Phthalic anhydride

Phthalic Anhydride is an important industrial chemical, primarily used in the production of plasticizers for plastics. It is a white crystalline solid that is the anhydride of phthalic acid.

History

Phthalic Anhydride was first reported in 1836 by Auguste Laurent. More practical methods for its production were developed in the late 19th and early 20th centuries, primarily involving the oxidation of naphthalene or o-xylene.

Production

The primary industrial route to Phthalic Anhydride is the oxidation of o-xylene or naphthalene, typically using an vanadium pentoxide catalyst. The process occurs in three steps: the formation of the initial radical, the conversion of the radical to an intermediate, and the conversion of the intermediate to Phthalic Anhydride.

Uses

The primary use of Phthalic Anhydride is in the production of plasticizers for plastics. These plasticizers, primarily phthalates, are used to increase the flexibility and durability of PVC and other plastics. Phthalic Anhydride is also used in the production of dyes, perfumes, pharmaceuticals, and resins.

Health and Safety

Exposure to Phthalic Anhydride can cause irritation to the eyes, skin, and respiratory tract. It is also a suspected respiratory sensitizer. Long-term exposure can lead to more serious health effects, including asthma and damage to the eyes and skin.

Environmental Impact

Phthalic Anhydride can contribute to air pollution, as it is a volatile organic compound that can react with other pollutants to form ozone. It is also toxic to aquatic life.

See Also

• Phthalic acid
• Plasticizers
• Phthalates
• Vanadium pentoxide