N-(2,6-Dichlorophenyl)-2-(naphthalen-1-yl)acetamide

In the title compound, C18H13Cl2NO, the naphthalene ring system and the benzene ring form dihedral angles of 74.73 (13) and 62.53 (16)°, respectively, with the acetamide grouping [maximum deviation = 0.005 (3) Å]. The naphthalene ring system forms a dihedral angle of 75.14 (13)° with the benzene ring. In the crystal, molecules are linked by N—H⋯O hydrogen bonds, forming C(4) chains propagating in [010]. The O atom also accepts two C—H⋯O interactions.


Comment
In continuation of our work on synthesis and structures of amides (Fun et al., 2010(Fun et al., , 2011a we report herein the crystal structure of the title compound. The molecular structure is shown in Fig. 1. Bond lengths are comparable to related structures (Fun et al., 2010(Fun et al., , 2011a. The naphthalene ring system (C9-C18, maximum deviation of 0.017 (3) Å at atom C9) and the benzene ring (C1-C6) form dihedral angles of 74.73 (13) and 62.53 (16)°, respectively, with the acetamide moiety (O1/N1/C7/C8, maximum deviation of 0.005 (3) Å at atom C7). The naphthalene ring system forms a dihedral angle of 75.14 (13)° with the benzene ring.
Experimental 1-Naphthalene acetic acid (0.186 g, 1 mmol) and 2,6-dichloroaniline (0.162 g, 1 mmol), 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (1.0 g, 0.01 mol) and were dissolved in dichloromethane (20ml). The mixture was stirred in presence of triethylamine at 273 K for about 3 h. The contents were poured into 100 ml of ice-cold aqueous hydrochloric acid with stirring, which was extracted thrice with dichloromethane. Organic layer was washed with saturated NaHCO 3 solution and brine solution, dried and concentrated under reduced pressure to give the title compound.
Colourless needles were grown from N,N-dimethyl formamide solution by the slow evaporation method (m.p.: 463K).

Refinement
Atom H1N1 was located in a difference Fourier map and refined freely with N1-H1N1 = 0.85 (4) Å. The remaining H atoms were positioned geometrically and refined using a riding model with C-H = 0.95 or 0.99 Å and U iso (H) = 1.2 U eq (C).  The molecular structure of the title compound showing 50% probability displacement ellipsoids for non-H atoms.

Figure 2
The crystal structure of the title compound, viewed along the a axis. H atoms not involved in hydrogen bonds (dashed lines) have been omitted for clarity.   (Cosier & Glazer, 1986) operating at 100.0 (1) K. 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.