Phthalic Anhydride, Isobenzofurandione, Benzene Dicarboxylic Anhydride Phthalic Acid, Acide Phtalique, 88-99-3

PHTHALIC ANHYDRIDE (PA)

Phthalic Anhydride / 1,3-Isobenzofurandione / Benzene-1,2-dicarboxylic Anhydride
CAS Number: 85-44-9
EC Number: 201-607-5

SECTION 1: PRODUCT IDENTIFICATION AND CHEMICAL IDENTITY

Phthalic anhydride is an aromatic dicarboxylic acid anhydride formed by the dehydration of phthalic acid. It is the most commercially important anhydride and serves as a key intermediate in the production of plasticizers (phthalates), unsaturated polyester resins (UPR), alkyd resins, and various other industrial chemicals. It is produced primarily by the catalytic oxidation of o-xylene or naphthalene.

SECTION 2: RELATIONSHIP BETWEEN PHTHALIC ANHYDRIDE AND PHTHALIC ACID

Conversion Reaction:
Phthalic Anhydride + H₂O → Phthalic Acid (exothermic hydrolysis)

SECTION 3: SYNONYMS AND OTHER NAMES

SECTION 4: CHEMICAL STRUCTURE

4.1. Molecular Structure

Phthalic anhydride consists of a benzene ring fused with an anhydride group (-CO-O-CO-) at adjacent positions (1,2). The anhydride group forms a five-membered ring with the benzene ring.

Structural Formula:

        O
        ||
        C
       / \
      /   \
     /     \
    C       C
    |       |
    C - O - C
    |       |
    C       C
     \     /
      \   /
       \ /
        C
         \
          C=O

Simplified Representation:

    O
    ||
    C
   / \
  /   \
 C     C
 |     |
 C - O - C
 |     |
 C     C
  \   /
   \ /
    C
     \
      C=O

4.2. Molecular Formula

C₈H₄O₃

4.3. Molecular Weight

148.06 g/mol

4.4. Key Structural Features

SECTION 5: PHYSICAL AND CHEMICAL PROPERTIES

SECTION 6: CHEMICAL PROPERTIES AND REACTIVITY

SECTION 7: REACTION EQUATIONS

7.1. Hydrolysis with Water (Exothermic)

C₈H₄O₃ + H₂O → C₈H₆O₄ (Phthalic Acid) + Heat

7.2. Esterification with Alcohols (Phthalate Production)

C₈H₄O₃ + 2 R-OH → C₈H₄(COOR)₂ + H₂O

7.3. Phthalimide Formation with Amines

C₈H₄O₃ + R-NH₂ → C₈H₄(CO)₂NR + H₂O

7.4. Production from o-Xylene (Main Industrial Process)

C₈H₁₀ (o-Xylene) + 3 O₂ → C₈H₄O₃ + 3 H₂O (with V₂O₅/TiO₂ catalyst, 350-400°C)

7.5. Production from Naphthalene (Traditional Process)

C₁₀H₈ (Naphthalene) + 4.5 O₂ → C₈H₄O₃ + 2 CO₂ + 2 H₂O (with V₂O₅ catalyst)

SECTION 8: PRODUCTION METHODS

SECTION 9: AVAILABLE FORMS AND SPECIFICATIONS

Typical Specifications (Technical Grade):

SECTION 10: APPLICATIONS AND INDUSTRIAL USES

10.1. Plasticizers (Phthalates) – Largest Use (~55%)

Phthalate Applications:

• PVC products (cables, pipes, flooring, wallcoverings)

• Automotive parts (dashboards, interior trim)

• Medical devices (blood bags, tubing)

• Toys

• Cosmetic products (shampoo, conditioner, lotion, nail polish, deodorant, perfume)

• Construction materials

• Food packaging

10.2. Unsaturated Polyester Resins (UPR) – Second Largest Use (~25%)

10.3. Alkyd Resins

10.4. Polyester Polyols

10.5. Dye and Pigment Industry

10.6. Pharmaceutical Industry

10.7. Agricultural Industry

10.8. Other Applications

SECTION 11: PHTHALATES (PLASTICIZERS) – DETAILED APPLICATIONS

Regulatory Note: Some phthalates (especially DEHP, DBP, BBP) are restricted in the European Union and other regions due to carcinogenic and endocrine-disrupting effects. DINP, DIDP, and DEP are considered safer alternatives.

