2-Methylbutanoic acid came to the attention of chemists more than a hundred years ago, riding on the wave of discoveries that shaped the early days of organic chemistry. As labs raced through cataloging molecules of life and industry, this small fatty acid emerged from natural sources like some fruits and cheeses. Early chemists mostly caught its scent by accident, tracing its presence in fermentation broths and ripening dairy. Over the decades, improvements in organic synthesis allowed consistent production, making 2-methylbutanoic acid more than a fleeting footnote in textbooks. Researchers steadily found more ways to use this molecule, and the story continues as technology opens new doors.
At its core, 2-methylbutanoic acid exists as a clear, oily liquid with a sharp, sour smell. Today, manufacturers prepare it both by biosynthetic processes and by classic chemical routes. It’s no one-trick pony: food, flavors, fragrances, and a growing list of specialty chemicals depend on this carboxylic acid. Analytical-grade batches end up in research labs, while bulk lots move through flavor houses and aroma factories to lend themselves to consumer goods. The product sells under many labels, depending on the intended market, reflecting a wide grip on commerce well beyond the lab bench.
2-Methylbutanoic acid has a boiling point around 178°C, with a melting point close to -60°C, putting it squarely in the liquid camp at room temperature. Its distinct sour odor and moderate volatility mean it announces itself fairly quickly. Solubility in water runs low but not nonexistent, while organic solvents like ethanol and ether mix well with it. As with similar carboxylic acids, this one can donate a proton readily, making it a mild acid. The combination of a small molecular size and a branching methyl group tunes both volatility and aroma, which might explain its special place in fragrances and flavors.
Bottles and drums of 2-methylbutanoic acid roll out of factories bearing information critical to safe handling and honest trade. Producers stamp purity, batch numbers, recommended storage conditions, shelf life, and regulatory codes on every label. The minimum accepted purity for industrial batches usually exceeds 98 percent, though the pharmaceutical industry demands even tighter tolerances. Anyone buying or selling this chemical tracks country-specific regulations, such as REACH compliance in Europe or TSCA in the United States. Label instructions vary, but the law requires hazard warnings and first-aid steps. The spread of digital barcoding now helps track material from tank to tabletop, a move toward transparency that makes sense in a globalized market.
Industrial synthesis of 2-methylbutanoic acid follows well-trodden chemical routes, such as hydrolysis of 2-methylbutyronitrile or oxidation of 2-methyl-1-butanol. Less often, fermentation of certain substrates by wild-type bacteria turns up small amounts, which specialty producers sometimes recover. Smaller quantities may get pulled from fractional distillation of natural essences, but supply rarely matches modern demand this way. Most chemical plants choose the nitrile hydrolysis route because it scales up well and handles variable feedstocks. Each method depends on cheap, available reagents and solid waste management, especially since regulatory authorities keep a sharp watch on any hazardous byproducts. Process chemists continue to shave costs, reduce emissions, and boost yields, but the underlying recipe has seen only minor tweaks over the past decades.
The chemistry of 2-methylbutanoic acid follows the familiar dances set by carboxylic acids everywhere. Under mild conditions, it reacts with alcohols to create fruity esters, a core feature that endears it to flavorists and perfumers. Reaction with bases forms the corresponding salts, which sometimes improve solubility in certain applications. Reducing agents can trim the acid group down, while strong oxidizers threaten to break the molecule apart. Substitution at the methyl position sometimes produces specialty derivatives found in pharmaceuticals and fine chemicals. Though straightforward, these reactions must be run with a care for purity, since even modest contamination can spoil a flavor or a therapeutic formula.
Walk through a chemical catalog, and 2-methylbutanoic acid pops up under several banners—2-methylbutyric acid, α-methyl-n-butyric acid, isopropylacetic acid, and sometimes just C5H10O2. Companies market it under customer-friendly trade names, especially in the ingredient business. For the flavor industry, it might appear as a “natural” additive if produced from bio-based sources; synthetic lots carry clear labeling as an artificial ingredient. Pharmacopeias and regulatory filings list CAS number 116-53-0, the unambiguous fingerprint in a tangled catalog of commercial aliases.
