Formaldehyde
Supplied as an aqueous solution, because the pure compound is a gas that will not sit still. The reactive carbonyl behind urea, phenolic and melamine resins.
Molecular Structure
What is Formaldehyde?
Formaldehyde is the simplest aldehyde — a single carbon double-bonded to oxygen and carrying two hydrogens. The pure compound is a gas boiling at −19 °C, and it will not stay as a monomer: it polymerises readily to paraformaldehyde on standing.
It is therefore always traded as an aqueous solution, normally 37 to 50 wt%. In water almost none of it is actually free formaldehyde. It hydrates to methylene glycol and then builds up short poly(oxymethylene) glycol chains, and it is the equilibrium between those species that the product's stability depends on.
Cool the solution and those chains grow long enough to drop out as solid paraformaldehyde. That is why storage temperature is a specification, not a suggestion: low-methanol 37% grades are held around 35 °C, and 50% grades warmer still. Methanol, added at anywhere from 0.5 to 15%, suppresses the polymerisation and allows cooler storage — at the cost of a lower flash point.
Chelora supplies formaldehyde at 37%, 42% and 50% concentration in low-methanol and stabilised grades. Because methanol content changes both the storage temperature and the transport classification, we confirm the grade, methanol level and required storage regime before shipment.
Quick Reference
Key Physical & Chemical Properties
Structure & Solution Chemistry
Formaldehyde's carbonyl is unusually exposed — no alkyl groups shielding it, no competing resonance — which makes it one of the most electrophilic carbonyls in industrial use. That is what drives its resin chemistry, and also what makes it a hazard to living tissue.
Structure — planar sp² carbon with C=O double bond
Structural Identity
- IUPAC NameMethanal
- Molecular FormulaCH₂O
- Molecular Weight30.03 g/mol
- Hybridisationsp² carbon
- GeometryTrigonal planar, ≈120° angles
- C=O bond length1.21 Å
- Dipole moment2.33 D
- In waterMethylene glycol + oligomers
- On coolingPrecipitates as paraformaldehyde
- CAS Number50-00-0
- InChI KeyWSFSSNUMVMOOMR-UHFFFAOYSA-N
Product Specifications
Chelora supplies Formaldehyde in standard and custom grades. Contact us for specification sheets tailored to your process.
| Chemical name | Formaldehyde solution (formalin) |
|---|---|
| CAS Number | 50-00-0 |
| Molecular formula | CH₂O |
| Molecular weight | 30.03 g/mol |
| Formaldehyde content | 37.0 / 42.0 / 50.0 wt% ± 0.5 |
| Methanol (low-methanol grade) | ≤ 1.0 wt% |
| Methanol (stabilised grade) | 1.0 – 15.0 wt% |
| Acidity as formic acid (max) | ≤ 0.02 wt% |
| Iron (max) | ≤ 1.0 ppm wt |
| Appearance | Clear, free of suspended matter |
| Colour | ≤ 10 Pt-Co (Hazen) |
| pH at 20 °C | 2.8 – 4.0 |
| Density at 20 °C | 1.08 – 1.13 g/cm³ |
| Storage temperature (37%, low-MeOH) | 32 – 40 °C |
| Storage temperature (50%) | 45 – 60 °C |
| Flash point | 50 – 85 °C, depending on methanol |
| UN Number (non-flammable soln) | UN 2209, Class 8, PG III |
| UN Number (flammable soln) | UN 1198, Class 3 + sub 8, PG III |
Downstream Applications & Derivatives
Key derivative chains and industrial uses of Formaldehyde.
Urea-Formaldehyde Resins
Condensation with urea gives UF resin — the dominant adhesive for particleboard, MDF and interior plywood. Emission class (E1, E0, CARB/TSCA Title VI) is set by the resin formulation.
Phenolic & Melamine Resins
With phenol it gives novolac and resol resins for exterior plywood, laminates, foundry binders and friction materials; with melamine, MF resins for durable surfaces and tableware.
Polyacetal (POM)
Polymerisation of formaldehyde or its trimer trioxane gives polyoxymethylene — a stiff, low-friction engineering plastic for gears, fuel-system parts and precision components.
MDI & Polyurethanes
Formaldehyde condenses aniline into the polymeric amine that is phosgenated to MDI, the isocyanate behind rigid polyurethane insulation foam.
Pentaerythritol & Polyols
Aldol chemistry with acetaldehyde gives pentaerythritol for alkyd resins, and related routes give neopentyl glycol, trimethylolpropane and hexamine.
Preservation & Disinfection
Protein cross-linking makes formaldehyde an effective biocide and fixative — used in tissue preservation, vaccine inactivation and industrial disinfection, under tightening regulation.
Why source Formaldehyde through Chelora Petrochem?
Verified Origin
Full origin certification and asset-backed supply chain documentation — no grey-market supply.
Grade Flexibility
37%, 42% and 50% concentrations in low-methanol and stabilised grades. Methanol content and acidity can be specified to suit your resin process and storage temperature.
Full Documentation
CoA, SDS, UN transport docs, REACH compliance, and destination-market certificates with every shipment.
Logistics Support
Experienced in heated-tank formaldehyde logistics — insulated and temperature-controlled tankers, storage-temperature planning, and correct UN 2209 or UN 1198 classification by grade.
Storage & Handling Guidelines
Always refer to the full SDS before handling. The following is a summary of key requirements.
- Hold storage at the temperature specified for the grade — too cool and paraformaldehyde precipitates, too warm and formic acid builds up.
- Use dedicated stainless steel (304/316) or lined tanks; formaldehyde solution attacks carbon steel and picks up iron, which discolours the product.
- Fit local exhaust ventilation at every sampling, loading and open-handling point, and monitor exposure against the ceiling or short-term limit rather than an 8-hour average alone.
- Circulate or agitate stored solution periodically, and inspect for haze or solids that indicate polymer is dropping out.
- Check acidity on receipt and during storage — rising formic acid signals oxidation and accelerates further degradation.
- Treat stabilised (higher-methanol) grades as flammable liquids: bonding, earthing and ATEX-rated equipment, since the flash point falls with methanol content.
- Keep away from strong oxidisers, acids, alkalis and amines, all of which react vigorously with formaldehyde.
- Have eyewash and safety showers immediately available; formaldehyde solution is corrosive to skin and eyes.
Hazard Summary
Classification: Carc. 1B (H350) · Muta. 2 (H341) · Acute Tox. 3 oral, dermal and inhalation (H301, H311, H331) · Skin Corr. 1B (H314) · Skin Sens. 1 (H317).
Carcinogenicity: Formaldehyde is classified Carc. 1B under CLP and sits in IARC Group 1, causally linked to nasopharyngeal cancer and to leukaemia. Exposure control is a regulatory requirement in most jurisdictions, not a matter of good practice.
Exposure limits: The EU binding limit is 0.3 ppm 8-hour TWA with a 0.6 ppm short-term limit; ACGIH sets a 0.3 ppm ceiling; the OSHA PEL is 0.75 ppm TWA with a 2 ppm STEL. These are very low numbers — general dilution ventilation will not reach them, and local exhaust at emission points is normally required.
Sensitisation: Formaldehyde is a skin sensitiser. Once a worker is sensitised, further contact can provoke a reaction at concentrations far below the exposure limit, so the response to a first case is exclusion from contact, not tighter PPE.
Corrosivity: The solution causes severe skin burns and serious eye damage. Splash protection and immediate access to eyewash and safety showers are essential.
PPE minimum: Chemical splash goggles or face shield, butyl or nitrile gloves with breakthrough data for formaldehyde, chemical-resistant clothing, and supplied-air or full-face respiratory protection wherever the ceiling limit could be exceeded.
Consult the full SDS for exposure limits, spill containment, emergency response, and disposal before any use.
Frequently Asked Questions
Technical and commercial questions about Formaldehyde sourcing and specifications.
Why is formaldehyde sold as a solution rather than pure?
Because pure formaldehyde will not stay pure. It is a gas at ambient temperature, boiling at −19 °C, and it polymerises spontaneously to solid paraformaldehyde. Dissolving it in water converts it to methylene glycol and short oligomers, which is a stable enough equilibrium to store and ship. Commercial concentrations run from 37% — the classic formalin — up to 50%.
Why does formaldehyde solution need heated storage?
The poly(oxymethylene) glycol chains in solution get longer as temperature falls, and past a certain point they precipitate as paraformaldehyde, fouling tanks, lines and filters. Higher concentrations need more heat: a low-methanol 37% solution is typically held at 32–40 °C, while 50% needs 45–60 °C. Overheating is also a problem, because it accelerates the Cannizzaro reaction that produces formic acid.
What does the methanol in formaldehyde solution do?
Methanol acts as a stabiliser, interrupting the polymerisation equilibrium so the solution can be stored at lower temperature without dropping out paraformaldehyde. The trade-off is flammability and downstream chemistry: methanol lowers the flash point, which can change the transport classification from UN 2209 Class 8 to UN 1198 Class 3, and it is inert ballast in a resin reactor. Low-methanol grades avoid both issues but demand tighter temperature control.
Which UN number applies to formaldehyde solution?
It depends on the grade. Solutions containing 25% or more formaldehyde that are not flammable ship as UN 2209, Formaldehyde solution, Class 8 (Corrosive), Packing Group III. Solutions with enough methanol to give a flash point below 60 °C ship as UN 1198, Formaldehyde solution flammable, Class 3 with a subsidiary corrosive risk. Confirm the flash point of the specific grade before preparing transport documents.
Is formaldehyde a carcinogen?
Yes. It is classified Carc. 1B under CLP and is in IARC Group 1, with established links to nasopharyngeal cancer and leukaemia. It is also a skin sensitiser and corrosive to skin and eyes. Occupational limits are correspondingly strict — 0.3 ppm as an 8-hour TWA in the EU — which generally means closed handling and local exhaust ventilation rather than general ventilation. Work to the full SDS and your national regulations.
What documentation does Chelora provide?
Every shipment includes a Certificate of Analysis covering formaldehyde content, methanol, acidity as formic acid, iron, colour, pH and density; a Safety Data Sheet (GHS/REACH); transport documentation under the correct UN number for the grade supplied; storage-temperature guidance; an origin certificate; and any destination-market certificates required.
Request a quote or specification sheet
Talk to Chelora's sourcing team about Formaldehyde grade, volume, logistics, documentation, and lead times. We respond within one business day.
