(1Z)-1-(2,4-Dichlorophenyl)ethan-1-one semicarbazone

In the title compound, C9H9Cl2N3O, the semicarbazone group is approximately planar, with an r.m.s deviation from the mean plane of 0.011 (2) Å. The dihedral angle between the least-squares planes through the semicarbazone group and the benzene ring is 38.76 (9)°. The crystal structure is further stabilized by N—H⋯O and C—H⋯O hydrogen bonding.

In the title compound, C 9 H 9 Cl 2 N 3 O, the semicarbazone group is approximately planar, with an r.m.s deviation from the mean plane of 0.011 (2) Å . The dihedral angle between the leastsquares planes through the semicarbazone group and the benzene ring is 38.76 (9) . The crystal structure is further stabilized by N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonding.

Comment
In organic chemistry, a semicarbazone is a derivative of an aldehyde or ketone formed by a condensation between a ketone or aldehyde and semicarbazide. They find immense applications in the field of synthetic chemistry, such as medicinal chemistry (Warren et al., 1977), organometallics (Chandra & Gupta, 2005), polymers (Jain et al., 2002) and herbicides (Pilgram, 1978). 4-Sulphamoylphenyl semicarbazones were synthesized and were found to possess anticonvulsant activity (Yogeeswari et al., 2004). Keeping in view of their biological importance, we hereby reporting crystal structure of the semicarbazone of commercial importance.
Experimental 3.16 g (28.3 mmol) of semicarbazide hydrochloride and 2.83 g (34.5 mmol) of crystallized sodium acetate was dissolved in 25 ml of water (Furniss et al., 1978). The reaction mixture was stirred at room temperature for 10 minutes. (5.0 g, 26.5 mmol) of 2,4-dichloroacetophenone in 25 ml of ethanol was then added and the mixture stirred well for 6 h. The separated semicarbazone was filtered, washed with chilled water and recrystallized from an ethanol-DMF mixture. Yield was found to be 5.23 g, 86.02%. M.p. 501-503 K.

Refinement
H atoms were positioned geometrically (C-H = 0.93-0.96 Å) and refined using a riding model with U iso (H) = 1.2U eq (C) and 1.5U eq (methyl C). A rotating-group model was used for the methyl groups. The nitrogen H atoms were located from the difference Fourier map [N-H = 0.85 (3)-0.91 (3) Å] and allowed to refine freely. Fig. 1. The molecular structure of (I), showing 50% probability displacement ellipsoids and the atom numbering scheme.

Figures
sup-2 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 Rfactors(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.