No smart lab or production line handles 2-methylbutanoic acid with indifference. Unchecked, its odor alone can trigger discomfort in close quarters, and its acidity irritates skin and eyes. Workers suit up with gloves, goggles, and aprons, managing spills with absorbent materials and proper ventilation. Storage requires tightly sealed containers, away from heat and strong bases or oxidizers. Training on handling procedures, spill response, and first aid belongs in every safety binder. Regulatory standards treat it as a flammable, corrosive liquid; safety data sheets stress the need to avoid ingestion and prolonged skin contact. Companies have learned costly lessons from mishaps; these rules grew out of real incidents and must stay part of daily routine.
Food manufacturers reach for 2-methylbutanoic acid to add punch to cheese, fruit, and butter flavors—both natural and synthetic. Perfumers and aroma technologists blend it into fragrances where a sharp, distinctive note gives products a signature. Animal feed producers use it to mimic or enhance palatability, helping animals eat more and grow faster. Chemical synthesis companies rely on its easy reactivity to build more complex molecules needed in pharmaceuticals and specialty materials. Some research groups even test its properties as an antifungal or antimicrobial, betting on its natural origins to dodge resistance pathways. Every use presses the need for supply traceability, consistent quality, and compliance with regional regulations covering ingestible and topical ingredients.
Research on 2-methylbutanoic acid increasingly links academia and industry. Current projects explore greener synthetic routes that lower emissions and improve energy efficiency. Metabolic engineering teams are tweaking microbial strains to increase biological yields, hoping to break away from fossil-based starting materials. Analytical chemists set their sights on better detection and purity evaluation methods, critical for keeping food and pharma products safe. Recent patents detail new uses in antimicrobial agents, and clinical studies sometimes use the substance as a marker molecule for metabolic disorders. Funding in this area tends to follow industry needs; whenever there's a fresh demand for better flavors or safer preservatives, laboratories kick into higher gear.
No substance escapes the need for close study of its health impacts, and 2-methylbutanoic acid draws scrutiny due to its food and fragrance uses. Animal studies have mapped acute and chronic exposure outcomes; the acid registers as a low-to-moderate toxicity risk. Inhalation triggers nose and throat irritation, and spilled material reddens skin within minutes. Long-term dietary intake in lab models finds no evidence of carcinogenicity at standard exposure levels, offering some peace of mind for food technologists and regulators. The acid breaks down swiftly in the environment, neat for those worried about bioaccumulation or long-term persistence in water and soil. Ongoing work keeps checking for less obvious risks: allergenicity, metabolic interference, or synergistic effects with other additives. Tracking and publishing these results helps policy setters adjust permissible limits as new knowledge comes to light.
Looking forward, 2-methylbutanoic acid holds promise in fields stretching from green chemistry to advanced biotechnology. Bio-based synthesis routes backed by renewable feedstocks could unlock lower-emission production, sidestepping the volatility and price swings of petroleum inputs. The molecule’s versatility in flavors, fragrances, and specialty chemicals appeals to industries eager for ingredients with documented safety and traceability. Flavors and fragrances trend toward transparency, and a molecule with a known pedigree fits those goals. Synthetic biology teams may soon turn out custom esters and derivatives tuned for specific tastes, odors, or biological effects. Regulatory authorities in Europe, North America, and Asia update their standards in step with new findings, aiming to balance consumer safety with market access. Companies that invest in closed-loop systems, advanced waste management, and carbon tracking stand to win both regulatory approval and lasting consumer trust. Each of these paths depends on collaboration—between researchers, manufacturers, regulators, and end-users. The story of 2-methylbutanoic acid keeps growing, and it’s worth watching where it goes from here.
2-Methylbutanoic acid, also called 2-methylbutyric acid, isn’t a name most people think about until they’re either reading a food label or sitting in a chemistry class. At first glance, this colorless liquid may seem like just another item on a long list of ingredients, but its effects turn up everywhere. I learned this firsthand the first time I walked into a commercial flavor lab — the space filled my nose with a tangy, almost cheesy aroma, and someone pointed to a bottle labeled “2-methylbutanoic acid.” The smell was sharp, memorable, and unmistakably real.
What stands out about this acid is how food scientists use it to create flavor and fragrance profiles found in cheddar cheese, chocolate, and strawberry. There’s a lot of work behind that familiar richness you taste in certain snacks, cheeses, and even in some candies. Take natural cheese flavor—without 2-methylbutanoic acid, it just doesn’t pop the same way. The molecule’s aroma comes close to aged cheese and fruits, which explains its use in artificial flavoring.
