4-[(Z)-(2-Ethoxy-4-oxochroman-3-ylidene)methylamino]benzenesulfonamide monohydrate

In the molecule of the title compound, C18H18N2O5S·H2O, the heterocyclic ring adopts a twisted conformation, while the aromatic rings are oriented at a dihedral angle of 45.46 (3)°. Intramolecular C—H⋯O and N—H⋯O interactions result in the formations of planar five- and six-membered rings. In the crystal structure, N—H⋯O hydrogen bonds link the NH2 and SO2 groups through R 2 2(8) ring motifs, while C—H⋯O and N—H⋯O hydrogen bonds result in the formation of R 2 1(7) ring motifs. N—H⋯O and O—H⋯O hydrogen bonds link the uncoordinated water molecules, forming a polymeric network. A weak C—H⋯π interaction is also present.

In the molecule of the title compound, C 18 H 18 N 2 O 5 SÁH 2 O, the heterocyclic ring adopts a twisted conformation, while the aromatic rings are oriented at a dihedral angle of 45.46 (3) . Intramolecular C-HÁ Á ÁO and N-HÁ Á ÁO interactions result in the formations of planar five-and six-membered rings. In the crystal structure, N-HÁ Á ÁO hydrogen bonds link the NH 2 and SO 2 groups through R 2 2 (8) ring motifs, while C-HÁ Á ÁO and N-HÁ Á ÁO hydrogen bonds result in the formation of R 2 1 (7) ring motifs. N-HÁ Á ÁO and O-HÁ Á ÁO hydrogen bonds link the uncoordinated water molecules, forming a polymeric network. A weak C-HÁ Á Á interaction is also present.
In the crystal structure, N-H···O hydrogen bonds link the NH 2 and SO 2 groups through R 2 2 (8) ring motifs, while C-H···O and N-H···O hydrogen bonds (Table 1) result in the formations of R 2 1 (7) ring motifs (Bernstein et al., 1995). On the other hand, N-H···O and O-H···O hydrogen bonds (Table 1) link the lattice water molecules to form a polymeric network ( Fig.   2), in which they may be effective in the stabilization of the structure. There also exists a weak C-H···π interaction.

S2. Experimental
3-Formylchromone (0.174 g, 1 mmol) in ethanol (5-7 ml) was stirred with heating until dissolved, then catalytic amount of p-toluenesulfonic acid was added, followed by 4-aminobenzenesulfonamide (0.172 g, 1 mmol) in equal amount of ethanol. Reaction mixture was refluxed with stirring for 4 h. The clear yellow solution was kept overnight and solvent was evaporated to yield bright yellow crystalline solid. Product was recrystallized from a mixture of ethanol and acetone (1:1) to yield fine transparent yellow needles.

S3. Refinement
H atoms (for NH 2 , OH 2 and methine) were located in a difference Fourier map and their coordinates were refined. The  The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
A partial packing diagram of the title compound. Hydrogen bonds are shown as dashed lines. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.25 e Å −3 Δρ min = −0.22 e Å −3 Special details Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.