SECTION 12: TOXICOLOGICAL INFORMATION

SECTION 13: GHS CLASSIFICATION

Signal Word: DANGER

Hazard Pictograms: GHS07 (Exclamation Mark), GHS08 (Health)

Hazard Statements (H-Codes):

SECTION 14: PRECAUTIONARY STATEMENTS (P-CODES)

SECTION 15: FIRST AID MEASURES

SECTION 16: FIRE-FIGHTING MEASURES

SECTION 17: ACCIDENTAL RELEASE MEASURES

SECTION 18: STORAGE AND SHELF LIFE

SECTION 19: PACKAGING OPTIONS

SECTION 20: TRANSPORT INFORMATION

SECTION 21: ENVIRONMENTAL INFORMATION

SECTION 22: REGULATORY INFORMATION

SECTION 23: OTHER NAMES AND DATABASE IDENTIFIERS

Phthalic Acid (Related Compound) – CAS 88-99-3

SECTION 24: QUICK REFERENCE TABLE

SECTION 25: CRITICAL NOTICES AND BEST PRACTICES

CRITICAL NOTICES:

1. Reaction with Water: Phthalic anhydride reacts violently with water in an exothermic reaction to form phthalic acid. Never add water to phthalic anhydride. Store in dry, airtight containers.

2. Sublimation: Phthalic anhydride sublimes above 130°C (solid to gas). When using molten form, closed systems and ventilation are required.

3. Sensitization Hazard: Repeated exposure may cause respiratory sensitization (asthma) and skin sensitization. Workers should be monitored for symptoms. Use respiratory protection.

4. Solidification: Below 131.6°C, molten phthalic anhydride solidifies. If solidification occurs in pipes or tanks, heat carefully (steam or hot water) – never use open flame.

5. Phthalates (Plasticizers): Phthalic anhydride is the primary raw material for phthalate plasticizers (DEHP, DINP, DIDP, BBP, DIBP), which are used to increase PVC flexibility. Some phthalates (DEHP, DBP, BBP) are restricted in many countries due to health concerns.

6. Phthalic Acid vs. Phthalic Anhydride: Phthalic acid (CAS 88-99-3) is formed by the hydrolysis of phthalic anhydride and is used as an intermediate in dyes, perfumes, saccharin, and phthalate production.

7. Saccharin Production: Phthalic anhydride is used in the production of the artificial sweetener saccharin.

8. Phthalocyanine Dyes: Phthalic anhydride is used in the production of bright blue and green phthalocyanine dyes.

BEST PRACTICE RECOMMENDATIONS:

• Storage: Store in a cool, dry, and well-ventilated area. Keep containers tightly closed. Protect from moisture.

• Handling: Use appropriate respiratory protection (dust mask or respirator). Use protective gloves, goggles, and face shield. Avoid dust formation.

• Molten Handling: Keep at 140-150°C. Use heated lines and tanks. Maintain under nitrogen atmosphere to prevent oxidation.

• Spill Management: Collect dry. Avoid contact with water. Neutralize residues with dilute base.

• Waste Management: Dispose of waste in accordance with local regulations. Controlled incineration is recommended.

LEGAL DISCLAIMER:

This Technical Data Sheet (TDS) is for informational purposes only and is prepared based on available technical data. The user is solely responsible for determining the suitability of the product for their specific application and for complying with all local, national, and international regulations. For complete safety, storage, handling, transport, waste, and regulatory compliance information, the official Safety Data Sheet (SDS/MSDS) provided by the manufacturer/supplier must be consulted. Phthalic anhydride is a corrosive and sensitizing substance and should be handled with extreme caution.