Organic substance maleic acid is the cis-isomer of butenedioic acid
Butenedioic acid's cis isomer, Maleic Acid, actually exists. As a result, it is referred to as cis-butenedioic acid in science. On the other hand, fumaric acid is the name of the trans isomer of butenedioic acid. The two chemical compounds maleic acid and fumaric acid are hence isomers of one another. However, malic acid should not be confused with this maleic acid. Malic acid is 2-hydroxybutanedioic acid, while Maleic Acid is cis-but-2-enedionic acid. Therefore, the main distinction between malic acid and fumaric acid/maleic acid is that the second carbon in malic acid has a hydroxyl group attached, whereas the second carbon in the structures of fumaric acid and maleic acid has a double bond.
