Maleic Anhydride is a highly important chemical intermediate widely used across multiple industries including polyester resins, coatings, pharmaceuticals, agrochemicals, and industrial additives.
It appears as a white to colorless crystalline solid with a sharp, acrid odor, and serves as a key raw material in the manufacture of unsaturated polyester resins (UPR), copolymers, and specialty chemicals.

Chemical Structure

Chemical Name (IUPAC): 2,5-Furandione
Molecular Formula: C₄H₂O₃
Structure Type: A reactive five-membered cyclic anhydride derived from maleic acid, exhibiting high electrophilicity — ideal for Diels–Alder, polymerization, and surface-modification reactions.

Physical and Chemical Properties

Property	Specification
Appearance	White or colorless crystalline solid with a pungent odor
Molecular Weight	98.06 g/mol
Density (20 °C)	~1.48 g/cm³
Melting Point	52–56 °C
Boiling Point	~202 °C at 760 mmHg (decomposes upon heating)
Vapor Pressure (20 °C)	~0.16 mmHg
Solubility in Water (25 °C)	~79 g/L – hydrolyzes rapidly to maleic acid
Stability	Moisture-sensitive; reacts exothermically with water
Odor	Sharp, irritating

Key Advantages

Essential intermediate for unsaturated polyester resins (UPR) used in FRP composites, coatings, and laminates
Starting material in the synthesis of 1,4-butanediol, tetrahydrofuran (THF), γ-butyrolactone (GBL), and other specialty monomers
Used in surfactants, agrochemical formulations, and personal care ingredients
Base component for engineering copolymers such as styrene–maleic anhydride (SMA)
High reactivity enables efficient chemical modifications and surface treatments

Limitations and Hazards

Corrosive and strong irritant to skin, eyes, and respiratory tract
May cause skin and respiratory sensitization (H317, H334)
Dust may form explosive mixtures with air — proper dust control required
Hydrolyzes quickly in humid air to maleic acid, reducing stability
Requires dry, controlled storage and careful handling

Applications

Polyester Resins (UPR): Used in FRP, coatings, adhesives, and gel coats
Plasticizers & PVC Modifiers: Improves flexibility and chemical resistance
Pharmaceuticals: Intermediate in the synthesis of active pharmaceutical ingredients (APIs)
Agrochemicals & Detergents: Intermediate for surfactants, wetting agents, and additives
Copolymers: Base monomer for SMA, ABS modification, and compatibilizers in polymer blends

Safety and Handling Information

GHS Classification: Corrosive / Harmful
Signal Word: ⚠️ DANGER

Hazard Statements:

H302: Harmful if swallowed
H314: Causes severe skin burns and eye damage
H317: May cause allergic skin reaction
H335: May cause respiratory irritation
H373: May cause damage to organs through prolonged exposure

Recommended PPE:

Chemical-resistant gloves (nitrile or butyl rubber)
Protective clothing and safety goggles or face shield
Dust mask or approved respirator (for airborne particulates)

Storage and Stability

Store in a cool, dry, well-ventilated area
Keep containers tightly closed and protected from moisture
Avoid exposure to heat, sparks, or open flames
Use non-corrosive, moisture-proof packaging (lined drums or bags)

Emergency Measures

Skin/Eye Contact: Flush immediately with water for at least 15 minutes; seek medical attention
Inhalation: Move person to fresh air; seek medical advice if symptoms persist
Ingestion: Do not induce vomiting; seek immediate medical assistance
Spillage: Avoid dust formation; collect dry and store safely for disposal

Summary

Maleic Anhydride is a versatile and reactive intermediate essential in polyester resins, copolymers, and chemical synthesis.
Its high reactivity, industrial relevance, and broad compatibility with organic systems make it a key material in modern chemical production — provided it is handled under strict safety and storage protocols.