Butenoic acid is any of three monocarboxylic acids with an unbranched 4-carbon chain with 3 single bonds and one double bond; that is, with the structural formula âÂÂâÂÂâÂÂH (2-butenoic) or âÂÂâÂÂâÂÂH (3-butenoic). All have the chemical formula or .
These compounds are technically mono-unsaturated fatty acids, although some authors may exclude them for being too short. The three isomers are: