Phthalic Anhydride

CAS NO.: 85-44-9
Molecular Formula: C₈H₄O₃
Molecular Weight: 148.12

Phthalic anhydride is a white crystalline compound and a key industrial chemical intermediate derived from naphthalene or ortho-xylene oxidation. It is an important building block in the production of a variety of plasticizers, resins, dyes, and other organic compounds. As a cyclic anhydride of phthalic acid, phthalic anhydride is known for its reactivity and versatility in chemical synthesis.

Main Applications:

Phthalic anhydride is widely used in the manufacture of plasticizers, especially dioctyl phthalate (DOP), which is used in flexible PVC products. It is also a crucial raw material for producing alkyd resins in paints and coatings, unsaturated polyester resins for fiberglass-reinforced plastics, and various dyes and pigments. Additionally, phthalic anhydride serves as a chemical intermediate in pharmaceuticals, agricultural chemicals, and flame retardants.

Typical Properties:

Property	Value
Appearance	White flakes or crystals
Assay	≥99.5%
Melting Point	131°C
Boiling Point	295°C
Flash Point	152°C
Ignition Temperature	580°C
Vapor Pressure (25°C)	0.0013 mmHg
Density (20°C)	1.53 g/cm³
Solubility in Water	Reacts slowly to form phthalic acid
Storage	Store in a cool, dry, and well-ventilated area

 

We supply two types of phthalic anhydride in regular quality grades: Naphthalene-based Phthalic Anhydride and Ortho-xylene-based Phthalic Anhydride. Both grades meet standard industrial specifications, while having slight differences in purity, impurity profile and application performance.

Ox based Phthalic anhydride:

Test Item	Unit	Standard Specification
Appearance	-	White Flakes or Crystals
Assay (Purity)	%	≥99.5
Melting Point	℃	≥130.5
Free Acid (Phthalic Acid)	%	≤0.2
Moisture	%	≤0.1
Ash Content	%	≤0.05
APHA Color (Molten State)	Pt-Co	≤20

 

Naphthalene-based Phthalic Anhydride features purer quality, fewer residual impurities and better thermal stability. It shows stable performance in high-end applications, and is more suitable for high-grade resins, paints, coatings and fine chemical products with strict quality requirements.

Na based phthalic anhydride:

Items	Unit	Standard Specs.
Content	%	≥99.5
Melt colour	(Pt/Co)	≤20
Heating colour	(Pt/Co)	≤50
Appearance	-	White flake or crystalline powder
Sulfuric acid colour	(Pt/Co)	≤40
Solidification point	℃	≥130.5
Free acid	%	≤0.2
Conclusion	-

 

Ortho-xylene-based Phthalic Anhydride has high effective content and stable batch consistency. It is cost-effective and widely used for general industrial purposes, including plasticizers, ordinary polyester resins and conventional chemical intermediates.

Phthalic anhydride from Snowhite ensures high purity, consistent quality, and stable performance for your industrial needs.