Maleic anhydride (MA) is an organic compound with the formula C2H2(CO)2O. It is the acid anhydride of maleic acid, which means that it is formed by removing water from two molecules of maleic acid. MA is a colorless or white solid with an acrid odor. It is produced industrially on a large scale for applications in coatings and polymers.
Structure and Properties of MA
The structure of MA consists of a central carbon atom that is bonded to two oxygen atoms and two double-bonded carbon atoms. The double bonds in the MA structure are responsible for its unsaturated nature, which is the source of its reactivity and versatility as a chemical intermediate.
The MA structure has a cyclic shape, which makes it a member of the furan family of heterocyclic compounds. The cyclic shape also gives MA some aromatic character, which means that it has a stable ring of electrons that are shared among the atoms. The aromatic character of MA increases its stability and reduces its reactivity compared to other unsaturated compounds.
The MA structure has some physical and chemical properties that are important for its industrial applications. Some of these properties are:
- Melting point: 52.8 °C
- Boiling point: 202 °C
- Density: 1.48 g/cm3
- Solubility: Reacts with water to form maleic acid
- Vapor pressure: 0.2 mmHg at 20 °C
- Flash point: 102 °C
- Explosive limits: 1.4%-7.1%
Applications of MA
MA is mainly used as a chemical intermediate to produce other compounds that have various industrial uses. Some of the major applications of MA are:
- Production of unsaturated polyester resins (UPR), which are used for making fiberglass, plastic bottles, pipes, tanks, etc.
- Production of alkyd resins, which are used for making paints, varnishes, coatings, etc.
- Production of fumaric acid and malic acid, which are used as food additives, flavor enhancers, etc.
- Production of 1,4-butanediol (BDO), which is used for making polyurethanes, polyesters, spandex, etc.
- Production of tetrahydrofuran (THF), which is used as a solvent and for making polyvinyl chloride (PVC), etc.
The following table shows some data on the global production and consumption of MA in 2020:
| Region | Production (kilotons) | Consumption (kilotons) |
|---|---|---|
| Asia | 2,100 | 1,900 |
| Europe | 600 | 500 |
| North America | 400 | 300 |
| Rest of the world | 100 | 100 |
| Total | 3,200 | 2,800 |
Extended Reading:
Maleic anhydride wastewater treatment process
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Use of maleic anhydride