Butenoic acid

Isomers of butenoic acid

Crotonic acid

Isocrotonic acid

3-Butenoic acid

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–CH
₂–H (2-butenoic) or HO(O=)C–CH
₂–CH=CH–H (3-butenoic). All have the chemical formula C
₃H
₅COOH or C
₄H
₆O
₂.

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).^[1]^[2]

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[1]

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