1-Chloromethyl-4-nitrobenzene

In the title compound, C7H6ClNO2, the nitro group is almost coplanar with the aromatic ring [dihedral angle = 2.9 (2)°], but the Cl atom deviates from the ring plane by 1.129 (1) Å. In the crystal, molecules are linked by weak C—H⋯O interactions to generate chains.

In the title compound, C 7 H 6 ClNO 2 , the nitro group is almost coplanar with the aromatic ring [dihedral angle = 2.9 (2) ], but the Cl atom deviates from the ring plane by 1.129 (1) Å . In the crystal, molecules are linked by weak C-HÁ Á ÁO interactions to generate chains.

Related literature
For background on the toxicity of nitro-aromatic compounds, see: Moreno et al. (1986). For the synthesis of the title compound, see: Livermore & Sealock (1947). For bond-length data, see: Allen et al. (1987).

Comment
The irreversible binding of the reductive intermediates of nitroaromatic compounds to protein and DNA is thought to be responsible for the carcinogenicity and mutagenicity of this class of compounds. Several studies revealed that some nitro radical metabolites with special features are expected to decompose to form neutral carbon-centered free radicals with not net reduction of the nitro group occurring. The radicals anions of p-and o-nitrobenzyl chloride are known to expel chloride to form the corresponding carbon-centered nitrobenzyl radicals with rate constants of 1 × 104 and 4 × 103 s -1 . Such species are highly reactive and could account for the unusual cytotoxicity of these nitrocompounds (Moreno et al., 1986). This structural report on 1-(chloromethyl)-4-nitrobenzene (p-nitrobenzyl chloride) might be helpful to carry out such studies on these nitroaromatic compounds in future.
In the crystal structure, there is no classic hydrogen bonds. A weak intermolecular C-H···O interaction contrubutes to the stability of the structure (Table 1, Fig. 2).

Experimental
The title p-nitrobenzyl chloride was prepared by adding 5.3 ml of benzyl chloride slowly and with stirring to 27.5 ml of a mixture of equal parts of concentrated nitric and sulfuric acids cooled to 283 K. The temperature rose to 303 K during the 10 min required for the addition. The mixture was stirred for 30 min and then poured into 50 g of crushed ice. The crude material was recrystallized from ethanol. Product obtained was dissolved in ethanol and crystallized by slow evaporation of the solvent to yield colourless needles of (I) in an over-all yield of 46% (Livermore & Sealock, 1947).

Refinement
H atoms were positioned geometrically (C-H = 0.93 and 0.97 Å) and allowed to ride on their parent atoms, with U iso (H) = 1.2U eq (C).
supplementary materials sup-2 Figures   Fig. 1. View of the title molecule, with displacement ellipsoids drawn at the 50% probability level.

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 e.s.d.'s are taken into account in the estimation of distances, angles and tor-

sion angles
Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted Rfactors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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.
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )