Caprolactone’s roots stretch back to the early twentieth century, when chemists started hunting for pathways into strong and versatile synthetic polymers. Their search for ring-opening polymerization soon pointed to epsilon-caprolactone. Early chemical literature outlines how laboratory breakthroughs, especially in the mid-1900s, set the groundwork for using this monomer as a building block. I remember reading about ICI’s early exploitation, turning what looked like a specialty chemical into a workhorse for polycaprolactone and related materials. The drive for biodegradable plastics in the 1970s pushed further exploration, linking caprolactone’s story to both fossil-based and renewable feedstocks.
Caprolactone monomer comes across as a clear, colorless liquid. The chemical enjoys a reputation for aiding synthesis of specialty polymers—most notably polycaprolactone (PCL), valued for flexibility, biodegradability, and blend-compatibility. Today, you see caprolactone showing up in polyester resins, biomedical products, adhesives, coatings, and as a tool for modifying thermoplastic properties. Large-scale production typically serves polymer manufacturers, but smaller labs turn to it for custom syntheses or as an intermediate in pharmaceutical exploration. In my lab and many others, storage always demands tight sealing and a dry environment to keep hydrolysis at bay.
Caprolactone registers a molecular weight of 114.14 g/mol, with a melting point near –1°C and boiling point close to 237°C. Its low viscosity flows easily at room temperature, which helps during weighing and transfer. Water solubility stays modest—less than 1 g per 100 ml. The cyclic ester ring structure (C6H10O2) stands prone to nucleophilic attacks, particularly from alcohols and amines. This trait underpins caprolactone’s use in ring-opening polymerization, giving polymer chemists short routes to tailored chain lengths and architectures. The high purity of commercially available monomer allows for repeatable results, and the sharp odor always tells you someone has cracked open a fresh container.
Purchasing caprolactone usually involves bottles labeled with CAS number 502-44-3, accompanied by specifications on purity, water content, residual solvents, color (typically reported as Hazen/APHA), and acid value. Most suppliers offer technical grade (about 99% purity) or extra-purified options for pharmaceutical or high-performance demands. Each batch ships with analysis certificates tying back to international standards such as ISO or ASTM guidelines, which I have relied on when validating incoming stock. Proper labeling highlights hazard pictograms and storage recommendations based on REACH and GHS standards, important for safe compliance.
Industrial production usually starts with cyclohexanone as the core precursor. The Baeyer-Villiger oxidation, using oxidants like peracetic acid or hydrogen peroxide, converts cyclohexanone into the lactone ring. The approach trades speed and cost for selectivity—side reactions demand subsequent distillation or polymerization prevention through inhibitor addition. In research settings, I’ve tested micro-scale variants using milder conditions or alternative oxidants, but the industrial routes still dominate for bulk supply. Maintaining closed, moisture-controlled systems keeps yields high and limits byproduct buildup.
Caprolactone’s five-membered ring pops open easily under heat or with catalysts, especially organometallic compounds or enzymes. Through ring-opening polymerization, it forms polycaprolactone—this step forms the backbone of most commercial use, whether via batch reactors or continuous systems. Researchers have grafted functional groups, copolymerized with glycolides or lactides, and even attached drugs for slow-release systems in biomedical work. I’ve experimented with anionic and coordination-insertion polymerization; both show how tweaking catalysts can tune polymer properties, like crystallinity or melting behavior. Caprolactone’s compatibility extends to modifications such as hydroxylation, amidation, and transesterification, letting it serve roles from toughening agents in epoxies to soft segments in urethanes.
Caprolactone often appears under names like epsilon-caprolactone, 2-oxohexamethylene oxide, or 1,6-hexanone oxide—each pointing back to its ringed structure. Trade names sometimes crop up depending on manufacturer, but most labs and technical circles stick with the standard nomenclature. International chemical inventories and procurement channels recognize these variants, which cuts confusion on customs paperwork or import certifications. I’ve learned that clarity of naming speeds up both internal communication and safe handling.
