N-Cyclohexyl-2-oxo-2-phenylacetamide

In the title compound, C14H17NO2, the two carbonyl groups are oriented with respect to each other with a torsion angle of −129.9 (3)°. The cyclohexane ring adopts a chair conformation. In the crystal, molecules are linked by N—H⋯O hydrogen bonds into a chain running along the a axis.

In the title compound, C 14 H 17 NO 2 , the two carbonyl groups are oriented with respect to each other with a torsion angle of À129.9 (3) . The cyclohexane ring adopts a chair conformation. In the crystal, molecules are linked by N-HÁ Á ÁO hydrogen bonds into a chain running along the a axis.

Ze-Jun Jia and Jin-Long Wu Comment
Several crystals of N-substituted phenylglyoxamide have been reported, and their great differences of the cystal form due to the N-H···O hydrogen bond linking form have been observed (Boryczka et al., 1998;Dai & Wu, 2011). In our research for exploring the effect rule of the N-substituted group of phenylglyoxamide to the crystal form, we have synthesized the title compound by condensation of phenylglyoxic acid with cyclohexylamine. The structure of the title compound has been characterized by spectroscopic methods and further confirmation by X-ray analysis. We report here its crystal structure. The two carbonyl groups of the molecule are oriented to each other with a torsion angle of -129.9 (3)°. Molecules are linked by intermolecular hydrogen bonds N-H···O into a one-dimensional chain (Fig. 2).

Experimental
Into a suspension of phenylglyoxylic acid (400 mg, 2.67 mmol) and cyclohexylamine (0.272 ml, 2.38 mmol) in methylene chloride (10 ml), N,N′-dicyclohexylcarbodiimide (DCC) (540 mg, 2.62 mmol) and 4-(dimethylamino)pyridine (DMAP) (66 mg, 0.54 mmol) was added respectively at room temperature and continuted stirring for 10 h. The reaction mixture was filtered and the filtrate was concentrated under reduced pressure, the residue was purified by colum chromatography (silica gel, 30% of ethyl acetate in hexane) to afford the title compound in 69% yield (379 mg) as a white solid, m.p. 384-385 K. Single crystals suitable for X-ray diffraction of the title compound were grown in a mixture of ethyl acetate and hexane.

Refinement
The H atoms were placed in calculated positions with C-H = 0.93-0.98 Å, N-H = 0.88 Å and included in the refinement as riding their carrier atoms with U iso (H) = 1.2U eq (C,N).

Computing details
Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT (Bruker, 1998  The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at 40% probability level. H atoms are presented as small spheres of arbitrary radius.

Figure 2
One-dimensional chain molecules of the title compound linked by two adjacent moleculars N-H···O hydrogen bonds (dotted lines). Symmetry code: (i) -0.5 + x, 0.5 -y, 1 -z. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.08 e Å −3 Δρ min = −0.10 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.