Maleic Anhydride
The key feedstock for unsaturated polyester resins — the reactive anhydride behind fibreglass composites, coatings and lubricant additives.
Chelora Chemicals supplies maleic anhydride in briquette, flake and molten form to UPR and specialty-chemical producers worldwide.
Product identity
- CAS Number
- 108-31-6
- IUPAC name
- Furan-2,5-dione
- Molecular formula
- C₄H₂O₃
- Molecular weight
- 98.06 g/mol
- Boiling point
- 202 °C
- Melting point
- 52.8 °C
- UN Number
- UN 2215
- HS Code
- 2917 14
Note: Maleic anhydride is often handled molten in bulk logistics given its moderate melting point. Confirm requirements with your regulatory affairs team.
What Maleic Anhydride is used for
Maleic Anhydride (MAN) is a white, crystalline solid with a sharp, acrid odour, melting just above room temperature and commonly handled molten in bulk. It is produced industrially by the catalytic vapour-phase oxidation of n-butane (the dominant modern route) or, in older plants, from benzene.
Maleic anhydride's largest use by far is as the feedstock for unsaturated polyester resins (UPR), reacted with propylene or ethylene glycol and crosslinked with styrene for fibreglass-reinforced composites, gel coats and cultured marble. It is also hydrogenated to 1,4-butanediol and tetrahydrofuran, converted to fumaric acid for food and resin use, and copolymerised into lubricant additives and agricultural adjuvants.
Where it sits in the petrochemical value chain
- n-Butane the feedstock, catalytically oxidised into maleic anhydride (sourced from LPG/NGL fractionation, not separately listed on this site).
- Maleic Anhydride (this product) the reactive anhydride for the UPR and derivative chains below.
- Unsaturated Polyester Resin the dominant downstream use, crosslinked with styrene and MPG/MEG. See Styrene Monomer.
Handling character
Maleic anhydride is corrosive to skin and eyes and a strong respiratory irritant/sensitiser, requiring careful handling whether solid or molten. Full hazard detail is in the Safety section below.
| Parameter | Typical value |
|---|---|
| Appearance | White briquettes, flakes, or molten liquid |
| Assay | 99.5% min (UPR grade) |
| Colour (molten, APHA) | Within producer specification |
| Free maleic acid | < 0.1% (typical) |
Important: the figures above are indicative of commercial material and are offered for planning only. The batch certificate of analysis is the governing document.
| Property | Value |
|---|---|
| Physical state | Crystalline solid, often handled molten above 53 °C |
| Melting point | 52.8 °C |
| Boiling point | 202 °C |
| Density | 1.48 g/cm³ |
| Water solubility | Reacts with water (hydrolyses to maleic acid) |
| Flash point | 102 °C (combustible) |
Physical constants compiled from public reference data for CAS 108-31-6 and rounded for readability. Treat them as orientation, not as a specification.
Where our customers put Maleic Anhydride to work
The reactive anhydride behind fibreglass composites, coatings and lubricant additives.
Unsaturated polyester resins
Reacted with glycols and crosslinked with styrene for fibreglass-reinforced composites and gel coats.
- UPR-grade specification
- Molten & solid bulk supply
- Technical desk review on request
1,4-Butanediol / THF chain
Hydrogenated into 1,4-butanediol and tetrahydrofuran for spandex and engineering-plastic chains.
- Industrial-grade specification
- Documented batch traceability
- Contract & spot supply
Fumaric acid
Isomerised to fumaric acid for food acidulant and resin applications.
- Full analytical documentation available
- Retained sample held against the lot
Lubricant additives
Copolymerised into polyisobutylene-maleic anhydride dispersants and lubricant additives.
- Documented batch traceability
- Technical desk review on request
Agricultural adjuvants
Copolymerised into agricultural adjuvants and surfactant intermediates.
- Research & process-scale quantities
- Full documentation supplied
Contract & scheduled supply
UPR and specialty-chemical plants running continuous consumption are supported with scheduled bulk delivery.
- Annual contracts with scheduled call-off
- Price held across the contract period
- Second source held in reserve
How we supply Maleic Anhydride
Chelora Chemicals is a supplier and sourcing partner, not a manufacturer. Colour grade and free-acid content are critical to UPR clarity and cure performance — that shapes how we manage this line.