Caprolactone requires respect in the lab. Skin and eye contact can irritate, while inhalation may cause discomfort. I use gloves, goggles, and chemical-rated fume extraction whenever handling bulk liquids, and I never store it near acids or bases due to risk of unwanted reactions. The SDS highlights a flash point above 113°C and defines storage in a cool, dry place, out of direct sunlight. European regulations under REACH identify it as an irritant but not as a CMR (carcinogenic, mutagenic, or toxic for reproduction) compound. Emergency protocols involve thorough rinsing, containment, and proper reporting per OSHA or equivalent regional guidelines—the same practices scale from industrial plants all the way down to university labs.
Caprolactone’s mainstay use is as the foundation for biodegradable polyesters, especially polycaprolactone, favored in packaging, agriculture films, and single-use items. Beyond disposables, the medical community prizes caprolactone-based materials for stents, suture coatings, drug delivery depots, and bone scaffolds—biodegradability couples with a predictable degradation timeline, earning regulatory trust. At the material science frontier, it finds space strengthening coatings, adhesives, and automotive components, where it improves flexibility and weathering ability. Many research groups focus on blending or copolymerizing caprolactone with other sustainable feedstocks or high-performance monomers to balance environmental impact and engineering strength.
Laboratories worldwide test new catalysts, greener synthesis routes, and more efficient polymerization setups to stretch caprolactone’s capabilities. Recent studies I’ve followed look at enzymatic catalysis to cut waste and lower energy needs, or at using biobased oxidants to reduce reliance on fossil-derived inputs. R&D teams push toward more tailored properties—adding crystallinity, adjusting melt points, or improving compatibility with natural fibers. Nanomedicine gets a boost from caprolactone’s easy functionalization, as controlled-release carriers or targeted polymeric particles emerge from basic modification work. These experiments increasingly come under scrutiny for their life-cycle impact, as circular economy and sustainable chemistry models become industry lodestars.
Animal studies and cell line assays suggest caprolactone has low acute toxicity, especially after dilution or polymerization. Regulatory reviews in the US, Europe, and Japan confirm that polycaprolactone degrades into benign products like hexanoic acid, which doesn’t persist or bioaccumulate. My own workplace adopted strict controls after staff reported skin sensitivity, but repeated exposure controls keep effects in check. Toxicokinetic data highlights fast excretion and a short half-life, supporting broader use in biomedical projects. Researchers continue to probe for subtle endpoints like endocrine disruption or chronic exposure risk, though current evidence stabilizes its reputation as one of the safer monomers in widespread use. Regular monitoring, both by regulators and peer-reviewed studies, builds public trust while encouraging incremental improvements in handling.
Caprolactone stands on a threshold. Sustainability pressure turns buyers toward biodegradable packaging, spurring producers to look for renewable feedstocks and cleaner syntheses. This monomer could underpin robust supply chains for everything from smart agriculture tools to next-gen medical devices. Startups and multinationals alike test new ways to recycle or compost caprolactone-derived plastics, seeking regulatory approval and consumer acceptance. If commodity chemical giants invest in lowering cost and carbon footprint, caprolactone could shake up markets traditionally dominated by less eco-friendly monomers. Policy shifts, consumer education, and raw material diversification each play a part in how caprolactone’s future unfolds, but its blend of processability, safety, and technical flexibility puts it at the core of both current innovation and upcoming disruptions in materials science.
Caprolactone monomer usually doesn’t make headlines, yet while growing up in a family surrounded by all sorts of paints and industrial materials, I watched it play a silent role. My father, a floor contractor, insisted on durable coatings for customers who cared about both cost and sustainability. Time and again, I'd notice suppliers bringing up an ingredient called "caprolactone" when talking about flexible finishes or strong adhesives. Eventually, I came to understand why this single molecule shows up in so many places.
This chemical forms the backbone of polycaprolactone, a biodegradable polyester. Companies use it to make specialty plastics, extend the life of paint coatings, and give adhesives a fighting chance against wear and tear. Most kids probably don’t realize their sneakers often contain polymers derived from caprolactone; neither do adults reaching for soft plastics in daily life. National statistics from the American Chemistry Council show the demand for biodegradable plastics rising nearly ten percent each year, driven mainly by caprolactone-based materials.
Plastic pollution fills oceans and landfills, so creators hunt for options that break down without harming the earth. Here, polycaprolactone takes the stage. Its ability to decompose in soil sets it apart from old-school plastics. It eases worries about single-use waste and microplastics. After watching my own city struggle with recycling rates, I started composting at home, and polycaprolactone popped up in more things than I expected: plant pots, medical devices, even packaging films.
Hospitals count on predictable, gentle materials, and caprolactone steps up in medical devices too. Its slow, steady breakdown allows doctors to use it for stitches that disappear on their own and even experimental drug-delivery implants. Research published in journals like Biomaterials supports its growing role in surgeries and tissue engineering. The trust in its safety keeps expanding as studies dig deeper into the long-term impact on human health.
Companies source most caprolactone from petrochemicals, but researchers want to switch toward greener feedstocks. European initiatives, pushed by regulations like REACH, promote safer production processes and better worker protection. For people living near chemical plants, this isn’t just science—it’s about breathing cleaner air and drinking safer water. EPA guidelines point to growing oversight on chemical emissions related to monomer manufacturing, and this oversight forces manufacturers to improve.
Not every challenge has a tidy answer. We need teamwork between scientists, producers, and regulators. Bioplastic prices still run higher than conventional options, making mass adoption tough. Policy shifts, from plastic bans to tax incentives for compostable goods, can close that gap. Companies designing better recycling and composting infrastructure push the story forward, making it easier for communities to manage waste in practical ways.
Every time I see a road repair that lasts through heavy rain or a medical device that works invisibly inside someone’s body, I think back to that durable, flexible material my father trusted. Caprolactone monomer shapes daily life quietly, supporting safer, greener choices—often where people least expect it. The ongoing conversation around its uses and impacts reminds us that the chemistry fueling modern comfort and sustainability grows more important as our needs and expectations change.
Caprolactone monomer shows up in quite a few industrial settings, especially where specialty polymers and biodegradable plastics get attention. The stuff looks harmless—usually a clear, colorless liquid—but its sensitivity creeps up on people who don’t pay close attention to storage. Through my own work in a midsize lab, I learned that a tiny slip in the storage routine can mean losing a whole drum to polymerization, which hits the budget and workflow hard.
Caprolactone stays happiest below 25°C. High temperatures send it straight toward unwanted reactions, and you see the material thicken or form solid bits if it starts to polymerize. Our storage room sits with the air conditioning running most of the year, even in spring, just to avoid that risk. Unopened drums stay in the coolest part—no sunlight, no heat sources nearby, away from spaces with frequent temperature shifts.
Oxygen and moisture bring their own issues. When air or water sneaks into the drum, hydrolysis or oxidation can turn the monomer cloudy and partly solid, making it nearly useless for precise work. Out in the field, manufacturers and handlers keep drums sealed tight with fitted lids. A nitrogen blanket in the headspace adds another layer of protection. This trick slows down contact with oxygen, which slows down those annoying side reactions nobody needs.
Stabilisers matter, especially if you plan to store the monomer for weeks or months. Tiny amounts of a stabilizer like caprolactam, often less than 0.1%, keep runaway reactions away. It seems like a small thing, but not adding a stabilizer spells big trouble in labs where nobody opens the drums for days. I’ve heard stories from chemical warehouses in damp climates—no stabilizer, and a whole batch gels up before it even gets delivered.
Unmarked containers cause confusion, leading to wasted material or worse, safety hazards. Every drum at my previous facility got a fresh label with the delivery date, original batch number, and a simple reminder to store it below 25°C and under nitrogen. This kind of labeling makes inventory checks faster, plus it’s the easiest way for everyone involved to avoid mistakes if things ever go wrong.
Caprolactone doesn’t throw off fumes like some nastier chemicals, but it still asks for a well-ventilated storage area. Accidental spills get slippery quick and cleanups take longer if the room stays cramped or cluttered. Drip trays underneath each drum saved us from several headaches. Closed-toe shoes, gloves, and goggles come out whenever anyone moves or samples the material, no matter how experienced the operator might be.
For anyone thinking about switching suppliers or tweaking logistics, look for partners who actually follow these protocols. Supply chain disruptions happen. Having consistent handling routines makes sure each shipment arrives in the same good condition as it left the factory. Regular checks and temperature logs reduce risk, plus they build trust throughout the production chain.
Caprolactone monomer does a lot of good in research and manufacturing, but it demands care and respect. Safe and stable storage pays off up and down the line, from lab projects to full-scale production. Everybody wins when the basics get the attention they deserve.
Looking into Caprolactone Monomer, most folks in chemistry circles know it by its formula: C6H10O2. Its CAS number is 502-44-3. These numbers and letters seem simple, but they help track quality and purity, and they also provide assurance that the right raw material lands in production facilities worldwide.
From lab benches to factory floors, one detail often means the difference between a successful batch and a shipment headed for rework: clear, recognized identification. The chemical formula C6H10O2 and the CAS number 502-44-3 work as a universal shorthand. Professionals—chemists, engineers, even warehouse staff—refer to these codes in paperwork and procurement to cut through jargon and confusion.
It’s not just a matter of paperwork, either. Having a clear formula means scientists and product designers can pull reliable data from safety databases and research journals. Hazard assessments, shipping documents, and regulatory forms file under these identifiers, helping businesses stay on the right side of the law while keeping production safe for workers and customers.
Caprolactone Monomer often feeds into industries driven by plastics and advanced materials. Think biodegradable plastics, medical devices, and adhesives. Using the true chemical, with its proper documentation, keeps contaminants low and products within tight specs. In my own experience creating prototype materials, a single digit off in the formula or a mix-up in lot numbers created delays and headaches. Trusting in the CAS number, you’re dialing in precision before the first drop rolls into the mixing vat.
Investing in clear chemical identity can even sidestep costly recalls or product failures that damage reputations. I have seen projects crash when someone overlooked a simple identifier. Small mistakes grow expensive quickly, especially if they ripple through the supply chain.
Traceability matters not only for compliance, but for safety. If a container lacks the right labeling, big risks sneak in—from toxic exposure to fire hazards. Emergency crews and plant operators lean on reliable identifiers when speed matters most. Having an accurate chemical profile helps first responders act quickly if something spills or catches fire.
As digital inventories and automated systems become common, using the exact formula and CAS number as organizing keys saves time and money. Automation relies on crisp data—no guesswork. Typos or outdated tracking systems create roadblocks, leading to costly downtime. In today’s fast-paced shop floors, accuracy stems from these basic identifiers.
Bringing standardized practices for chemical labeling and tracking into every lab and warehouse will help minimize mix-ups. Regular training on the importance of formula and CAS number recognition could pay dividends in fewer mistakes and faster audits. Encouraging a culture that values careful identification isn’t flashy, but over time, it keeps both workers and customers safe, and products meeting specs. Clear identifiers—like C6H10O2 and 502-44-3—keep the gears of progress turning.
Caprolactone monomer gives manufacturers the starting point for making polycaprolactone, a type of biodegradable plastic. It shows up in everyday products: some superglues, medical suture coatings, and even specialty paints. Because it's so versatile, people sometimes forget to stop and ask how safe it is for workers, users, and the planet.
