Ethyl 4-fluoro-3-nitrobenzoate

In the title compound, C9H8FNO4, C—H⋯O intermolecular interactions form dimers with R 2 2(10) motifs. These dimers are arranged into chains parallel to the b axis and the chains are stacked down the c axis.

In the title compound, C 9 H 8 FNO 4 , C-HÁ Á ÁO intermolecular interactions form dimers with R 2 2 (10) motifs. These dimers are arranged into chains parallel to the b axis and the chains are stacked down the c axis.

Comment
The nitro benzoic acid intermediates are convenient starting materials for the synthesis of various biologically active heterocycles e.g. benzimidazoles (Ishida et al., 2006) and benzoxazoles (Rida et al., 2005). As a part of our ongoing studies on new nitro benzoic acid derivatives (Mohd. Maidin, Abdul Rahim, Abdul Hamid et al., 2008), we have synthesized the title compound as an intermediate and report its structure here.
The bond lengths (Allen et al., 1987) and angles observed in (I) are within normal ranges and are consistent with other related structures (Mohd. Maidin, Abdul Rahim, Osman et al., 2008;Li et al., 2009;Li et al., 2008). The C1-H1A···O4 i intermolecular interactions (Table 2) linked the molecules into dimers forming 10-membered rings with R 2 2 (10) motifs (Bernstein et al., 1995). In the crystal structure, these dimers are arranged into chains parallel to the b axis. The chains are stacked down the c axis (Fig. 2).

Experimental
For the preparation of the title compound, 4-fluoro-3-nitro-benzoic acid (5.0 g, 0.027 mol) was refluxed in absolute ethanol (50 ml) and conc. H 2 SO 4 (2.0 ml) for 8 h. Upon reaction completion, ethanol was evaporated and the reaction mixture was diluted with water. The aqueous layer was extracted with ethyl acetate (25 x 2 ml). The combined organic layer was collected and dried over anhydrous MgSO 4 . The solvent was removed under reduced pressure to afford yellow oil as the crude product. Recrystallization with hot ethyl acetate and petroleum ether (60-80) yielded colourless crystals that were found suitable for X-ray analysis.

Refinement
All the H atoms were positioned geometrically and refined using a riding model with C-H = 0.93Å for aromatic and 0.96Å for CH 3 . The U iso values were constrained to be -1.5U eq of the carrier atom for the methyl H atoms and -1.2U equ for the remaining hydrogen atoms. The rotating model group was considered for the methyl group.

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K. 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.