Phosphate ester flame retardants came to the fore during a period marked by industrial accidents and a rising demand for safer materials. Picture the chemical industry in the 1960s — full of ambition, yet not without its mishaps. At that time, fire hazards were daily threats in factories, textiles, plastics, and construction. Early phosphorus-based fire suppressors started out harsh, hard to handle, sometimes just as risky as the fires they were meant to fight. Over the years, persistent reports of workplace injuries, alongside growing public scrutiny, pushed chemists and engineers to fine-tune their approach. Researchers experimented with organic and inorganic phosphates, trialed blend after blend, and compared results with halogenated solutions. The result was a shift toward less toxic, more effective compounds. Phosphate esters became a staple thanks to better cost, performance, and adaptability. Innovations driven by necessity can shape entire sectors, and the ongoing development of these chemicals is evidence of that.
Phosphate ester flame retardants aren’t a single substance; they’re a whole family. Triaryl phosphates, alkyl aryl phosphates, and trialkyl phosphates each step up for specific uses. Out in the wild, these materials drop into plastics, synthetic fibers, rubber, coatings, adhesives, and hydraulic fluids. Their main job is stopping fire from spreading. By breaking burning chains at the molecular level, they choke flames before disaster strikes. There’s no “one size fits all” here — manufacturers must pick from a menu of options that balance performance, safety, price, and environmental impact. The products show up as clear or lightly colored liquids and sometimes in viscous forms. Brands market specific blends under names like “Reofos,” “Disflamoll,” “Kronitex,” “Fyrol,” and “Durad,” but at their core, these items play a similar—and critical—role: buying time when things catch fire.
Phosphate esters display a range of properties shaped by their chemistry. They resist heat, keep stable under pressure, and dissolve in organic solvents while remaining stubborn against water. With their relatively high flash points, many of these substances stay inert under normal conditions, but shift gears when temperatures soar. Viscosity can vary based on substitutions within the molecular backbone, affecting ease of processing and blending. They show up with mild to no odor, usually transparent with the slight yellow tinge that hints at their complex chemistry. Refractive indices are close to those of similar organophosphate compounds. Compatibility with plastics like PVC and polyurethane is good, thanks to their ability to blend without clouding or separation. Hydrolytic stability isn’t always perfect; moisture and heat may eventually degrade some types, releasing alcohols and acids, creating both design challenges and safety concerns.
Industry standards for phosphate esters set strict thresholds. Technical data sheets publish acid value, phosphorus content (usually 8–12%), density (often 1.15–1.26 g/cm³), and flash point (150°C or above for most grades). Labels carry the UN hazard number, signal words, hazard statements, and pictograms. Global harmonized labeling ensures workers recognize key risks at a glance — skin irritation, respiratory danger, environmental persistence. For certain blends, suppliers note maximum allowable concentrations in air, storage temperature recommendations (5°C to 40°C), and shelf life. Quality control labs regularly run GC-MS, IR spectroscopy, and titration to confirm compliance before shipping. Regulatory pressure demands details on impurities, stabilizer content, and residual solvents. The amount of paperwork reflects a real truth: small mistakes can have real, lasting consequences.
Creating phosphate ester flame retardants takes deliberate chemistry. Commercial plants often use the esterification of phosphorus oxychloride or phosphoric acid with alcohols such as phenol, cresol, isopropanol, or octanol. Reactors run with continuous monitoring of pH and temperature. Sometimes, steps require base catalysis and water removal to drive the reaction forward. After reaction, mixtures are neutralized, washed, filtered, and vacuum-distilled to purify the product. Any unreacted alcohols and by-products need proper treatment, both for yield and worker safety. Production cycles don’t forgive mistakes — fouling, exotherms, and off-spec batches chew through profits and can impact surrounding communities. Environmental engineers watch for stable containment, because accidental releases can build up downstream. Manufacturers understand that safety and efficiency go together, so upgrades frequently target both.
The chemistry of phosphate esters doesn’t stop at manufacture. Formulators tweak their properties with co-additives, branching, or functional group substitutions. Reactivity can involve hydrolysis, oxidation, or even photodegradation, depending on use. Modifying aryl substituents, for instance, can manage volatility, compatibility, or toxicity. Blending with synergists—like antimony trioxide or melamine—boosts fire resistance. Some chemical modifications focus on incorporating extra phosphorus atoms to improve charring, which physically blocks flame spread. Not every change pans out; too much tweaking may affect thermal stability or break down into hazardous by-products. Research on greener functionalizations keeps evolving. Chemists know that trade-offs between performance and impact show up on the bottom line as well as in regulatory filings.
This product family gets called by many names. Triphenyl phosphate, tricresyl phosphate, and isopropylphenyl phosphate serve as generic identifiers. Commercial brands label their blends “Reofos 50,” “Durad 125,” “Disflamoll TOF,” “Fyrolflex,” and “Kronitex TCP,” each carrying slight differences in alkyl or aryl group composition. On safety reports, synonyms turn up: TPP, TCP, TCEP, TCPP, and their longer chemical names. Confusing jargon sometimes masks unsafe practices, especially across language barriers or in smaller markets. Anyone working with these fluids learns to study technical bulletins and cross-check international chemical identifiers. Mistaking one variant for another means risk for operators and for consumers alike.
Handling phosphate ester flame retardants isn’t like dealing with water or vegetable oil. Operators put on gloves, goggles, and chemical-resistant clothing. Material Safety Data Sheets spell out each step for spills, exposure, and disposal. Many forms post moderate mammalian toxicity, requiring good ventilation and limits on airborne concentrations. Chronic exposure research reveals organ toxicity potential, particularly for some chlorinated forms. Industrial hygiene staff tracks use patterns with regular air monitoring and biological sampling. Containment and spill response training cut down on workplace accidents. Manufacturers design storage tanks with bunding, temperature controls, and vapor management. Once, I spent a week on-site at a resin plant, where a missed valve on a storage drum nearly cleared the building. No one got hurt, but the memory lingers. Mistakes travel fast down the supply chain, affecting everyone from production to shipping to landfill disposal.
You’ll find phosphate esters wherever fire safety matters. PVC wiring insulation uses these to prevent electrical fires, one of the leading causes of urban structure collapse. Synthetic fibers in public transport, office furniture, and airplanes depend on phosphate esters for mandatory flammability benchmarks. Hydraulic fluids in mining and heavy industry benefit from their combination of thermal stability and fire suppression; a single system failure underground can escalate fast. Adhesives, varnishes, and coatings for construction must prove their resilience during fire testing before approval. One cannot walk into a hospital, a concert hall, or a school without meeting the invisible protection these chemicals offer, yet most people never notice. These applications highlight the importance of continued investment into both the chemistry and the engineering of flame retardant systems.
Universities and corporations outlay millions each year on fire safety chemistry. Projects focus on pushing up phosphorus content, cutting toxicity, and reducing persistence in the environment. Academic labs work with polymers, trying to “lock” the flame retardant inside the material, slashing leaching and dusting, which improves both safety and performance. Better analytical techniques—chromatography, mass spectrometry, next-gen computational modeling—help researchers screen dozens of new candidates for each possible application. Testing doesn’t happen in a vacuum; new laws in Europe and North America mean buzzwords like “non-halogen,” “bio-based,” and “low-leaching” show up in patent filings. Teams study real fire events, then use that knowledge to feed back into the next generation of chemicals. Failures teach hard lessons, and every step forward changes the playbook for product safety and regulatory approval.
Public health experts keep a close eye on phosphate esters’ effects. While many forms are considered relatively low in toxicity, exceptions like tris(2-chloroethyl) phosphate (TCEP) and tris(1,3-dichloro-2-propyl) phosphate (TDCPP) have turned up in human tissues and environmental samples. Researchers link long-term exposure to possible issues with neurodevelopment, hormone disruption, and cancer. Observational studies show these substances accumulate in household dust, raising concerns for infants and toddlers. Older products sometimes don’t meet modern safety benchmarks, creating real dilemmas for retrofitting or recycling. Regulatory agencies—ECHA, EPA, NIOSH—track these chemicals and update occupational and consumer guidance with each new study. I’ve met environmental engineers who spend whole careers evaluating new safer alternatives; their patience keeps communities safe, but they operate against a backdrop where public trust in chemical safety runs thin.