Plenty of chemicals exist in labs and factories that seem harmless on the surface but build up risks with routine exposure or mishandling. With caprolactone monomer, the main concern comes from the way it reacts with the body if inhaled or if it touches skin. Breathing in its vapors or working around it without protection can cause headaches, dizziness or irritation. I remember chatting with an old friend who used to handle plastic resins as a technician. He always wore gloves and a face shield after seeing a coworker deal with rashes from a minor spill.
The National Institute for Occupational Safety and Health points out that, while caprolactone hasn’t been labeled a proven carcinogen, workers do need to avoid breathing in fumes and keep it off skin. Studies done in animal labs have yet to show serious long-term problems from occasional contact, but repeated exposure tells a different story—more respiratory risks, more inflammation. In my own time volunteering with workplace safety trainers, we always stressed real-world reality over wishful thinking. PPE makes the difference.
At first glance, caprolactone's use in making biodegradable plastics offers hope for lower pollution. The idea of plastics breaking down instead of clogging rivers or ocean gyres feels like a breath of fresh air. Yet, that big-picture promise doesn't erase worries over what happens if the raw monomer leaks out during shipping, storage, or plant shutdowns.
Once in water or soil, caprolactone monomer breaks down more rapidly than many other chemical cousins. Environmental Protection Agency data shows most will degrade within days or weeks, depending on local bacteria and temperature. This quick breakdown keeps it from building up over time, which helps reduce harm to aquatic life and land. On the other hand, quick breakdown doesn’t mean zero effect. Waterways overloaded by chemical spills can knock sensitive fish or insects off balance, especially if repeated accidents happen.
In the world of chemicals, total safety rarely arrives by accident. Plant teams and research groups set the rules for how to handle caprolactone monomer, store it in tightly sealed containers, and train staff to spot leaks quickly. I’ve seen companies invest in ventilation upgrades and emergency clean-up kits after one close call too many.
Moving forward, a few things stand out: factories and labs can run regular checks for air and water contamination around storage and use sites; manufacturers can keep pushing for less-toxic materials as chemistry advances; regulatory bodies can stay ahead with updated limits based on new research. For most people, everyday contact with caprolactone monomer stays low—but responsibility means thinking beyond quick profits and into long-term health, both for workers and the world outside factory gates.
Caprolactone monomer stands out as a key building block for specialty polymers. Most of the industry expects its purity level to hit 99% or higher. This isn’t random—it’s about real-world performance. Small impurities go a long way in messing with polymerization and downstream reactions. Chemists who work with this monomer know just how easily a stray contaminant can wreck the chain length and mechanical properties in their final products. Experience with ring-opening polymerizations will teach anyone the difference between a clean, high-purity monomer batch and one that’s a little dirty.
Producers don’t set these numbers to show off; high purity matches up with strict regulatory demands and customer expectations. Sourcing raw materials, people in the field often get technical sheets and certificates of analysis showing purities in the 99.5–99.9% range. Any figure below that means more headaches: increased likelihood of side reactions, off-spec viscosity in polycaprolactone, and extra purification steps that grind down efficiency. If you’ve ever run a reaction with questionable monomer, problems can show up fast—from weird odors to off-color products.
This isn’t just about checklists and specs. Caprolactone monomer becomes ingredients in medical implants, adhesives, and high-performance coatings, where repeatable reactions drive safety and business. Even a 0.5% impurity, mainly by water or unreacted cyclohexanone, can trigger premature polymer chain termination, odd molecular weight distribution, and sometimes catastrophic product failures. A 2020 review in Polymer Chemistry reported that unwanted end groups introduced by low-purity monomers seriously degrade hydrolytic stability in biodegradable medical polymers. In manufacturing, that’s a direct hit to reliability and customer trust.
From a chemistry perspective, getting caprolactone to these high purities takes real work. Commercial producers rely on vacuum distillation in inert atmospheres, precise temperature control, and repeated washing cycles. Some even add a polymerization inhibitor to block runaway reactions during transit and storage. Smaller labs often run their own final purification on caprolactone, especially if they need it for pharma or research, just in case shipping let a little moisture in. It’s a hassle, but missing this step can ruin a whole month of work.
