Isolation of 3-amino-4-nitrobenzyl acetate: Evidence of an undisclosed impurity in 5-amino-2-nitrobenzoic acid

Yellow crystals of the title compound 3-amino-4-nitrobenzyl acetate, C₉H₁₀N₂O₄, were isolated from the reaction of acetic anhydride with (5-amino-2-nitrophenyl)methanol, prepared from reduction of commerically available 5-amino-2-nitrobenzoic acid with borane-THF. The molecule is essentially planar (r.m.s. deviation = 0.028 Å). The molecules are linked by intermolecular N - H⋯O hydrogen-bonding interactions between the carbonyl and amine groups, forming a zigzag chain along the b-axis direction lying in a plane parallel to (1¯02). The chains are stacked along the c axis by π-π interactions [centroid-centroid distances = 3.6240 (3) and 3.5855 (4) Å]. A strong intramolecular N - H⋯O hydrogen-bonding interaction is observed between the nitro group and the amine group [2.660 (2) Å].