Definition

Noun: A colorless, crystalline organic acid. It is an unsaturated dicarboxylic acid with the chemical formula C₄H₄O₄. It is found in some unripe fruits and is primarily used in industrial chemical synthesis.

Examples of Usage

• The presence of maleic acid contributes to the sour taste of unripe apples.
• Maleic acid is a key raw material in the production of certain plastics and coatings.
• Chemists often study the isomerization of maleic acid to fumaric acid.

Advanced Usage

• As a chemical intermediate: In industrial chemistry, maleic acid is described as a crucial intermediate for manufacturing products like agricultural chemicals, dyes, and plasticizers.
  • The facility converts maleic acid into anhydride for resin production.
• In scientific contexts: The term is used precisely to distinguish it from its stereoisomer, fumaric acid, highlighting differences in physical properties and biological activity.
  • Unlike its isomer fumaric acid, maleic acid is toxic and not part of the human metabolic cycle.

Variants and Related Words

• Maleic anhydride (noun): The anhydride form of maleic acid, widely used in the production of polyester and alkyd resins.
• Maleate (noun): A salt or ester of maleic acid.

Synonyms

• (scientific synonym)
• (an older, less common name)

Notes on Different Meanings

The term maleic acid has a single, specific meaning in chemistry and biology. It does not have common idiomatic or figurative uses. Its definition is strictly tied to its chemical identity and industrial applications.

Noun

1. a colorless crystalline compound found in unripe fruit (such as apples or tomatoes or cherries) and used mainly to make polyester resins