Ethyl 4-[3-(2-methylbenzoyl)thioureido]benzoate

The molecular conformation of the title compound, C18H18N2O3S, is stabilized by an intramolecular N—H⋯O hydrogen bond. The crystal packing shows centrosymmetric dimers connected by N—H⋯S hydrogen bonds. The terminal ethoxy substituents are statistically disordered [occupancy ratio 0.527 (5):0.473 (5)].

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: IM2145). trophenyl)-3-(2,2-dimethylpropionyl)thiourea (Saeed et al., 2009). As part of our work on the structure of thioureas, we report here the structure of the title derivative, I, Fig 1. The molecular conformation of the title compound, C 18 H 18 N 2 O 3 S, is stabilized by intramolecular N-H···O hydrogen bonds. The crystal packing shows centrosymmetric dimers connected by N-H···S hydrogen bonds (Table 1). Terminal ethoxy substituents are statistically disordered.

Experimental
A solution of 2-methylbenzoyl chloride (10 mmol) in acetone (50 ml) was added dropwise to a suspension of potassium thiocyanate (10 mmol) in acetone (30 ml) and the reaction mixture was refluxed for 30 min. After cooling to room temperature, a solution of 4-aminobenzoic acid ethyl ester (10 mmol) in acetone (10 ml) was added and the resulting mixture refluxed for 3 h. The reaction mixture was poured into cold water and the precipitated thiourea was recrystallized from aqueous ethanol. Anal. calcd. for C 18 H 18 N 2 O 3 S: C, 63.14; H, 5.30; N, 8.18; S, 9.36% found: C, 63.26; H, 5.34; N, 8.21; S, 9.27%;

Refinement
H atoms were positioned geometrically and refined using a riding model with fixed individual displacement parameters [U(H) = 1.2 U eq (C,N) or U(H) = 1.5 U eq (C methyl )] using a riding model with C-H(aromatic) = 0.95 Å, C-H(methyl) = 0.98 Å, or C-H(methylene) = 0.99 Å, respectively. H atoms bonded to N were set to the position where they were found in the difference map. The ethoxy group is disordered over two positions with a site occupation factor of 0.527 (5) for the major occupied site.

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 > σ(F 2 ) is used only for calculating Rfactors(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.