2-Hydroxy-N′-methylbenzohydrazide

In the title molecule, C8H10N2O2, there is an intramolecular hydrogen bond involving the hydroxy group and the O atom of the carbonyl group. The dihedral angle between the benzene ring and the amide fragment is 87.16 (10)°. The C—N—N—C torsion angle is 88.87 (18)°. In the crystal, N—H⋯N and N—H⋯O hydrogen bonds connect molecules into chains along [100]. In addition, there is a weak C—H⋯π interaction.

In the title molecule, C 8 H 10 N 2 O 2 , there is an intramolecular hydrogen bond involving the hydroxy group and the O atom of the carbonyl group. The dihedral angle between the benzene ring and the amide fragment is 87.16 (10) . The C-N-N-C torsion angle is 88.87 (18) . In the crystal, N-HÁ Á ÁN and N-HÁ Á ÁO hydrogen bonds connect molecules into chains along [100]. In addition, there is a weak C-HÁ Á Á interaction.
Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL. Materials such as the title compound and the recently determined crystal structure of 4-(5-bromo-2-hydroxybenzoyl)thiosemicarbazide (Jin, 2007) are potentially important ligands and intermediates (Zhang et al., 2012;Jin et al., 2011). Part of our studies is to find new methods to synthesize derivatives of saylicylic acid and study their structures and activities. In this paper, the X-ray crystal structure determination of the title compound (I) is reported.
The molecular structure of the title compound is shown in Fig. 1. The geometric parameters of (I) agree with those related in the structure published by Jin (2007). The atoms C1-C7/O1/O2 are essentially co-planar with an r.m.s deviation of 0.016Å. There is intramolecular hydrogen bond involving the hydroxy group and the O atom of the carbonyl group. In the crystal, N-H···N and N-H···O hydrogen bonds connect molecules into one-dimensional chains along [100] (see Table 1 and Fig. 2). In addition, there is a weak intermolecular C-H···π interaction. There are some intermolecular contacts which are shorter than the sums of the van der Waals radii of the atoms involved i.e. N1···N2 iv

Experimental
Methyl salicylate (15.2 g, 0.10 mol) and methylhydrazine in aqueous solution (23.0 g, 0.20 mol) were mixed at 273 K and stirred for 1 h. The reaction mixture was slowly warmed to 338 K and refluxed for a further 12 h. After the resulting mixture was concentrated under reduced pressure, the residue was adjusted to pH 8 with acetic acid. After staying for 1 h in a refrigerator, the resulting precipitate was filtered and rinsed with ethyl ether. A white solid formed was recrystallized to give 7.0 g (42% yield) of N-methyl-salicylhydrazide. A block-like crystal suitable for X-ray analysis was grown from a solution of the title compound in methanol at room temperature by slow evaporation.

Refinement
The hydroxy H atom was located in a difference Fourier map and refined isotropically [O-H = 0.91 (2) Å] with U iso (H) = 1.5U eq (O). The H atoms bonded to N atoms were located in a difference Fourier map and refined isotropically (N-H = 0.859 (19) and 0.884 (18) Å) with U iso (H) = 1.2U eq (N). All other H atoms were included in a riding-model approximation, with C-H distances of 0.93 (aromatic H atoms) and 0.96 Å (methyl atoms). The isotropic displacement parameters were set to 1.2U eq (C) for the aromatic H atoms and to 1.5U eq (C) for the methyl H atoms.

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.