N-(4-Methylphenyl)formamide

In the title compound, C8H9NO, the amide group makes a dihedral of 32.35 (1)° with the benzene ring. In the crystal, pairs of strong N—H⋯O hydrogen bonds link the molecules into inversion dimers. Weak C—H⋯O interactions further connect the molecules into chains along the a axis.

In the title compound, C 8 H 9 NO, the amide group makes a dihedral of 32.35 (1) with the benzene ring. In the crystal, pairs of strong N-HÁ Á ÁO hydrogen bonds link the molecules into inversion dimers. Weak C-HÁ Á ÁO interactions further connect the molecules into chains along the a axis.

Related literature
For the structures and properties of related compounds, see: Tam et al. (2003); Omondi et al. (2005).

Min-Min Zhao
Comment N-(4-Chlorophenyl)formamide and N-(2,6-dichlorophenyl)formamide exhibit phase transitions under different thermal conditions from disordered model to ordered model (Tam et al., 2003;Omondi et al., 2005). Therefore, with the purpose of obtaining phase transition crystals of organic compounds, various similar organic molecules have been studied. The title compound has been synthesized to determine its crystal structure and dielectric properties. In this article, the synthesis and crystal structure of the title compound are reported.
In the title compound ( Fig. 1), the amide group (O1/N1/C1) makes a dihedral of 32.35 (1)° with the benzene ring (C2-C7). In the crystal structure, the H atom bonded to the N atom is involved in a strong intermolecular N1-H1B···O1 hydrogen bond. In addition, weak C7-H7A···O1 further stabilize the crystal structure. These H-bonding interactions connect the molecules into a 1D chain along the a-axis ( Fig. 2 and Table 1). The bond lengths and bond angles in the title molecule agree very well with the corresponding bond distances and bond angles reported in closely related compounds (Tam et al., 2003;Omondi et al., 2005) Experimental A mixture of formic acid (30 mmol), 4-toluidine (10 mmol), H 2 SO 4 (0.5 ml, molar concentration 98%) and ethanol (50 mL) in a 100 ml flask was stirred at 333 K for 10 h. Colourless crystals suitable for X-ray diffraction were obtained by slow evaporation of the solution.

Refinement
All H atoms were positioned geometrically and refined using a riding model, with distances N-H = 0.86 Å and C-H = 0.93 and 0.96 Å, for aryl and methyl H-atoms, respectively. The U iso (H) were allowed at 1.5U eq (C methyl) or 1.2U eq (N/C non-methyl).

Computing details
Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure:  The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are presented as small spheres of arbitrary radius.

Figure 2
A view of the N-H···O and C--H···O hydrogen bonds (dotted lines) in the crystal structure of the title compound. H atoms non-participating in hydrogen-bonding were omitted for clarity.

N-(4-Methylphenyl)formamide
Crystal data C 8 H 9 NO M r = 135.16 Triclinic, P1 Hall symbol: -P 1 a = 6.5511 (11) Å b = 6.9192 (12) Å c = 8.0265 (17)  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.24 e Å −3 Δρ min = −0.21 e Å −3 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.