What happens next will depend on balancing performance with health and environmental trade-offs. Market forces push for greener solutions, but reliable fire protection stays non-negotiable. Biobased chemicals, enzyme-catalyzed reactions, and fully recyclable materials promise a different landscape in the next ten years. Regulatory reform can drive change or slow development, depending on whether agencies see real data or just good marketing. New construction methods and global supply chains only add complexity—as buildings and electronics change, flame retardants must evolve alongside them. Investment in research, international dialogue, and public transparency will keep this field moving forward. The story of phosphate ester flame retardants isn’t finished. Fire isn’t going away, and neither is the demand for safer, smarter answers.
Phosphate ester flame retardants sound technical, but picture them as chemical shields that slow down fires. You’ll find these compounds blended into products made from plastic, foam, or textiles. Think about electrical cables, car interiors, or the seat cushions in a movie theater—many of them get an extra layer of fire protection thanks to this technology.
To understand their role, let’s look at what happens during a fire. When heat builds up, certain materials reach their ignition point and begin to burn, spreading flames and releasing smoke. Phosphate ester flame retardants step in by forming a barrier when exposed to high temperatures. The chemistry behind this involves phosphate groups triggering a kind of “chemical shield” that keeps the surface cool and delays the spread of fire.
This barrier has two main jobs. First, it helps slow the release of combustible gases—the fuel that feeds the flames. Second, it encourages the material to form a charred layer rather than turning into ash and smoke. This charred surface acts almost like a fire blanket: it insulates the rest of the material, buying precious time for people to get out safely.
Flame retardants aren’t restricted to industrial items. They show up in everyday life, tucked within those couch cushions or hidden inside the walls of modern airplanes. Flexible foam in furniture proved particularly vulnerable when cigarette fires were common, and phosphate esters helped cut down on house fires that got out of control in seconds. The chemistry works across different products, which explains why their use spread quickly as manufacturing ramped up after the twentieth century.
With new gadgets and construction materials showing up year after year, the issue of fire safety stays in the spotlight. Phosphate ester flame retardants give engineers a tool that doesn’t just shove the problem elsewhere. Instead, they address it at the source—right where fires begin, at the surface of materials.
Life gets complicated when safety measures might create new problems. Some phosphate esters leach out of products, collecting in dust or the environment. Studies link certain types to health concerns, including hormone disruption and risks to aquatic life. Once awareness grew, regulators began watching chemical additives more closely—Europe even restricted some variants to keep people and the environment safer.
This isn’t the end of the story for flame retardants. Manufacturers continue searching for products that work as well as, or better than, the old recipes without the unwanted side effects. Newer formulations promise less toxicity or persistence, and research backs a shift toward chemicals that break down safely.
Rather than relying on chemicals alone, the conversation now includes smarter design and creative engineering. Use of smoke detectors, safer wiring, better building codes, and non-flammable materials creates a layered approach to fire safety. Companies already experiment with safer, bio-based flame retardants made from natural ingredients like starches, in hopes they can work just as well.
As someone who pays attention to both safety and health, I see value in asking tough questions about what we breathe, touch, or sit on every day. Flame retardants need to work as intended, but transparent research and closer scrutiny make sure that solutions don’t carry long-term costs. Investing in both smarter chemistry and smarter design looks like the right path for safer homes and public spaces.
Phosphate ester flame retardants help keep everyday products from going up in flames at the wrong moment. In my own house, I’ve seen these chemicals doing real work behind the scenes. Take that phone charging next to your bed, or the old-school TV humming in the corner—plastic cases and circuit boards often have phosphate esters mixed right in. The goal is clear: limit fire risks if something overheats or shorts out. Without some kind of flame protection in our gadgets, we’d see more accidents and lose a lot of trust in the brands behind them.
Couches, mattress foams, and carpets also gain a helping hand. Years back, I remember an apartment fire that started from a candle. The entire room didn’t turn to ash, partly because modern upholstery incorporates flame retardants. It’s not always about stopping flames dead in their tracks, but giving folks enough time to respond. As homes fill up with synthetic materials, the demand for safer, more reliable flame stoppers like phosphate esters just keeps climbing.
Anyone who’s ever been in a server room knows things get hot, quick. Wires tangle under desks and inside walls all around us, hidden but vital. Phosphate esters keep plastic insulation on cables and wires from catching fire in office buildings, airplanes, and subway trains. Think about a hospital: if the wiring failed by catching fire, it’d take down critical machines and put lives on the line.
