Diethyl 4,4′-(ethane-1,2-diyldioxy)dibenzoate

The title compound, C20H22O6, was obtained by the reaction of ethyl 4-hydroxybenzoate with 1,2-dichloroethane in dimethylformamide. The molecule lies around the crystallographic inversion center at (0,0,0), with the asymmetric unit consisting of one half of the molecule. The two ethyl groups are in trans positions. The ethyl, carboxyl, aryl and O—CH2 groups are coplanar with an r.m.s. deviation of 0.0208 (9) Å. The whole molecule is planar with an r.m.s. deviation of 0.0238 (9) Å for the 19 atoms used in the calculation and 0.0071 (9) Å for the two aryl groups in the molecule. A weak intermolecular C—H⋯O hydrogen bond and a C—H⋯π interaction help to consolidate the three-dimensional network.


Comment
There has been, in recent years, a considerable interest in the study of esters (Hou & Kan, 2007;Tashiro et al., 1990;Zhang et al., 2007), since these compounds are commodity chemicals used as intermediates in the manufacture of acids and to produce many important industrial products. Hence, our current work aims to prepare esters to produce acids and investigate their coordination behaviors with metal ions and study their applications in many fields (Chen & Liu, 2002). Herein, we report a new diester which was obtained by reaction of ethyl 4-hydroxybenzoate with 1,2-dichloroethane in DMF and its structure was confirmed by elemental analysis, IR, NMR spectra and X-ray crystal analysis.
The structure consists of a neutral molecular unit (Fig. 1).The molecule lies on a crystallographic inversion center at (0, 0, 0), thus leading to one half of the molecule being present per asymmetric unit. All bond lengths and angles are within normal ranges (Allen et al., 1987). The ethyl, aryl, carboxyl and the O-CH 2 groups of one half molecule are coplanar to form one plane with an r.m.s. deviation of 0.0208 (9) Å. By symmetry, the whole molecule is coplanar with an r.m.s deviation of 0.0238 (9) Å for 19 atoms being used for calculation and 0.0071 (9) Å for the two aryl groups at the molecule. Because of the symmetry of the inversion center, the two ethyl groups at the molecule are in a trans position. One weak hydrogen bond between one hydrogen atom and the oxygen atom of a neighboring molecule is present in the structure: H6A on C6 and O2 ii [symmetry code: (ii) x, -y+1/2, z-1/2] ( Table 1). The molecules display intermolecular C-H···π interactions between a -CH 2 -(C10) and a neighboring aryl group [H..Cg 2.647 Å, Cg is the centroid of the six membered ring of C4 iii -C9 iii , symmetry code: (iii) x+1, y, z].
supplementary materials sup-2 Refinement All H atoms were positioned geometrically and refined using a riding model with C-H = 0.93 -0.97 Å and with U iso (H) = 1.2 times U eq (C).

Special details
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.