2,2,6,6-Tetrabromo-3,4,4,5-tetramethoxycyclohexanone

In the title compound, C10H14Br4O5, synthesized from the methoxy Schiff base N-(pyridin-2-ylmethyl)methoxyaniline and molecular bromine, the cyclohexanone ring has a chair conformation with one of the four methoxy groups equatorially orientated with respect to the carbonyl group and the others axially orientated. The C—Br bond lengthsvary from 1.942 (4) to1.964 (4) Å. In the crystal, weak C—H⋯Ocarbonyl hydrogen-bonding interactions generate chains extending along the b-axis direction. Also present in the structure are two short intermolecular Br⋯Omethoxy interactions [3.020 (3) and 3.073 (4) Å].

In the title compound, C 10 H 14 Br 4 O 5 , synthesized from the methoxy Schiff base N-(pyridin-2-ylmethyl)methoxyaniline and molecular bromine, the cyclohexanone ring has a chair conformation with one of the four methoxy groups equatorially orientated with respect to the carbonyl group and the others axially orientated. The C-Br bond lengthsvary from 1.942 (4) to1.964 (4) Å . In the crystal, weak C-HÁ Á ÁO carbonyl hydrogen-bonding interactions generate chains extending along the b-axis direction. Also present in the structure are two short intermolecular BrÁ Á ÁO methoxy interactions [3.020 (3) and 3.073 (4) Å ].

Comment
Brominated organic compounds have a broad spectrum of applications. The polybrominated biphenyls, polybrominated diphenylethers and hexabromobenzene are widely used as flame retardants. Other brominated molecules such as 1,4-dibromobenzene (1,4-DBB) and bromoxynil serve as fumigants, as intermediates in the synthesis of dyes, as agrochemicals, pharmaceuticals, or herbicides (Alaee et al., 2003;Czerski et al., 2005;Cupples et al., 2005). Very few examples of the synthesis and applications of compounds similar to the title compound, C 10 H 14 Br 4 O 5 , 2,2,6,6-tetrabromo-3,4,4,5-tetramethoxycyclohexanone (TBTM) have been reported in the literature (Khan et al., 2004). Our synthesis of this compound, by the reaction of the Schiff base N-(pyridin-2-ylmethyl)methoxyaniline (PMMA) with molecular bromine in methanol has not previously been reported and its structure is reported herein.

Experimental
Molecular bromine (0.15 g, 1.00 mmol) was added carefully to a methanolic solution (10 mL) of N-(pyridin-2-ylmethyl)methoxyaniline (0.20 g, 1.00 mmol). The color of the reaction mixture turned immediately from yellow to red and a yellow precipitate formed after one hour of stirring. The precipitate was filtered off, washed first with acetone then with diethylether and then redissolved in deuterated methanol and kept in an NMR tube for crystallization. Crystals of the title compound suitable for X-ray analysis was obtained within 15 days by slow evaporation of the solvent.

Refinement
All H-atoms were positioned geometrically and refined using a riding model with C-H = 0.98 ° (methylene) or 0.96 Å (methyl) and U iso (H) = 1.2 or 1.5U eq (C).  The molecular conformation and atom-numbering scheme for the title compound, with non-H atoms drawn as 40% probability displacement ellipsoids.

Figure 2
The one-dimensional hydrogen-bonded chain structure in the title compound extending along b, with hydrogen bonds shown as dashed lines.  The molecular packing viewed along the c-axial direction. 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 > 2sigma(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.