These flame retardants also make their way into roofing, flooring, and wall panels. My brother-in-law works construction, and he’s told stories about fire regulations getting tighter every year. Products with phosphate esters help meet those codes, so new buildings stand a better chance when disaster strikes. It’s not a silver bullet for fireproofing, but it’s a leap beyond what we had a generation ago.
Not every application involves consumer goods. In steel mills and power plants, presses and turbines rely on hydraulic fluids that work under heat and pressure. Phosphate ester-based fluids have a lower risk of catching fire compared to traditional mineral oils. I’ve toured an industrial site where sparks fly regularly and seen how important these fluids are. If a hose bursts in a high-heat zone, you want every ounce of protection you can get.
Fire safety isn’t as simple as tossing in more chemicals. Over the years, questions have come up about toxicity and what happens when these substances escape into waterways or get into the air as dust. We want fire-resistant homes and electronics, but not at the cost of our health. Some research suggests a link between certain flame retardants and developmental problems in children. The route forward will take more careful balance—a mix of using the safest phosphate variants available and supporting greener chemistry.
Better rules and smarter chemical design give a fighting chance at safer homes and workplaces without making folks choose between health and protection. People’s lives depend on clear standards and up-to-date science, especially as electronics, construction, and industry keep changing the mix. I like to see companies and regulators turning to alternatives and investing in better testing, but it’s clear that for now, phosphate ester flame retardants still hold an important role in keeping many parts of daily life less flammable.
Everyday objects you can find in homes, cars, and offices—think couches, foam mattresses, electronics cases, laminates—often contain flame retardants. Among the most common are phosphate ester flame retardants. Big companies add them during manufacturing to slow down fire if something catches a spark. Fewer house fires used to mean one less thing to lose sleep over, so flame retardants became pretty routine after the 1970s. For many years, regulations nudged them into furniture and electronics.
Phosphate esters do their job—things don’t burn as quickly. Still, a chemical that’s good at stopping fire isn’t the same as a chemical that belongs close to your skin, lungs, or food. Once these molecules land in foam or plastics, small particles and vapors drift into the air and dust. Without us giving it much thought, our hands pick them up, we breathe them in, they collect in our homes. Wipes and dust samples have found phosphate esters even in places that seem clean. Some researchers went hunting for these chemicals and found them in urine and blood, especially in kids, since they crawl and put things in their mouths.
Many manufacturers vouch for their safety, pointing at dozens of animal studies and short-term tests. On paper, these studies look reassuring. But flip through the public health journals and there’s another side. A few phosphate esters, like TCEP and TDCIPP, have raised more than eyebrows. Evidence links them to hormone disruption in animals, slower child brain development, and possible links to cancer. That’s enough concern for several countries in Europe to ban or limit specific types in toys and furniture.
TDCIPP caused tumors in lab rodents and acts as a suspected carcinogen in California’s official Prop 65 listing. Some work shows these substances may act on thyroid hormones, which kids’ developing brains depend on. Still, much of the research focuses on high doses in animals, not the real-world levels we encounter in homes. Nobody can guarantee these mimic-all exposures won’t build toward unexpected health issues years later.
Companies often substitute chemicals facing public scrutiny with “new” versions, sometimes swapping brominated flame retardants for phosphate esters. But history keeps repeating: we replace one headache with another and find out afterward it carries its own risks. Many times, the replacements haven't been much different in their impact, just better at slipping through old regulations.
Some countries have started to demand more transparent safety data before a new flame retardant enters the supply chain for consumer products. More robust “pre-market” testing helps. I’ve seen campaigns for clearer warning labels and for setting up registries that help track health trends in workers and communities. Doctors and toxicologists want the power to call for withdrawal of certain chemicals fast if evidence mounts against them.
People deserve furniture and electronics that don’t pose long-term health puzzles. It’s not too much to ask for big manufacturers to explore safer design—less flammable materials and clever product engineering can do more than just filtering for new chemicals. Better ventilation at home helps lower exposure. Regular hand washing, especially for young kids, does make a difference since dust is a primary route for these chemicals.
Regulators and watchdog groups need to step up screening on new flame retardant chemicals. More focused studies looking at what real-world levels do to people over years are needed. Funding for independent science, plus community input, can keep industry in check. No shortcut replaces long-term safety, and consumers shouldn’t play guessing games about what’s in products used every day.
