Maleic Anhydride
The unsaturated dicarboxylic anhydride supplied by Chelora Chemicals — the essential feedstock for unsaturated polyester resin, alkyd coating and lubricant-additive manufacture — exported from Indonesia as molten liquid or briquetted flake with full batch documentation on every shipment.
What Maleic Anhydride is, and why buyers source it
A working overview of the compound's chemistry, its role as a reactive unsaturated anhydride, and the grades Chelora Chemicals keeps in regular supply.
Maleic anhydride is the cyclic anhydride of cis-butenedioic acid, combining a reactive carbon-carbon double bond with two carbonyl groups held in a five-membered ring. That combination makes it both a good Diels-Alder dienophile and an efficient acylating agent, reacting readily with alcohols, amines and dienes — the chemistry behind its two largest industrial uses.
At room temperature it is a white crystalline solid or flake with a sharp, acrid odour, readily hydrolysed by moisture to maleic acid and soluble in most polar organic solvents. It is commonly shipped and handled as a molten liquid above its 53 °C melting point to simplify large-scale handling, and requires dry, moisture-free storage and transport since it reacts with water on contact.
Where it fits in the synthesis chain
Maleic anhydride's largest use is as a comonomer, condensed with glycols and unsaturated diacids, in unsaturated polyester resins (UPR) used for fibreglass-reinforced plastics, gelcoats and marine/construction composites. It is also esterified into plasticisers and lubricant-performance additives, reacted with dienes in Diels-Alder chemistry to make specialty resins, and copolymerised into maleated polymers used as compatibilisers and dispersants.
Grade we supply
Chelora Chemicals offers Maleic Anhydride in briquette/flake and molten-liquid form (99.5%+ assay) suitable for unsaturated polyester resin, alkyd coating and lubricant-additive manufacture, supplied with a batch-wise certificate of analysis.
How Maleic Anhydride is made
An overview of the production route for orientation purposes. Our manufacturing partners' own process parameters and in-process controls are proprietary and are not disclosed beyond what is needed to interpret the certificate of analysis.
Maleic anhydride is manufactured almost exclusively by the catalytic gas-phase oxidation of n-butane (or, in older plants, benzene) with air over a vanadium-phosphorus-oxide catalyst in a fixed- or fluidised-bed reactor: C₄H₁₀ + 3.5 O₂ → C₄H₂O₃ + 4 H₂O. The crude anhydride vapour is then recovered, purified and either cast into briquettes/flake or kept molten for bulk shipment.
Why n-butane oxidation is the standard process
n-Butane oxidation converts a cheap, widely available light hydrocarbon directly into maleic anhydride in a single catalytic step with good selectivity, which is why it has displaced the older benzene-oxidation route and is now the dominant commercial process used worldwide.
Industries and processes that use it
Maleic Anhydride is consumed across composites, coatings, lubricant-additive and specialty-resin manufacture, where its combination of ring reactivity and unsaturation is the main draw. The fields below account for most of the demand we see through our export desk.
Unsaturated Polyester Resins (UPR)
Condensed with glycols and other diacids to make unsaturated polyester resins used in fibreglass-reinforced plastics, gelcoats and marine/construction composites.
Lubricant & Fuel Additives
Reacted with dienes and further derivatised into succinimide-type dispersant and detergent additives used in lubricant and fuel formulation.
Alkyd & Coating Resins
Used alongside phthalic anhydride in alkyd resin cooking, improving drying speed, hardness and chemical resistance of paint and coating formulations.
Maleated Polymers & Compatibilisers
Grafted onto polyolefins and other polymers to make maleated compatibilisers and dispersants used in polymer blending and composite manufacture.
How the molecule is typically carried forward
The ring strain, carbonyl reactivity and carbon-carbon double bond together govern almost all of this molecule's further reaction chemistry. Reaction classes below account for most of the ways Maleic Anhydride is converted into a finished product or intermediate.
Polyesterification
The anhydride ring opens and condenses with glycols and other diacids, releasing water and building the unsaturated polyester backbone used in UPR manufacture.
Diels-Alder Cycloaddition
Acts as an efficient dienophile, reacting with dienes such as butadiene to build specialty resins and the backbone for certain lubricant and fuel additives.
Free-Radical Grafting (Maleation)
Grafted onto polyolefin backbones under radical conditions to introduce polar anhydride functionality, the basis of maleated compatibiliser and dispersant chemistry.
Catalytic Gas-Phase Oxidation (Upstream)
n-Butane and air react over a vanadium-phosphorus-oxide catalyst to form maleic anhydride itself, the dominant industrial route in the whole chain.
