Isolation of 3-amino-4-nitro-benzyl acetate: evidence of an undisclosed impurity in 5-amino-2-nitro-benzoic acid.

Yellow crystals of the title compound 3-amino-4-nitro-benzyl acetate, C9H10N2O4, were isolated from the reaction of acetic anhydride with (5-amino-2-nitro-phen-yl)methanol, prepared from reduction of commerically available 5-amino-2-nitro-benzoic acid with borane-THF. The mol-ecule is essentially planar (r.m.s. deviation = 0.028 Å). The mol-ecules are linked by inter-molecular N-H⋯O hydrogen-bonding inter-actions between the carbonyl and amine groups, forming a zigzag chain along the b-axis direction lying in a plane parallel to (-102). The chains are stacked along the c axis by π-π inter-actions [centroid-centroid distances = 3.6240 (3) and 3.5855 (4) Å]. A strong intra-molecular N-H⋯O hydrogen-bonding inter-action is observed between the nitro group and the amine group [2.660 (2) Å].