Acrylic acid is an organic compound with the formula CH₂=CHCOOH. It is the simplest unsaturated carboxylic acid, consisting of a vinyl group directly attached to a carboxyl terminal. This colorless liquid has a distinct sour odor. It is miscible with water, alcohols, ethers, and chloroform. More than one million tons are produced annually.
Acrylic acid is used in various industrial and everyday applications. By polymerization or esterification, different acrylic derivatives are obtained. These derivatives are used in industries such as glass, ceramics, soap, fertilizers, paint, textiles, cosmetics, pharmaceuticals, adhesives, sealants, water treatment, and many others.
Chemical and Physical Properties of Acrylic Acid:
• Molecular weight: 72.06 g/mol
• Melting point: 13°C
• Boiling point: 141°C
• Density: 1.05 g/mL
• Solubility: High in water and alcohol, moderate in ether, low in chloroform
• pKa value: 4.25
Production Methods of Acrylic Acid:
• Propylene Oxidation Method: This is the most common production method for acrylic acid. Propylene undergoes a two-step oxidation reaction to form acrolein and then acrylic acid. Water is also produced as a byproduct.
• Ethylene Oxide-Hydrocyanic Acid Condensation Method: This is an alternative production method for acrylic acid. Ethylene oxide is condensed with hydrocyanic acid to produce cyanoacetaldehyde, which is then hydrolyzed to form acrylic acid. Ammonia is also produced in this process.
• Acetylene-Carbon Monoxide-Water Reaction Method: This is an older production method for acrylic acid. Acetylene reacts with carbon monoxide and water to produce propionaldehyde, which is then oxidized to acrylic acid. Hydrogen is also generated as a byproduct.
Applications of Acrylic Acid:
• Glass Industry: Acrylic acid is used in the glass industry. Acrylic polymers applied to glass surfaces enhance light transmission and durability. Acrylic adhesives are also used for glass bonding.
• Ceramics Industry: Acrylic acid is utilized in the ceramics industry. Acrylic polymers added to ceramic mixtures regulate fluidity and firing properties. Acrylic coatings are also used for polishing ceramics.
• Soap Industry: Acrylic acid is used in soap manufacturing. It is involved in the saponification of fats used in soap production. Acrylic polymers also enhance foam formation and improve resistance to hard water.
• Fertilizer Industry: Acrylic acid is used in fertilizer production. It prevents the explosion of ammonium nitrate in fertilizers. Acrylic polymers also improve water retention in fertilizers and enhance nutrient absorption by plants.
• Paint Industry: Acrylic acid is widely used in the paint industry. It increases the solubility of resins and pigments in paints. Acrylic polymers also improve paint adhesion, drying time, and gloss.
• Textile Industry: Acrylic acid is applied in the textile industry. It is used in fabric dyeing, printing, and finishing processes. Acrylic polymers enhance fabric colors, provide softness, and prevent wrinkling.