2,4,6-Trinitrophenyl 3-methylbenzoate

In the title benzoate derivative, C14H9N3O8, the benzene rings form a dihedral angle of 87.48 (5)°. The central ester unit forms an angle of 19.42 (7)° with the methylbenzene ring, indicating a significant twist. In the crystal, the molecules are linked by weak C—H⋯O interactions forming a helical chain along [010].


Comment
The structure determination of 2,4,6-trinitrophenyl 3-methylbenzoate, (I), is part of a series of studies on novel nitro aryl benzoates, carried out in our research group. This molecular system is strongly defined by the presence of the phenyl moiety coming from picric acid (TNP), which has not been employed previously in the synthesis of the title ester. TNP is interesting because of its widespread use in the synthesis of charge transfer complexes, which often tend to have significant crystalline properties (Siddaraju et al., 2012;Refat et al., 2010;El-Medania et al., 2003), pharmacological activity as anti-microbial agents and DNA-binding systems (Khan & Ovesb, 2010;Khan et al., 2011) and good non-linear optical (NLO) properties (Zaderenko et al., 1997). However, the properties of esters having the TNP moiety remain largely unknown. Therefore, this research will present a new compound, (I), with the aim to understand its properties.
Moreover, is well known that nitroaromatics and their derivatives constitute a main class of industrial chemicals and are widely used as intermediates in the synthesis of many varied products, ranging from drugs, pigments, pesticides and plant growth regulators to the explosives (Ju & Parales, 2010).
The molecular structure of (I) is shown in Fig The molecules are packed through weak C-H···O interactions forming one-dimensional helical chains along [010] (see Table 1, Nardelli, 1995). These intermolecular contacts are explained in terms of the substructure shown in Fig. 2. The C3 atom of the phenyl ring at (x,y,z) acts as a hydrogen-bond donor to carbonyl atom O8 at (-x-1, +y-1/2, -z-1/2). Growth in this direction is reinforced by the weak C13-H13···O3 interaction, in which the C13 atom of the benzoate ring at (x,y,z) acts as hydrogen-bond donor to atom O3 from one of the nitro groups at (-x-1, +y+1/2, -z-1/2). The combination of these two contacts generate edge-fused rings R 2 2 (10) (Etter, 1990), along [010].

Experimental
The reagents and solvents for the synthesis were obtained from the Aldrich Chemical Co., and were used without additional purification. The title molecule was obtained through a two-step reaction. First, 3-methylbenzoic acid (0.25 g, 1.838 mmol) was refluxed in excess thionyl chloride (10 ml) for an hour. Then, the thionyl chloride was distilled off under reduced pressure to purify the 3-methylbenzoyl chloride obtained as a pale-yellow translucent liquid.

Refinement
All H-atoms were positioned at geometrically idealized positions with C-H distance of 0.93 Å and U iso (H) = 1.2 times U eq of the C-atoms to which they were bonded.  Part of the crystal structure of (I), showing the formation of chains running along [010]. Symmetry code: (i) -x -1,+y -1/2,-z -1/2; (ii) -x -1,+y + 1/2,-z -1/2. 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 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.