2-(4-Nitrophenyl)-1,3-dithiane

The nitro group in the title compound, C10H11NO2S2, is almost coplanar with the benzene ring, making a dihedral angle of 3.42 (8)°. The 1,3-dithiane ring adopts a chair conformation. The crystal structure is stabilized by intermolecular C—H⋯O and C—H⋯π [C⋯Cg = 3.4972 (10) Å] interactions.


Comment
Thioacetal protection of carbonyl groups is of paramount importance in synthetic organic chemistry and hence, the development of novel thionation reactions remains of great interest (Goswami & Maity, 2008;Fun et al., 2009). In addition, thioacetals are also utilized as masked acyl anions or masked methylene functions in carbon-carbon bond forming reactions.

Experimental
To a stirred dichloromethane (50 mL) solution, maintained at 273 K, of 4-nitrobenzaldehyde (500 mg, 3.31 mmol) and boron trifluoride etherate (0.5 mL) was added dropwise 1,3-propanedithiol (450 mg, 4.1 mmol) over 15 min. The mixture was stirred at room temperature for 4 h and the progress of the reaction monitored by TLC. After completion of the reaction, NaHCO 3 solution was added carefully at room temperature to neutralize the mixture which was then extracted with dichloromethane. The organic layer was dried (anhydrous Na 2 SO 4 ) and the solvent removed under reduced pressure. The crude product was purified by column chromatography using silica gel with 10% ethyl acetate in petroleum ether as eluant to afford (I) (674 mg, 84%) as a colourless crystalline solid along with the other thiane derivatives.

Refinement
All hydrogen atoms were positioned geometrically and refined with a riding model approximation with C-H = 0.93-0.98 Å, and with U iso (H) = 1.2 U eq (C). Fig. 1. The molecular structure of (I), showing 50% probability displacement ellipsoids and the atomic numbering.

Special details
Experimental. The low-temperature data was collected with the Oxford Cyrosystem Cobra low-temperature attachment.
supplementary materials sup-3 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.