Maleic Anhydride against other amines we supply
Buyers sourcing Maleic Anhydride for composites, coatings or lubricant-additive manufacture often need a related anhydride or acid-chemistry intermediate. A quick reference to what else is on our regular supply list.
| Product | CAS Number | Category | Notes |
|---|---|---|---|
| Maleic Anhydride | 108-31-6 | Unsaturated dicarboxylic anhydride | The product on this page — the feedstock for UPR, alkyd resins and lubricant additives. |
| Phthalic Anhydride | 85-44-9 | Aromatic dicarboxylic anhydride | The related aromatic anhydride used alongside maleic anhydride in alkyd and UPR resins — see its product page. |
| Acrylic Acid | 79-10-7 | Vinyl carboxylic acid monomer | Another reactive unsaturated acid-chemistry monomer — see its product page. |
| Mono Ethylene Glycol | 107-21-1 | Diol / polyester comonomer | A common glycol comonomer condensed with maleic anhydride in UPR manufacture — see its product page. |
Exact physical constants and purity specifications are confirmed per batch on the certificate of analysis — treat the notes above as a sourcing guide, not a specification sheet, for products other than Maleic Anhydride.
Safety classification at a glance
Based on GHS classification as commonly listed for this substance. This is a summary for orientation only — always work from the current safety data sheet supplied with your specific batch.
Harmful if swallowed.
Causes skin irritation.
Causes serious eye damage.
May cause allergy or asthma symptoms or breathing difficulties if inhaled.
Chemical-resistant gloves, splash goggles and respiratory protection against dust/fume are mandatory for routine handling.
Keep strictly dry; contact with water or moisture generates maleic acid and heat.
Repeated exposure can cause respiratory sensitisation; good ventilation and dust/fume control are essential.
Danger — GHS05 corrosive, GHS07 irritant and GHS08 respiratory-sensitiser pictograms apply.
This compound is harmful if swallowed, causes skin irritation and serious eye damage, and may cause allergy or asthma symptoms or breathing difficulties if inhaled, including through sensitisation on repeated exposure. It must be handled only with chemical-resistant gloves, splash-proof eye protection, and respiratory protection against dust or fume, and kept strictly dry. Full first-aid, storage, spill and PPE guidance is in the MSDS issued with every shipment, and must be read in full and followed without exception before this material is handled.
Keeping it on spec between delivery and use
General storage guidance for this grade. Site-specific storage rules, segregation requirements and re-test intervals should follow your own EHS procedures and the MSDS issued with your batch.
Store in a dry, sealed area away from moisture, strong bases and oxidizing agents. The molten-liquid grade must be kept in a heated, insulated tank above its 53 °C melting point with dry nitrogen blanketing to prevent hydrolysis and oxidation. Only trained personnel using proper PPE and dust/fume control should handle this material. If a batch is held past its retest date, re-check assay and free maleic acid content before use.
How it ships from Indonesia
Standard packing and export terms for this product. Confirm exact figures against your order — they vary slightly by destination and quantity.
What travels with every batch
Specification is agreed before the purchase order, not discovered on arrival. Every shipment of Maleic Anhydride leaves with a documented, checkable paper trail.
Certificate of Analysis
Batch-wise assay (by titration/GC), colour and relevant physical constants, issued against the agreed specification so your QC team can check it, not just file it.
Safety Data Sheet
GHS-format SDS in English covering hazard classification, handling, storage, first-aid and spill response for the exact grade of Maleic Anhydride shipped.
Technical Data Sheet
Reference physical and chemical properties, recommended storage and typical applications, for internal circulation to your process or R&D teams.
Certificate of Origin
Confirms Indonesian origin for customs clearance and any preferential-duty claim at your destination port.
Dangerous Goods Declaration
UN packing group, classification and shipper's declaration prepared ahead of loading so documentation never holds up customs.
Third-Party Inspection
Independent pre-shipment inspection and re-sampling can be arranged on request, at your cost, for buyers who require it as a matter of policy.
Frequently asked questions
What buyers most often ask our sales desk about this grade.
01What is Maleic Anhydride used for?+
02What is the CAS number of Maleic Anhydride?+
03How is Maleic Anhydride made?+
04What grades does Chelora Chemicals supply?+
05Why is Maleic Anhydride shipped molten?+
06Is Maleic Anhydride hazardous?+
07What packing options are available?+
08How long does delivery take?+
09Can I get a sample before placing a bulk order?+
10Do you supply Phthalic Anhydride as well?+
Need Maleic Anhydride on spec, on time?
Send us your required purity, quantity, packing preference and destination port. Our desk quotes most enquiries within one working day.