4-[2-(1-Acetyl-2-oxopropylidene)hydrazino]-N-(pyrimidin-2-yl)benzenesulfonamide

In the title compound, C15H15N5O4S, the dihedral angle between the pyrimidine and benzene rings is 84.56 (2)°. Intramolecular hydrazine–carbonyl N—H⋯O and intermolecular sulfonamide–pyridimine N—H⋯N hydrogen bonds stabilize the molecular and crystal structures, respectively.

In the title compound, C 15 H 15 N 5 O 4 S, the dihedral angle between the pyrimidine and benzene rings is 84.56 (2) . Intramolecular hydrazine-carbonyl N-HÁ Á ÁO and intermolecular sulfonamide-pyridimine N-HÁ Á ÁN hydrogen bonds stabilize the molecular and crystal structures, respectively.
KKU and SU are grateful to the UGC, New Delhi, for financial support.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: TK2450).
Within the molecule, there is a prominent intramolecular interaction between the hydrazo-N-H and the carbonyl-O3 atoms,  Table 1.

Experimental
Compound (I) was synthesized using the literature procedure (Novinson et al., 1976) as follows. Sulfadiazine (2 mmol, 501 mg) and sodium nitrite (~4 mmol, 300 mg) were dissolved separately in conc. HCl (2 ml) and distilled water (10 ml), respectively, followed by their cooling on crushed ice. The cooled sodium nitrite solution was added to the sulfdiazine solution with constant stirring while maintaining ice-cold temperature. The resulting yellow solution was added to a mixture of acetyl acetone (2 mmol, 0.2 ml) and sodium acetate (~37 mmol, 3 g) in distilled water (15 ml) with continuous stirring.
The stirring was continued for 2 h maintaining the temperature of the reaction vessel between 293-298 K. The resulting solids were filtered, washed with water, ethanol and finally, by diethyl ether. The crude product was recrystallized from a water-ethanol mixture (50% v/v) and dried in vacuo. Crystals of (I) were developed by layering its supersaturated solution in ethanol with diethylether and leaving for a few days.

Refinement
All H atoms were placed in the idealized positions with C-H = 0.93-0.96 Å and N-H = 0.86 Å, and with U iso (H) = 1.2-1.5 U eq (C, N).

Figures
Fig . 1. The molecular structure of (I) showing the atom-labeling scheme. Displacement ellipsoids are drawn at the 50% probability level.