(E)-N-Butyl-3-(3,4-dihy­droxy­phen­yl)acryl­amide hemihydrate

In the title compound, C₁₃H₁₇NO₃·0.5H₂O, a new caffeic acid amide derivative, the solvent water mol­ecule lies on a twofold axis and the terminal ethyl group appears disordered with occupancy factors of 0.525 (6) and 0.475 (6). The benzene ring makes an angle of 17.3 (2)° with the C=C—C—O linker. The presence of an ethyl­enic spacer in the caffeic acid amide mol­ecule allows the formation of a conjugated system, strongly stabilized through π-electron delocalization. The C=C double bond in the linker is trans, similar to those previously reported in caffeic esters. The crystal is stabilized by O—H...O, N—H...O and C—H...O hydrogen bonds. The mol­ecules of the caffeic acid amide form a supermolecular planar structure through O—H...O hydrogen bonds between a hy­droxy group of one caffeic acid mol­ecule and a carbonyl O atom of another. These planes inter­act via C—H...O, O—H...O and N—H...O hydrogen bonds to form a three-dimensional network.