talk to toxicologists, and stories come up about how the breakdown product, 4-nitrophenol, shows up as a low-level environmental contaminant in rivers, especially near factories. Animal studies link 4-nitrophenol with blood trouble, kidney stress, and, at higher doses, liver effects. That doesn’t mean a one-time lab spill turns your organs inside out, but repeated or careless exposure adds up. Over time, chronic inhalation or skin contact can lead to real health problems. No surprise, safety posters treat 4-nitrophenyl butyrate as “hazardous,” not “benign.”
Industries use far bigger amounts than a college class ever would. Every drum gets strict handling requirements: ventilation, chemical-resistant gloves, and waste treatment plans. I met a chemical plant worker who said their waste streams go through several detox steps before disposal, since water boards watch for nitro compounds. That’s a clear signal that this chemical carries enough risk to affect water quality and community health.
Safer labs teach one lesson: predictable habits cut risks. Wearing gloves, sealing bottles tight, and avoiding food in chem areas all sound like nagging advice. But those routines built by experience keep accidents rare. Teams with experienced mentors pass along small tricks — like checking gloves for holes with a quick squirt from the wash bottle. Good disposal habits help, too. Diluted solutions end up in special waste containers, not the sink, because no one wants nitro breakdown products running downstream.
Not every chemical in a lab equals poison gas or instant harm, but stories of small accidents teach respect fast. 4-nitrophenyl butyrate sits in the “potentially hazardous” category for a reason. Small, invisible exposures add up if ignored. Common sense, steady habits, and real safety gear take the edge off its risks, both for the user and the world outside. In the end, any chemical hazard lives in how people treat the bottle in their hands.
In every lab where enzyme assays run and esterase activity gets tracked, 4-nitrophenyl butyrate makes its way onto the bench. You pop open a bottle of this pale yellow compound, weigh out a few milligrams, and then the real challenge kicks in: getting it to dissolve in water. Anyone who has tried to coax 4-nitrophenyl butyrate into an aqueous solution knows this job needs both patience and a bit of knowhow.
Fresh out of the bottle, this nitroaromatic ester looks innocent. Put it into water at room temperature, and you’ll see what happens: not much, except maybe a few floating flecks. Data from recognized sources such as Merck and Sigma-Aldrich, alongside published assays, give a solubility number in the range of 0.014 g per liter. In everyday terms, that’s next to nothing. For a typical 100 mL assay, the most you can get dissolved is about 1.4 mg, and even that needs constant stirring and maybe some heating. Researchers have to use organic solvents or cosolvents, such as DMSO or acetonitrile, to stock up a working solution for biochemical tests.
Trying to measure enzyme activity using 4-nitrophenyl butyrate in pure water can feel like running a marathon in sand. This low solubility jams up assay sensitivity, slows down reactions, and leaves another variable for scientists to control. You only get reliable results if your compound is mixed through the solution. That means giving up on water as a reliable solvent or tweaking your protocol until you find something that works. Enzyme labs often use a tiny amount of an organic solvent to make a strong stock solution. After diluting into buffer, you end up with less than 1% organic solvent—usually safe enough for most enzymes.
The complications don’t stop at the bench. If you’re working on teaching or demonstrating esterase activity, a poor solubility leads to lower color development and weak results. The yellow color from the release of 4-nitrophenol—the readout in standard spectrophotometric assays—never quite develops to its full potential unless the substrate is fully dissolved.
The struggle with 4-nitrophenyl butyrate’s solubility traces back to its structure. Both the aromatic ring and the butyrate moiety hate mingling with water molecules. Water wants to stick with itself, and the 4-nitrophenyl butyrate prefers to huddle in little clumps rather than break apart in the crowd. Labs rely on DMSO, acetonitrile, or sometimes ethanol to bridge the gap. These cosolvents help scatter 4-nitrophenyl butyrate at doses high enough for useful experiments but low enough to avoid damaging sensitive enzymes.
Anyone teaching undergraduate biochemistry soon learns to keep a bottle of DMSO handy. It surprises no one that poor solubility catches students off-guard, especially in early experiments where everyone assumes a laboratory chemical will simply “dissolve.” We may wish every chemical mixed as easily as sugar, but 4-nitrophenyl butyrate simply refuses. That means understanding, adaptation, and rolling with chemistry’s quirks—it keeps science honest, and it keeps students humble.
The truth is, you don’t have to work around poor solubility with guesswork. Reliable solutions involve accuracy: weigh your substrate, mix your cosolvents, and report the cosolvent concentration in all documentation or publications. Transparency buys trust. Checking enzyme tolerance to DMSO or any added cosolvent builds credibility in published results and students’ reports. Preparation and knowledge remain the best tools for getting consistent, real-world results from trickier molecules.
| Names | |
| Preferred IUPAC name | 4-nitrophenyl butanoate |
| Other names |
p-Nitrophenyl butyrate PNPB 4-Nitrophenyl butanoate Butyric acid 4-nitrophenyl ester para-Nitrophenyl butyrate |
| Pronunciation | /ˌfɔːrˌnaɪ.trəʊˈfiː.nɪl ˈbjuː.tɪ.reɪt/ |
| Identifiers | |
| CAS Number | 2635-84-9 |
| Beilstein Reference | 1634157 |
| ChEBI | CHEBI:64104 |
| ChEMBL | CHEMBL17815 |
| ChemSpider | 15943 |
| DrugBank | DB08174 |
| ECHA InfoCard | 27d63aae-6de6-48c8-a7b4-e8cf7cbc0d0d |
| EC Number | 205-529-6 |
| Gmelin Reference | 82157 |
| KEGG | C06152 |
| MeSH | D009642 |
| PubChem CID | 95722 |
| RTECS number | UJ5950000 |
| UNII | 1N9S913D87 |
| UN number | UN2811 |
| CompTox Dashboard (EPA) | DTXSID8021218 |
| Properties | |
| Chemical formula | C10H11NO5 |
| Molar mass | 209.19 g/mol |
| Appearance | White to yellow crystalline powder |
| Odor | Odorless |
| Density | 1.2 g/cm³ |
| Solubility in water | insoluble |
| log P | 1.93 |
| Vapor pressure | 25 °C: 0.000206 mmHg |
| Acidity (pKa) | 8.02 |
| Basicity (pKb) | 7.04 |
| Magnetic susceptibility (χ) | -55.0×10⁻⁶ cm³/mol |
| Refractive index (nD) | 1.522 |
| Viscosity | 3.61 cP (25°C) |
| Dipole moment | 5.74 D |
| Thermochemistry | |
| Std molar entropy (S⦵298) | 389.8 J·mol⁻¹·K⁻¹ |
| Hazards | |
| GHS labelling | GHS02, GHS07 |
| Pictograms | GHS07 |
| Signal word | Warning |
| Hazard statements | H302: Harmful if swallowed. |
| Precautionary statements | Precautionary statements: P261, P264, P271, P280, P301+P312, P305+P351+P338, P405, P501 |
| NFPA 704 (fire diamond) | 2-2-1 |
| Flash point | 106 °C |
| Lethal dose or concentration | LD₅₀ (oral, rat): 945 mg/kg |
| LD50 (median dose) | LD50 (median dose): Oral rat LD50 = 325 mg/kg |
| NIOSH | RQ1425000 |
| PEL (Permissible) | Not established |
| REL (Recommended) | 25 mg |
| IDLH (Immediate danger) | Not Listed |
| Related compounds | |
| Related compounds |
4-Nitrophenol Phenyl butyrate p-Nitrophenyl acetate p-Nitrophenyl palmitate p-Nitrophenyl phosphate |