Manufacturers rely on this acid to create that “real” dairy note in processed foods. In my time interviewing product formulators, they often mention how such acids let them replicate expensive natural aging or fermentation processes without needing to actually store and age the food itself. This means broader access to familiar flavors, fewer spoilage risks, and lower production costs for staples like cheese-flavored chips or processed spreads.
The reach of 2-methylbutanoic acid isn’t just in the food world. Take a walk down the soap or candle aisle, and chances are you’ll encounter it again. Its fruity, pungent character builds complexity in perfumes and household fragrances. Perfumers use it to impart tang and realism to fruit notes or to add a mature nuance to floral blends. Its volatility means it vaporizes easily, delivering strong, upfront scents that fill a room. I once attended a fragrance seminar where a single drop shifted an entire blend’s character from bland to bold.
Industrial chemistry takes things further, putting this acid to use as an intermediate for other compounds, like pharmaceuticals and insect attractants. Some pest management projects even depend on organizing traps baited with solutions containing this acid, since it’s attractive to certain insect species. Lab workers handle it with care: the strong odor, while useful in tiny quantities, can overwhelm in larger amounts.
In the world of food and fragrance, trust matters. Food scientists working under strict regulations ensure that only safe quantities of ingredients end up in finished products. The U.S. Food and Drug Administration lists 2-methylbutanoic acid as “generally recognized as safe” for its intended use in flavoring. That said, excessive inhalation or skin contact—like with many concentrated organic acids—irritates sensitive tissues. I’ve seen labs strictly control its use and storage, reflecting the broader industry’s approach to safety.
Every ingredient in consumer goods faces growing scrutiny. Shoppers now ask hard questions about what goes into snacks and cosmetics. Explicit disclosure and science-backed evaluations protect people who want real transparency. That’s especially true when artificial flavors replace costly, sometimes less sustainable, natural options.
Demand for bold, authentic flavors and scents keeps rising. At the same time, nobody wants harmful residues or undisclosed chemicals in their food or home. Keeping that balance means research teams continue digging deep into toxicological data, refining their formulations, and embracing clearer labeling. When done right, 2-methylbutanoic acid can help bring more authentic experiences to daily life, without hidden risks.
2-Methylbutanoic acid often comes up in discussions around flavors and fragrances. Anyone who has cracked open the bottle will remember the strong, sour odor, no matter how long they’ve worked with chemicals. This acid packs a punch: it causes skin and eye irritation, can trigger asthma-like symptoms, and leaves a nasty residue if spilled. Its volatility makes accidental splashes and inhalation a risk even during careful handling. I remember a colleague, after a minor fume exposure, coughing for hours—nobody presses the need for proper ventilation until they see symptoms up close.
The safety data tells a clear story. Contact with 2-methylbutanoic acid leads to burning eyes or itching skin if gloves or safety glasses get skipped. Breathing in vapors brings headaches, coughing, or even more severe respiratory symptoms. Spills evaporate quickly, so the hazard extends beyond the liquid. The main lesson: no shortcut replaces good habits. It’s a corrosive, inhalable irritant, and that means it commands respect from anyone nearby.
Gloves and goggles aren’t optional gear; they’re necessary even for quick sample transfers. Skin exposure from bare fingers or flecks near the wrists can burn and itch for days. Well-fitting nitrile gloves block direct contact, and chemical splash goggles protect from both droplets and vapor. Lab coats help reduce the chance of soaking through clothing, and a closed lab shoe beats open sandals any day. Respirators come in for bigger spills or work in poorly ventilated rooms, since the fumes can get strong fast.
Labs sometimes rely more on habit than airflow readings, risking health for convenience. I saw this when moving to a new building: fume hoods kept off unless “absolutely needed,” until headaches started. Active ventilation and use of certified fume hoods should stay the default—these remove vapors before they spread. Turning on exhaust fans or opening windows helps, but strong air draw from a hood traps the chemicals at the source.
Minor acid leaks get contained with proper absorbent pads, not old towels or paper. A small pool can still send fumes across the room. I once watched a technician race for the spill kit before acid spread across a bench. Baking soda neutralizes, but it fizzes up—cover gently, not recklessly, or else the reaction sprays droplets. Soak up, neutralize, then throw waste into a labeled container with an acid warning—nobody enjoys an unmarked bottle leaking in the trash.
Stashing 2-methylbutanoic acid in a basic cabinet forgets the real risk. Dedicated acid cabinets cut the odds of accidental mixing. Labeling stands out as the simplest defense—nobody should mistake a clear liquid for water or mix acids by accident. Tight seals on bottles keep fumes where they belong, not drifting across storage rooms. Keeping inventory short highlights expired containers, which tend to leak or pressurize.
New lab staff sometimes treat chemical handling like cookbook baking, skimming steps and skipping safety reminders. Real-world training, not just written instructions, builds habits. Watching someone work, with time for questions and honest mistakes (supervised), leads to safer labs. Posters on walls remind workers, but hands-on walkthroughs set routines in stone. It’s better to spend an extra hour learning protective steps than facing weeks off from a preventable injury.
Ask anyone who has spent time in a chemistry lab, and they’ll probably talk about that moment of clarity when a chemical formula suddenly makes sense. Take 2-methylbutanoic acid. This compound might sound complicated, but it actually boils down to a simple arrangement of carbon, hydrogen, and oxygen atoms. Its chemical formula is C5H10O2. Every student faces these kinds of formulas at some point, probably during organic chemistry class—where you wonder if these chains and branches will ever mean more than homework assignments.
One of the things that stands out about 2-methylbutanoic acid is its branched structure. Picture a butanoic acid chain—four carbons linked together as a backbone. Throw in a methyl group (that’s a CH3 tacked onto the second carbon), and you’ve got the “2-methyl” part. The rest of the chain is what gives the molecule its unique properties, especially once that carboxylic acid group (–COOH) shows up at the end. The formula C5H10O2 captures it neatly, but it hides the story of its shape and reactivity.
Ask any food scientist or fragrance expert about 2-methylbutanoic acid and you’ll get a smile. For years, this compound has filled a niche in the world of flavor and fragrance. It’s found naturally in some cheeses and certain fruits. Anyone who’s spent time working with natural flavors learns how delicate these compounds can be—and how small changes in structure send taste in a whole new direction. The methyl branch in this acid tweaks its aroma, making it tangy and almost fruity, while still sharp enough to notice.
Years ago, I helped a cousin experiment with making artisanal cheese. That sour, funky smell as the curds matured? A reminder of how molecules like 2-methylbutanoic acid shape experiences that seem far removed from chemistry textbooks. Research at the University of Copenhagen has shown that this acid is key to the profile of hard cheeses and plays a role in how people respond to “aged” flavors. Ratios of compounds like this one influence what tastes “authentic” or rich. There’s a link here between the formula you see on the board and the flavors that show up in kitchens worldwide.
Getting hands-on with chemicals, even those in food, means paying attention to safety. Food-grade forms of 2-methylbutanoic acid follow tough regulations for purity. Workers in fragrance and flavor labs know how quickly exposure to strong acids gets uncomfortable. The U.S. FDA lists this compound as “generally recognized as safe” when used in trace amounts for flavoring. Attention to quality and safe handling—paired with ongoing research—helps ensure products meet consumer expectations and keep workers protected on the job.
One challenge in using 2-methylbutanoic acid comes from sourcing and environmental safety. Sustainable supply chains have become a real concern, especially as natural flavors grow more popular. Green chemistry practices—using renewable feedstocks, safer solvents, and waste reduction—are making a difference here. Companies like Givaudan and Firmenich have published concrete advances in improving the environmental profile of molecules like 2-methylbutanoic acid without sacrificing their sensory punch. These solutions reflect a movement toward responsibility, not just innovation for its own sake.
Plenty of folks see acids as glass bottles behind dusty fume hoods, labeled with warnings. In a busy lab, proper storage of chemicals like 2-methylbutanoic acid makes the difference between safety and disaster. I learned pretty quickly during my graduate years that even the smallest mishap—spilled liquid, broken lid—can wreck weeks of work or even put people at risk. Fragile bottles, sharp odors, skin burns: these things stick with you. Not every acid lets you know it’s dangerous with a violent hiss or an obvious reaction, but underestimate it and you’ll pay for it.
