数据之源，洞见之始

Metabolite Card

Note

Maleic acid is a dicarboxylic acid, a molecule with two carboxyl groups. It consists of an ethylene group flanked by two carboxylic acid groups. Maleic acid is the cis isomer of butenedioic acid, whereas fumaric acid is the trans isomer. The cis isomer is the less stable one of the two; the difference in heat of combustion is 22.7 kJ/mol. The physical properties of maleic acid are very different from that of fumaric acid. Maleic acid is soluble in water whereas fumaric acid is not and the melting point of maleic acid (130 - 131 oC) is also much lower than that of fumaric acid (287 oC). Maleic acid is converted into maleic anhydride by dehydration, to malic acid by hydration, and to succinic acid by hydrogenation. Maleic acid is used in making polyesters for fibre-reinforced laminated moldings and paint vehicles. More specifically it is used in the manufacture of phthalic-type alkyd and polyester resins, surface coatings, copolymers, plasticizers, lubricant additives and agricultural chemicals. It is also found in adhesives and sealants and as a preservative for oils and fats. In the natural world, maleic acid has been identified in ginseng, pineapple, cacao plants, sour cherries and corn. A large number of microbes are able to convert maleic acid to D-malate using the enzyme maleate hydratase (PMID: 1444397).