Crystal structures of two 4H-chromene derivatives: 2-amino-3-cyano-4-(3,4-di-chloro-phen-yl)-7-hy-droxy-4H-benzo[1,2-b]pyran 1,4-dioxane monosolvate and 2-amino-3-cyano-4-(2,6-di-chloro-phen-yl)-7-hy-droxy-4H-benzo[1,2-b]pyran.

In the title compounds, C16H9Cl2N2O2·C4H8O2 and C16H9Cl2N2O2, the bicyclic 4H-chromene cores are nearly planar with maximum deviations of 0.081 (2) and 0.087 (2) Å. In both structures, the chromene derivative mol-ecules are linked into centrosymmetric dimers by pairs of N-H⋯O hydrogen bonds, forming R2 2 (16) motifs. These dimers are further linked in the 3,4-di-chloro-phenyl derivative by N-H⋯N hydrogen bonds into double layers parallel to (100) and in the 2,6-di-chloro-phenyl derivative by O-H⋯N hydrogen bonds into ribbons along the [10] direction. In the 3,4-di-chloro-phenyl derivative, the 1,4-dioxane solvent mol-ecules are connected to the chromene mol-ecules via O-H⋯O hydrogen bonds. © Silambarasan et al. 2019.