3,3′-Dinitrobisphenol A

The title compound [systematic name: 2,2′-dinitro-4,4′-(propane-2,2-diyl)diphenol], C15H14N2O6, crystallizes with two molecules in the asymmetric unit. Both have a trans conformation for their OH groups, and in each, the two aromatic rings are nearly orthogonal, with dihedral angles of 88.30 (3) and 89.62 (2)°. The nitro groups are nearly in the planes of their attached benzene rings, with C—C—N—O torsion angles in the range 1.21 (17)–4.06 (17)°, and they each accept an intramolecular O—H⋯O hydrogen bond from their adjacent OH groups. One of the OH groups also forms a weak intermolecular O—H⋯O hydrogen bond.

The title compound [systematic name: 2,2 0 -dinitro-4,4 0 -(propane-2,2-diyl)diphenol], C 15 H 14 N 2 O 6 , crystallizes with two molecules in the asymmetric unit. Both have a trans conformation for their OH groups, and in each, the two aromatic rings are nearly orthogonal, with dihedral angles of 88.30 (3) and 89.62 (2) . The nitro groups are nearly in the planes of their attached benzene rings, with C-C-N-O torsion angles in the range 1.21 (17)-4.06 (17) , and they each accept an intramolecular O-HÁ Á ÁO hydrogen bond from their adjacent OH groups. One of the OH groups also forms a weak intermolecular O-HÁ Á ÁO hydrogen bond.  (2007); Okada (1996); Wang et al. (1982). For graph-set analysis, see: Etter (1990 Table 1 Hydrogen-bond geometry (Å , ). least, in part, the toxic effects of BPA. It has been shown, for instance, that nitrated and chlorinated products of BPA, which could be formed in vivo in hypochlorous acid and peroxynitrite mediated oxidations, exhibit higher toxicity than BPA itself and often elaborate mutagenic and/or genotoxic effects (Masuda et al., 2005;Toyoizumi et al., 2007). To better understand the molecular targets for nitrated products of BPA and the likely disruption of endocrine function, in the present report we have synthesized 3,3'-dinitrobisphenol A, (I), using acetone/nitric acid mixtures and characterized the product by IR, NMR, and GC-MS following necessary purification and recrystallization from ethanol. The structural co-ordinates obtained from the crystallographic studies are presented here with the anticipation that they could be used in computational studies aimed at understanding the molecular docking and energetics of binding to possible targets such as the androgen and estrogen receptors and serum proteins.

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The two independent molecules in the asymmetric unit are illustrated in Fig. 1

sup-2
Similar intramolecular hydrogen bonds are found in the crystal structure of 2,2',6,6'-tetranitro-4,4-isopropylidenediphenol (Wang et al., 1982), which has two nitro groups adjacent to each OH. As in the title structure, the hydrogen-bonded nitro group lies near the plane of the phenyl group, while the other nitro group twists 46.5 (3)° out of plane.
Nitration of BPA was performed according to the method of Murrell (2006) with minor modifications (Fig. 3). Briefly, BPA (5.1 g; 22.4 mmol) was dissolved in 50 ml of acetone in a round-bottom flask and HNO 3 (4.2 ml; 66.3 mmol) was added drop-wise over a period of 30 min with continuous mixing. Throughout the course of nitration, the temperature of the flask was maintained at 0-5°C using an ice-water bath. At the end of HNO 3 addition, the reaction mixture was brought to room temperature over a period of 1 h, while the contents were continuously stirred and then quenched in cold water. The yellow/orange precipitate was filtered and washed with an ice cold mixture of acetone and water (3:1). The precipitate was dried for 24 h at 37°C and purified further by recrystallization from ethanol.
The nitro product of BPA was dissolved in DMSO-d6 and analyzed for 1 H-and 13 C-NMR spectra using a Bruker Avance  Fig. 1. Following silylation using the TRI-SIL/TBT reagent, the nitroproduct of BPA was analyzed by GC-MS using an Agilent Technologies 7890 A gas chromatograph equipped with an Agilent Technologies 5975 C V L triple-axis MSD and a HP-5MS capillary column (length: 30 m; internal diameter: 0.25 mm; and film thickness: 0.25 µm). Helium was used as the carrier gas (total flow: 3 ml/min; split ratio: 1:50) with temperature programming as follows: 40 °C for 2 min (isothermal); 20 °C/min up to 150 °C (ramp 1), 150 °C for 3 min (isothermal); 20 °C/min up to 300 °C (ramp 2), and 300 °C for 2 min (isothermal) (total run time: 20 min; temperature of the inlet port: 270°C). Under these conditions, the silylated product of nitro-BPA resolved as a single peak with a retention time of 19.61 min (Fig. 6) (Fig. 7). The proposed routes of fragmentation of the molecular ion of silylated 3,3'-dinitrobisphenol A, giving various daughter ions, are given in Fig. 8.
supplementary materials sup-3 Refinement H atoms on C were placed in idealized positions, with C-H distances 0.95 -0.98 Å. A torsional parameter was refined for each methyl group. Hydroxy H atom positions were refined. U iso for H were assigned as 1.2 times U eq of the attached atoms (1.5 for methyl and OH). Fig. 1. The molecular structure of (I) with ellipsoids at the 50% level, with H atoms having arbitrary radius.         (6)  0.0264 (5) 0.0546 (7) 0.0569 (7) (14)