Either of two isomers with the formula HCOOHC=CHCOOH. Both compounds can be regarded as derivatives of ethene in which a hydrogen atom on each carbon has been replaced by a –COOH group. The compounds show cis-trans isomerism. The trans form is fumaric acid (r.d. 1.64; sublimes at 165°C) and the cis form is maleic acid (r.d. 1.59; m.p. 139–140°C). Both are colourless crystalline compounds used in making synthetic resins. The cis form is rather less stable than the trans form and converts to the trans form at 120°C. Unlike the trans form it can eliminate water on heating to form a cyclic anhydride containing a –CO.O.CO– group (maleic anhydride). Fumaric acid is an intermediate in the Krebs cycle.
Butenedioic acid
- primary wave
- primary winding
- primase
- primate city
- Primates
- prime
- prime decomposition
- prime element
- prime focus
- prime ideal
- prime implicant
- prime knot
- prime matter
- prime meridian
- prime mover
- prime number theorem
- prime rate
- prime subfield
- prime vertical
- priming
- primitive
- primitive circle
- primitive element
- primitive node
- primitive(nth root of unity)