1-Methoxycarbonyl-2-(4-nitrophenyl)ethanaminium nitrate

In the title compound, C10H13O4N2 +·NO3 −, the nitro group and the benzene ring are essentially coplanar. The dihedral angle between the benzene ring and the methylcarboxylate plane is 49.6 (3)°. The crystal structure is stabilized by cation–anion N—H⋯O and N—H⋯N hydrogen bonds, building sheets parallel to (001).

In the title compound, C 10 H 13 O 4 N 2 + ÁNO 3 À , the nitro group and the benzene ring are essentially coplanar. The dihedral angle between the benzene ring and the methylcarboxylate plane is 49.6 (3) . The crystal structure is stabilized by cationanion N-HÁ Á ÁO and N-HÁ Á ÁN hydrogen bonds, building sheets parallel to (001).

Comment
Amino acid derivatives are important compounds due to their biological activities, and there has been an increased interest in the enantiomeric preparation of α-amino acid derivatives as precursors for the synthesis of novel biologically active molecules (Lucchese et al., 2007;Arki et al., 2004;Hauck et al., 2006;Azim et al., 2006;Dai et al., 2008;Wen, 2008).
Here we report the crystal structure of the title compound.
The asymmetric unit of the title compound contains a organic cation and a NO 3 anion ( Fig. 1). The nitro group and the benzene ring are essentially coplanar, and the methyl 2-aminopropanoate substituent group is in an extended conformation.

Experimental
Under nitrogen protection, 2-amino-3-phenylpropanoic acid (30 mmol), nitric acid (50 mmol) and sulfuric acid (20 mmol) were added in a flask. The mixture was stirred at 383 K for 3 h. The resulting solution was poured into ice water (100 ml), then filtered and washed with distilled water. The nitration amino acid was esterified with H 2 SO 4 and CH 3 OH at 383 K for 12 h. The crude product obtained by evaporation of the solution was recrystallized with distilled water (15 ml)-HNO 3 (1 ml) to yield colourless block-like crystals, suitable for X-ray analysis.
Figures Fig. 1. The molecular structure of the title compound, with the atomic numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.

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.