(3E)-4-[(Naphthalen-1-yl)amino]-pent-3-en-2-one hemihydrate.

The title compound, C15H15NO·0.5H2O, was prepared from α-naphthyl-amine and 2,4-penta-nedione in a 1:1 ratio. An intra-molecular N-H⋯O hydrogen bond in the N-naphthyl-pent-3-en-2-one mol-ecule involving the amine and carbonyl groups strengthens the structure. The water mol-ecule interacts with two symmetry-related N-naphthyl-pent-3-en-2-one mol-ecules viaby O-H⋯O hydrogen bonds.