2-Azido-1-(4-methylphenyl)ethanone

In the molecule of the title compound, C9H9N3O, the angle formed by the least-squares line through the azide group with the normal to the plane of the benzene plane ring is 46.62 (16)°. The crystal structure features C—H⋯O hydrogen bonds, which link the molecules into zigzag chains running parallel to [010].

In the molecule of the title compound, C 9 H 9 N 3 O, the angle formed by the least-squares line through the azide group with the normal to the plane of the benzene plane ring is 46.62 (16) . The crystal structure features C-HÁ Á ÁO hydrogen bonds, which link the molecules into zigzag chains running parallel to [010].
The structure of the title compound ( Fig. 1) is similar to that of our recently published compound 2-azido-1-(4-fluorophenyl)ethanone (Yousuf et al., 2012) with the difference that the fluorophenyl ring is replaced by a toluene ring. The bond lengths and angles are similar to those found in the previously reported compound. The azide group is not linear (N3-N2-N1 = 170.84 (11)°) and the least-square line through it forms with the normal to the plane of benzene ring an angle of 46.62 (16)°. The crystal structure is stabilized by C-H···O intermolecular hydrogen bonds (Table 1) forming zig-zag chains parallel to the b axis (Fig. 2).
Experimental 1-p-Tolylethanone (8.32 mmol, 1.0 equiv.) was dissolved in acetonitrile (20 ml) in a round bottom flask. To the stirred mixture, p-toluene sulphonic acid (12.5 mmol, 1.5 equiv.) and N-bromosuccinimide (11.6 mmol, 1.4 equiv.) were added, and the mixtyre refluxed for 1 to 1.5 h until TLC analysis showed no starting material present. The reaction mixture was cooled to room temperature, sodium azide (24.9 mmol, 3.0 equiv.) was added and the mixture further stirred for 2 to 3 hrs followed by the addition of ice cooled water to quench the reaction. The reaction mixture was extracted with ethylacetate (25 ml × 2) and the combined organic layer were dried over anhydrous Na 2 SO 4 , filtered and concentrated in vacuum to get the crude product. The crude product was purified by flash silica gel chromatography (EtOAc/hexane, 1/9-3/7 v/v) to afford the crystalline title compound in 70% yield. The crystals were found to be suitable for single-crystal X-ray studies.
All chemicals were purchased from Sigma-Aldrich.

Refinement
H atoms were positioned geometrically with C-H = 0.93-0.97 Å, and constrained to ride on their parent atoms with U iso (H) = 1.2U eq (C) or 1.5U eq (C) for methyl H atoms. A rotating group model was applied to the methyl group.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. 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.