1,10-Bis(4-nitrophenoxy)decane

The title compound, C22H28N2O6, crystallizes with four half-molecules in the asymmetric unit: each molecule is located about a crystallographic inversion centre. The central methylene groups of two molecules are disordered over two sets of equally occupied sites. The crystal packing is characterized by sheets of molecules parallel to (14).

The title compound, C 22 H 28 N 2 O 6 , crystallizes with four halfmolecules in the asymmetric unit: each molecule is located about a crystallographic inversion centre. The central methylene groups of two molecules are disordered over two sets of equally occupied sites. The crystal packing is characterized by sheets of molecules parallel to (114).

Data collection
Stoe IPDS II two-circle diffractometer 24686 measured reflections 7975 independent reflections 3974 reflections with I > 2(I) R int = 0.097 Refinement R[F 2 > 2(F 2 )] = 0.054 wR(F 2 ) = 0.132 S = 0.83 7975 reflections 559 parameters 8 restraints H-atom parameters constrained Á max = 0.33 e Å À3 Á min = À0.26 e Å À3 Data collection: X-AREA (Stoe & Cie, 2001); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97. The title dinitro compound is a precursor for aromatic diamines which are important compounds for the synthesis of thermally-stable polyimides (Mehdipour-Ataei, 2005). Polyimides are an important class of high-performance polymers having useful properties such as excellent thermal and mechanical strength, good solvent resistance and adhesion to glass and metals (Mehdipour-Ataei et al., 2006). However, applications of polyimides are limited because they are difficult to process due to their reduced solubility in organic solvents. Solubility problems arise due to chain stiffness and intermolecular hydrogen bonding (Hsiao and Leu, 2004). The title compound was synthesized with the aim to design new monomers containing an aryl-ether linkage for processable high-performance polyimides which contain methylene spacers between the aromatic rings connected by an ether moiety. The aryl-ether linkage is well known for imparting properties such as improved solubility and melt processing characteristics . Moreover, the introduction of long flexible aliphatic chains into the aromatic backbone will effectively disrupt the intermolecular interactions between the aromatic moieties responsible for their high glass transition (Tg) temperatures (Schab-Balcerzak et al., 2002).
The title compound crystallizes with four half molecules in the asymmetric unit, see Fig. 1 for a representative molecule.
Each molecule is located about a crystallographic inversion centre. The central methylene groups of two molecules are disordered over two equally occupied sites. The crystal packing is characterized by sheets of molecules parallel to the (1 1 4) plane.

Experimental
A three-necked round bottom flask equipped with thermometer, magnetic stirrer and nitrogen inlet was charged with a suspension of p-nitrophenol (5 g, 35 mol) and anhydrous potassium carbonate (5 g, 0.035 mol) in N,N'-dimethyl formamide (DMF; 60 ml) and stirred (at room temperature) for 1 h. After that solution of 1, 10-dibromodecane (5.2 g, 70 mol) in DMF (10 ml) was added drop wise and the mixture was refluxed for 16 h at 120°C. The progress of reaction was monitored by TLC [ethyl acetate: n-hexane, 1:4]. After the reaction completed, reaction mixture was poured into distilled water (500 ml) which led to precipitation of the product as a solid yellow mass. The crude product was filtered, washed thoroughly with water, dissolved in ethanol, and set aside for crystallization. Yield 86%, m.p. 351-352 K.
The central methylene groups of two molecules are disordered over two equally occupied sites. Bond distances involving the disordered C atoms were restrained to 1.50 (1) Å. Fig. 1. A view of one of the four molecules in the unit cell of the title compound, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii. Only the symmetry independent atoms are labelled. Symmetry operator for the generated atoms -x+2, -y+1, -z.

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 > σ(F 2 ) is used only for calculating Rfactors(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.