Maleic Acid is also known as cis-butenedioic acid, toxilic acid, cis-1,2-Ethylenedicarboxylic acid. It is commercially available as the crystalline material or as an aqueous solution in water (40%). It may contain fumaric acid (0.1%) and water (less than 0.5%) as impurities. It is mainly used for making Maleate Salts of Bulk-Drugs like Pheneramine Maleate, Chloropheneramine Maleate and others. It is also used to prevent rancidity in oils.
Maleic acid is not very important economically, since the anhydride is easier to use. It is used in the manufacture of phthalic-type alkyd and polyester resins, surface coatings, copolymers, plasticizers, lubricant additives and agricultural chemicals; in adhesives and sealants; as a preservative for oils and fats; organic synthesis; dyeing and finishing wool, cotton and silk; and preparing the maleate salts of antihistamines and similar drugs.
Maleic acid is a white crystals easily soluble in water, acetone, and alcohol, is an unsaturated organic dibasic acid which carboxylic acid groups are next to each other in the cis form. Its trans form isomer is fumaric acid, both are used in making polyesters, alkyd resins, plasticizers and lubricating oils. Maleic acid is prepared commercially by the oxidation of benzene. Maleic acid is used in the manufacture of fumaric acid and other chemical products as a carboxylating agent. It is used as an oil and fat preservative and food acidulant.