Crystal structure of 1-(2,4-di-methyl-phen-yl)urea.

In the title urea derivative, C9H12N2O, the dihedral angle between the benzene ring and the mean plane of the urea group, N-C(=O)-N, is 86.6 (1)°. In the crystal, the urea O atom is involved in three N-H⋯O hydrogen bonds. Mol-ecules are linked via pairs of N-H⋯O hydrogen bonds, forming inversion dimers with an R (2) 2(8) ring motif. The dimers are linked by further N-H⋯O hydrogen bonds, forming two-dimensional networks lying parallel to (100).


S1. Comment
Urea and its derivatives are important key starting materials for the construction of biologically important heterocycles (Ramalingan & Kwak, 2008;Ramalingan et al., 2010;Yang et al., 2013;Safari & Gandomi-Ravandi, 2014). They display various biological activities viz. antibacterial (Suzuki et al., 2013), antiproliferative and antitumor (Boulahjar et al., 2012), and HIV-1 integrase (Zhang et al., 2014). As a vital reactant and intermediate for the construction of heterocyclic chemical entities of biological importance, the title compound has been synthesized and single crystals were grown by slow evaporation in ethanol.
In the crystal, three strong N-H···O hydrogen bonds stabilize the molecular packing ( Fig. 2 and Table 1). Molecules are linked via pairs of N-H···O hydrogen bonds forming inversion dimers with an R 2 2 (8) ring motif. The dimers are linked by further N-H···O hydrogen bonds forming two-dimensional networks lying parallel to (100); see Table 1 and Fig. 2.

S2. Experimental
To a solution of 2,6-dimethylaniline (0.1 mol) in glacial acetic acid (30 ml), was added distilled water (70 ml). Sodium cyanate (0.1 mol) in medium-hot water (50 ml) was then added in a slow manner with constant stirring. The resulted solution was allowed to stand for 60 min. and then cooled in ice. It was then filtered using a Buchner funnel and the solid obtained was dried using high-vacuum. Single crystals of the title compound were obtained by slow evaporation of a solution in ethanol at room temperature.

S3. Refinement
Atoms H2A and H2B were located from a difference Fourier map and freely refined. The remaining H atoms were positioned geometrically and allowed to ride on their parent atoms, with N-H = 0.86 Å and C-H = 0.93-0.96 Å and with U iso (H) = 1.5U eq (C) for methyl H atoms and = 1.2U eq (N,C) for other H atoms.  The molecular structure of the title compound, with atom labelling. Displacement ellipsoids are drawn at the 30% probability level.

Figure 2
A projection of the crystal packing of the title compound, along the a axis. Hydrogen bonds are shown as dashed lines (see Table 1 for details; H atoms not involved in hydrogen bonding have been omitted for clarity). where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.87 e Å −3 Δρ min = −0.32 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq O1 0.40043 (