What is Phthalic Anhydride CAS 85-44-9?

Phthalic Anhydride, also called 1,2-benzenedicarboxylic anhydride or PA, is a cyclic anhydride with the molecular formula C8H4O3 and molecular weight 148.12 g/mol. It is normally supplied as white crystalline flakes, needles, or solid material with an assay of about 99.0-99.8% in industrial grade.

How does Phthalic Anhydride behave in water or moist air?

The anhydride ring hydrolyzes to phthalic acid on contact with water, and the reaction is faster in hot water or humid conditions. Because moisture changes its chemical form, sealed packaging and low-humidity handling are important throughout storage and transport.

Is Phthalic Anhydride the same as phthalic acid?

No, they are related but not the same material. Phthalic Anhydride CAS 85-44-9 is the cyclic anhydride, while phthalic acid CAS 88-99-3 is the dicarboxylic acid formed by hydrolysis; under suitable dehydration conditions the anhydride can be reformed.

What melting and boiling behavior should formulators expect?

Phthalic Anhydride typically melts around 131 C and boils or sublimes around 284-295 C depending on heating conditions. These thermal properties are useful for resin cooking, esterification, and processes that require the anhydride to be handled as a melt or vapor.

How should Phthalic Anhydride be stored?

Store it in tightly closed, moisture-resistant containers in a cool, dry, well-ventilated area, away from water, steam, and incompatible reactive substances. Keeping the flakes or solid dry preserves chemical identity and minimizes caking or partial hydrolysis.

Phthalic Anhydride CAS 85-44-9

Phthalic Anhydride, also called 1,2-benzenedicarboxylic anhydride, CAS 85-44-9, a cyclic aromatic anhydride supplied as white crystalline flakes, needles, or solid, is positioned as an intermediate for plasticizers, resins, and chemical synthesis. Confirm the required grade, then request a quotation with COA/TDS/SDS for bulk supply.

CAS: 85-44-9
Synonyms: 1,2-Benzenedicarboxylic anhydride; PA
Einecs: 201-607-5
Molecular Formula: C8H4O3
Grade: Industrial grade
Package: Standard export packaging

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Product Description

Phthalic Anhydride CAS 85-44-9 is a cyclic aromatic anhydride with EC 201-607-5 and molecular formula C8H4O3.

Synonyms: 1,2-Benzenedicarboxylic anhydride; PA.

CAS: 85-44-9.

Molecular formula: C8H4O3.

It is supplied as white crystalline flakes, needles, or solid material.

It has a molecular weight of about 148.12 g/mol.

It is positioned as a key intermediate for plasticizers, resins, and chemical synthesis.

It is used to make phthalate plasticizers for flexible PVC.

It is used to make alkyd resins, unsaturated polyester resins, and dye or pigment intermediates.

Its aromatic anhydride structure provides reactivity and rigid backbone character.

Confirm assay, appearance, and related specifications for the chosen grade.

Check compatibility with the target resin, esterification, or chemical synthesis conditions.

Store in tightly closed, moisture-resistant containers in a cool, dry, well-ventilated area.

Use appropriate PPE and minimize exposure to moisture, steam, and incompatible substances.

Confirm packaging suitable for the solid form and order quantity, and follow the current SDS.

Every batch is checked for assay, appearance, and related specifications, with COA/TDS/SDS supplied per grade.

Confirm grade, packaging, and specification as required.

The page is an RFQ entry point and does not state stock, price, MOQ, or fixed lead time.

For an RFQ, state the intended application, required grade, quantity, packaging, destination, and document needs.

FAQ - Technical & Supply Chain

Q:
What is Phthalic Anhydride CAS 85-44-9?

A: Phthalic Anhydride, also called 1,2-benzenedicarboxylic anhydride or PA, is a cyclic anhydride with the molecular formula C8H4O3 and molecular weight 148.12 g/mol. It is normally supplied as white crystalline flakes, needles, or solid material with an assay of about 99.0-99.8% in industrial grade.
Q:
What are the main industrial uses of Phthalic Anhydride?

A: Phthalic Anhydride is a key intermediate for phthalate plasticizers used in flexible PVC, and is also used to make alkyd resins, unsaturated polyester resins, and dye or pigment intermediates. Its aromatic anhydride structure provides both reactivity and rigid backbone character in these applications.
Q:
How does Phthalic Anhydride behave in water or moist air?

A: The anhydride ring hydrolyzes to phthalic acid on contact with water, and the reaction is faster in hot water or humid conditions. Because moisture changes its chemical form, sealed packaging and low-humidity handling are important throughout storage and transport.
Q:
Is Phthalic Anhydride the same as phthalic acid?

A: No, they are related but not the same material. Phthalic Anhydride CAS 85-44-9 is the cyclic anhydride, while phthalic acid CAS 88-99-3 is the dicarboxylic acid formed by hydrolysis; under suitable dehydration conditions the anhydride can be reformed.
Q:
What melting and boiling behavior should formulators expect?

A: Phthalic Anhydride typically melts around 131 C and boils or sublimes around 284-295 C depending on heating conditions. These thermal properties are useful for resin cooking, esterification, and processes that require the anhydride to be handled as a melt or vapor.
Q:
How should Phthalic Anhydride be stored?

A: Store it in tightly closed, moisture-resistant containers in a cool, dry, well-ventilated area, away from water, steam, and incompatible reactive substances. Keeping the flakes or solid dry preserves chemical identity and minimizes caking or partial hydrolysis.

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