2′-Chloro-4-methoxy-3-nitrobenzil

In the title compound, C15H10ClNO5, the dihedral angle between the aromatic rings is 87.99 (5)°. The O—C—C—O torsion angle between the two carbonyl units is −119.03 (16)°. The crystal structure is stabilized by a weak intermolecular C—H⋯O hydrogen bond.

In the title compound, C 15 H 10 ClNO 5 , the dihedral angle between the aromatic rings is 87.99 (5) . The O-C-C-O torsion angle between the two carbonyl units is À119.03 (16) . The crystal structure is stabilized by a weak intermolecular C-HÁ Á ÁO hydrogen bond.   Table 1 Hydrogen-bond geometry (Å , ).  The geometric parameters of the title compound ( Fig. 1) agree with those in the reported structures (Fun & Kia, 2008a,b) and the literature values (Allen et al., 1987). The dihedral angle between the two rings is 87.99 (5)°. The mean plane of methoxy and nitro groups are twisted at an angle of 4.95 (8) and 32.19 (6)°, respectively, with the benzene ring (C9-C14).
The crystal structure exhibit weak C-H···O (Table 1

Experimental
The title compound was synthesized in two steps. The first step involves the benzoin condensation. 4 g of KCN was dissolved in 75cc of water in a one litre flask. To this was added 6.8 g (0.05 mole) of anisaldehyde, 7 g (0.05mole) of 2-chloro benzaldeyde and 75 cc of 95% ethanol. The mixture formed a solution at the boiling temperature and was refluxed for one and half hours. Steam was then passed through the solution until all the alcohol and nearly all the unchanged aldehyde were removed. The condensed water was decanted from the product and later set away to crystallize. The product was then pressed as free as possible from oily material on a suction funnel and washed with cold alcohol. In this way about 9 g of crude product was obtained. The crude mixture was dissolved in hot alcohol and allowed to crystallize slowly. The 2'chloro-4-methoxy benzoin crystallizes out as colourless, hexagonal crystals. From the benzoin about 1 gram was taken and treated with concentrated nitric acid by heating in a water bath inside a fume cupboard for about 3 h until it is free from the smell of nitrogen dioxide. It is then cooled and crystallized using hot ethanol. The obtained benzil is recrystallized using chloroform / acetone in the ratio 3:1. Pure crystals of benzil separates out. The yield is about 70-80%.

Refinement
H atoms were positioned geometrically and refined using riding model with C-H = 0.93 Å and U iso (H) = 1.2Ueq(C) for aromatic C-H and C-H = 0.96 Å and U iso (H) = 1.5Ueq(C) for CH 3 .
supplementary materials sup-2 Figures   Fig. 1. The molecular structure of the title compound, with atom labels and 30% probability displacement ellipsoids for non-H atoms.