Specialty Additives Available — Bulk Only

Phthalic Anhydride (PA)

PA
CAS 85-44-9 · Formula C8H4O3 · MW 148.11 g/mol

A cornerstone aromatic anhydride feeding plasticizers, polyester and alkyd resins, and epoxy curing. Industry references record its use in phthalate plasticizers, unsaturated polyester and alkyd resins, dyes and pigments, and as a curing agent for epoxy resins.

Request SDS
UN Number
UN 2214
Hazard Class
Class 8
HS Code
2917.35
At a Glance
Material Family
Specialty Additives
Record Type
Pure compound
Primary Role
Crosslinking / Curing · Synthesis Intermediate
Functional Roles
Crosslinking / Curing Synthesis Intermediate
INCI Name
PHTHALIC ANHYDRIDE
CosIng Functions
NOT REPORTED
Industries Served
Beauty & Personal Care Coatings & Construction Plastics & Polymers
Applications & Use Cases
  • ▸ Plasticizers: Feedstock for phthalate ester plasticizers.
  • ▸ Polyester resins: Building block for unsaturated polyester resins.
  • ▸ Alkyd resins: Used in alkyd resin manufacture for coatings.
  • ▸ Epoxy curing: Anhydride curing agent for epoxy resins.
  • ▸ Dyes and pigments: Intermediate for dyes and pigments.
Physical Properties
Physical Description
Phthalic anhydride appears as a colorless to white lustrous solid in the form of needles with a mild distinctive odor. Moderately toxic by inhalation or ingestion and a skin irritant. Melting point 18 °C Flash point 152 °C. Forms a corrosive solution when mixed with water. Used in the manufacture of materials such as artificial resins
Appearance
White solid (flake) or a clear colorless liquid (molten)
Odor
Characteristic, acrid odor
Boiling Point
295 °C at 760 mmHg (sublimes)
Melting Point
131 °C
Flash Point
165 °C (Open cup); 152 °C (Closed cup)
Density
1.2 at 135 °C 1.53 at 20 °C (solid)
Vapor Density
5.1
Vapor Pressure
0.0002 mmHg at 20 °C; 0.001 mmHg at 30 °C
LogP
log Kow = 1.60
Autoignition Temperature
570 °C
Viscosity
1.19 mPa.s at 132 °C; 1.125 mPa.s at 155 °C
Heat Of Combustion
-3259 kJ/mol at 25 °C [
Heat of Vaporization
65.3 kJ/mol at 131 °Cl
Surface Tension
35.5 dynes/cm = 0.0355 N/m at 155 °C
Ionization Potential
10.00 eV
Odor Threshold
Air: 0.053 ul/l; odor safety class C; C= < 50% of distracted persons perceive warning of TLV
Safety & Handling
Full SDS available on request

A grade-specific Safety Data Sheet (SDS) — with the complete hazard classification, handling precautions, and transport information — is supplied with every shipment and available on request. Confirm all safety and regulatory details against the SDS for your specific grade.

Request SDS →
DOT / UN Transport Classification
DOT hazard class 8 placard
UN / DOT NumberUN 2214
Hazard Class / DivisionClass 8
Packing GroupIII
Proper Shipping NamePhthalic anhydride with more than .05 percent maleic anhydride

Transport classification per the UN Model Regulations / 49 CFR 172.101 Hazardous Materials Table. Confirm against the grade-specific SDS (Section 14) before shipping.

HS / Tariff Classification
Harmonized System (HS) Code — 6-digit international heading
2917 . 35
Chapter 29
Organic chemicals
Heading 29.17
Internationally harmonized (WCO HS)
Subheading 2917.35
6-digit international code — national tariff line adds further digits
Chemical Identity
CAS Number
85-44-9
Molecular Formula
C8H4O3
Molecular Weight
148.11 g/mol
IUPAC Name
2-benzofuran-1,3-dione
INCI Name
PHTHALIC ANHYDRIDE
PubChem CID
6811
InChI Key
LGRFSURHDFAFJT-UHFFFAOYSA-N
Synonyms & Trade Names
PHTHALIC ANHYDRIDE 1,3-Isobenzofurandione 2-Benzofuran-1,3-dione Phthalandione Retarder esen 1,3-Dioxophthalan 1,3-Phthalandione Phthalic acid anhydride Retarder AK Retarder PD o-Phthalic acid anhydride Phthalsaeureanhydrid ESEN Vulkalent B/C Anidride ftalica Ftalowy bezwodnik Ftaalzuuranhydride 1,2-Benzenedicarboxylic acid anhydride Anhydride phtalique Ftalanhydrid
Full Description

Phthalic anhydride (CAS 85-44-9) is an aromatic anhydride and a high-volume chemical intermediate. Industry references record its use in phthalate plasticizers, unsaturated polyester and alkyd resins, dyes and pigments, and as a curing agent for epoxy resins. Supplied as a bulk chemical intermediate.

Frequently Asked Questions

What is phthalic anhydride used for?

Phthalic anhydride (CAS 85-44-9) is a high-volume chemical intermediate used to make phthalate ester plasticizers, unsaturated polyester and alkyd resins for coatings, dyes and pigments, and as an anhydride curing agent for epoxy resins. RawSource supplies it as a bulk intermediate.

What is another name for phthalic anhydride?

Phthalic anhydride is also abbreviated PA and known by its IUPAC name 1,3-isobenzofurandione. CAS is 85-44-9, formula C8H4O3, HS code 2917.35.

What is the chemical formula and molecular weight of phthalic anhydride?

The formula is C8H4O3 with a molecular weight of approximately 148.1 g/mol. It is an aromatic anhydride supplied in flake or molten bulk form.

How is phthalic anhydride classified for shipping?

Phthalic anhydride ships under UN 2214. RawSource supplies it with SDS and DOT documentation; confirm packaging (bags, drums, or bulk) and form with your rep when requesting a quote.

What is the price of bulk phthalic anhydride?

Pricing varies with form, packaging, and volume. RawSource quotes bulk phthalic anhydride to spec — request a current quote with your target quantity and delivery point.

Related Products
Butylated Hydroxytoluene (BHT)
CAS 128-37-0 · C15H24O
Specialty Additives
Naphthenic Oil (Naphthenic Base Oil)
CAS 64742-52-5
Specialty Additives
2,4-Diethylthioxanthone (DETX)
CAS 82799-44-8 · C17H16OS
Specialty Additives
Papaya Leaf Extract (Carica Papaya)
CAS 91722-56-4 · Mixed
Natural Extracts & Oils
Disclaimer. Information on this page — including properties, identifiers, hazard, transport (DOT/UN) and tariff (HS) classifications, and applications — is provided for general reference and is compiled from authoritative public sources (e.g. PubChem/ECHA, 49 CFR 172.101, the Harmonized Tariff Schedule). Values are typical and are not a guaranteed specification; the Certificate of Analysis (CoA) for the lot purchased governs. Products are sold for industrial and professional use only. Nothing here is a medical, health, or efficacy claim or advice. Always consult the current Safety Data Sheet (SDS) before handling, storage, transport or disposal, and confirm regulatory status, classification and suitability for your application and jurisdiction. Hazard, transport and tariff classifications must be verified for your specific shipment. RawSource makes no warranty, express or implied, and assumes no liability for use of this information. Trademarks. Third-party trademarks and brand names are the property of their respective owners; any reference is nominative — used only to identify a comparable product — and does not imply affiliation with, sponsorship by, or endorsement by the trademark owner.

Ready to Source Phthalic Anhydride (PA)?

Our procurement team handles specification confirmation, lead time, and logistics.

Request a Quote