We place your order with whichever qualified producer best matches your required grade, your price point and your delivery window, and confirm your jurisdiction's import requirements before booking.
We keep a second qualified source on this line, so a single-plant disruption never becomes your production problem.
- Colour grade and free-acid content confirmed before we quote. Consistency matters to downstream UPR clarity and cure performance.
- UN 2215 documentation managed end to end. Classification, labelling and carrier compliance confirmed before booking, whether solid or molten.
- Scheduled call-off scheduling. We hold contracted tonnage and release it against your consumption calendar.
- Batch traceability to the producing plant. Full chain of custody documentation on request.
- Export machinery handled in-house. Classification, approved packing, labelling, freight booking and customs paperwork are ours to manage.
- UPR-grade and technical-grade both sourced. Matched precisely to your end-use specification.
Solid or molten, packed to your process
Briquette/flake bags, totes or molten bulk tank — tell us your preferred format and we will quote and arrange it.
25 kg bags
Multi-wall bags of briquetted or flaked solid for smaller-volume orders and trial quantities.
~1,000 kg bulk bags
Flexible intermediate bulk containers sized for mid-volume converter orders.
Temperature-controlled bulk shipment
Heated ISO tank bulk shipment for continuous-consumption UPR plants.
Incoterms to suit you
Quoted on the Incoterm your purchasing team works to, with documentation filed before booking.
Trial / sample quantities
Small packs dispatched for process trials before a commercial order is placed.
Contracted call-off supply
We hold contracted tonnage and release it against your consumption calendar.
Corrosive & sensitising — handle accordingly
Maleic anhydride is corrosive to skin and eyes, a strong respiratory irritant, and a known respiratory and skin sensitiser. The summary below is orientation only — the safety data sheet supplied with your specific batch is the authoritative document.
Classified hazards
H314Causes severe skin burns and eye damage.H335May cause respiratory irritation.H317+H334May cause an allergic skin reaction; may cause allergy or asthma symptoms or breathing difficulties if inhaled.
Control dust and avoid any skin/eye contact. Maleic anhydride reacts with moisture (including sweat) to form corrosive maleic acid on contact; always read the SDS issued with your specific batch.
Storage
Store solid product in tightly sealed, moisture-proof containers; store molten product in heated, corrosion-resistant, nitrogen-padded tanks away from moisture and oxidising agents.
Handling
Use chemical-resistant gloves, face shield, and respiratory protection where dust or fumes may be generated. Avoid any skin or eye contact and inhalation of dust or vapour; ensure good ventilation during molten transfer.
Transport
Shipped as UN 2215 (Maleic anhydride), a corrosive solid or molten substance. We confirm and document exact classification for your specific shipment and destination.
Every batch, documented
We verify documentation before dispatch so there are no surprises at your incoming-goods bench.
Specification agreed
Assay, colour grade and free-acid content confirmed against your process requirement before order placement.
Producer batch testing
The producing plant tests each batch against the agreed specification before release.
Documentation review
COA, SDS and transport paperwork checked by our desk before the shipment is booked.
Traceable dispatch
Each shipment is traceable to its producing batch, with full chain-of-custody records on request.
How Maleic Anhydride is made
Maleic anhydride is produced industrially by the catalytic vapour-phase oxidation of n-butane over vanadium-phosphorus-oxide catalysts, the dominant modern route, having largely displaced the older benzene-oxidation process on cost and environmental grounds. The crude product is purified by distillation and crystallised or kept molten for bulk handling.
We do not publish operating process parameters here; this is background only. Full technical documentation accompanies every shipment, and any process-specific detail you need is best confirmed directly with our technical desk.
| Chemical family | Cyclic anhydride (unsaturated dicarboxylic) |
|---|---|
| Functional groups | Cyclic anhydride with an internal carbon-carbon double bond |
| Reactivity | Esterification with glycols; Diels-Alder and ene reactions; hydrolysis to maleic acid |
| Related compounds | Phthalic Anhydride (related anhydride), Styrene Monomer, Mono Propylene Glycol (UPR co-reactants) |
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