Illustrated Glossary of Organic Chemistry

Maleic acid: A four carbon molecule consisting of two carboxylic acid groups bonded to the opposite ends of a carbon-carbon double bond, in a cis configuration. IUPAC name (Z)-butenedioic acid.

Molecular structure of maleic acid.

Diethyl malonate
An ester
Maleic anhydride
An anhydride
Some maleic acid derivatives.