Introduction to Fumaric Acid
Fumaric acid is an oxidized form ofmaleic acid, which is a dicarboxylic acid that contains two carboxylic acid groups. It is an off-white solidwith a melting point of 289°C and a boiling point of 300°C. In its pure form, fumaric acid is odorless and has a sour taste. It is poorly soluble in water but highly soluble in alcohol and ether.
Chemical Properties of Fumaric Acid
Chemically, fumaric acid is known as (2E)-butenedioic acid with a molecular formula of C4H4O4 and molecular weight of 116.07 g/mol. Its systematic IUPAC name is (2E)-but-2-enedioic acid.Fumaric acid has two carboxyl groups (-COOH) that are located at the 1 and 4 positions on the ethylene bridge of the butenedioic acid structure. This gives it a cis configuration, meaning both carboxyl groups are on the same side of the double bond. It is the cis isomer of maleic acid which has the trans configuration.
Applications of Fumaric Acid
Due to its acidity and reactivity, fumaric acid finds many applications:
Unsaturated Polyester Resins: Fumaric Acid is widely used in manufacturing unsaturated polyester resins which are used to make reinforced plastics. As a comonomer, it improves cured resin properties like flexibility and chemical resistance.
Alkyd Resins: It is also used in making alkyd resins, which are used in paints, varnishes and other protective coatings. Fumaric acid improves resin compatibility, flexibility and water resistance.
Food Additive: Being recognized as safe, fumaric acid is approved as a food additive with E number E297. It is commonly used in baked goods, frozen foods, snacks and beverages as an acidity regulator.
Animal Feed: Fumaric acid supplementation in animal feed helps improve growth rates and feed conversion efficiency in poultry and swine. It acts as an alternative to antibiotics in feed.
Pharmaceutical Excipient: The acid finds usage as an excipient in pharmaceutical formulations. It aids in increasing solubility and bioavailability of medications.
Personal Care Products: Fumaric acid moisturizes skin and helps treat psoriasis. It is used in anti-dandruff shampoos, facial cleansers, and other personal care products.
Manufacturing Process of Fumaric Acid
Fumaric acid is commercially produced by the hydration of maleic anhydride through a vapor phase reaction and condensation. Maleic anhydride reacts with water in a double substitution reaction to yield fumaric acid. The main reaction steps are:
1) Maleic anhydride (C4H2O3) and steam are fed into the reactor at high temperature (300-400°C).
2) Maleic anhydride reacts with steam to form maleic acid ((HOOC-CH=CH-COOH)) in vapor phase.
3) Maleic acid undergoes rearrangement to the more stable cis isomer - fumaric acid.
4) The reaction products including fumaric acid vapor are rapidly cooled and condensed.
5) The crude fumaric acid obtained is purified by recrystallization to obtain pure white crystalline fumaric acid.
6) The purified fumaric acid crystals are dried and packed for industrial applications.
This commercial process is cost-effective for large-scale production of fumaric acid from readily available maleic anhydride. The overall yield of the process is around 85-90%.
Conclusion
In summary, fumaric acid is an important unsaturated dicarboxylic acid with widespread applications in industries such as plastics, coatings, food, pharmaceuticals and personal care products. Though available naturally in certain plant and fungus species, it is mainly produced commercially through the hydration of maleic anhydride. Proper understanding of its chemical and physical properties aids in optimizing its production and expanding its product applications.
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