Phthalic Anhydride
The key feedstock for PVC plasticisers and alkyd resins — the link between ortho-xylene and the flexible-PVC, paint and coatings industries.
Chelora Chemicals supplies phthalic anhydride in flake or molten form to plasticiser and resin producers worldwide, with full documentation.
Product identity
- CAS Number
- 85-44-9
- IUPAC name
- 2-Benzofuran-1,3-dione
- Molecular formula
- C₈H₄O₃
- Molecular weight
- 148.12 g/mol
- Boiling point
- 295 °C
- Melting point
- 131.6 °C
- UN Number
- UN 2214
- HS Code
- 2917 35
Note: Phthalic anhydride is commonly handled molten in bulk logistics given its moderate melting point. Confirm requirements with your regulatory affairs team.
What Phthalic Anhydride is used for
Phthalic Anhydride (PAN) is a white, crystalline, flaked solid with a characteristic sharp odour, produced by the catalytic vapour-phase oxidation of ortho-xylene (the dominant route) or naphthalene, over vanadium pentoxide catalysts.
Phthalic anhydride's historically largest use is as the feedstock for PVC plasticisers — esterified with 2-ethylhexanol or isononanol to make DOP/DEHP and DINP, which flexibilise PVC for cable, film and flooring (though regulatory pressure has shifted some demand toward non-phthalate plasticisers). It is also esterified into alkyd resins for paints and coatings, and condensed into unsaturated polyester resins for gel coats and lower-reactivity composite formulations.
Where it sits in the petrochemical value chain
- Ortho-Xylene the feedstock, catalytically oxidised into phthalic anhydride. See that page.
- Phthalic Anhydride (this product) the aromatic anhydride for the plasticiser and resin chains below.
- Polyvinyl Chloride the flexible-PVC end use via plasticiser esters. See that page.
Handling character
Phthalic anhydride is a respiratory and skin sensitiser and causes serious eye damage, requiring careful dust and fume control whether solid or molten. Full hazard detail is in the Safety section below.
| Parameter | Typical value |
|---|---|
| Appearance | White flakes or molten liquid |
| Assay | 99.8% min (plasticiser/resin grade) |
| Colour (molten, APHA) | Within producer specification |
| Maleic anhydride content | < 0.15% (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 132 °C |
| Melting point | 131.6 °C |
| Boiling point | 295 °C |
| Density | 1.53 g/cm³ |
| Water solubility | Hydrolyses slowly to phthalic acid |
| Flash point | 152 °C (combustible) |
Physical constants compiled from public reference data for CAS 85-44-9 and rounded for readability. Treat them as orientation, not as a specification.
Where our customers put Phthalic Anhydride to work
The anhydride behind flexible PVC, alkyd coatings and unsaturated polyester resins.
PVC plasticisers (DOP / DINP)
Esterified with 2-ethylhexanol or isononanol into plasticisers that flexibilise PVC for cable, film and flooring.
- Plasticiser-grade specification
- Molten & flake bulk supply
- Technical desk review on request
Alkyd resins
Esterified with polyols and fatty acids into alkyd resins for architectural and industrial paints.
- Industrial-grade specification
- Documented batch traceability
- Contract & spot supply
Unsaturated polyester resins
Condensed with glycols into lower-reactivity UPR grades for gel coats and casting resins.
- Full analytical documentation available
- Retained sample held against the lot
Polyester polyols
Feedstock for polyester polyols used in rigid polyurethane foam and coatings.
- Documented batch traceability
- Technical desk review on request
Dyes & pigments
Feedstock for phthalocyanine pigments and certain dye intermediates.
- Research & process-scale quantities
- Full documentation supplied
Contract & scheduled supply
Plasticiser, alkyd and polyester-resin 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 Phthalic Anhydride
Chelora Chemicals is a supplier and sourcing partner, not a manufacturer. Colour grade and trace maleic anhydride content are critical to plasticiser and alkyd 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 trace impurities confirmed before we quote. Consistency matters to downstream plasticiser and alkyd resin performance.
- UN 2214 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.
- Plasticiser-grade and resin-grade both sourced. Matched precisely to your end-use specification.
Solid or molten, packed to your process
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 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 plasticiser and resin 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.
Sensitising & corrosive to eyes — handle accordingly
Phthalic anhydride causes serious eye damage, respiratory irritation, and is 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
H318Causes serious 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 fume during handling. Prolonged exposure can sensitise the respiratory tract and skin; 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 tanks away from moisture and strong oxidising agents.
Handling
Use chemical-resistant gloves, face shield, and respiratory protection where dust or fumes may be generated. Avoid any eye contact and inhalation of dust or vapour; ensure good ventilation during molten transfer.
Transport
Shipped as UN 2214 (Phthalic anhydride), a corrosive/irritant 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 trace maleic anhydride 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 Phthalic Anhydride is made
Phthalic anhydride is produced industrially by the catalytic vapour-phase oxidation of ortho-xylene over vanadium pentoxide-titanium dioxide catalysts, the dominant modern route, with a smaller share made from naphthalene oxidation in some regions. The crude product is purified by distillation and either flaked for solid handling or kept molten for bulk logistics.
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 | Aromatic cyclic anhydride |
|---|---|
| Functional groups | Cyclic anhydride fused to a benzene ring |
| Reactivity | Esterification with alcohols (plasticisers, alkyds); condensation with glycols (polyester resins) |
| Related compounds | Ortho-Xylene (feedstock), Maleic Anhydride (related anhydride), PVC (plasticiser end use) |
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Phthalic Anhydride, answered
What is Phthalic Anhydride used for?
How is Phthalic Anhydride made?
Is Phthalic Anhydride hazardous?
What grade do you supply?
What packing do you offer?
Do you manufacture this yourself?
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