Phthalic anhydride is a colorless, solid chemical compound used in the production of many chemicals and industrial products. It is mainly used as a raw chemical in the production of plastics, resins, dyes, softeners, and also in the pharmaceutical and cosmetic industries. Phthalic anhydride was first reported in 1836 by Auguste Laurent. Early procedures involved liquid-phase mercury-catalyzed oxidation of naphthalene. The modern industrial variant process instead uses vanadium pentoxide as the catalyst in a gas-phase reaction with naphthalene using molecular oxygen. The overall process involves oxidative cleavage of one of the rings and loss of two of the carbon atoms as carbon dioxide. An alternative process involves oxidation of the two methyl groups of o-xylene, a more atom-economical process. In industry, this compound is used as a key chemical in the production of polyesters and various additives. Phthalic anhydride decomposes easily at high temperatures, humidity, and alkaline environments and reacts with water to produce phthalic acid.
Technical Characteristics
| Chemical Formula | C8H4O3 |
| Other names | – 2-Benzofuran-1,3-dione – Isobenzofuran-1,3-dione – Phthalic anhydride |
| CAS Number | 85-44-9 |
| Molar mass | 148.1 g/mol |
| Melting Point | 131.6 °C |
| Boiling Point: | 295 °C sublimates |
| Density | 1.53 g/cm3 (solid) |
| Flash point | 152 ºC |
| Solubility in water | 0.62 g/100g (20-25 °C) |
| Appearance | white flake |
Applications
- Synthesis of plasticizers, alkyd resins and unsaturated polyester resins
- Production of softeners such as DIDP, DOP, BBP and DINP
- Compositions of the main plasticizers for polyvinyl chloride resins
- A monomer for synthetic resins such as glyptal, alkyd resins and polyester resins
- Precursor of some chemicals like fluorescein and xanthene dyes
Environmental impact of Phthalic anhydride
Phthalic anhydride can have negative effects on the environment. If this chemical enters water bodies illegally, it can cause water pollution and be toxic to aquatic organisms. Phthalic anhydride vapors can also harm the atmosphere and, if released into the soil, can cause soil pollution and negative effects on ecosystems. For this reason, proper management and control of the release of this substance into the environment is of great importance.
Safety Measures and Regulations for Handling Phthalic anhydride
When working with phthalic anhydride, appropriate personal protective equipment such as gloves, safety glasses and protective clothing should be used to prevent direct contact with the skin and eyes. This substance should be stored in well-ventilated areas and away from sources of heat and fire, as its vapors can be dangerous. Upon contact with water, phthalic anhydride converts to phthalic acid, so to prevent possible damage, it should be avoided in humid environments and its waste should be managed according to environmental regulations.
Packing
Phthalic anhydride cis supplied in 25 kg bags or 1000 kg big bags.