2-(2-Chlorophenyl)-N-cyclohexyl-2-oxoacetamide

In the title compound, C14H16ClNO2, the cyclohexyl ring has a chair conformation. The dihedral angle between the benzene ring and the mean plane of the four planar C atoms of the cyclohexyl ring is 45.2 (3)°. The two carbonyl groups are trans to one another, with an O=C—C=O torsion angle of −137.1 (3)°. In the crystal, molecules are linked by N—H⋯O hydrogen bonds forming chains propagating along [001]. A region of disordered electron density, situated near the unit-cell corners, was treated using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148–155]. It gave a solvent-accessible void of ca 400 Å3 for only 21 electrons. It is probably due to traces of the solvent of crystallization and was not taken into account during structure refinement.

In the title compound, C 14 H 16 ClNO 2 , the cyclohexyl ring has a chair conformation. The dihedral angle between the benzene ring and the mean plane of the four planar C atoms of the cyclohexyl ring is 45.2 (3) . The two carbonyl groups are trans to one another, with an O C-C O torsion angle of À137.1 (3) . In the crystal, molecules are linked by N-HÁ Á ÁO hydrogen bonds forming chains propagating along [001]. A region of disordered electron density, situated near the unitcell corners, was treated using the SQUEEZE routine in PLATON [Spek (2009). Acta Cryst. D65,[148][149][150][151][152][153][154][155]. It gave a solvent-accessible void of ca 400 Å 3 for only 21 electrons. It is probably due to traces of the solvent of crystallization and was not taken into account during structure refinement.

Xiu-Dan Jin and Jin-Long Wu Comment
The crystal structure of several substituted phenylglyoxamides have been reported (Boryczka, et al., 1998;Dai & Wu, 2011;Jia & Wu, 2012). The differences in their molecular packing depends on the hydrogen bonds present. In our effort to explore the effect of the substituent groups of phenylglyoxamide on the crystal form, we have synthesized the title compound by acetylation of cyclohexylamine with 2-chlorophenylglyoxyl chloride obtained from 2-chlorophenylglyoxic acid with oxalyl dichloride. We report herein on its crystal structure.
In the title molecule ( Fig. 1), the cyclohexane ring has a chair conformation. The dihedral angle between the phenyl ring and the mean plane of the four planar C atoms of the cyclohexane ring (C10/C11/C13/C14) is 45.2 (3) °. The two carbonyl groups of the molecule are trans oriented to each other with a torsion angle O1═C7-C8 ═O2 of -137.1 (3) °.
In the crystal, molecules are linked by N-H···O hydrogen bonds forming chains extending in the c axis direction (Table   1 and Fig. 2).

Experimental
To a solution of 2-chlorophenylglyoxylic acid (184 mg, 1.0 mmol) in dichloromethane (3 mL), was added oxalyl chloride (0.22 mL, 2.5 mmol) over 5 min. DMF (dimethylformamide) ( 1 drop) was then added and the solution was warmed to room temperature and stirred for 1.5 h. The solvent was removed under reduced pressure to afford 2-chlorophenylglyoxyl chloride which was used for the next step without further purification. To a solution of cyclohexylamine (0.23 mL, 2.0 mmol) and triethylamine (0.83 mL, 6.0 mmol) in dichloromethane (5 mL), was added dropwise the solution of the above glyoxyl chloride in dichloromethane (1 mL) at 273 K under N 2 , and the mixture was stirred for 4 h. The reaction was quenched with saturated NH 4 Cl solution (2 mL), then the organic layer was separated and the aqueous layer was extracted with dichloromethane (5 mL). The combined organic layers were washed with brine, dried over anhydrous Na 2 SO 4 and filtered, the filtrate was concentrated under reduced pressure. The resulting residue was purified by column chromatography (silica gel, 20% ethyl acetate in hexane) to afford the title compound as colourless needles (227 mg, 85% yield from glyoxylic acid), m.p. 375-376 K. Single crystals suitable for X-ray diffraction were grown from a mixture of dichloromethane and hexane (1:1 v/v).

Refinement
A region of disordered electron density, situated near the unit cell corners, was treated using the SQUEEZE routine in PLATON (Spek, 2009). It gave a solvent accessible void of ca. 400 Å 3 for only 21 electrons. It is probably due to traces of the solvent of crystallization and was not taken into account during structure refinement.
The H atoms were placed in calculated positions and treated as riding atoms: N-H = 0.86 Å, C-H = 0.93, 0.98 and 0.97 Å for CH(aromatic), CH and CH 2 atoms, respectively, with U iso (H) = 1.2U eq (N,C).

Special details
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell esds are taken into account in the estimation of distances, angles and torsion angles 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.