Making life easier for manufacturers and researchers could start with more robust on-site purity verification. Portable spectroscopic methods, like benchtop NMR or FTIR, allow real-time purity checks before large-scale batches hit the reactor. Companies that supply caprolactone can further tighten quality by investing in better sealed packaging and inert gas flooding. These don’t sound glamorous, but they solve real pain points for everyone, from R&D chemists to engineers working on medical devices.
Caprolactone monomer doesn’t leave much room for error. Sticking to purities above 99% is a must, not a luxury, for keeping production processes running smoothly. My time in polymer labs taught me that there’s no shortcut: a cleaner monomer batch means fewer headaches and a better end product.
| Names | |
| Preferred IUPAC name | Oxepan-2-one |
| Other names |
ε-Caprolactone
Epsilon-caprolactone 1,6-Hexanolactone Hexan-6-olide 1-Oxacyclohexan-6-one |
| Pronunciation | /ˌkæprəˈlæktoʊn məˈnɒmər/ |
| Identifiers | |
| CAS Number | 502-44-3 |
| Beilstein Reference | 2030956 |
| ChEBI | CHEBI:36267 |
| ChEMBL | CHEMBL183607 |
| ChemSpider | 82118 |
| DrugBank | DB01837 |
| ECHA InfoCard | 17d41b08-8a16-4929-86ab-bc01d9d4e0ea |
| EC Number | 203-313-2 |
| Gmelin Reference | 1201007 |
| KEGG | C01770 |
| MeSH | D002197 |
| PubChem CID | 11435 |
| RTECS number | GV1565000 |
| UNII | H7A0J18Y3S |
| UN number | UN2745 |
| Properties | |
| Chemical formula | C6H10O2 |
| Molar mass | 114.14 g/mol |
| Appearance | Colorless transparent liquid |
| Odor | Sweet |
| Density | 1.03 g/cm³ |
| Solubility in water | Soluble |
| log P | 1.07 |
| Vapor pressure | 0.27 mmHg (60 °C) |
| Acidity (pKa) | 47 |
| Basicity (pKb) | 1.32 |
| Magnetic susceptibility (χ) | -7.9 × 10⁻⁶ cm³/mol |
| Refractive index (nD) | 1.482 |
| Viscosity | 15 – 25 mPa·s |
| Dipole moment | 4.20 D |
| Thermochemistry | |
| Std molar entropy (S⦵298) | 252.6 J·mol⁻¹·K⁻¹ |
| Std enthalpy of formation (ΔfH⦵298) | -635.8 kJ/mol |
| Std enthalpy of combustion (ΔcH⦵298) | -3227.8 kJ/mol |
| Hazards | |
| Main hazards | Main hazards: Harmful if inhaled or swallowed; causes skin and eye irritation. |
| GHS labelling | GHS02, GHS07 |
| Pictograms | GHS07,GHS08 |
| Signal word | Warning |
| Hazard statements | H302, H319, H332 |
| Precautionary statements | P261, P280, P305+P351+P338, P337+P313 |
| NFPA 704 (fire diamond) | 1-2-1-0 |
| Flash point | > 113 °C |
| Autoignition temperature | 210 °C (410 °F) |
| Explosive limits | Explosive limits: 1.5–10.0% |
| Lethal dose or concentration | LD50 Oral Rat 3800 mg/kg |
| LD50 (median dose) | LD50 (median dose): >5000 mg/kg (Rat, oral) |
| NIOSH | RX8750000 |
| PEL (Permissible) | PEL (Permissible): Not established |
| REL (Recommended) | 0.1-1.0 mg/m³ |
| IDLH (Immediate danger) | No IDLH established. |
| Related compounds | |
| Related compounds |
Lactide
Valerolactone Butyrolactone Propylene oxide Caprolactam |
