2,2′-[Ethane-1,2-diylbis(oxy)]dibenzaldehyde

In the title compound, C16H14O4, the benzene rings are inclined at a dihedral angle of 75.14 (9)°. The torsion angle of the bridging O—C—C—O group is −76.50 (11)°. In the crystal, molecules are linked by C—H⋯O hydrogen bonds, forming C(6) chains along [100]. Furthermore, C—H⋯π interactions and π–π stacking interactions [centroid–centroid distances = 3.6957 (7) and 3.6735 (8) Å] contribute to the stability of the crystal packing.

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BT6920). The synthesis of bis functionalized compounds has attracted the interest of chemists in chemical industry. Such compounds are considered as significant precursores for building blocks of vital molecules in different studies such as supramolecular chemistry and nanoscience (Holland et al., 2007), bioactive bis heterocyclic compounds (Pedras et al., 2010;Mabkhot et al., 2012), and binucleating ligand designs (Gavrilova & Bosnich, 2004). In this concept the title compound has been synthesized among several derivatives of bis functionalized compounds as precursers for the synthesis of a series of macromolecular compounds.

Experimental
A solution of 1.22 g m (0.01 mol) salicyldehyde in hot ethanolic KOH (prepared by dissolving 560 mg (0.01 mol) KOH in 100 ml of absolute ethanol) was stirred until a clear solution was obtained, which was then evaporated under vacuum.
The residue was dissolved in DMF (25 ml) and 940 mg (0.005 mol) of dibromoethane was added. The reaction mixture was refluxed for 5 minutes, during which KBr was separated out. The solvent was then removed in vacuo and the remaining solid was washed with water and crystallized from ethanol to give high quality crystals (Mp. 393 K) suitable for X-ray analysis in an good yield (84%).

Refinement
All H atoms were found in a difference map, but placed geometrically with C-H = 0.95 Å (aromatic H) and 0.99 Å (methylene H) and were refined using a riding model with U iso (H) = 1.2U eq (C).

Figure 2
Partial packing diagram of the title compound showing hydrogen bonds as dashed lines. H atoms not involved in hydrogen bonds have been omitted for clarity.

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 e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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.