N-(2,4-Difluorophenyl)-5-methyl-1,2-oxazole-4-carboxamide hemihydrate

In the title compound, C11H8F2N2O2·0.5H2O, the dihedral angle between the benzene and isoxazole rings is 8.08 (3)°. In the crystal, the components are linked by O—H⋯N and N—H⋯O hydrogen bonds, in which the water molecule acts as both a donor and an acceptor, into a tape with an R 4 4(16) graph-set motif along the a axis. The water molecule is located on a twofold rotation axis. The methyl H atoms were treated as disordered groups over two sites with a refined site-occupancy ratio of 0.48 (6):0.52 (6).

In the title compound, C 11 H 8 F 2 N 2 O 2 Á0.5H 2 O, the dihedral angle between the benzene and isoxazole rings is 8.08 (3) . In the crystal, the components are linked by O-HÁ Á ÁN and N-HÁ Á ÁO hydrogen bonds, in which the water molecule acts as both a donor and an acceptor, into a tape with an R 4 4 (16) graph-set motif along the a axis. The water molecule is located on a twofold rotation axis. The methyl H atoms were treated as disordered groups over two sites with a refined siteoccupancy ratio of 0.48 (6):0.52 (6).
After stirring for 20 minutes, the precipitated 2,4-difluoroaniline hydrochloride was filtered off and washed with 10 ml portions of acetonitrile, and the combined filtrates were concentrated under reduced pressure. 8.7g (73.10% yield) of white crystalline N-(2,4-difluorophenyl)-5-methylisoxazole-4-carboxamide were thus obtained. Crystals of the title compound suitable for X-ray diffraction were obtained by slow evaporation of a toluene solution.

Refinement
H atoms of the water molecule were located in a difference Fourier map and refined as riding with O-H = 0.85 Å, with U iso (H) = 1.5 U eq . Carbon and nitrogen bound H atoms were placed at calculated positions and were treated as riding on the parent C or N atoms with C-H = 0.96 (methyl), 0.93 (methylene) and N-H = 0.88 Å, U iso (H) = 1.2 or 1.5 U eq (C, N).
The methyl H atoms are treated as disordered groups over two sites with a refined site-occupancy ratio of 0.48: 0.52 (6).
The hydrogen atoms involving the hydrogen bonding interaction perform not well when freely refined and it can not provide a reasonable basis for discussion of hydrogen bonding interaction supplementary materials sup-2 Acta Cryst. (2012). E68, o2325

Figure 1
The structure of the title compound, showing the atomic numbering scheme. Non-H atoms are shown with 30% probability displacement ellipsoids.  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.28 e Å −3 Δρ min = −0.18 e Å −3 Extinction correction: SHELXL97 (Sheldrick, 2008), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.0247 (19) Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (