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

In the title compound, C 13H 17NO 3·0. 5H 2O, 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 ethyl-enic 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.