Pentenoic acid
Pentenoic acid is any of five mono-carboxylic acids whose molecule has an unbranched chain of five carbons connected by three single bonds and one double bond. That is, any compound with one of the formulas HO(O=)C−CH=CH−CH2−CH3 (2-pentenoic), HO(O=)C−CH2−CH=CH−CH3 (3-pentenoic), or HO(O=)C−CH2−CH2−CH=CH2 (4-pentenoic). In the IUPAC-recommended nomenclature, these acids are called pent-2-enoic, pent-3-enoic, and pent-4-enoic, respectively. All these compounds have the empirical formula C
5H
8O
2.
Pentenoic acids are technically mono-unsaturated fatty acids, although they are rare or unknown in biological lipids (fats, waxes, phospholipids, etc.). A salt or ester of such an acid is called a pentenoate.