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 Both compounds can be regarded as derivatives of ethene in which a hydrogen atom on each carbon has been replaced by a –COOH group.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
- profit-and-loss account
- profit maximization
- profit motive
- profit-related pay
- profit-sharing
- profit-sharing arrangement
- profit-taking
- profit warning
- pro-foreland basin
- profundal
- Proganochelys quenstedii
- progenesis
- progeny
- progesterone
- progestogen
- proglacial
- proglottid
- progradation
- prograde metamorphism
- prograde motion
- prograde orbit
- program
- program analysis
- program compatibility
- program control