1,2-Bis(4-methoxyphenoxy)ethane

The whole molecule of the title compound, C16H18O4, is generated by twofold rotational symmetry; the twofold axis bisects the central C—C bond. The O—C—C—O torsion angle about the central C—C bond is 69.45 (16)°. Symmetry-related benzene rings are inclined to one another by 64.91 (8)°. In the crystal, molecules are connected by C—H⋯O hydrogen bonds, forming a three-dimensional network.

The whole molecule of the title compound, C 16 H 18 O 4 , is generated by twofold rotational symmetry; the twofold axis bisects the central C-C bond. The O-C-C-O torsion angle about the central C-C bond is 69.45 (16) . Symmetryrelated benzene rings are inclined to one another by 64.91 (8) . In the crystal, molecules are connected by C-HÁ Á ÁO hydrogen bonds, forming a three-dimensional network.

Related literature
For the synthesis, uses and properties of the title compound, see: Saito et al. (1988). For bond-length data, see: Allen et al. (1987).
The molecular structure of the title molecule is shown in Fig. 1. The bond lengths (Allen et al., 1987) and angles are within normal ranges. The molecule has two-fold rotational symmetry, the 2-fold axis bisecting bond C8-C8A. The In the crystal, molecules are linked via C-H···O hydrogen bonds forming a three-dimensional network ( Fig. 2 and Table 1).

Experimental
The title compound was prepared by a method reported in literature (Saito et al., 1988). To a solution of 1,2-dibromoethane (2.3 g, 12 mmol) and 4-methoxyphenol (3.1 g, 25 mmol) in acetonitrile (100 ml) was added anhydrous potassium carbonate (6.2 g, 45 mmol), and the mixture was stirred overnight at 338 K. The reaction mixture was filtered and the filtrate evaporated under reduced pressure. The residue was subjected to flash chromatography on silica gel, eluting with (10:1/ petroleum ether:ethyl acetate) to give title compound (Yield 2.13 g). Colourless block-like crystals of the title compound were obtained by slow evaporation of a solution in ethanol (20 ml) after about 7 d.

Refinement
All H atoms were positioned geometrically and constrained to ride on their parent atom: C-H = 0.93 Å (aromatic H), 0.97 Å (CH 2 ), and 0.96 Å (CH 3 ) with U iso (H) = k × U eq (C), where k = 1.5 for CH 3 H atoms, and = 1.2 for other H atoms.

Computing details
Data collection: CAD-4 Software (Enraf-Nonius, 1985); cell refinement: CAD-4 Software (Enraf-Nonius, 1985); data reduction: XCAD4 (Harms & Wocadlo,1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).    Table 1 for details; H atoms not involved in these interactions have been omitted for clarity).  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.26 e Å −3 Δρ min = −0.29 e Å −3 Extinction correction: SHELXL97 (Sheldrick, 2008), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.020 (6) 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 esds are taken into account in the estimation of distances, angles and torsion angles 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.