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 HO(O=)C–CH=CH–CH2–H (2-butenoic) or HO(O=)C–CH2–CH=CH–H (3-butenoic). All have the chemical formula C3H5COOH or C4H6O2. These compounds are technically mono-unsaturated fatty acids, although some authors may exclude them for being too short. The three isomers are:
crotonic acid (trans-2-butenoic or (2E)-but-2-enoic acid) isocrotonic acid (cis-2-butenoic or (2Z)-but-2-enoic acid) 3-butenoic acid (but-3-enoic acid).
See also Methacrylic acid, also C3H5COOH but branched like isobutene; a.k.a. isobutenoic acid Butyric acid, C3H7COOH; a.k.a. butanoic acid Butenedioic acid
References