(Z)-3-Hy-droxy-4-(4-meth-oxy-phen-yl)but-3-en-2-one.

The title compound, C11H12O3, is potentially a butane-2,3-dione derivative but exists in the enol form in the solid state. In the mol-ecule, the 3-hy-droxy-but-3-en-2-one, benzene and methoxyl fragments are almost co-planar. The 3-hy-droxy-but-3-en-2-one fragment is almost planar with an r.m.s. deviation of 0.040 Å. The dihedral angle between this plane and that of the benzene ring is 5.88 (4)°. The 4-meth-oxy group also lies close to the benzene ring plane, with deviations of 0.0206 (11) Šfor the O and 0.087 (2) Šfor methyl C atoms. Hence, the whole mol-ecule is almost planar with an r.m.s. deviation of 0.0617 Šfrom a plane through all 14 non-H atoms. In the crystal, the molecules are linked by O-H⋯O hydrogen bonds, generating [010] chains.