N-Butanoyl-N-(3-chloro-1,4-dioxonaphthalen-2-yl)butanamide

In the title compound, C18H18ClNO4, the imide group with its two alkyl substituents is approximately perpendicular to the plane of the naphthoquinone ring system [dihedral angle = 78.5 (1)°]. Further, the imide carbonyl groups are oriented in an anti sense. In the crystal, the substituted naphthoquinone rings form π–π stacks in the a-axis direction [perpendicular centroid–centroid distance = 3.209 (2) Å and slippage = 4.401 Å].

In the title compound, C 18 H 18 ClNO 4 , the imide group with its two alkyl substituents is approximately perpendicular to the plane of the naphthoquinone ring system [dihedral angle = 78.5 (1) ]. Further, the imide carbonyl groups are oriented in an anti sense. In the crystal, the substituted naphthoquinone rings formstacks in the a-axis direction [perpendicular centroid-centroid distance = 3.209 (2) Å and slippage = 4.401 Å ].

Related literature
For the synthesis and biological evaluation of some imidosubstituted 1,4-naphthoquinone derivatives, see; Bakare et al.
The title compound, C 18 H 18 ClNO 4 , was synthesized as previously reported (Bakare et al. (2003)). The crystal structure of the title compound 1 shows that the imide group with its two alkyl substituents is almost perpendicular to the plane of the naphthoquinone ring (dihedral angle between planes of 78.5 (1)°. Further the two imide carbonyls are oriented anti to each other. The naphthoquinone rings form π-π stacks in the a direction (perpendicular Cg···Cg distance of 3.209 Å with slippage of 4.401 Å).

Experimental
The title compound 1 was synthesized by refluxing 2-amino-3-chloro-1,4-naphthoquinone in butyryl chloride as previously reported (Bakare et al. (2003)). The compound was crystallized from the crude below 0°C with diethyl ether to obtain yellow crystals.

Refinement
H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms with a C-H distances of 0.93 and 0.97 Å U iso (H) = 1.2U eq (C) and 0.96 Å for CH 3 [U iso (H) = 1.5U eq (C)].    The molecular packing for C 18 H 18 ClNO 4 viewed along the b axis and showing the π-π stacking in the a direction.  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.39 e Å −3 Δρ min = −0.24 e Å −3 Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 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.

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