(2E,6E)-2,6-Bis(2,6-dichlorobenzylidene)cyclohexanone

The title compound, C20H14Cl4O, was prepared by the reaction of 2,6-dichlorobenzaldehyde and cyclohexanone. In the molecule, the central cyclohexanone ring adopts an envelope conformation, while the terminal benzene rings make a dihedral angle of 57.87 (9)°.

The title compound, C 20 H 14 Cl 4 O, was prepared by the reaction of 2,6-dichlorobenzaldehyde and cyclohexanone. In the molecule, the central cyclohexanone ring adopts an envelope conformation, while the terminal benzene rings make a dihedral angle of 57.87 (9) .
In the molecule of the title compound, (Fig. 1), the bond lengths and angles are within normal ranges (Yu et al., 2000;Zhou, 2007). A dihedral angle of 57.87 (9) A is found between the mean planes of the two benzene rings.

Experimental
To a 10 ml solution of KOH (0.11 g) in ethanol at 313 K in a round bottom flask, cyclohexanone (5.0 mmol, 0.50 g) and 2,6-dichlorobenzaldehyde (10 mmol, 1.75 g) was added and the mixture was stirred for 2 min. The resulting product was then isolated by simple filtration from the reaction mixture and given washings with water to remove any trace of KOH remaining on the product. Yellow crystals, yield 97%, 1.98 g, m. p. 455-458 K.

Refinement
All H atoms were positioned geometrically with C-H = 0.93-0.97 Å and constrained to ride on their parent atoms, with U iso (H) = 1.2U eq (C).  The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.

Data collection
Stoe IPDS 2T diffractometer Radiation source: fine-focus sealed tube Graphite monochromator rotation method scans 13510 measured reflections 4946 independent reflections 4682 reflections with I > 2σ(I) 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.