Used in making flavors, fragrances, and sometimes as a reagent, 2-methylbutanoic acid comes with its own headaches. The strong, cheesy-smelling vapor can escape if the cap isn’t tight, making nearby rooms unpleasant fast. Any spilled drops will linger for days and turn hands red and sore. With a boiling point around 178°C and pretty decent volatility for a carboxylic acid, it evaporates enough to make people uncomfortable.
Storing chemicals like this starts with recognizing that exposure is rough on both people and the lab space. Strong fumes don’t belong anywhere food or papers sit uncovered. It will burn skin, irritate airways, and mix badly with oxidizers or strong bases. Safety comes before convenience every single time.
Glass bottles with secure, intact lids work best for acids in labs. I always check these for damage before storing anything. Flimsy plastic doesn’t hold up. If I’m not sure about the bottle, I transfer the acid to one that I trust. Good labels mean no guessing later—permanent marker, chemical-resistant tape, nothing fancy but clear.
Storage cabinets designed for corrosives help keep acids contained if leaks or drips happen. These cabinets sit away from direct sunlight or any heat sources. People sometimes skip this step and leave acids out on benches, usually for convenience. Those shortcuts build up until someone regrets it. Acids go on lower shelves, not above shoulder height, to reduce the risk if bottles drop.
A chemical inventory log adds a layer of accountability. If everyone knows what’s stored where, fewer accidents happen. Regular checks help spot damaged containers before a big mess starts. Fume hoods aren’t only for pouring or measuring out liquids; freshly delivered bottles go straight in there to minimize vapor exposure, then back to storage.
Not every place has industrial-grade storage, but crowded prep rooms and classrooms can still keep things safe. Even something as basic as a lockable steel cabinet with acid-resistant liner makes a huge difference. I’ve seen vinegar bottles serve as makeshift storage—dangerous and unnecessary when better gear costs very little.
Routine matters more than fancy equipment. Lab teams that clean up spills immediately, keep storage neat, and train newcomers avoid most problems. Clear up residue with water and a mild base, using gloves and goggles. If eyes or skin get splashed, plenty of running water right away keeps injuries from getting worse.
The attitude in the lab—do it carefully the first time—keeps people healthy. Proper training, sturdy containers, careful shelving, and regular checks handle nearly every risk I’ve ever seen involving 2-methylbutanoic acid. If you’re stubborn about good habits, even a stubborn chemical like this stays under control.
2-Methylbutanoic acid pops up in several everyday products. This chemical brings a fruity and sometimes sweaty odor, which finds its way into flavorings and fragrances. It also occurs naturally in some foods and is created during fermentation. Yet the transition from trace amounts in foods to higher concentrations in factories or laboratories raises the issue of how safe this substance really is—both for people and for the places we live.
Most of us won’t stumble across 2-methylbutanoic acid outside lab work or industrial settings. As a pure or concentrated chemical, it can irritate the eyes, skin, and the lining of the throat. Breathing in high levels might spark coughing, a scratchy feeling, or even headaches and dizziness. Some studies on animals hint at more serious trouble—from damage to organs, including the liver, to trouble with breathing. Nothing points to widespread harm from routine exposure through flavored foods or perfumes, but accidents in handling bulk quantities can happen in workplaces. Folks spending eight or more hours around open drums or mixing vats have much higher odds of getting exposed.
Spills and leaks matter most for rivers, streams, and the land close to chemical plants. This acid breaks down in the environment, especially in sunny, warm weather. Yet when it pours out in large amounts or runs off during storms, it can push up the acidity of local water. Fish, frogs, and small critters need a certain balance, so a sudden flush of acid doesn’t go unnoticed. That may not sound like a big deal in theory, but for a small stream or pond, it only takes a modest spill to nudge the system out of whack.
Adding this acid to soil can change the way plants grow—sometimes hurting the root systems or making it harder for crops to thrive. Most areas won’t see those effects unless someone handles the chemical carelessly. Keeping it contained, with spill kits and good waste practices, prevents most trouble.