Every parent double-checks the labels for kids’ pajamas or electronics at home, especially after hearing about another house fire on the news. No one wants flammable sofa foam or wires that catch fire in an instant. Over the years, I’ve seen countless products with promises about “flame resistance.” Phosphate ester flame retardants get called out as a go-to for safety, but people often wonder if this type really holds an edge against the rest.
Phosphate esters build their reputation by forming a protective char when exposed to high heat. That barrier slows down flames, gives off less smoke, and can keep a fire from spreading. This matters in places like car interiors, trains, and building insulation—where seconds count. The chemical backbone of phosphate esters carries both carbon and phosphorous, and that mix gives them a flexibility other retardant classes can’t always match. Polyurethanes, often used in furniture foam, respond particularly well to these retardants, and the result often means the difference between a small scorch and a disaster.
Halogenated flame retardants pop up in plenty of older electronics, and they’re strong performers at stopping fire, no argument there. The trouble arrives with their environmental baggage. Living near a landfill as a kid, I saw neighbors burning waste, including trashed electronics. The air would get thick, and the health warnings were serious. Studies now link some halogenated chemicals to issues like hormone disruption and slow breakdown in soil. Compared to that, phosphate esters look a lot less threatening. They break down more easily outside, and they’re less likely to build up in our bodies.
Of course, these chemicals aren’t risk-free. Phosphate esters can leach out over time—rain, sweat, and cleaning products all speed up the process. That stuff ends up not just in the ground, but also in rivers and sometimes in drinking water. Low levels already show up in urban streams. Some versions of these chemicals even tie in with nervous system troubles or hormone tweaks, though far less dramatically than many halogenated flame retardants. My daughter’s school swapped out treated mats last year for environmental reasons, and even the teacher group worried about potential health fallout from the next-best alternative.
The real draw? Phosphate esters balance fire protection with lower toxicity and easier clean-up in the environment. Furniture makers and electronics brands keep reaching for them because the alternatives pose even trickier challenges. Mineral flame retardants—like alumina or magnesium compounds—skip the toxic side effects, but often need to be used in huge amounts. That can turn a soft seat into a rock; in building wire, it means extra weight or thickness. Silicone-based flame retardants show new promise, but cost more and face tougher supply chains.
Improvement comes from more than one place. Clearer product labeling—spelling out not just what chemical is used, but potential health and environmental impacts—would put power in the hands of families and builders. Investing money and talent in green chemistry can nudge the industry away from old habits, giving rise to materials that resist fire but don’t linger in soil and water. Most of the breakthroughs happen in the shadows at first, inside labs and test rigs, but they only matter if adopted across the supply chain. Encouraging big companies to put health before the lowest price can push even phosphate esters into a better class of fire safety solutions.
Fire safety keeps homes and offices safer, but the chemicals that make it happen come with a complicated price tag. Phosphate ester flame retardants, used in everything from electronics casings to furnishings, have helped reduce fire-related injuries. Still, what happens to these chemicals after our stuff lands in a landfill paints a different picture.
Phosphate esters don't just stay locked away in furniture foam or circuit boards. Over time and with weather changes, they can leak out. Rainwater runs through a landfill, and then those compounds start showing up in water sources. Research in the last decade has flagged these esters in rivers and drinking water near waste sites. Studies out of Europe and the United States back this up, showing phosphate esters showing up in sediment and aquatic life. Fish exposed to these pollutants can end up with liver damage, reproductive problems, and altered behavior.
These pollutants don't just stick with the wildlife. Kids and adults living near sites with lots of dumped plastics may notice an invisible threat. Phosphate esters have earned a spot in some studies asking if there's a link to hormone disruption, especially as kids get exposed while playing indoors, where dust can collect these flame retardants. Other researchers are tracking whether long-term exposure could raise the risk of learning problems or contribute to metabolic issues.
People rely on safety standards to keep dangerous levels of flame retardants out of new products. The European Union keeps a close watch with strict chemical registration rules under REACH. Over in the United States, the EPA limits some forms of phosphate esters, but not all get the same level of oversight. Furniture makers will often switch one compound for another to meet regulations, only to realize down the line that the replacement brings along new concerns.
A single country can only do so much on its own. Pollution doesn't recognize borders, especially with so many goods moving worldwide. Gaps grow when one region outlaws a chemical but its neighbor has no rules, creating a patchwork of safety that leaves loopholes.
Nobody wants to go back to the days when a house fire could spread in minutes. Yet, chasing fire safety doesn’t have to mean ignoring environmental damage. One promising path involves rethinking product design so materials themselves resist ignition, without relying on added chemicals. Companies testing this angle use mineral- or bio-based alternatives, or even tweak the plastic itself.
In my own neighborhood, we joined a local group pushing for right-to-know laws. That step forced manufacturers selling goods here to report what chemicals they used, so buyers could choose safer options. It’s not a perfect solution, but it gives families a way to steer clear of the worst offenders.
People will keep looking for safer fire safety. Researchers keep testing new substitutes, policymakers wrestle with tougher standards, and neighbors share information so we don’t trade one danger for another. Until then, paying attention to what goes into the things we buy and asking questions stays a powerful tool for change.
| Names | |
| Preferred IUPAC name | Organophosphate flame retardant |
| Other names |
Triaryl phosphate Phosphoric acid ester Aryl phosphate Trialkyl phosphate |
| Pronunciation | /ˈfɒs.feɪt ˈɛs.tər fleɪm rɪˈtɑː.dənt/ |
| Identifiers | |
| CAS Number | 68937-41-7 |
| Beilstein Reference | 626137 |
| ChEBI | CHEBI:83132 |
| ChEMBL | CHEMBL2103831 |
| ChemSpider | 26509 |
| DrugBank | DB11360 |
| ECHA InfoCard | 03fa6eaf-e0b2-452c-9454-174c1aecf6d3 |
| EC Number | 80913-60-4 |
| Gmelin Reference | 1572999 |
| KEGG | C18225 |
| MeSH | D010682 |
| PubChem CID | 6679 |
| RTECS number | TG2975000 |
| UNII | 9CY54HM4FS |
| UN number | UN2584 |
| Properties | |
| Chemical formula | C9H21O4P |
| Molar mass | Varies depending on specific compound |
| Appearance | Colorless or light yellow transparent liquid |
| Odor | Odorless |
| Density | 1.26 g/cm³ |
| Solubility in water | insoluble |
| log P | 4.68 |
| Vapor pressure | Negligible |
| Acidity (pKa) | 1.2 – 2.2 |
| Basicity (pKb) | 11.9 |
| Magnetic susceptibility (χ) | Diamagnetic |
| Refractive index (nD) | 1.5180 |
| Viscosity | 14-24 mm²/s (40°C) |
| Dipole moment | 3.89 D |
| Thermochemistry | |
| Std enthalpy of formation (ΔfH⦵298) | -1387.2 kJ/mol |
| Std enthalpy of combustion (ΔcH⦵298) | -6300 kJ/mol |
| Pharmacology | |
| ATC code | D08AX02 |
| Hazards | |
| Main hazards | May cause irritation to skin, eyes, and respiratory tract; toxic if ingested or inhaled; potential environmental hazard. |
| GHS labelling | GHS02, GHS07, GHS08 |
| Pictograms | GHS05,GHS06,GHS08,GHS09 |
| Signal word | Warning |
| Hazard statements | H315: Causes skin irritation. H319: Causes serious eye irritation. H332: Harmful if inhaled. |
| Precautionary statements | P210, P260, P273, P280, P305+P351+P338, P308+P313 |
| NFPA 704 (fire diamond) | Health: 2, Flammability: 1, Instability: 0, Special: - |
| Flash point | > 250°C |
| Autoignition temperature | 450°C |
| Lethal dose or concentration | LD₅₀ (oral, rat): > 5,000 mg/kg |
| LD50 (median dose) | > 1,880 mg/kg (rat, oral) |
| NIOSH | FMAM |
| PEL (Permissible) | PEL (Permissible Exposure Limit) for Phosphate Ester Flame Retardant: 3 mg/m³ (as total dust, 8-hour TWA) |
| REL (Recommended) | 0.1 mg/m3 |
| IDLH (Immediate danger) | IDLH: 1200 mg/m³ |
| Related compounds | |
| Related compounds |
Triphenyl phosphate Tris(2-chloroethyl) phosphate Tricresyl phosphate Tris(1,3-dichloro-2-propyl) phosphate Tetrakis(hydroxymethyl) phosphonium chloride Dimethyl methylphosphonate |
