What Is Methacrylic Acid?
Methacrylic acid, known as alpha-methylacrylic acid or 2-methylpropenoic acid, is an unsaturated carboxylic acid and a clear, colorless liquid with a pungent odor. It plays a critical role in the chemical industry, particularly in the production of polymers and resins.
Uses of Methacrylic Acid
As a versatile synthetic material, methacrylic acid is foundational in creating water-soluble polymers, copolymers with vinyl compounds, and ion exchange resins. Its ester, methyl methacrylate, is vital for manufacturing acrylic resins used as organic glass in various applications, including aircraft windows, automotive glass, lighting fixtures, and contact lenses. Additionally, methacrylic acid finds use in dental materials, paints, paper processing, fiber treatments, adhesives, and electrical insulators.
Properties of Methacrylic Acid
With the formula CH2=C(CH3)COOH, methacrylic acid features a melting point of 15°C, a boiling point of 159°C, and a specific gravity of 1.015. It exhibits strong acidity and is prone to polymerization. To prevent unwanted polymerization, hydroquinone is often added as a stabilizer. Methacrylic acid enhances the adhesion, stability, and durability of acrylic resins against various environmental factors.
Production Methods of Methacrylic Acid
Methacrylic acid is produced industrially through the ACH method and the isobutylene method. The ACH method involves the conversion of acetone cyanohydrin into methacrylic acid via a series of chemical reactions, utilizing hazardous materials like hydrogen cyanide. The isobutylene method, preferred in Japan, involves the direct oxidation of isobutylene using a molybdenum-based catalyst. Recent developments also include a process starting from ethylene to synthesize methacrylic acid through propionic acid.
Both production methods highlight the chemical industry’s efforts to optimize efficiency and safety in producing this essential compound.