The legal world sets limits for chemicals like 2-methylbutanoic acid in air and water. Companies have a duty to protect workers, not just by passing out gloves and masks, but by making sure spills get caught at the source—by drains, in storage rooms, or on factory floors. In my own work, the places with the fewest incidents always trained new folks with real-life scenarios, not just binders full of safety rules.
Researchers keep exploring ways to replace more hazardous acids and solvents in industry. Some food companies use natural versions, pulled from fruits or brewed in yeast, which tend to show up at much milder levels and pose less of a challenge for both factory workers and neighbors downwind. That process takes time, but demand for safer flavors has pushed more brands to ask how ingredients behave from field to fork.
Anyone living or working near a plant handling this kind of chemical can ask about spill history, storage methods, and emergency steps in place. For the rest of us, washing hands after work with solvents and not breathing in strong vapors makes a bigger difference than most people guess. Asking for transparency and safer alternatives—at the grocery store or the ballot box—keeps things moving in the right direction. No need for panic, but no reason to let slip-ups slide, either. Knowing what’s in the neighborhood leads to better choices—from both companies and communities.
| Names | |
| Preferred IUPAC name | 2-Methylbutanoic acid |
| Other names |
2-Methylbutyric acid
alpha-Ethylpropionic acid Ethylacetic acid Ethylpropionic acid Ethylpropanoic acid |
| Pronunciation | /tuː ˌmɛθ.ɪl.bjuːˈteɪ.nɪk ˈæs.ɪd/ |
| Identifiers | |
| CAS Number | 116-53-0 |
| Beilstein Reference | 1718735 |
| ChEBI | CHEBI:30884 |
| ChEMBL | CHEMBL14235 |
| ChemSpider | 13498 |
| DrugBank | DB03842 |
| ECHA InfoCard | EC Number: 211-518-3 |
| EC Number | EC 209-796-1 |
| Gmelin Reference | 7148 |
| KEGG | C02388 |
| MeSH | D016281 |
| PubChem CID | 8093 |
| RTECS number | EK6300000 |
| UNII | YUU9285PZO |
| UN number | UN2346 |
| Properties | |
| Chemical formula | C5H10O2 |
| Molar mass | 102.13 g/mol |
| Appearance | Colorless to pale yellow liquid |
| Odor | unpleasant, rancid, cheesy |
| Density | 0.936 g/mL at 25 °C |
| Solubility in water | slightly soluble |
| log P | 0.93 |
| Vapor pressure | 0.107 mmHg (25 °C) |
| Acidity (pKa) | 4.84 |
| Basicity (pKb) | pKb ≈ 13.7 |
| Magnetic susceptibility (χ) | -65.0e-6 cm³/mol |
| Refractive index (nD) | nD 1.403 |
| Viscosity | 1.09 mPa·s (25 °C) |
| Dipole moment | 1.763 D |
| Thermochemistry | |
| Std molar entropy (S⦵298) | 248.7 J·mol⁻¹·K⁻¹ |
| Std enthalpy of formation (ΔfH⦵298) | -447.2 kJ/mol |
| Std enthalpy of combustion (ΔcH⦵298) | -2676.3 kJ/mol |
| Pharmacology | |
| ATC code | A16AB15 |
| Hazards | |
| GHS labelling | GHS05, GHS07 |
| Pictograms | GHS05, GHS07 |
| Signal word | Warning |
| Hazard statements | H314: Causes severe skin burns and eye damage. |
| Precautionary statements | P280, P301+P312, P305+P351+P338, P310 |
| NFPA 704 (fire diamond) | 2-1-0 |
| Flash point | 73 °C |
| Autoignition temperature | 481 °C |
| Explosive limits | Explosive limits: 1.4–7% |
| Lethal dose or concentration | LD50 oral rat 1550 mg/kg |
| LD50 (median dose) | LD50 (median dose) of 2-Methylbutanoic Acid: "1,950 mg/kg (rat, oral) |
| NIOSH | NA0525000 |
| PEL (Permissible) | PEL (Permissible Exposure Limit) for 2-Methylbutanoic Acid: Not established |
| REL (Recommended) | 200 mg/L |
| IDLH (Immediate danger) | IDLH: 200 ppm |
| Related compounds | |
| Related compounds |
Isovaleric acid
Pentanoic acid 3-Methylbutanoic acid Valeric acid 2-Methylbutyric acid |
